Science.gov

Sample records for diffusion electrical mobility

  1. Electrical transport in a disordered medium: NMR measurement of diffusivity and electrical mobility of ionic charge carriers.

    PubMed

    Heil, S R; Holz, M

    1998-11-01

    Electrical transport in porous media plays an important role in many fields of pure and applied science. The basic microscopic processes of the charge transport have attracted considerable theoretical interest for a long time. However, on a microscopic level there was up to now no experimental access to this problem. In the present paper we demonstrate, by using a suited porous system, that two combined NMR methods can offer such a first experimental access. We apply common PFG NMR methods and the special electrophoretic NMR (ENMR) technique for the measurement of self-diffusion coefficient D+ and electric mobility u+ of a cation ((C4H9)+4) in a disordered gel-like medium (Sephadex LH-20) filled with electrolyte solution. We find a, qualitatively expected, observation time-dependence of D+, but for the first time such a time-dependence is also observed for u+, which means the detection of the phenomenon of "anomalous field assisted diffusion" or "anomalous mobility." For the measurement of the short-time behavior of the mobility a new pulse sequence is presented. The time-dependent mobilities were measured at three different external electrical fields E. From the long-time behavior of D+, u+, and DH2O three independent values for the tortuosity T of the porous system could be derived. We find equality of the tortuosities T(D+) and T(u+), which represents a first experimental proof of the validity of the Einstein relation (D+ approximately u+) in a disordered medium. Finally, we discuss advantages of the possible use of "anomalous field assisted diffusion" over the commonly used "anomalous diffusion" in morphology studies by dynamic imaging in porous media. PMID:9799669

  2. Drag force, diffusion coefficient, and electric mobility of small particles. II. Application.

    PubMed

    Li, Zhigang; Wang, Hai

    2003-12-01

    We propose a generalized treatment of the drag force of a spherical particle due to its motion in a laminar fluid media. The theory is equally applicable to analysis of particle diffusion and electric mobility. The focus of the current analysis is on the motion of spherical particles in low-density gases with Knudsen number Kn>1. The treatment is based on the gas-kinetic theory analysis of drag force in the specular and diffuse scattering limits obtained in a preceding paper [Z. Li and H. Wang, Phys. Rev. E., 68, 061206 (2003)]. Our analysis considers the influence of van der Waals interactions on the momentum transfer upon collision of a gas molecule with the particle and expresses this influence in terms of an effective, reduced collision integral. This influence is shown to be significant for nanosized particles. In the present paper, the reduced collision integral values are obtained for specular and diffuse scattering, using a Lennard-Jones-type potential energy function suitable for the interactions of a gas molecule with a particle. An empirical formula for the momentum accommodation function, used to determine the effective, reduced collision integral, is obtained from available experimental data. The resulting treatment is shown to be accurate for interpreting the mobility experiments for particles as small as approximately 1 nm in radius. The treatment is subsequently extended to the entire range of the Knudsen number, following a semiempirical, gas-kinetic theory analysis. We demonstrate that the proposed formula predicts very well Millikan's oil-droplet experiments [R. A. Millikan, Philos. Mag. 34, 1 (1917); Phys. Rev. 22, 1 (1923)]. The rigorous theoretical foundation of the proposed formula in the Kn>1 limit makes the current theory far more general than the semiempirical Stokes-Cunningham formula in terms of the particle size and condition of the fluid and, therefore, more attractive than the Stokes-Cunningham formula. PMID:14754192

  3. Drag force, diffusion coefficient, and electric mobility of small particles. II. Application

    NASA Astrophysics Data System (ADS)

    Li, Zhigang; Wang, Hai

    2003-12-01

    We propose a generalized treatment of the drag force of a spherical particle due to its motion in a laminar fluid media. The theory is equally applicable to analysis of particle diffusion and electric mobility. The focus of the current analysis is on the motion of spherical particles in low-density gases with Knudsen number Kn≫1. The treatment is based on the gas-kinetic theory analysis of drag force in the specular and diffuse scattering limits obtained in a preceding paper [Z. Li and H. Wang, Phys. Rev. E., 68, 061206 (2003)]. Our analysis considers the influence of van der Waals interactions on the momentum transfer upon collision of a gas molecule with the particle and expresses this influence in terms of an effective, reduced collision integral. This influence is shown to be significant for nanosized particles. In the present paper, the reduced collision integral values are obtained for specular and diffuse scattering, using a Lennard-Jones-type potential energy function suitable for the interactions of a gas molecule with a particle. An empirical formula for the momentum accommodation function, used to determine the effective, reduced collision integral, is obtained from available experimental data. The resulting treatment is shown to be accurate for interpreting the mobility experiments for particles as small as ˜1 nm in radius. The treatment is subsequently extended to the entire range of the Knudsen number, following a semiempirical, gas-kinetic theory analysis. We demonstrate that the proposed formula predicts very well Millikan’s oil-droplet experiments [R. A. Millikan, Philos. Mag. 34, 1 (1917); Phys. Rev. 22, 1 (1923)]. The rigorous theoretical foundation of the proposed formula in the Kn≫1 limit makes the current theory far more general than the semiempirical Stokes-Cunningham formula in terms of the particle size and condition of the fluid and, therefore, more attractive than the Stokes-Cunningham formula.

  4. AEROSOL SIZE MEASUREMENT BY ELECTRICAL MOBILITY AND DIFFUSION ANALYSIS - A COMPARISON OF METHODS

    EPA Science Inventory

    The principle of the electrical aerosol analyzer method is reviewed and the diffusion battery method is described in detail. An appendix explains the basis of the calculations used. The diffusion battery method is complicated by counting losses of very small particles, inherent t...

  5. Diffusion and Electric Mobility of KCI within Isolated Cuticles of Citrus aurantium 1

    PubMed Central

    Tyree, Melvin T.; Wescott, Charles R.; Tabor, Christopher A.; Morse, Anne D.

    1992-01-01

    Fick's second law has been used to predict the time course of electrical conductance change in isolated cuticles following the rapid change in bathing solution (KCI) from concentration C to 0.1 C. The theoretical time course is dependent on the coefficient of diffusion of KCI in the cuticle and the cuticle thickness. Experimental results, obtained from cuticles isolated from sour orange (Citrus aurantium), fit with a diffusion model of an isolated cuticle in which about 90% of the conductance change following a solution change is due to salts diffusing from polar pores in the wax, and 10% of the change is due to salt diffusion from the wax. Short and long time constants for the washout of KCI were found to be 0.11 and 3.8 hours, respectively. These time constants correspond to KCI diffusion coefficients of 1 × 10−15 and 3 × 10−17 square meters per second, respectively. The larger coefficient is close to the diffusion coefficient for water in polar pores of Citrus reported elsewhere (M Becker, G Kerstiens, J Schönherr [1986] Trees 1: 54-60). This supports our interpretation of the washout kinetics of KCI following a change in concentration of bathing solution. PMID:16668971

  6. Diffusion and Electric Mobility of KCI within Isolated Cuticles of Citrus aurantium.

    PubMed

    Tyree, M T; Wescott, C R; Tabor, C A; Morse, A D

    1992-07-01

    Fick's second law has been used to predict the time course of electrical conductance change in isolated cuticles following the rapid change in bathing solution (KCI) from concentration C to 0.1 C. The theoretical time course is dependent on the coefficient of diffusion of KCI in the cuticle and the cuticle thickness. Experimental results, obtained from cuticles isolated from sour orange (Citrus aurantium), fit with a diffusion model of an isolated cuticle in which about 90% of the conductance change following a solution change is due to salts diffusing from polar pores in the wax, and 10% of the change is due to salt diffusion from the wax. Short and long time constants for the washout of KCI were found to be 0.11 and 3.8 hours, respectively. These time constants correspond to KCI diffusion coefficients of 1 x 10(-15) and 3 x 10(-17) square meters per second, respectively. The larger coefficient is close to the diffusion coefficient for water in polar pores of Citrus reported elsewhere (M Becker, G Kerstiens, J Schönherr [1986] Trees 1: 54-60). This supports our interpretation of the washout kinetics of KCI following a change in concentration of bathing solution. PMID:16668971

  7. Diffusion and Electric Mobility of Ions within Isolated Cuticles of Citrus aurantium 1

    PubMed Central

    Tyree, Melvin T.; Wescott, Charles R.; Tabor, Christopher A.

    1991-01-01

    We report a new method for measuring cation and anion permeability across cuticles of sour orange, Citrus aurantium, leaves. The method requires the measurement of two electrical parameters: the diffusion potential arising when the two sides of the cuticle are bathed in unequal concentrations of a Cl− salt; and the electrical conductance of the cuticle measured at a salt concentration equal to the average of that used in the diffusion-potential measurement. The permeabilities of H+, Li+, Na+, K+, and Cs+ ranged from 2 × 10−8 to 0.6 × 10−8 meters per second when cuticles were bathed in 2 moles per cubic meter Cl− salts. The permeability of Cl− was 3 × 10−9 meters per second. The permeability of Li+, Na+, and K+ was about five times less when measured in 500 moles per cubic meter Cl− salts. We also report an asymmetry in cuticle-conductance values depending on the magnitude and the direction of current flow. The asymmetry disappears at low current-pulse magnitude and increases linearly with the magnitude of the current pulse. This phenomenon is explained in terms of transport-number effects in a bilayer model of the cuticle. Conductance is not augmented by current carried by exchangeable cations in cuticles; conductance is rate limited by the outer waxy layer of the cuticle. PMID:16668382

  8. Note: the role of external electric fields in enhancing ion mobility, drift velocity, and drift-diffusion rates in aqueous electrolyte solutions [J. Chem. Phys. 134, 114504 (2011)].

    PubMed

    Murad, Sohail

    2012-02-21

    The effect of external electric fields on enhancing ion mobility, drift velocity, and drift diffusion as a function of solution concentration has been investigated using molecular dynamics simulations. Our results show that the unusual nonlinear behavior observed when the solution concentration matches seawater is also observed when the concentration is reduced to half of that value. These results are of significance in designing processes for desalinating seawater using electro-deionization in which the concentration would decrease during salt removal, and for purification of brackish waters which also have lower salt content. PMID:22360264

  9. Note: The role of external electric fields in enhancing ion mobility, drift velocity, and drift-diffusion rates in aqueous electrolyte solutions [J. Chem. Phys. 134, 114504 (2011)

    NASA Astrophysics Data System (ADS)

    Murad, Sohail

    2012-02-01

    The effect of external electric fields on enhancing ion mobility, drift velocity, and drift diffusion as a function of solution concentration has been investigated using molecular dynamics simulations. Our results show that the unusual nonlinear behavior observed when the solution concentration matches seawater is also observed when the concentration is reduced to half of that value. These results are of significance in designing processes for desalinating seawater using electro-deionization in which the concentration would decrease during salt removal, and for purification of brackish waters which also have lower salt content.

  10. Diffusion and Electric Mobility of Ions within Isolated Cuticles of Citrus aurantium: Steady-State and Equilibrium Values.

    PubMed

    Tyree, M T; Wescott, C R; Tabor, C A

    1991-09-01

    We report a new method for measuring cation and anion permeability across cuticles of sour orange, Citrus aurantium, leaves. The method requires the measurement of two electrical parameters: the diffusion potential arising when the two sides of the cuticle are bathed in unequal concentrations of a Cl(-) salt; and the electrical conductance of the cuticle measured at a salt concentration equal to the average of that used in the diffusion-potential measurement. The permeabilities of H(+), Li(+), Na(+), K(+), and Cs(+) ranged from 2 x 10(-8) to 0.6 x 10(-8) meters per second when cuticles were bathed in 2 moles per cubic meter Cl(-) salts. The permeability of Cl(-) was 3 x 10(-9) meters per second. The permeability of Li(+), Na(+), and K(+) was about five times less when measured in 500 moles per cubic meter Cl(-) salts. We also report an asymmetry in cuticle-conductance values depending on the magnitude and the direction of current flow. The asymmetry disappears at low current-pulse magnitude and increases linearly with the magnitude of the current pulse. This phenomenon is explained in terms of transport-number effects in a bilayer model of the cuticle. Conductance is not augmented by current carried by exchangeable cations in cuticles; conductance is rate limited by the outer waxy layer of the cuticle. PMID:16668382

  11. The role of external electric fields in enhancing ion mobility, drift velocity, and drift-diffusion rates in aqueous electrolyte solutions.

    PubMed

    Murad, Sohail

    2011-03-21

    Molecular simulations have been carried out using the method of molecular dynamics to investigate the role of external electric fields on the ion mobility, drift velocity, and drift-diffusion rate of ions in aqueous electrolyte solutions. These properties are critical for a range of processes including electrodialysis, electro-deionization, electrophoresis, and electroosmosis. Our results show that external electric fields relax the hydrated ion structure at significantly larger time scales (between 300 and 800 ps), than most other relaxation processes in solutions (generally of the order of 1 ps). Previous studies that did not account for the much longer relaxation times did not observe this behavior for ions even with very high electric fields. External electric fields must also overcome several (at least two or more) activation energy barriers to significantly change the structure of hydrated ions. As a result, the dynamic behavior changes almost in bands as a function of electric field strengths, rather than linearly. Finally, the effect of the field is much less dramatic on water than the ions. Thus electric fields will be of more significance in processes that involve the transport of ions (such as electro-deionization) than the transport of water (electroosmosis). PMID:21428629

  12. The role of external electric fields in enhancing ion mobility, drift velocity, and drift-diffusion rates in aqueous electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Murad, Sohail

    2011-03-01

    Molecular simulations have been carried out using the method of molecular dynamics to investigate the role of external electric fields on the ion mobility, drift velocity, and drift-diffusion rate of ions in aqueous electrolyte solutions. These properties are critical for a range of processes including electrodialysis, electro-deionization, electrophoresis, and electroosmosis. Our results show that external electric fields relax the hydrated ion structure at significantly larger time scales (between 300 and 800 ps), than most other relaxation processes in solutions (generally of the order of 1 ps). Previous studies that did not account for the much longer relaxation times did not observe this behavior for ions even with very high electric fields. External electric fields must also overcome several (at least two or more) activation energy barriers to significantly change the structure of hydrated ions. As a result, the dynamic behavior changes almost in bands as a function of electric field strengths, rather than linearly. Finally, the effect of the field is much less dramatic on water than the ions. Thus electric fields will be of more significance in processes that involve the transport of ions (such as electro-deionization) than the transport of water (electroosmosis).

  13. Nonlocal electrical diffusion equation

    NASA Astrophysics Data System (ADS)

    Gómez-Aguilar, J. F.; Escobar-Jiménez, R. F.; Olivares-Peregrino, V. H.; Benavides-Cruz, M.; Calderón-Ramón, C.

    2016-07-01

    In this paper, we present an analysis and modeling of the electrical diffusion equation using the fractional calculus approach. This alternative representation for the current density is expressed in terms of the Caputo derivatives, the order for the space domain is 0<β≤1 and for the time domain is 0<γ≤2. We present solutions for the full fractional equation involving space and time fractional derivatives using numerical methods based on Fourier variable separation. The case with spatial fractional derivatives leads to Levy flight type phenomena, while the time fractional equation is related to sub- or super diffusion. We show that the mathematical concept of fractional derivatives can be useful to understand the behavior of semiconductors, the design of solar panels, electrochemical phenomena and the description of anomalous complex processes.

  14. Mobile electric power

    SciTech Connect

    Bloomfield, V.J.; Bloomfield, D.P.; Johnson, B.Q.

    1992-01-30

    Analytic Power has proven the feasibility of a mobile electric power unit in the form of a hydride fueled ion-exchange membrane (IEM) fuel cell stack. We have over 5 years experience building and testing IEM fuel cells. The power section of a 350 watt fuel cell stack weighs 4.65 pounds based on our five cell sub-stack component weights. The composite stack structure is fabricated from two components; a unitized flow field and catalyzed membrane. The lightweight unitized flow field concept was proven in the first three months of the contract. A single unit flow field weighs 0.155 pounds and can seal to 60 psi. The single cell catalyzed Nafion membrane exceeded our performance goal of 0.6 volts at 100 ASF. Stack performance points were 0.42 volts at 113 ASF and .75 volts at 96 asf.

  15. Drag force, diffusion coefficient, and electric mobility of small particles. I. Theory applicable to the free-molecule regime.

    PubMed

    Li, Zhigang; Wang, Hai

    2003-12-01

    The transport of small particles in the free-molecule regime is investigated on the basis of gas kinetic theory. Drag force formulations were derived in two limiting collision models-namely, specular and diffuse scattering-by considering the potential force of interactions between the particle and fluid molecules. A parametrized drag coefficient equation is proposed and accounts for the transition from specular to diffuse scattering as particle size exceeds a critical value. The resulting formulations are shown to be consistent with the Chapman-Enskog theory of molecular diffusion. In the limit of rigid-body interactions, these formulations can be simplified also to Epstein's solutions [P. S. Epstein, Phys. Rev. 23, 710 (1924)]. PMID:14754191

  16. Experimental correlations for transient soot measurement in diesel exhaust aerosol with light extinction, electrical mobility and diffusion charger sensor techniques

    NASA Astrophysics Data System (ADS)

    Bermúdez, Vicente; Pastor, José V.; López, J. Javier; Campos, Daniel

    2014-06-01

    A study of soot measurement deviation using a diffusion charger sensor with three dilution ratios was conducted in order to obtain an optimum setting that can be used to obtain accurate measurements in terms of soot mass emitted by a light-duty diesel engine under transient operating conditions. The paper includes three experimental phases: an experimental validation of the measurement settings in steady-state operating conditions; evaluation of the proposed setting under the New European Driving Cycle; and a study of correlations for different measurement techniques. These correlations provide a reliable tool for estimating soot emission from light extinction measurement or from accumulation particle mode concentration. There are several methods and correlations to estimate soot concentration in the literature but most of them were assessed for steady-state operating points. In this case, the correlations are obtained by more than 4000 points measured in transient conditions. The results of the new two correlations, with less than 4% deviation from the reference measurement, are presented in this paper.

  17. Income, Inequality, Market Potential, and Diffusion of Mobile Telephony

    ERIC Educational Resources Information Center

    Kim, Sungjoong

    2009-01-01

    The diffusion of many previous innovations eventually slowed down and reached an equilibrium level. Despite continued rapid growth, it is possible that the diffusion of mobile telephony will also begin to decelerate and reach a saturation level. Whether universal service can be achieved with the help of mobile telephony will therefore depend…

  18. Electric wind in a Differential Mobility Analyzer

    SciTech Connect

    Palo, Marus; Meelis Eller; Uin, Janek; Tamm, Eduard

    2015-10-25

    Electric wind -- the movement of gas, induced by ions moving in an electric field -- can be a distorting factor in size distribution measurements using Differential Mobility Analyzers (DMAs). The aim of this study was to determine the conditions under which electric wind occurs in the locally-built VLDMA (Very Long Differential Mobility Analyzer) and TSI Long-DMA (3081) and to describe the associated distortion of the measured spectra. Electric wind proved to be promoted by the increase of electric field strength, aerosol layer thickness, particle number concentration and particle size. The measured size spectra revealed three types of distortion: widening of the size distribution, shift of the mode of the distribution to smaller diameters and smoothing out the peaks of the multiply charged particles. Electric wind may therefore be a source of severe distortion of the spectrum when measuring large particles at high concentrations.

  19. Electric wind in a Differential Mobility Analyzer

    DOE PAGESBeta

    Palo, Marus; Meelis Eller; Uin, Janek; Tamm, Eduard

    2015-10-25

    Electric wind -- the movement of gas, induced by ions moving in an electric field -- can be a distorting factor in size distribution measurements using Differential Mobility Analyzers (DMAs). The aim of this study was to determine the conditions under which electric wind occurs in the locally-built VLDMA (Very Long Differential Mobility Analyzer) and TSI Long-DMA (3081) and to describe the associated distortion of the measured spectra. Electric wind proved to be promoted by the increase of electric field strength, aerosol layer thickness, particle number concentration and particle size. The measured size spectra revealed three types of distortion: wideningmore » of the size distribution, shift of the mode of the distribution to smaller diameters and smoothing out the peaks of the multiply charged particles. Electric wind may therefore be a source of severe distortion of the spectrum when measuring large particles at high concentrations.« less

  20. Diffusion and mobility of anisotropic particles in tilted periodic structures

    NASA Astrophysics Data System (ADS)

    Wu, Jian-chun; Chen, Qun; Wang, Rang; Ai, Bao-quan

    2015-02-01

    We numerically investigated the transport of anisotropic particles in tilted periodic structures. The diffusion and mobility of the particles demonstrate distinct behaviors dependence on the shape of the particles. In two-dimensional (2D) periodic potentials, we find that the mobility is influenced a little by the anisotropy of the particle, while the diffusion increases monotonically with the increasing of the particle anisotropy for large enough biased force. However, due to the sensitivity of the channels for the particle anisotropy, the transport in smooth channels is obviously different from that in energy potentials. The mobility decreases monotonically with the increasing of the particle anisotropy, while the diffusion can be a non-monotonic function of the particle anisotropy with a peak under appropriate biased force.

  1. Mobility and Diffusion-Ordered Two-Dimensional NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Morris, Kevin Freeman

    Mobility and diffusion-ordered two-dimensional nuclear magnetic resonance spectroscopy experiments have been developed for the analysis of mixtures. In the mobility -ordered experiments, the full range of positive and negative electrophoretic mobilities is displayed in one dimension and chemical shifts are displayed in the other. A concentric cylindrical tube electrophoresis chamber was designed to reduce the effective pathlength for current and to provide unidirectional flow for ions of interest. Techniques based upon the reverse precession method were also implemented to recover the signs of the mobilities and improved resolution in the mobility dimension was obtained by replacing Fourier transformation of truncated data sets with a linear prediction analysis. In the diffusion-ordered two-dimensional NMR experiments, the conventional chemical shift spectrum is resolved in one dimension and spectra of diffusion rates or molecular radii are resolved in the other. Diffusion dependent pulsed field gradient NMR data sets were inverted by means of the computer programs SPLMOD or DISCRETE, when discrete diffusion coefficients were present, and CONTIN when continuous distributions were present. Since the inversion is ill -conditioned, it was necessary to introduce additional information to limit the range of the solutions. In addition to prior knowledge of the decay kernels and non-negativity of amplitudes and damping constants, a set of rejection criteria was constructed for the discrete analysis case that took into account physical limits on diffusion coefficients, experimentally accessible values, and variations in effective decay kernels resulting from instrumental non-linearities. Examples of analyses of simulated data and experimental data for mixtures are presented as well as two-dimensional spectra generated by CONTIN for polydisperse polymer samples. Also, resolution in the diffusion dimension was increased by performing experiments on hydrophobic molecules in

  2. Drift tube measurements of mobilities and longitudinal diffusion coefficients of ions in gases

    SciTech Connect

    Chelf, R.D.

    1982-01-01

    The zero-field mobilities of Br/sup -/ and NH/sub 4//sup +/ in O/sub 2/ were determined as a function of gas temperature in a high pressure drift tube mass spectrometer. The mobilities and longitudinal diffusion coefficients of the ion-gas combinations Br/sup -/ in Ne and Kr, Li/sup +/ in Xe, and Tl//sup +/ in Kr and Xe were determined as a function of E/N, where E is the electric field strength and N is the gas number density in a low pressure drift tube mass spectrometer. The measured longitudinal diffusion coefficients were used for a test and comparison of the generalized Einstein relations of Viehland-Mason and Waldman-Mason theories. The measured mobilities of Br/sup -/ in Kr and Tl//sup +/ in Kr were used in an iterative-inversion scheme from which the ion-neutral interaction potentials were determined.

  3. New method for obtaining drift mobility and diffusion coefficient and their relation in photorefractive polymers

    NASA Astrophysics Data System (ADS)

    Hirao, Akiko; Nishizawa, Hideyuki; Tsukamoto, Takayuki; Matsumoto, Kazuki

    1999-10-01

    A new easy method for obtaining a drift mobility and a diffusion coefficient from a nondispersive time-of-flight transient has been developed. Nondispersive transients are described well in the theoretical photocurrent equation (PTE) based on the fact that a carrier packet drifts at a constant velocity and is spread by diffusion, the top electrode acts as a reflecting and partially absorbing wall, and the counter electrode acts as an absorbing wall. The fitting of the PTE to photocurrent transients gives the mobility and the diffusion coefficient (D) simultaneously. These are suitable characteristic values for descriptions of carriers transport because they do not show the thickness dependence and the negative field dependence in a low electric field. The mobility that sometimes shows the thickness dependence and the negative field dependence in a low electric field, however, has usually been measured from the time of the intersection of the asymptotes to the plateau and trailing edge of the transients. In order to obtain (mu) a from photocurrent transients by a simple method, we have tried to describe t0 and tail-broadening parameter W as functions of (mu) a and D, where W is defined as (t1/2 - t0)/t1/2 and t1/2 is the time at which the current is a half of that in the plateau region. The dependences of calculated (mu) k and W on the electric field and the sample thickness agreed well with those of the experimental data. These results verify the PTE and suggest that (mu) a and D can be calculated from t0 and W. We also report that the diffusion coefficient is proportional to the power of 2 of the mobility. This result agrees with a theory based on the Langevin equation which describes motions of carriers in a fluctuated field.

  4. Solid state cloaking for electrical charge carrier mobility control

    DOEpatents

    Zebarjadi, Mona; Liao, Bolin; Esfarjani, Keivan; Chen, Gang

    2015-07-07

    An electrical mobility-controlled material includes a solid state host material having a controllable Fermi energy level and electrical charge carriers with a charge carrier mobility. At least one Fermi level energy at which a peak in charge carrier mobility is to occur is prespecified for the host material. A plurality of particles are distributed in the host material, with at least one particle disposed with an effective mass and a radius that minimize scattering of the electrical charge carriers for the at least one prespecified Fermi level energy of peak charge carrier mobility. The minimized scattering of electrical charge carriers produces the peak charge carrier mobility only at the at least one prespecified Fermi level energy, set by the particle effective mass and radius, the charge carrier mobility being less than the peak charge carrier mobility at Fermi level energies other than the at least one prespecified Fermi level energy.

  5. A field method to quantify exchange with less-mobile porosity in streambeds using electrical hysteresis

    NASA Astrophysics Data System (ADS)

    Briggs, M. A.; Day-Lewis, F. D.; Zarnetske, J. P.; Harvey, J. W.; Lane, J. W., Jr.

    2015-12-01

    Heterogeneous streambed materials may be expected to develop two general porosity domains: a more-mobile porosity dominated by advective exchange, and a less-mobile porosity dominated by diffusive exchange. Less-mobile porosity containing unique redox conditions or contaminant mass may be invisible to traditional porewater sampling methods, even using "low-flow" techniques, because these methods sample water preferentially from the mobile porosity domain. Further, most tracer breakthrough curve analyses have only provided indirect information (tailing) regarding the prevalence and connectivity of less-mobile porosity, typically over experimental flowpath scales between 1-10 meters. To address the limitations of conventional methods, we use electrical geophysical methods to aid in the inference of less-mobile porosity parameters. Unlike traditional fluid sampling, electrical methods can directly sense less-mobile solute and can target specific points along subsurface flowpaths. We demonstrate how the geophysical methodology developed for dual-domain groundwater transport can be scaled to the streambed through synthetic, laboratory column, and field experiments; further we show how previously-used numerical modeling techniques can be replaced by a more-simple analytical approach. The new analytical method is based on electrical theory, and involves characteristics of electrical hysteresis patterns (e.g. hinge point values) that are used to quantify (1) the size of paired mobile and less-mobile porosities, and (2) the exchange rate coefficient through simple curve fitting. Results from the analytical approach compare favorably with results from calibration of numerical models and also independent measurements of mobile and less-mobile porosity. Lastly, we demonstrate a method of focused solute streambed injection to quantify less-mobile porosity and explain redox zonation in contrasting stream environments.

  6. Communication: Charge, diffusion, and mobility of proteins through nanopores

    PubMed Central

    Muthukumar, M.

    2014-01-01

    Implementation of Einstein's law connecting charge, diffusion coefficient, and mobility to interpret experimental data on proteins from single molecule electrophoresis through nanopores faces serious difficulties. The protein charge and diffusion coefficient, inferred with the Einstein law, can be orders of magnitude smaller than their bare values depending on the electrolyte concentration, pore diameter, chemical nature of the pore wall, and the externally applied voltage. The main contributors to the discrepancies are the coupled dynamics of the protein and its counterion cloud, confinement effects inside the pore, and the protein-pore-surface interaction. We have addressed these ingredients by harking on classical theories of electrophoresis of macroions and hydrodynamics inside pores, and deriving new results for pore-protein interactions. Putting together various components, we present approximate analytical formulas for the effective charge, diffusion coefficient, and mobility of a protein in the context of single molecule electrophoresis experiments. For the omnipresent pore-protein interactions, nonlinear dependence of the velocity of protein on voltage sets in readily and analytical formulas for this effect are presented. The derived formulas enable the determination of the bare charge and size of a protein from the experimentally measured apparent values. PMID:25172998

  7. Electric Field Enhanced Diffusion of Salicylic Acid through Polyacrylamide Hydrogels

    NASA Astrophysics Data System (ADS)

    Niamlang, Sumonman; Sirivat, Anuvat

    2008-03-01

    The release mechanisms and the diffusion coefficients of salicylic acid -loaded polyacrylamide hydrogels were investigated experimentally by using a modified Franz-diffusion cell at 37 ^oC to determine the effects of crosslinking ratio and electric field strength. A significant amount of salicylic acid is released within 48 hours from the hydrogels of various crosslinking ratios, with and without electric field. The release characteristic follows the Q vs. t^1/2 linear relationship. Diffusion coefficient initially increases with increasing electric field strength and reaches the maximum value at electric field strength of 0.1 V; beyond that it decreases with electric field strength and becomes saturated at electric field strength of 5 V. The diffusion coefficient increases at low electric field strength (less 0.1 V) as a result of the electrophoresis of the salicylic acid, the expansion of pore size, and the induced pathway in pigskin. For electric field strength higher than 0.1 V, the decrease in the diffusion coefficient is due to the reduction of the polyacrylamide pore size. The diffusion coefficient obeys the scaling behavior D/Do=(drug size/pore size)^m, with the scaling exponent m equal to 0.93 and 0.42 at electric fields of 0 and 0.1 V, respectively.

  8. Electrical Circuit Analogues of Thermal Conduction and Diffusion

    ERIC Educational Resources Information Center

    Tomlin, D. H.; Fullarton, G. K.

    1978-01-01

    After briefly reviewing equations of conduction and diffusion, and voltage and charge in electrical circuits, a simple experiment is given that allows students practical experience in a theoretical realm of physics. (MDR)

  9. Modeling the Determinants Influencing the Diffusion of Mobile Internet

    NASA Astrophysics Data System (ADS)

    Alwahaishi, Saleh; Snášel, Václav

    2013-04-01

    Understanding individual acceptance and use of Information and Communication Technology (ICT) is one of the most mature streams of information systems research. In Information Technology and Information System research, numerous theories are used to understand users' adoption of new technologies. Various models were developed including the Innovation Diffusion Theory, Theory of Reasoned Action, Theory of Planned Behavior, Technology Acceptance Model, and recently, the Unified Theory of Acceptance and Use of Technology. This research composes a new hybrid theoretical framework to identify the factors affecting the acceptance and use of Mobile Internet -as an ICT application- in a consumer context. The proposed model incorporates eight constructs: Performance Expectancy (PE), Effort Expectancy (EE), Facilitating Conditions (FC), Social Influences (SI), Perceived Value (PV), Perceived Playfulness (PP), Attention Focus (AF), and Behavioral intention (BI). Individual differences-namely, age, gender, education, income, and experience are moderating the effects of these constructs on behavioral intention and technology use.

  10. Interplay between barrier contact, mobility models, and traps in the electrical characteristics of OTFT

    NASA Astrophysics Data System (ADS)

    Di Carlo, Aldo; Bolognesi, Alessandro; Berliocchi, Marco; Lugli, Paolo

    2003-11-01

    We have investigated the electrical properties of organic thin-film transistor by using two-dimensional drift-diffusion simulations. The dependence of electrical haracteristics on the mobility model and on the barrier height of the contacts is carried out. We found that the field dependence of the carrier mobility is responsible for non-linearity of the drain current. This non-linear behavior is mainly related to the field-dependence of the mobility and to the barrier height of the contacts. The simulation allow us to clear understand the differences in the mobility derived by the analysis of I-V curve (as done experimentally by using standard MOSFET theory) and the intrinsic mobility of the organic layer. The effects of the interface traps has also be considered. The dependence of the threshold voltage on the density, energy level and model of the traps has been outlined. Results of the simulations have been compared with experimental data. The comparison between experimental data and simulation allow us to clearly identify the physical mechanism responsible for the measured characteristics. Finally we also consider the effect of the device bending on the electrical characteristic of all-plastic OTFT.

  11. Viscoelasticity in the diffuse electric double layer.

    PubMed

    Etchenique, Roberto; Buhse, Thomas

    2002-10-01

    The electroacoustical impedance of the quartz crystal microbalance (QCM) in contact with aqueous electrolyte solutions was measured using the transfer function method in a flow injection system . Measurements of both components of the impedance of the QCM, the resistance R and the inductive reactance XL, have been performed for modified and bare gold and silver surfaces and for different concentrations of several aqueous electrolyte solutions. For the experimental concentration range of 0-50 mM, unexpectedly the QCM impedance does not follow the Kanazawa equation, as is usual for bulk newtonian liquids. This behavior indicates the presence of a nanometric sized viscoelastic layer between the piezoelectric crystal and the bulk electrolyte solution. This layer can only be identified as the Gouy-Chapman diffuse double layer (DDL). Its elasticity and viscosity have been estimated by the measurement of R and XL. The viscoelasticity of the DDL appears to be independent of the chemical nature of the surface and of the solution viscosity but strongly dependent on the surface charge, the bulk electrolyte concentration and the dielectric constant of the solvent. PMID:12430608

  12. Effects of extracellular potassium diffusion on electrically coupled neuron networks

    NASA Astrophysics Data System (ADS)

    Wu, Xing-Xing; Shuai, Jianwei

    2015-02-01

    Potassium accumulation and diffusion during neuronal epileptiform activity have been observed experimentally, and potassium lateral diffusion has been suggested to play an important role in nonsynaptic neuron networks. We adopt a hippocampal CA1 pyramidal neuron network in a zero-calcium condition to better understand the influence of extracellular potassium dynamics on the stimulus-induced activity. The potassium concentration in the interstitial space for each neuron is regulated by potassium currents, Na+-K+ pumps, glial buffering, and ion diffusion. In addition to potassium diffusion, nearby neurons are also coupled through gap junctions. Our results reveal that the latency of the first spike responding to stimulus monotonically decreases with increasing gap-junction conductance but is insensitive to potassium diffusive coupling. The duration of network oscillations shows a bell-like shape with increasing potassium diffusive coupling at weak gap-junction coupling. For modest electrical coupling, there is an optimal K+ diffusion strength, at which the flow of potassium ions among the network neurons appropriately modulates interstitial potassium concentrations in a degree that provides the most favorable environment for the generation and continuance of the action potential waves in the network.

  13. Diffusivities and Atomic Mobilities of Sn-Bi and Sn-Pb Melts

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Min; Zhang, Li-Jun; Liu, Dan-Dan; Du, Yong; Tan, Cheng-Yu

    2013-06-01

    The recently developed Arrhenius formula of the modified Sutherland equation was first employed to calculate the self- and impurity diffusivities in liquid Sn, Bi, and Pb. The reliability of the calculated results was validated in comparison with the critically reviewed literature data. Based on the reliable tracer and chemical diffusivities available in the literature, the atomic mobility parameters in both Sn-Bi and Sn-Pb melts were then evaluated by the DICTRA (DIffusion-Controlled TRAnsformations) software package with the aid of thermodynamic parameters. Comprehensive comparisons show that most of the measured and theoretical diffusivities in Sn-Bi and Sn-Pb melts can be reasonably reproduced by the currently obtained atomic mobilities. Moreover, the atomic mobilities were further verified by comparing the model-predicted concentration profiles and the measured ones in various liquid Sn-Bi and Sn-Pb diffusion couples.

  14. Mental Health Mobile Apps: From Infusion to Diffusion in the Mental Health Social System.

    PubMed

    East, Marlene Lynette; Havard, Byron C

    2015-01-01

    The roles of mental health educators and professionals in the diffusion of mental health mobile apps are addressed in this viewpoint article. Mental health mobile apps are emerging technologies that fit under the broad heading of mobile health (mHealth). mHealth, encompassed within electronic health (eHealth), reflects the use of mobile devices for the practice of public health. Well-designed mental health mobile apps that present content in interactive, engaging, and stimulating ways can promote cognitive learning, personal growth, and mental health enhancement. As key influencers in the mental health social system, counselor educators and professional associations may either help or hinder diffusion of beneficial mHealth technologies. As mental health mobile apps move towards ubiquity, research will continue to be conducted. The studies published thus far, combined with the potential of mental health mobile apps for learning and personal growth, offer enough evidence to compel mental health professionals to infuse these technologies into education and practice. Counselor educators and professional associations must use their influential leadership roles to train students and practitioners in how to research, evaluate, and integrate mental health mobile apps into practice. The objectives of this article are to (1) increase awareness of mHealth and mental health mobile apps, (2) demonstrate the potential for continued growth in mental health mobile apps based on technology use and acceptance theory, mHealth organizational initiatives, and evidence about how humans learn, (3) discuss evidence-based benefits of mental health mobile apps, (4) examine the current state of mHealth diffusion in the mental health profession, and (5) offer solutions for impelling innovation diffusion by infusing mental health mobile apps into education, training, and clinical settings. This discussion has implications for counselor educators, mental health practitioners, associations

  15. Mental Health Mobile Apps: From Infusion to Diffusion in the Mental Health Social System

    PubMed Central

    2015-01-01

    The roles of mental health educators and professionals in the diffusion of mental health mobile apps are addressed in this viewpoint article. Mental health mobile apps are emerging technologies that fit under the broad heading of mobile health (mHealth). mHealth, encompassed within electronic health (eHealth), reflects the use of mobile devices for the practice of public health. Well-designed mental health mobile apps that present content in interactive, engaging, and stimulating ways can promote cognitive learning, personal growth, and mental health enhancement. As key influencers in the mental health social system, counselor educators and professional associations may either help or hinder diffusion of beneficial mHealth technologies. As mental health mobile apps move towards ubiquity, research will continue to be conducted. The studies published thus far, combined with the potential of mental health mobile apps for learning and personal growth, offer enough evidence to compel mental health professionals to infuse these technologies into education and practice. Counselor educators and professional associations must use their influential leadership roles to train students and practitioners in how to research, evaluate, and integrate mental health mobile apps into practice. The objectives of this article are to (1) increase awareness of mHealth and mental health mobile apps, (2) demonstrate the potential for continued growth in mental health mobile apps based on technology use and acceptance theory, mHealth organizational initiatives, and evidence about how humans learn, (3) discuss evidence-based benefits of mental health mobile apps, (4) examine the current state of mHealth diffusion in the mental health profession, and (5) offer solutions for impelling innovation diffusion by infusing mental health mobile apps into education, training, and clinical settings. This discussion has implications for counselor educators, mental health practitioners, associations

  16. How dangerous are mobile phones, transmission masts, and electricity pylons?

    PubMed

    Wood, A W

    2006-04-01

    Electrical power and mobile communications deliver enormous benefit to society, but there are concerns whether the electric and magnetic field (EMF) emissions associated with the delivery of this benefit are linked to cancer or other health hazards. This article reviews the strength of the available epidemiological and laboratory evidence and notes that this falls short of what is normally required to establish a causal link. However, because of scientific uncertainty a cautious approach is often advocated, but here, too, there may be a tendency to judge these risks more harshly than those in other areas with similar strength of evidence. PMID:16551794

  17. How dangerous are mobile phones, transmission masts, and electricity pylons?

    PubMed Central

    Wood, A W

    2006-01-01

    Electrical power and mobile communications deliver enormous benefit to society, but there are concerns whether the electric and magnetic field (EMF) emissions associated with the delivery of this benefit are linked to cancer or other health hazards. This article reviews the strength of the available epidemiological and laboratory evidence and notes that this falls short of what is normally required to establish a causal link. However, because of scientific uncertainty a cautious approach is often advocated, but here, too, there may be a tendency to judge these risks more harshly than those in other areas with similar strength of evidence. PMID:16551794

  18. Electric field-induced lateral mobility of photosystem I in the photosynthetic membrane

    PubMed Central

    Brumfeld, Vlad; Miller, Israel R.; Korenstein, Rafi

    1989-01-01

    Electrophoretic movement of photosystem I (PS I) along the photosynthetic membrane of hypotonically swollen thylakoid vesicles was studied by analyzing the electric field-stimulated delayed luminescence (electrophotoluminescence) emitted from PS I. The electrophoretic mobility was inferred from the differences in electrophotoluminescence (EPL) of the photosynthetic vesicles in presence and absence of trains of low amplitude (<80 V/cm) prepulses of 1 ms duration at 4 ms spacing. The average apparent electric mobility, determined from the time course of EPL increase on one hemisphere or its decrease on the other one, as function of prepulse length and intensity was of the order of 3 · 10-5 cm2V-1s-1. The assymetric distribution of the PS I reached a steady state when the diffusional, electrostatic, and elastic forces balanced the electrophoretic driving force. A lateral diffusion coefficient of ∼5 · 10-9 cm2s-1 was found for the PS I complex from the diffusional relaxation after cessation of the electric field pulse train. Experimental conditions such as concentration, temperature, and viscosity of the aqueous solution were not critical for the effect. Between 23 and 150 electron charges per moving particle were estimated from the measured electrophoretic mobility. PMID:19431746

  19. Diffusion of Electric Vehicles and Novel Social Infrastructure from the Viewpoint of Systems Innovation Theory

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takaaki

    This paper describes diffusion of electric vehicles and novel social infrastructure from the viewpoint of systems innovation theory considering both human society aspects and elemental technological aspects. Firstly, fundamentals of the systems innovation theory and the platform theory are mentioned. Secondly, discussion on mobility from the viewpoint of the human-society layer and discussion of electrical vehicles from the viewpoint of the elemental techniques are carried out. Thirdly, based on those, R & D, measures are argued such as establishment of the ubiquitous noncontact feeding and authentication payment system is important. Finally, it is also insisted that after the establishment of this system the super smart grid with temporal and spatial control including demand itself with the low social cost will be expected.

  20. Nanoengineering the built-in electric field of a photonic device by interstitial-ion diffusion

    NASA Astrophysics Data System (ADS)

    Nasir, A.; Makarovsky, O.; Kumar, S.; Fay, M. W.; Campion, R.; Rastelli, A.; Schmidt, O. G.; Eaves, L.; Patanè, A.

    2012-05-01

    We use focused laser annealing to activate the diffusion of Mn-interstitial ions (Mni2+) from a p-(GaMn)As layer towards the intrinsic GaAs/AlAs quantum well (QW) region of a p-i-n light emitting diode (LED). The random clustering of the Mni2+ ions creates a complex potential landscape U and electric field FMn=-∇U in the QW plane, which we probe with nanoscale precision by monitoring the quantum-confined Stark shift of the “natural” quantum dots formed in the QW. The use of focused laser annealing to form electric field landscapes at predetermined positions is potentially applicable to other material systems containing mobile dopant atoms and is relevant to research on nanophotonics and manipulation of quantum devices.

  1. Electric and magnetic contributions to spatial diffusion in collisionless plasmas

    SciTech Connect

    Smets, R.; Belmont, G.; Aunai, N.

    2012-10-15

    We investigate the role played by the different self-consistent fluctuations for particle diffusion in a magnetized plasma. We focus especially on the contribution of the electric fluctuations and how it combines with the (already investigated) magnetic fluctuations and with the velocity fluctuations. For that issue, we compute with a hybrid code the value of the diffusion coefficient perpendicular to the mean magnetic field and its dependence on the particle velocity. This study is restricted to small to intermediate level of electromagnetic fluctuations and focuses on particle velocities on the order of few times the Alfven speed. We briefly discuss the consequences for cosmic ray modulation and for the penetration of thermal solar wind particles in the Earth magnetosphere.

  2. Using Mobile Agents and Overlay Networks to Secure Electrical Netoworks

    SciTech Connect

    Dawes, Neal A.; Prosser, Bryan J.; Fulp, Errin W.; McKinnon, Archibald D.

    2013-04-01

    ABSTRACT The use of wandering, mobile agents can provide a robust approach for managing, monitoring, and securing electrical distribution networks. However, the topological structure of electrical networks can affect system performance. For example, if the multi-agent system relies on a regular inspection rate (on average, points of interest are inspected with equal frequency), then locations that are not well connected will on average be inspected less frequently. This paper discusses creation and use of overlay networks that create a virtual grid graph can provide faster coverage and a more uniform average agent sampling rate. Using overlays agents wander a virtual neighborhood consisting of only points of interest that are interconnected in a regular fashion (each point has the same number of neighbors). Experimental results will show that an overlay can often provide better network coverage and a more uniform inspection rate, which can improve cyber security by providing a faster detection of threats

  3. Experimental evaluation of electrical conductivity imaging of anisotropic brain tissues using a combination of diffusion tensor imaging and magnetic resonance electrical impedance tomography

    NASA Astrophysics Data System (ADS)

    Sajib, Saurav Z. K.; Jeong, Woo Chul; Kyung, Eun Jung; Kim, Hyun Bum; Oh, Tong In; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2016-06-01

    Anisotropy of biological tissues is a low-frequency phenomenon that is associated with the function and structure of cell membranes. Imaging of anisotropic conductivity has potential for the analysis of interactions between electromagnetic fields and biological systems, such as the prediction of current pathways in electrical stimulation therapy. To improve application to the clinical environment, precise approaches are required to understand the exact responses inside the human body subjected to the stimulated currents. In this study, we experimentally evaluate the anisotropic conductivity tensor distribution of canine brain tissues, using a recently developed diffusion tensor-magnetic resonance electrical impedance tomography method. At low frequency, electrical conductivity of the biological tissues can be expressed as a product of the mobility and concentration of ions in the extracellular space. From diffusion tensor images of the brain, we can obtain directional information on diffusive movements of water molecules, which correspond to the mobility of ions. The position dependent scale factor, which provides information on ion concentration, was successfully calculated from the magnetic flux density, to obtain the equivalent conductivity tensor. By combining the information from both techniques, we can finally reconstruct the anisotropic conductivity tensor images of brain tissues. The reconstructed conductivity images better demonstrate the enhanced signal intensity in strongly anisotropic brain regions, compared with those resulting from previous methods using a global scale factor.

  4. Contrasting Diffusion Patterns for PC and Mobile Videos: A User-Centric View of the Influencing Factors

    ERIC Educational Resources Information Center

    Wu, Baixue

    2010-01-01

    As both computer and mobile phone reach nearly ubiquity in the U.S. market, the slow uptake of mobile video, in contrast to the thriving usage of PC-based video, warrants a deeper understanding of user-oriented factors contributing to the two diffusion paths. Unlike the majority of existing diffusion research practices, the dissertation…

  5. High precision measurements of carbon disulfide negative ion mobility and diffusion

    NASA Astrophysics Data System (ADS)

    Snowden-Ifft, D. P.; Gauvreau, J.-L.

    2013-05-01

    High precision measurements were made of reduced mobility, lateral and longitudinal diffusion of CS2- ions in 40 Torr CS2 and a 30-10 Torr CS2-CF4 gas mixture. The reduced mobility was found to be 0.4645 ± 0.0006 cm2 atm/s V in CS2 and 0.523 ± 0.001 cm2 atm/s V in the CS2-CF4 gas mixture at STP. The lateral diffusion temperatures for these two gases (295 ± 15 K and 297 ± 6 K) were found to be in good agreement with room temperature. By contrast longitudinal diffusion temperature was found to be slightly elevated (319 ± 10 (stat) ± 8 (sys) K and 310 ± 20 (stat) ± 6 (sys) K) though given the errors, room temperature diffusion cannot be ruled out. For lateral diffusion, significant capture distances (0.21 ± 0.07 mm and 0.15 ± 0.03 mm) were measured while for longitudinal diffusion the results were not conclusive.

  6. Anomalous diffusion due to hindering by mobile obstacles undergoing Brownian motion or Orstein-Ulhenbeck processes.

    PubMed

    Berry, Hugues; Chaté, Hugues

    2014-02-01

    In vivo measurements of the passive movements of biomolecules or vesicles in cells consistently report "anomalous diffusion," where mean-squared displacements scale as a power law of time with exponent α<1 (subdiffusion). While the detailed mechanisms causing such behaviors are not always elucidated, movement hindrance by obstacles is often invoked. However, our understanding of how hindered diffusion leads to subdiffusion is based on diffusion amidst randomly located immobile obstacles. Here, we have used Monte Carlo simulations to investigate transient subdiffusion due to mobile obstacles with various modes of mobility. Our simulations confirm that the anomalous regimes rapidly disappear when the obstacles move by Brownian motion. By contrast, mobile obstacles with more confined displacements, e.g., Orstein-Ulhenbeck motion, are shown to preserve subdiffusive regimes. The mean-squared displacement of tracked protein displays convincing power laws with anomalous exponent α that varies with the density of Orstein-Ulhenbeck (OU) obstacles or the relaxation time scale of the OU process. In particular, some of the values we observed are significantly below the universal value predicted for immobile obstacles in two dimensions. Therefore, our results show that subdiffusion due to mobile obstacles with OU type of motion may account for the large variation range exhibited by experimental measurements in living cells and may explain that some experimental estimates are below the universal value predicted for immobile obstacles. PMID:25353510

  7. Comparison of diffusion charging and mobility-based methods for measurement of aerosol agglomerate surface area

    PubMed Central

    Ku, Bon Ki; Kulkarni, Pramod

    2015-01-01

    We compare different approaches to measure surface area of aerosol agglomerates. The objective was to compare field methods, such as mobility and diffusion charging based approaches, with laboratory approach, such as Brunauer, Emmett, Teller (BET) method used for bulk powder samples. To allow intercomparison of various surface area measurements, we defined ‘geometric surface area’ of agglomerates (assuming agglomerates are made up of ideal spheres), and compared various surface area measurements to the geometric surface area. Four different approaches for measuring surface area of agglomerate particles in the size range of 60–350 nm were compared using (i) diffusion charging-based sensors from three different manufacturers, (ii) mobility diameter of an agglomerate, (iii) mobility diameter of an agglomerate assuming a linear chain morphology with uniform primary particle size, and (iv) surface area estimation based on tandem mobility–mass measurement and microscopy. Our results indicate that the tandem mobility–mass measurement, which can be applied directly to airborne particles unlike the BET method, agrees well with the BET method. It was also shown that the three diffusion charging-based surface area measurements of silver agglomerates were similar within a factor of 2 and were lower than those obtained from the tandem mobility–mass and microscopy method by a factor of 3–10 in the size range studied. Surface area estimated using the mobility diameter depended on the structure or morphology of the agglomerate with significant underestimation at high fractal dimensions approaching 3. PMID:26692585

  8. Anomalous diffusion due to hindering by mobile obstacles undergoing Brownian motion or Orstein-Ulhenbeck processes

    NASA Astrophysics Data System (ADS)

    Berry, Hugues; Chaté, Hugues

    2014-02-01

    In vivo measurements of the passive movements of biomolecules or vesicles in cells consistently report "anomalous diffusion," where mean-squared displacements scale as a power law of time with exponent α <1 (subdiffusion). While the detailed mechanisms causing such behaviors are not always elucidated, movement hindrance by obstacles is often invoked. However, our understanding of how hindered diffusion leads to subdiffusion is based on diffusion amidst randomly located immobile obstacles. Here, we have used Monte Carlo simulations to investigate transient subdiffusion due to mobile obstacles with various modes of mobility. Our simulations confirm that the anomalous regimes rapidly disappear when the obstacles move by Brownian motion. By contrast, mobile obstacles with more confined displacements, e.g., Orstein-Ulhenbeck motion, are shown to preserve subdiffusive regimes. The mean-squared displacement of tracked protein displays convincing power laws with anomalous exponent α that varies with the density of Orstein-Ulhenbeck (OU) obstacles or the relaxation time scale of the OU process. In particular, some of the values we observed are significantly below the universal value predicted for immobile obstacles in two dimensions. Therefore, our results show that subdiffusion due to mobile obstacles with OU type of motion may account for the large variation range exhibited by experimental measurements in living cells and may explain that some experimental estimates are below the universal value predicted for immobile obstacles.

  9. Degenerate mobilities in phase field models are insufficient to capture surface diffusion

    NASA Astrophysics Data System (ADS)

    Lee, Alpha A.; Münch, Andreas; Süli, Endre

    2015-08-01

    Phase field models frequently provide insight into phase transitions and are robust numerical tools to solve free boundary problems corresponding to the motion of interfaces. A body of prior literature suggests that interface motion via surface diffusion is the long-time, sharp interface limit of microscopic phase field models such as the Cahn-Hilliard equation with a degenerate mobility function. Contrary to this conventional wisdom, we show that the long-time behaviour of degenerate Cahn-Hilliard equation with a polynomial free energy undergoes coarsening, reflecting the presence of bulk diffusion, rather than pure surface diffusion. This reveals an important limitation of phase field models that are frequently used to model surface diffusion.

  10. Analysing the diffusion and adoption of mobile IT across social worlds.

    PubMed

    Nielsen, Jeppe Agger; Mengiste, Shegaw Anagaw

    2014-06-01

    The diffusion and adoption of information technology innovations (e.g. mobile information technology) in healthcare organizations involves a dynamic process of change with multiple stakeholders with competing interests, varying commitments, and conflicting values. Nevertheless, the extant literature on mobile information technology diffusion and adoption has predominantly focused on organizations and individuals as the unit of analysis, with little emphasis on the environment in which healthcare organizations are embedded. We propose the social worlds approach as a promising theoretical lens for dealing with this limitation together with reports from a case study of a mobile information technology innovation in elderly home care in Denmark including both the sociopolitical and organizational levels in the analysis. Using the notions of social worlds, trajectories, and boundary objects enables us to show how mobile information technology innovation in Danish home care can facilitate negotiation and collaboration across different social worlds in one setting while becoming a source of tension and conflicts in others. The trajectory of mobile information technology adoption was shaped by influential stakeholders in the Danish home care sector. Boundary objects across multiple social worlds legitimized the adoption, but the use arrangement afforded by the new technology interfered with important aspects of home care practices, creating resistance among the healthcare personnel. PMID:24810724

  11. Ammonia mobility in chabazite: insight into the diffusion component of the NH3-SCR process.

    PubMed

    O'Malley, Alexander J; Hitchcock, Iain; Sarwar, Misbah; Silverwood, Ian P; Hindocha, Sheena; Catlow, C Richard A; York, Andrew P E; Collier, P J

    2016-06-29

    The diffusion of ammonia in commercial NH3-SCR catalyst Cu-CHA was measured and compared with H-CHA using quasielastic neutron scattering (QENS) and molecular dynamics (MD) simulations to assess the effect of counterion presence on NH3 mobility in automotive emission control relevant zeolite catalysts. QENS experiments observed jump diffusion with a jump distance of 3 Å, giving similar self-diffusion coefficient measurements for both Cu- and H-CHA samples, in the range of ca. 5-10 × 10(-10) m(2) s(-1) over the measured temperature range. Self-diffusivities calculated by MD were within a factor of 6 of those measured experimentally at each temperature. The activation energies of diffusion were also similar for both studied systems: 3.7 and 4.4 kJ mol(-1) for the H- and Cu-chabazite respectively, suggesting that counterion presence has little impact on ammonia diffusivity on the timescale of the QENS experiment. An explanation is given by the MD simulations, which showed the strong coordination of NH3 with Cu(2+) counterions in the centre of the chabazite cage, shielding other molecules from interaction with the ion, and allowing for intercage diffusion through the 8-ring windows (consistent with the experimentally observed jump length) to carry on unhindered. PMID:27306298

  12. Using Measurements of Mobility, Diffusion, and Dispersion to Predict Separation Resolution in DNA Electrophoresis

    NASA Astrophysics Data System (ADS)

    Lo, Roger

    2005-03-01

    Electrophoresis of DNA continues to be a key component in a wide variety of genomic analysis assays. In order to customize and optimize these assay systems, much effort has been directed to improve and predict separation resolution using various sieving matrices and experimental platforms. Predicting separation resolution requires a much more detailed understanding of mobility, diffusion, and dispersion phenomena of DNA fragments migrating in the sieving matrix than is currently available in literature. In this study, we address this issue by obtaining a series of systematic measurements of mobility, diffusion, and dispersion using an automated DNA sequencer. Using this data, we are able to isolate key factors governing separation performance, and make comparisons with biased reptation theory to extract information on gel structure and predict achievable resolution under each set of operating conditions. We are also able to predict the separation resolution under specific run conditions, thereby giving researchers and engineers the ability to easily tailor DNA separation systems for required separation performance.

  13. Monte Carlo Demonstration of Solid-State Diffusion in an Electric Field.

    ERIC Educational Resources Information Center

    Murch, G. E.

    1979-01-01

    Describes the phenomenological and microscopic aspects of solid-state diffusion in an electric field and presents a Monte Carlo method which is used to stimulate an atomistic model of diffusion in an electric field. The Nernst-Einstein relation is also discussed. (HM)

  14. Neuromuscular Electrical Stimulation for Mobility Support of Elderly.

    PubMed

    Mayr, Winfried

    2015-08-24

    The stimulator for neuromuscular electrical stimulation for mobility support of elderly is not very complicated, but for application within "MOBIL" we have some additional demands to fulfill. First we have specific safety issues for this user group. A powerful compliance management system is crucial not only to guide daily application, but for creating hard data for the scientific outcome. We also need to assure easy handling of the stimulator, because the subjects are generally not able to cope with too difficult and complex motor skills. So, we developed five generations of stimulators and optimizing solutions after field tests. We are already planning the sixth generation with wireless control of the stimulation units by the central main handheld control unit. In a prototype, we have implemented a newly available high capacity memory, a breakthrough in "compliance data storage" as they offer the necessary high storage capacity and fast data handling for an affordable prize. The circuit also contains a 3D accelerometer sensor which acts as a further important safety features: if the control unit drops, this event is detected automatically by the sensor and activates an emergency switch-off that disables the stimulation to avoid associated risks. Further, we have implemented a hardware emergence shutdown and other safety measures. Finally, in the last example muscle torque measurements are referenced with compliance data. In the study normalized maximum voluntary contraction (MVC) and maximum stimulation induced contraction (MSC) were assessed in regular check-ups along the training period. With additional consideration of adjusted stimulation intensity for training out of the compliance data records we are able to estimate the induced contraction strength, which turned out to amount in average 11% of MVC. This value may seem on a first sight rather low, and ought to be considered in relation to the results at the end of the training period. Therefore the

  15. Influence of diffusive porosity architecture on kinetically-controlled reactions in mobile-immobile models

    NASA Astrophysics Data System (ADS)

    Babey, T.; Ginn, T. R.; De Dreuzy, J. R.

    2014-12-01

    Solute transport in porous media may be structured at various scales by geological features, from connectivity patterns of pores to fracture networks. This structure impacts solute repartition and consequently reactivity. Here we study numerically the influence of the organization of porous volumes within diffusive porosity zones on different reactions. We couple a mobile-immobile transport model where an advective zone exchanges with diffusive zones of variable structure to the geochemical modeling software PHREEQC. We focus on two kinetically-controlled reactions, a linear sorption and a nonlinear dissolution of a mineral. We show that in both cases the structure of the immobile zones has an important impact on the overall reaction rates. Through the Multi-Rate Mass Transfer (MRMT) framework, we show that this impact is very well captured by residence times-based models for the kinetic linear sorption, as it is mathematically equivalent to a modification of the initial diffusive structure; Consequently, the overall reaction rate could be easily extrapolated from a conservative tracer experiment. The MRMT models however struggle to reproduce the non-linearity and the threshold effects associated with the kinetic dissolution. A slower reaction, by allowing more time for diffusion to smooth out the concentration gradients, tends to increase their relevance. Figure: Left: Representation of a mobile-immobile model with a complex immobile architecture. The mobile zone is indicated by an arrow. Right: Total remaining mass of mineral in mobile-immobile models and in their equivalent MRMT models during a flush by a highly under-saturated solution. The models only differ by the organization of their immobile porous volumes.

  16. Temperature dependence of diffusion length, lifetime and minority electron mobility in GaInP

    SciTech Connect

    Schultes, F. J.; Haegel, N. M.; Christian, T.; Alberi, K.; Fluegel, B.; Jones-Albertus, R.; Pickett, E.; Liu, T.; Misra, P.; Sukiasyan, A.; Yuen, H.

    2013-12-09

    The mobility of electrons in double heterostructures of p-type Ga{sub 0.50}In{sub 0.50}P has been determined by measuring minority carrier diffusion length and lifetime. The minority electron mobility increases monotonically from 300 K to 5 K, limited primarily by optical phonon and alloy scattering. Comparison to majority electron mobility over the same temperature range in comparably doped samples shows a significant reduction in ionized impurity scattering at lower temperatures, due to differences in interaction of repulsive versus attractive carriers with ionized dopant sites. These results should be useful in modeling and optimization for multi-junction solar cells and other optoelectronic devices.

  17. Monitoring of gliomas in vivo by diffusion MRI and (1)H MRS during gene therapy-induced apoptosis: interrelationships between water diffusion and mobile lipids.

    PubMed

    Liimatainen, Timo; Hakumäki, Juhana M; Kauppinen, Risto A; Ala-Korpela, Mika

    2009-04-01

    The measurement of water diffusion by diffusion-weighted MRI (DWI) in vivo offers a non-invasive method for assessing tissue responses to anti-cancer therapies. The pathway of cell death after anti-cancer treatment is often apoptosis, which leads to accumulation of mobile lipids detectable by (1)H MRS in vivo. However, it is not known how these discrete MR markers of cell death relate to each other. In a rodent tumour model [i.e. ganciclovir-treated herpes simplex thymidine kinase (HSV-tk) gene-transfected BT4C gliomas], we studied the interrelationships between water diffusion (Trace{D}) and mobile lipids during apoptosis. Water diffusion and water-referenced concentrations of mobile lipids showed clearly increasing and interconnected trends during treatment. Of the accumulating (1)H MRS-visible lipids, the fatty acid --CH==CH-- groups and cholesterol compounds showed the strongest associations with water diffusion (r(2) = 0.30; P < 0.05 and r(2) = 0.48; P < 0.01, respectively). These results indicate that the tumour histopathology and apoptotic processes during tumour shrinkage can be interrelated in vivo by DWI of tissue water and (1)H MRS of mobile lipids, respectively. However, there is considerable individual variation in the associations, particularly at the end of the treatment period, and in the relative compositions of the accumulating NMR-visible lipids. The findings suggest that the assessment of individual treatment response in vivo may benefit from combining DWI and (1)H MRS. Absolute and relative changes in mobile lipids may indicate initiation of tumour shrinkage even when changes in tissue water diffusion are still small. Conversely, greatly increased water diffusion probably indicates that substantial cell decomposition has taken place in the tumour tissue when the (1)H MRS resonances of mobile lipids alone can no longer give a reliable estimate of tissue conditions. PMID:19009568

  18. Neuromuscular Electrical Stimulation for Mobility Support of Elderly

    PubMed Central

    2015-01-01

    The stimulator for neuromuscular electrical stimulation for mobility support of elderly is not very complicated, but for application within “MOBIL” we have some additional demands to fulfill. First we have specific safety issues for this user group. A powerful compliance management system is crucial not only to guide daily application, but for creating hard data for the scientific outcome. We also need to assure easy handling of the stimulator, because the subjects are generally not able to cope with too difficult and complex motor skills. So, we developed five generations of stimulators and optimizing solutions after field tests. We are already planning the sixth generation with wireless control of the stimulation units by the central main handheld control unit. In a prototype, we have implemented a newly available high capacity memory, a breakthrough in “compliance data storage” as they offer the necessary high storage capacity and fast data handling for an affordable prize. The circuit also contains a 3D accelerometer sensor which acts as a further important safety features: if the control unit drops, this event is detected automatically by the sensor and activates an emergency switch-off that disables the stimulation to avoid associated risks. Further, we have implemented a hardware emergence shutdown and other safety measures. Finally, in the last example muscle torque measurements are referenced with compliance data. In the study normalized maximum voluntary contraction (MVC) and maximum stimulation induced contraction (MSC) were assessed in regular check-ups along the training period. With additional consideration of adjusted stimulation intensity for training out of the compliance data records we are able to estimate the induced contraction strength, which turned out to amount in average 11% of MVC. This value may seem on a first sight rather low, and ought to be considered in relation to the results at the end of the training period. Therefore the

  19. Electric field-induced lateral mobility of photosystem I in the photosynthetic membrane: A study by electrophotoluminescence.

    PubMed

    Brumfeld, V; Miller, I R; Korenstein, R

    1989-09-01

    Electrophoretic movement of photosystem I (PS I) along the photosynthetic membrane of hypotonically swollen thylakoid vesicles was studied by analyzing the electric field-stimulated delayed luminescence (electrophotoluminescence) emitted from PS I. The electrophoretic mobility was inferred from the differences in electrophotoluminescence (EPL) of the photosynthetic vesicles in presence and absence of trains of low amplitude (<80 V/cm) prepulses of 1 ms duration at 4 ms spacing. The average apparent electric mobility, determined from the time course of EPL increase on one hemisphere or its decrease on the other one, as function of prepulse length and intensity was of the order of 3 . 10(-5) cm(2)V(-1)s(-1). The assymetric distribution of the PS I reached a steady state when the diffusional, electrostatic, and elastic forces balanced the electrophoretic driving force. A lateral diffusion coefficient of approximately 5 . 10(-9) cm(2)s(-1) was found for the PS I complex from the diffusional relaxation after cessation of the electric field pulse train. Experimental conditions such as concentration, temperature, and viscosity of the aqueous solution were not critical for the effect. Between 23 and 150 electron charges per moving particle were estimated from the measured electrophoretic mobility. PMID:19431746

  20. Thermally Activated Point Defect Diffusion in Methylammonium Lead Trihalide: Anisotropic and Ultrahigh Mobility of Iodine.

    PubMed

    Delugas, P; Caddeo, C; Filippetti, A; Mattoni, A

    2016-07-01

    We study the diffusion of point defects in crystalline methylammonium lead halide (MAPI) at finite temperatures by using all-atoms molecular dynamics. We find that, for what concerns intrinsic defects, iodine diffusion is by far the dominant mechanism of ionic transport in MAPI, with diffusivities as high as 7.4 × 10(-7) and 4.3 × 10(-6) cm(2) s(-1) at 300 K and single activation energies of 0.24 and 0.10 eV, for interstitials and vacancies, respectively. The comparison with common covalent and oxide crystals reveals the ultrahigh mobility of defects in MAPI. Though at room temperature the vacancies are about 1 order of magnitude more diffusive, the anisotropic interstitial dynamics increases more rapidly with temperature, and it can be dominant at high temperatures. Present results are fully consistent with the involvement of iodide ions in hysteresis and have implications for improvement of the material quality by better control of defect diffusion. PMID:27237630

  1. ELECTROKINETIC PHENOMENA : XI. ACTION OF UNI-UNIVALENT ELECTROLYTES ON ELECTRIC MOBILITY OF PROTEINS.

    PubMed

    Abramson, H A

    1933-03-20

    By assuming that the electric charge of proteins is primarily determined by the hydrogen ion activity of the medium, and by making corrections when necessary for the effect of salt, it is possible to derive a simple relationship between the electric mobility of proteins and the effective reciprocal thickness of the electric double layer. The decrease in electric mobility of proteins in solutions is readily predicted for gelatin in acetate buffers and for egg albumin in the presence of the alkali halides, of acetate buffers, and of hydrochloric acid on the basis of the assumptions made. PMID:19872724

  2. Mechanical analysis of photo-electricity measure equipment shafting in mobile-platform

    NASA Astrophysics Data System (ADS)

    Jiang, Weiwei; Hu, Hongyi; Tan, Yi; Liu, Ruzhen

    2015-02-01

    Along with the development of technology, photo-electricity measure equipment has been from ground-fixed to mobile-platform borne, So it is need to mechanical analysis of shafting for adapt movement environment of mobile-platform. First listed three kinds of shafting form, then analysis mechanical station of the foremost component bearing in vertical load, radial load, swing load station, last work out the formulas, which was the theory for the shafting design in mobile-platforms photo-electricity equipment.

  3. On the calculation of electric diffusion coefficient of radiation belt electrons with in situ electric field measurements by THEMIS

    NASA Astrophysics Data System (ADS)

    Liu, Wenlong; Tu, Weichao; Li, Xinlin; Sarris, Theodore; Khotyaintsev, Yuri; Fu, Huishan; Zhang, Hui; Shi, Quanqi

    2016-02-01

    Based on 7 years' observations from Time History of Events and Macroscale Interactions during Substorms (THEMIS), we investigate the statistical distribution of electric field Pc5 ULF wave power under different geomagnetic activities and calculate the radial diffusion coefficient due to electric field, , for outer radiation belt electrons. A simple empirical expression of is also derived. Subsequently, we compare to previous DLL models and find similar Kp dependence with the model, which is also based on in situ electric field measurements. The absolute value of is constantly higher than , probably due to the limited orbital coverage of CRRES. The differences between and the commonly used and models are significant, especially in Kp dependence and energy dependence. Possible reasons for these differences and their implications are discussed. The diffusion coefficient provided in this paper, which also has energy dependence, will be an important contributor to quantify the radial diffusion process of radiation belt electrons.

  4. Discrete-continuous reaction-diffusion model with mobile point-like sources and sinks.

    PubMed

    Kondrat, Svyatoslav; Zimmermann, Olav; Wiechert, Wolfgang; von Lieres, Eric

    2016-01-01

    In many applications in soft and biological physics, there are multiple time and length scales involved but often with a distinct separation between them. For instance, in enzyme kinetics, enzymes are relatively large, move slowly and their copy numbers are typically small, while the metabolites (being transformed by these enzymes) are often present in abundance, are small in size and diffuse fast. It seems thus natural to apply different techniques to different time and length levels and couple them. Here we explore this possibility by constructing a stochastic-deterministic discrete-continuous reaction-diffusion model with mobile sources and sinks. Such an approach allows in particular to separate different sources of stochasticity. We demonstrate its application by modelling enzyme-catalysed reactions with freely diffusing enzymes and a heterogeneous source of metabolites. Our calculations suggest that using a higher amount of less active enzymes, as compared to fewer more active enzymes, reduces the metabolite pool size and correspondingly the lag time, giving rise to a faster response to external stimuli. The methodology presented can be extended to more complex systems and offers exciting possibilities for studying problems where spatial heterogeneities, stochasticity or discreteness play a role. PMID:26830760

  5. Diffusion, Dispersion, and Mobility of Single-stranded DNA in Polyacrylamide Gel Electrophoresis

    NASA Astrophysics Data System (ADS)

    Lo, Roger; Ugaz, Victor

    2004-03-01

    The ability to perform DNA electrophoresis in miniaturized microfluidic systems has the potential to provide a new generation of low-cost high-throughput genomic analysis technology. Further progress toward improving separation performance under these conditions, however, requires a more detailed understanding of diffusion and dispersion phenomena in the gel matrix. Unfortunately, it has thus far proven difficult to obtain extensive measurements of these quantities due in large part to the lack of a convenient experimental platform. In this paper, we demonstrate the use of microfabricated gel electrophoresis devices to measure diffusion, dispersion, and mobility of single-stranded DNA fragments in crosslinked and uncrosslinked polyacrylamide gels. The microdevice format allows a complete set of diffusion and dispersion data to be collected in approximately one hour, as opposed to experiment times lasting several days using conventional sequencing equipment. By comparing runs using identical DNA samples, gel formulations, and operating conditions in both microfabricated electrophoresis devices and an ALF Express automated DNA sequencer, we are able to isolate the key factors governing separation performance in each system. The results of these experiments are then compared with biased reptation theory to extract information about the gel structure and predict achievable resolution. The effects of gel composition and polymerization chemistry are also explored.

  6. Comparison of the Unique Mobility and DOE-developed ac electric drive systems

    SciTech Connect

    Cole, G.H.

    1993-01-01

    A comparison was made between the most recent DOE-developed AC electric vehicle drive systems and that which is independently under development by Unique Mobility of Golden, Colorado. The DOE-developed AC systems compared in this study are the Single-Shaft Electric Propulsion System (ETX-II) developed by Ford Motor Company and the General Electric Company under contract number DE-AC07-85NV10418, the Dual-Shaft Electric Propulsion (DSEP) System developed by Eaton Corporation under contract number DOE-AC08-84NV-10366, and the anticipated results of the Modular Electric Vehicle (MEV) system currently being developed by Ford and General Electric under contract number DE-AC07-90ID13019. The Unique Mobility brushless DC electric vehicle drive system represents their latest electric drive technology and is being developed in cooperation with BMW Technik Gmbh of Germany. Comparisons of specific volume, specific weight, efficiency and expected vehicle performance are made of the different systems based upon measured system performance data where available. One conclusion presented is that the Unique Mobility drive system under development with BMW appears to provide comparable performance to the AC systems studied.

  7. An electrically assisted device for protein crystallization in a vapor-diffusion setup

    PubMed Central

    Flores-Hernández, Edith; Stojanoff, Vivian; Arreguín-Espinosa, Roberto; Moreno, Abel; Sánchez-Puig, Nuria

    2013-01-01

    A new easy-to-use device has been designed and implemented for electric field-induced protein crystallization in a vapor-diffusion configuration. The device not only controls crystal nucleation by means of the electrical current, but also favors crystal growth owing to its vapor-diffusion setup. Crystallization was conducted in the presence of an internal electric field and direct current. The proteins investigated were lysozyme, as model protein, and 2TEL–lysozyme (a synthetic protein consisting of two tandem alpha helix motifs connected to a lysozyme moiety). Lysozyme crystals that grew attached to the cathode were larger than those grown attached to the anode or in the absence of an electric current. On the other hand, crystals of 2TEL–lysozyme qualitatively showed a better X-ray diffraction pattern when grown in the presence of an electric current. PMID:23682197

  8. Mobility Measurement Based on Visualized Electric Field Migration in Organic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Manaka, Takaaki; Liu, Fei; Weis, Martin; Iwamoto, Mitsumasa

    2009-06-01

    Based on the transient electric field migration directly probed by the time-resolved microscopic optical second-harmonic generation (TRM-SHG) technique, we developed a “dynamic” approach to evaluate the carrier mobility in organic field-effect transistor (OFET). The accuracy of this potential- and current-independent approach was well confirmed by computational simulations and a comparison with the conventional mobility measured by OFET transfer characteristics.

  9. Molecular dynamics simulation of diffusion and electrical conductivity in montmorillonite interlayers

    DOE PAGESBeta

    Greathouse, Jeffery A.; Cygan, Randall T.; Fredrich, Joanne T.; Jerauld, Gary R.

    2016-01-20

    In this study, the diffusion of water and ions in the interlayer region of smectite clay minerals represents a direct probe of the type and strength of clay–fluid interactions. Interlayer diffusion also represents an important link between molecular simulation and macroscopic experiments. Here we use molecular dynamics simulation to investigate trends in cation and water diffusion in montmorillonite interlayers, looking specifically at the effects of layer charge, interlayer cation and cation charge (sodium or calcium), water content, and temperature. For Na-montmorillonite, the largest increase in ion and water diffusion coefficients occurs between the one-layer and two-layer hydrates, corresponding to themore » transition from inner-sphere to outer-sphere surface complexes. Calculated activation energies for ion and water diffusion in Na-montmorillonite are similar to each other and to the water hydrogen bond energy, suggesting the breaking of water–water and water–clay hydrogen bonds as a likely mechanism for interlayer diffusion. A comparison of interlayer diffusion with that of bulk electrolyte solutions reveals a clear trend of decreasing diffusion coefficient with increasing electrolyte concentration, and in most cases the interlayer diffusion results are nearly coincident with the corresponding bulk solutions. Trends in electrical conductivities computed from the ion diffusion coefficients are also compared.« less

  10. Progress in utilization of a mobile laboratory for making storm electricity measurements

    NASA Technical Reports Server (NTRS)

    Rust, W. David

    1988-01-01

    A mobile atmospheric science laboratory has been used to intercept and track storms on the Great Plains region of the U.S., with the intention of combining the data obtained with those from Doppler and conventional radars, NASA U-2 aircraft overflights, balloon soundings, and fixed-base storm electricity measurements. The mobile lab has proven to be valuable in the gathering of ground truth verifications for the two commercially operated lightning ground-strike locating systems. Data acquisition has recently been expanded by means of mobile ballooning before and during storms.

  11. Mobile impurities in one-dimensional cold gases: subdiffusive, diffusive and ballistic regimes

    NASA Astrophysics Data System (ADS)

    Kantian, Adrian; Giamarchi, Thierry

    2012-02-01

    Advances in cold gases physics are beginning to enable experiments involving the direct manipulation and observation of single- or few-atom mobile impurities [1] within a many-body quantum system, a topic of longstanding interest for condensed matter theory, where it is related to studies of e.g. conductivity and the X-ray edge problem. Further progress in this direction is expected from the latest generation of experiments offering single-site addressability in optical lattices [2,3]. In light of these developments we study the dynamics of mobile impurities in 1D quantum liquids using a DMRG technique. We address the recently proposed subdiffusive regime of impurity motion [4], a class of excitations beyond those described by the standard Tomonaga-Luttinger theory. We study the conditions for observing this regime and its' crossover to the ballistic regime. We furthermore examine the possibilities to observe the intermediate diffusive motion of impurities in these systems. [4pt] [1] J. Catani, G. Lamporesi, D. Naik et. al., arXiv:1106.0828[0pt] [2] W. S. Bakr, J. I. Gillen, A. Peng et. al., Nature 462, 74 (2009)[0pt] [3] J. F. Sherson, C. Weitenberg, M. Endres et. al., Nature, 467, 7311 (2010)[0pt] [4] M. B. Zvonarev, V. V. Cheianov, T. Giamarchi, PRL 99, 240404 (2007); PRL 103, 110401 (2009)

  12. Theory of activated glassy relaxation, mobility gradients, surface diffusion, and vitrification in free standing thin films

    SciTech Connect

    Mirigian, Stephen E-mail: smirigian@gmail.com; Schweizer, Kenneth S. E-mail: smirigian@gmail.com

    2015-12-28

    We have constructed a quantitative, force level, statistical mechanical theory for how confinement in free standing thin films introduces a spatial mobility gradient of the alpha relaxation time as a function of temperature, film thickness, and location in the film. The crucial idea is that relaxation speeds up due to the reduction of both near-surface barriers associated with the loss of neighbors in the local cage and the spatial cutoff and dynamical softening near the vapor interface of the spatially longer range collective elasticity cost for large amplitude hopping. These two effects are fundamentally coupled. Quantitative predictions are made for how an apparent glass temperature depends on the film thickness and experimental probe technique, the emergence of a two-step decay and mobile layers in time domain measurements, signatures of confinement in frequency-domain dielectric loss experiments, the dependence of film-averaged relaxation times and dynamic fragility on temperature and film thickness, surface diffusion, and the relationship between kinetic experiments and pseudo-thermodynamic measurements such as ellipsometry.

  13. Theory of activated glassy relaxation, mobility gradients, surface diffusion, and vitrification in free standing thin films.

    PubMed

    Mirigian, Stephen; Schweizer, Kenneth S

    2015-12-28

    We have constructed a quantitative, force level, statistical mechanical theory for how confinement in free standing thin films introduces a spatial mobility gradient of the alpha relaxation time as a function of temperature, film thickness, and location in the film. The crucial idea is that relaxation speeds up due to the reduction of both near-surface barriers associated with the loss of neighbors in the local cage and the spatial cutoff and dynamical softening near the vapor interface of the spatially longer range collective elasticity cost for large amplitude hopping. These two effects are fundamentally coupled. Quantitative predictions are made for how an apparent glass temperature depends on the film thickness and experimental probe technique, the emergence of a two-step decay and mobile layers in time domain measurements, signatures of confinement in frequency-domain dielectric loss experiments, the dependence of film-averaged relaxation times and dynamic fragility on temperature and film thickness, surface diffusion, and the relationship between kinetic experiments and pseudo-thermodynamic measurements such as ellipsometry. PMID:26723700

  14. Theory of activated glassy relaxation, mobility gradients, surface diffusion, and vitrification in free standing thin films

    NASA Astrophysics Data System (ADS)

    Mirigian, Stephen; Schweizer, Kenneth S.

    2015-12-01

    We have constructed a quantitative, force level, statistical mechanical theory for how confinement in free standing thin films introduces a spatial mobility gradient of the alpha relaxation time as a function of temperature, film thickness, and location in the film. The crucial idea is that relaxation speeds up due to the reduction of both near-surface barriers associated with the loss of neighbors in the local cage and the spatial cutoff and dynamical softening near the vapor interface of the spatially longer range collective elasticity cost for large amplitude hopping. These two effects are fundamentally coupled. Quantitative predictions are made for how an apparent glass temperature depends on the film thickness and experimental probe technique, the emergence of a two-step decay and mobile layers in time domain measurements, signatures of confinement in frequency-domain dielectric loss experiments, the dependence of film-averaged relaxation times and dynamic fragility on temperature and film thickness, surface diffusion, and the relationship between kinetic experiments and pseudo-thermodynamic measurements such as ellipsometry.

  15. Optimum mobility, contact properties, and open-circuit voltage of organic solar cells: A drift-diffusion simulation study

    NASA Astrophysics Data System (ADS)

    Tress, Wolfgang; Leo, Karl; Riede, Moritz

    2012-04-01

    We investigate the role charge carrier mobility plays for loss mechanisms in organic bulk heterojunction solar cells. For this purpose, we perform drift-diffusion calculations for several recombination models and properties of the contacts. We show that in case of selective contacts, higher mobilities increase device efficiency, independent of injection barrier heights, energy level bending at the contacts, and the amount of background dark carriers in the device. Nonselective contacts provide a source of photocarrier loss at the “wrong” electrode. This is evident from a decrease of the open-circuit voltage (Voc) with an increased role of charge carrier diffusion, which originates from a higher mobility or from interface barriers reducing the built-in potential. In this case, Voc furthermore depends on the device thickness. Considering the effect of different recombination models, a too high mobility of one charge carrier decreases Voc significantly for Langevin recombination. That is why balanced mobilities are desirable for high efficiency in this case. In presence of recombination via CT states, Voc is mainly governed by the dynamics of the charge transfer state. Based on these differentiations we show that the existence of an optimum mobility derived from simulation depends strongly on the assumptions made for contact and recombination properties and obtain a comprehensive picture how charge carrier mobility influences the parameters of organic solar cells.

  16. The influence of electric field and mobility profile on GaAs MESFET characteristics

    NASA Astrophysics Data System (ADS)

    Chen, Chung-Hsu; Arch, David K.

    1989-11-01

    Analytical approximations for the drain I-V relationship, including the mobility profile and field distribution in the channel from the drain to the source, of GaAs MESFETs are derived. The model includes the extended depletion from the gate to the drain for nonself-aligned devices. The calculation of the electric field along the channel is in very good agreement with existing analytical models and a two-dimensional numerical simulation. Experimentally, the authors fabricated and tested tilted angle lightly doped drain (LDD) GaAs MESFETs. It was found that the LLD MESFET structure suppresses the peak electric field under the gate near the drain region. A lower output conductance and higher drain-to-source breakdown were observed as expected. In addition to the electric field, the mobility profile is another factor that influences the performance of the devices. The accuracy of describing the low-field transconductance is strongly dependent on the mobility profile. Moreover, the mobility profile modifies the electric field along the channel and also influences the shape of the drain I-V curves. It is found that more accurate I-V curves can be obtained once the mobility profile is taken into account.

  17. Reliability and Validity Study of the Mobile Learning Adoption Scale Developed Based on the Diffusion of Innovations Theory

    ERIC Educational Resources Information Center

    Celik, Ismail; Sahin, Ismail; Aydin, Mustafa

    2014-01-01

    In this study, a mobile learning adoption scale (MLAS) was developed on the basis of Rogers' (2003) Diffusion of Innovations Theory. The scale that was developed consists of four sections. These sections are as follows: Stages in the innovation-decision process, Types of m-learning decision, Innovativeness level and attributes of m-learning.…

  18. Reliability and Validity Study of the Mobile Learning Adoption Scale Developed Based on the Diffusion of Innovations Theory

    ERIC Educational Resources Information Center

    Celik, Ismail; Sahin, Ismail; Aydin, Mustafa

    2014-01-01

    In this study, a mobile learning adoption scale (MLAS) was developed on the basis of Rogers' (2003) Diffusion of Innovations Theory. The scale that was developed consists of four sections. These sections are as follows: Stages in the innovation-decision process, Types of m-learning decision, Innovativeness level and attributes of m-learning. There…

  19. Electrical determination of the diffusion barrier for gold in ZnTe

    NASA Astrophysics Data System (ADS)

    El Akkad, Fikry

    2013-12-01

    We report on the effect of Au diffusion on the electrical properties of ZnTe films deposited on Au coated substrates using rf magnetron sputtering. A drop over about 8 decades in the room temperature conductivity is observed for a change in substrate temperature from 60 °C to 325 °C. The results are interpreted in terms of a point-defect model that takes into account the interaction between the in-diffused Au and the intrinsic defects. The analysis of the results on the basis of this model yields a diffusion barrier of 0.40 eV for gold in ZnTe.

  20. Effect of mobile ions on the electric field needed to orient charged diblock copolymer thin films

    SciTech Connect

    Dehghan, Ashkan; Shi, An-Chang; Schick, M.

    2015-10-07

    We examine the behavior of lamellar phases of charged/neutral diblock copolymer thin films containing mobile ions in the presence of an external electric field. We employ self-consistent field theory and focus on the aligning effect of the electric field on the lamellae. Of particular interest are the effects of the mobile ions on the critical field, the value required to reorient the lamellae from the parallel configuration favored by the surface interaction to the perpendicular orientation favored by the field. We find that the critical field depends strongly on whether the neutral or charged species is favored by the substrates. In the case in which the neutral species is favored, the addition of charges decreases the critical electric field significantly. The effect is greater when the mobile ions are confined to the charged lamellae. In contrast, when the charged species is favored by the substrate, the addition of mobile ions stabilizes the parallel configuration and thus results in an increase in the critical electric field. The presence of ions in the system introduces a new mixed phase in addition to those reported previously.

  1. A Novel Electrical Model for Advection-Diffusion-Based Molecular Communication in Nanonetworks.

    PubMed

    Azadi, Mehdi; Abouei, Jamshid

    2016-04-01

    In this paper, we propose an end-to-end electrical model to characterize the communication between two nanomachines via advection-diffusion motion along the conventional pipe medium. For this modeling, we consider three modules consisting of transmitter, advection-diffusion propagation and receiver. The modulation scheme and releasing molecules through the conventional pipe medium from the transmitter nanomachine is represented in the transmitter module. The advection-diffusion propagation of molecules along the flow-induced path is shown in advection-diffusion propagation module, and the demodulation scheme of bounded particles at the receiver nanomachine is characterized in the receiver module. Our objective is to find an electrical model of each module under the zero initial condition which enables us to represent the electrical circuit related to each module. The transmitter and the signal propagation models are built on the basis of the molecular advection-diffusion physics, whereas the receiver model is interpreted by stemming from the theory of the ligand-receptor binding chemical process. In addition, we employ the transfer function of modules to derive the normalized gain and the delay of each module. Supported by numerical results, we analyze the effect of physical parameters of the pipe medium on the total normalized gain and delay of molecular communications. PMID:27046879

  2. Ion Permeability of Artificial Membranes Evaluated by Diffusion Potential and Electrical Resistance Measurements

    ERIC Educational Resources Information Center

    Shlyonsky, Vadim

    2013-01-01

    In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and "n"-decane. The electrical resistance and potential…

  3. Cell stimulation and calcium mobilization by picosecond electric pulses.

    PubMed

    Semenov, Iurii; Xiao, Shu; Kang, Dongkoo; Schoenbach, Karl H; Pakhomov, Andrei G

    2015-10-01

    We tested if picosecond electric pulses (psEP; 190 kV/cm, 500 ps at 50% height), which are much shorter than channel activation time, can activate voltage-gated (VG) channels. Cytosolic Ca(2+) was monitored by Fura-2 ratiometric imaging in GH3 and NG108 cells (which express multiple types of VG calcium channels, VGCC), and in CHO cells (which express no VGCC). Trains of up to 100 psEP at 1 kHz elicited no response in CHO cells. However, even a single psEP significantly increased Ca(2+) in both GH3 (by 114 ± 48 nM) and NG108 cells (by 6 ± 1.1 nM). Trains of 100 psEP amplified the response to 379 ± 33 nM and 719 ± 315 nM, respectively. Ca(2+) responses peaked within 2-15s and recovered for over 100 s; they were 80-100% inhibited by verapamil and ω-conotoxin, but not by the substitution of Na(+) with N-methyl-D-glucamine. There was no response to psEP in Ca(2+)-free medium, but adding external Ca(2+) even 10s later evoked Ca(2+) response. We conclude that electrical stimuli as short as 500 ps can cause long-lasting opening of VGCC by a mechanism which does not involve conventional electroporation, heating (which was under 0.06 K per psEP), or membrane depolarization by opening of VG Na(+) channels. PMID:26011130

  4. Electrical control of Co/Ni magnetism adjacent to gate oxides with low oxygen ion mobility

    SciTech Connect

    Yan, Y. N.; Zhou, X. J.; Li, F.; Cui, B.; Wang, Y. Y.; Wang, G. Y.; Pan, F.; Song, C.

    2015-09-21

    We investigate the electrical manipulation of Co/Ni magnetization through a combination of ionic liquid and oxide gating, where HfO{sub 2} with a low O{sup 2−} ion mobility is employed. A limited oxidation-reduction process at the metal/HfO{sub 2} interface can be induced by large electric field, which can greatly affect the saturated magnetization and Curie temperature of Co/Ni bilayer. Besides the oxidation/reduction process, first-principles calculations show that the variation of d electrons is also responsible for the magnetization variation. Our work discloses the role of gate oxides with a relatively low O{sup 2−} ion mobility in electrical control of magnetism, and might pave the way for the magneto-ionic memory with low power consumption and high endurance performance.

  5. Data-driven estimation of cardiac electrical diffusivity from 12-lead ECG signals.

    PubMed

    Zettinig, Oliver; Mansi, Tommaso; Neumann, Dominik; Georgescu, Bogdan; Rapaka, Saikiran; Seegerer, Philipp; Kayvanpour, Elham; Sedaghat-Hamedani, Farbod; Amr, Ali; Haas, Jan; Steen, Henning; Katus, Hugo; Meder, Benjamin; Navab, Nassir; Kamen, Ali; Comaniciu, Dorin

    2014-12-01

    Diagnosis and treatment of dilated cardiomyopathy (DCM) is challenging due to a large variety of causes and disease stages. Computational models of cardiac electrophysiology (EP) can be used to improve the assessment and prognosis of DCM, plan therapies and predict their outcome, but require personalization. In this work, we present a data-driven approach to estimate the electrical diffusivity parameter of an EP model from standard 12-lead electrocardiograms (ECG). An efficient forward model based on a mono-domain, phenomenological Lattice-Boltzmann model of cardiac EP, and a boundary element-based mapping of potentials to the body surface is employed. The electrical diffusivity of myocardium, left ventricle and right ventricle endocardium is then estimated using polynomial regression which takes as input the QRS duration and electrical axis. After validating the forward model, we computed 9500 EP simulations on 19 different DCM patients in just under three seconds each to learn the regression model. Using this database, we quantify the intrinsic uncertainty of electrical diffusion for given ECG features and show in a leave-one-patient-out cross-validation that the regression method is able to predict myocardium diffusion within the uncertainty range. Finally, our approach is tested on the 19 cases using their clinical ECG. 84% of them could be personalized using our method, yielding mean prediction errors of 18.7ms for the QRS duration and 6.5° for the electrical axis, both values being within clinical acceptability. By providing an estimate of diffusion parameters from readily available clinical data, our data-driven approach could therefore constitute a first calibration step toward a more complete personalization of cardiac EP. PMID:24857832

  6. Simultaneous and direct measurement of carrier diffusion constant and mobility in organic semiconductors and deviation from standard Einstein relation

    NASA Astrophysics Data System (ADS)

    Tripathi, Awnish K.; Tripathi, Durgesh C.; Mohapatra, Y. N.

    2011-07-01

    We show that the shape of electroluminescence transients in organic semiconductors can be conveniently used to obtain the diffusion constant D of injected charge carriers, enabling the study of generalized Einstein relationship under nonequilibrium conditions as a function of the electric field. The appearance of peak at the onset of transient is shown to be the signature of diffusive regime of transport. We demonstrate it for two representative materials, Alq3 and polymer poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene], with the focus on the role of hot carriers in transport and their diffusivity.

  7. Relationship of the magnetic and electric diffusion of energetic ions in the radiation belts of the earth

    SciTech Connect

    Goryainov, M.F.; Panasyok, M.I.

    1986-01-01

    This paper presents an expression for the electric diffusion coefficient on the basis of analysis of the amplitudes of the power spectra of electric fields within the equatorial radiation belts, which indicate their strong attenuation with a decrease in geocentric distance. Comparison of the obtained electric coefficient with the magnetic coefficient obtained typical of the intermediate disturbed state in the magnetosphere and with the magnetic diffusion coefficient taking into account the presence of inhomogeneities in the high-frequency part of the power spectrum of the geomagnetic field leads to the conclusion that electric diffusion can dominate at L>5 and at L<2.

  8. Spherical Ethylene/Air Diffusion Flames Subject to Concentric DC Electric Field in Microgravity

    NASA Technical Reports Server (NTRS)

    Yuan, Z. -G.; Hegde, U.; Faeth, G. M.

    2001-01-01

    It is well known that microgravity conditions, by eliminating buoyant flow, enable many combustion phenomena to be observed that are not possible to observe at normal gravity. One example is the spherical diffusion flame surrounding a porous spherical burner. The present paper demonstrates that by superimposing a spherical electrical field on such a flame, the flame remains spherical so that we can study the interaction between the electric field and flame in a one-dimensional fashion. Flames are susceptible to electric fields that are much weaker than the breakdown field of the flame gases owing to the presence of ions generated in the high temperature flame reaction zone. These ions and the electric current of the moving ions, in turn, significantly change the distribution of the electric field. Thus, to understand the interplay between the electric field and the flame is challenging. Numerous experimental studies of the effect of electric fields on flames have been reported. Unfortunately, they were all involved in complex geometries of both the flow field and the electric field, which hinders detailed study of the phenomena. In a one-dimensional domain, however, the electric field, the flow field, the thermal field and the chemical species field are all co-linear. Thus the problem is greatly simplified and becomes more tractable.

  9. Self-diffusion measurements by a mobile single-sided NMR sensor with improved magnetic field gradient

    NASA Astrophysics Data System (ADS)

    Rata, D. G.; Casanova, F.; Perlo, J.; Demco, D. E.; Blümich, B.

    2006-06-01

    A simple and fast method of measuring self-diffusion coefficients of protonated systems with a mobile single-sided NMR sensor is discussed. The NMR sensor uses a magnet geometry that generates a highly flat sensitive volume where a strong and highly uniform static magnetic field gradient is defined. Self-diffusion coefficients were measured by Hahn- and stimulated echoes detected in the presence of the uniform magnetic field gradient of the static field. To improve the sensitivity of these experiments, a Carr-Purcell-Meiboom-Gill pulse sequence was applied after the main diffusion-encoding period. By adding the echo train the experimental time was strongly shortened, allowing the measurement of complete diffusion curves in less than 1 min. This method has been tested by measuring the self-diffusion coefficients D of various organic solvents and poly(dimethylsiloxane) samples with different molar masses. Diffusion coefficients were also measured for n-hexane absorbed at saturation in natural rubber with different cross-link densities. The results show a dependence on the concentration that is in good agreement with the theoretical prediction. Moreover, the stimulated-echo sequence was successfully used to measure the diffusion coefficient as a function of the evolution time in systems with restricted diffusion. This type of experiment proves the pore geometry and gives access to the surface-to-volume ratio. It was applied to measure the diffusion of water in sandstones and sheep Achilles tendon. Thanks to the strong static gradient G0, all diffusion coefficients could be measured without having to account for relaxation during the pulse sequence.

  10. Forced diffusion via electrically induced crystallization for fabricating ZnO–Ti–Si structures

    SciTech Connect

    Chen, Yen-Ting; Hung, Fei-Yi

    2014-11-15

    Highlights: • ZnO–Ti–Si system is very important for the structural design. • The electrically induced crystallization method is useful to diffusion process. • Intermetallic compound characteristics have been presented using electrically induced crystallization. • Interface mechanism about diffusion of TZO–TiSi{sub x}–Si structure is presented. - Abstract: Electrically induced crystallization (EIC) is a recently developed process for material modification. This study is applied to EIC to fabricate ZnO–Ti–Si multi-layer structures of various thicknesses to dope Ti into ZnO thin film and to form TiSi{sub x} intermetallic compound (IMC) in a single step. The IMC layer was confirmed using transmission electron microscopy images. The Ti layer thickness was more than 40 nm, which enhanced electron transmission and decreased the total electrical resistance in the structure. Finally, the diffusion mechanisms of EIC and the annealing process were investigated. This study shows that the EIC process has potential for industrial applications.

  11. a Diffusive-Transport Approach to Determine the Electrical Conductance of AN Imperfect Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Grado-Caffaro, Maria Angeles; Grado-Caffaro, Martin

    2014-05-01

    In this paper, we propose a diffusive-transport-based analytical formulation to calculate the linear electrical conductance through a multiwalled carbon nanotube with defects. In fact, on the one hand, by considerations on diffusive transport and, on the other hand, using the Drude model, we find out that the conductance (at Fermi energy) of an imperfect multiwalled carbon nanotube is approximately equal to the fundamental conductance quantum multiplied by the number of layers (or shells) of the tube. Our result agrees with experimental data.

  12. Cation diffusion in the electrical double layer enhances the mass transfer rates for Sr2+, Co2+ and Zn2+ in compacted illite

    NASA Astrophysics Data System (ADS)

    Glaus, M. A.; Aertsens, M.; Appelo, C. A. J.; Kupcik, T.; Maes, N.; Van Laer, L.; Van Loon, L. R.

    2015-09-01

    Enhanced mass transfer rates have been frequently observed in diffusion studies with alkaline and earth alkaline elements in compacted clay minerals and clay rocks. Whether this phenomenon - often termed surface diffusion - is also relevant for more strongly sorbing species is an open question. We therefore investigated the diffusion of Sr2+, Co2+ and Zn2+ in compacted illite with respect to variations of the concentration of the background electrolyte, pH and carbonate. New experimental techniques were developed in order to avoid artefacts stemming from the confinement of the clay sample. A distinct dependence of the effective diffusion coefficients on the concentration of the background electrolyte was observed for all three elements. A similar correlation was found for the sorption distribution ratio (Rd) derived from tracer breakthrough in the case of Sr2+, while this dependence was much weaker for Co2+ and Zn2+. Model calculations using Phreeqc resulted in a good agreement with the experimental data when it was assumed that the cationic species, present in the electrical double layer (EDL) of the charged clay surface, are mobile. Species bound to the specific surface complexation sites at the clay edges were assumed to be immobile. An assessment of the mobility of the type of cationic elements studied here in argillaceous media thus requires an analysis of their distribution among specifically sorbed surface species and species in the EDL. The normal approach of deriving unknown effective diffusion coefficients from reference values of an uncharged water tracer may significantly underestimate the mobility of metal cations in argillaceous media.

  13. Changes in mobile phase ion distribution when combining pressurized flow and electric field.

    PubMed

    Eriksson, Björn O; Dahl, Magnus; Andersson, Magnus B O; Blomberg, Lars G

    2004-10-01

    The distribution of ions in a capillary with both pressurized flow and an electric field has been studied. We have earlier reported that the overall concentration of ions increase in a capillary with high electric field and a pressurized flow. Now we describe how the ions are distributed in the capillary both along the capillary length and in the radial direction as a result of the parabolic flow profile. We have combined current measurements with finite element techniques in order to get better understanding of the system. We have found that the concentration of the ions that because of the electric mobility moves towards the flow primarily increases at the beginning of the electric field and close to the capillary wall. In view of the results we have proposed an alterative explanation of earlier published results concerning voltage-induced variation in capacity factors. PMID:15472979

  14. Electric field driven plasmon dispersion in AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Tan, Ren-Bing; Qin, Hua; Zhang, Xiao-Yu; Xu, Wen

    2013-11-01

    We present a theoretical study on the electric field driven plasmon dispersion of the two-dimensional electron gas (2DEG) in AlGaN/GaN high electron mobility transistors (HEMTs). By introducing a drifted Fermi—Dirac distribution, we calculate the transport properties of the 2DEG in the AlGaN/GaN interface by employing the balance-equation approach based on the Boltzmann equation. Then, the nonequilibrium Fermi—Dirac function is obtained by applying the calculated electron drift velocity and electron temperature. Under random phase approximation (RPA), the electric field driven plasmon dispersion is investigated. The calculated results indicate that the plasmon frequency is dominated by both the electric field E and the angle between wavevector q and electric field E. Importantly, the plasmon frequency could be tuned by the applied source—drain bias voltage besides the gate voltage (change of the electron density).

  15. Temperature and electric field dependent mobility in poly(3-hexylthiophene) diodes

    NASA Astrophysics Data System (ADS)

    Giulianini, Michele; Waclawik, Eric R.; Bell, John M.; Motta, Nunzio

    2010-07-01

    Current-voltage (I-V) curves of poly(3-hexylthiophene) (P3HT) diodes have been collected to investigate the polymer hole-dominated charge transport. At room temperature and at low electric fields the I-V characteristic is purely Ohmic whereas at medium-high electric fields, experimental data shows that the hole transport is trap dominated in the space charge limited current (SCLC) regime. In this regime, it is possible to extract the I-V characteristic of the P3HT/Al junction showing the ideal Schottky diode behavior over five orders of magnitude. At high-applied electric fields, holes' transport is found to be in the trap free SCLC regime. We have measured and modeled in this regime the holes' mobility to evaluate its dependence from the electric field applied and the temperature of the device.

  16. Fractional diffusion models of cardiac electrical propagation: role of structural heterogeneity in dispersion of repolarization

    PubMed Central

    Bueno-Orovio, Alfonso; Kay, David; Grau, Vicente; Rodriguez, Blanca; Burrage, Kevin

    2014-01-01

    Impulse propagation in biological tissues is known to be modulated by structural heterogeneity. In cardiac muscle, improved understanding on how this heterogeneity influences electrical spread is key to advancing our interpretation of dispersion of repolarization. We propose fractional diffusion models as a novel mathematical description of structurally heterogeneous excitable media, as a means of representing the modulation of the total electric field by the secondary electrical sources associated with tissue inhomogeneities. Our results, analysed against in vivo human recordings and experimental data of different animal species, indicate that structural heterogeneity underlies relevant characteristics of cardiac electrical propagation at tissue level. These include conduction effects on action potential (AP) morphology, the shortening of AP duration along the activation pathway and the progressive modulation by premature beats of spatial patterns of dispersion of repolarization. The proposed approach may also have important implications in other research fields involving excitable complex media. PMID:24920109

  17. Mobile phone use among motorcyclists and electric bike riders: A case study of Hanoi, Vietnam.

    PubMed

    Truong, Long T; Nguyen, Hang T T; De Gruyter, Chris

    2016-06-01

    Motorcyclist injuries and fatalities are a major concern of many developing countries. In Vietnam, motorcycles are involved in more than 70% of all road traffic crashes. This paper aims to explore the prevalence and factors associated with mobile phone use among motorcyclists and electric bike riders, using a case study of Hanoi, Vietnam. A cross-sectional observation survey was undertaken at 12 sites, in which each site was surveyed during a two-hour peak period from 16:30 to 18:30 for two weekdays and one weekend day. A total of 26,360 riders were observed, consisting of 24,759 motorcyclists and 1601 electric bike riders. The overall prevalence of mobile phone use while riding was 8.4% (95% CI: 8.06-8.74%) with calling having higher prevalence than screen operation: 4.64% (95% CI: 4.39-4.90%) vs. 3.76% (95% CI: 3.52-3.99%) respectively. Moreover, the prevalence of mobile phone use was higher among motorcyclists than electric bike riders: 8.66% (95%CI: 8.30-9.01%) vs. 4.43% (95% CI: 3.40-5.47%) respectively. Logistic regression analyses revealed that mobile phone use while riding was associated with vehicle type, age, gender, riding alone, weather, day of week, proximity to city centre, number of lanes, separate car lanes, red traffic light duration, and police presence. Combining greater enforcement of existing legislations with extensive education and publicity programs is recommended to reduce potential deaths and injuries related to the use of mobile phones while riding. PMID:27015225

  18. Design Of An Electrical Flywheel For Surge Power Applications In Mobile Robots

    NASA Astrophysics Data System (ADS)

    Wright, David D.

    1987-01-01

    An energy boost system based on a flywheel has been designed to supply the surge power needs of mobile robots for operating equipment like transmitters, drills, manipulator arms, mobility augmenters, and etc. This flywheel increases the average power available from a battery, fuel cell, generator, RPG or solar array by one or more orders of magnitude for short periods. Flywheels can be charged and discharged for thousands of battery lifetimes. Flywheels can deliver more than ten times the power per unit weight of batteries. The electromechanical details of a reliable, energy efficient and (relatively) low cost flywheel are described. This flywheel is the combination of a highly efficient brushless motor and a laminated steel rotor operating in an hermetically sealed container with only electrical input and output. This design approach overcomes the inefficiencies generally associated with mechanically geared devices. Electrical round trip efficiency is 94% under optimum operating conditions.

  19. Electrical synapse formation disrupts calcium-dependent exocytosis, but not vesicle mobilization.

    PubMed

    Neunuebel, Joshua P; Zoran, Mark J

    2005-06-01

    Electrical coupling exists prior to the onset of chemical connectivity at many developing and regenerating synapses. At cholinergic synapses in vitro, trophic factors facilitated the formation of electrical synapses and interfered with functional neurotransmitter release in response to photolytic elevations of intracellular calcium. In contrast, neurons lacking trophic factor induction and electrical coupling possessed flash-evoked transmitter release. Changes in cytosolic calcium and postsynaptic responsiveness to acetylcholine were not affected by electrical coupling. These data indicate that transient electrical synapse formation delayed chemical synaptic transmission by imposing a functional block between the accumulation of presynaptic calcium and synchronized, vesicular release. Despite the inability to release neurotransmitter, neurons that had possessed strong electrical coupling recruited secretory vesicles to sites of synaptic contact. These results suggest that the mechanism by which neurotransmission is disrupted during electrical synapse formation is downstream of both calcium influx and synaptic vesicle mobilization. Therefore, electrical synaptogenesis may inhibit synaptic vesicles from acquiring a readily releasable state. We hypothesize that gap junctions might negatively interact with exocytotic processes, thereby diminishing chemical neurotransmission. PMID:15765535

  20. Diffusion, swelling and electrical properties of polyisoprene/multiwall carbon nanotube composites in organic solvent vapours.

    PubMed

    Knite, M; Sakale, G; Teteris, V

    2012-10-01

    Polyisoprene/nanostructured carbon composites have been fabricated utilizing multiwall carbon nanotubes and carbon black nanoparticles as electrically conductive filler materials. Simultaneous measurements of (1) absorbed mass of organic solvent vapours (OSV), (2) swelling predicted elongation of sample and (3) electrical resistance changes versus the time of the presence of polyisoprene/multiwall carbon nanotube composites (PCNTC) in the OSV ambience were carried out by an in-house computerized setup. Non-Fickian anomalous diffusion has been found for all PCNTC samples as well as for reference samples of polyisoprene/high structure carbon black composites (PCBC). Obtained results indicate that the filler material content can play a substantial role in vapour diffusion into the composite. An advanced tunneling-percolation model was developed and used for describing of the OSV sensing effect in PCNTC and PCBC. PMID:23421188

  1. Diffusivity and mobility of non-equilibrium carriers in organic semiconductors: Existence of critical field determining temperature dependence

    NASA Astrophysics Data System (ADS)

    Tripathi, Durgesh C.; Sinha, Dhirendra K.; Mohapatra, Y. N.

    2013-10-01

    The role of disorder in controlling diffusivity and mobility of charge-carriers in the hopping regime of transport within a potential landscape has become especially significant for organic semiconductors. The temperature and field dependence of diffusivity (D) and mobility (μ) of injected charge-carriers have been simultaneously measured using electroluminescence transients for representative organic thin-films of tris(8-hydroxyquinoline) aluminum (III) (Alq3) and poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO). Significantly, the field dependence of diffusivity at different temperatures is similar except for a shift of a critical field beyond which it shows a sharp increase. The critical field is shown to be linearly decreasing with temperature ultimately vanishing at a characteristic limit T∗, and the slope is a measure of the localization length. The normalization of diffusivity is used to demonstrate the role of field in controlling temperature dependence. The scheme has been used to neatly decouple contributions from energetic (diagonal) and positional (off-diagonal) disorder thus enabling independent experimental determination of all the parameters of standard and correlated versions of Gaussian disorder model. The results demonstrate the validity of Gaussian disorder model even for non-equilibrium carriers, and that the parameters can be obtained with appropriate scaling of the field in such cases.

  2. The detection and measurement of the electrical mobility size distributions associated with radon decay products

    SciTech Connect

    Fei, Lin

    1996-04-01

    The potential risk of lung cancer has evoked interest in the properties of radon decay products. There are two forms of this progeny: either attached to ambient aerosols, or still in the status of ions/molecules/small clusters. This ``unattached`` activity would give a higher dose per unit of airborne activity than the ``attached`` progeny that are rather poorly deposited. In this thesis, a system for determining unattached radon decay products electrical mobility size distribution by measuring their electrical mobilities was developed, based on the fact that about 88% of {sup 218}Po atoms have unit charge at the end of their recoil after decay from {sup 222}Rn, while the remainder are neutral. Essential part of the setup is the radon-aerosol chamber with the Circular Electrical Mobility Spectrometer (CEMS) inside. CEMS is used for sampling and classifying the charged radioactive clusters produced in the chamber. An alpha- sensitive plastic, CR-39 disk, is placed in CEMS as an inlaid disk electrode and the alpha particle detector. CEMS showed good performance in fine inactive particles` classification. If it also works well for radon decay products, it can offer a convenient size distribution measurement for radioactive ultrafine particles. However, the experiments did not obtain an acceptable resolution. Suggestions are made for solving this problem.

  3. A study of rock matrix diffusion properties by electrical conductivity measurements

    SciTech Connect

    Ohlsson, Y.; Neretnieks, I.

    1999-07-01

    Traditional rock matrix diffusion experiments on crystalline rock are very time consuming due to the low porosity and extensive analysis requirements. Electrical conductivity measurements are, on the other hand, very fast and larger samples can be used than are practical in ordinary diffusion experiments. The effective diffusivity of a non-charged molecule is readily evaluated from the measurements, and influences from surface conductivity on diffusion of cations can be studied. A large number of samples of varying thickness can be measured within a short period, and the changes in transport properties with position in a rock core can be examined. In this study the formation factor of a large number of Aespoe diorite samples is determined by electrical conductivity measurements. The formation factor is a geometric factor defined as the ratio between the effective diffusivity of a non-charged molecule, to that of the same molecule in free liquid. The variation of this factor with position among a borecore and with sample length, and its coupling to the porosity of the sample is studied. Also the surface conductivity is studied. This was determined as the residual conductivity after leaching of the pore solution ions. The formation factor of most of the samples is in the range 1E-5 to 1E-4, with a mean value of about 5E-5. Even large samples (4--13 cm) give such values. The formation factor increases with increasing porosity and the change in both formation factor and porosity with position in the borecore can be large, even for samples close to each other. The surface conductivity increases with increasing formation factor for the various samples but the influence on the pore diffusion seems to be higher for samples of lower formation factor. This suggests that the relation between the pore surface area and the pore volume is larger for samples of low formation factor.

  4. Electric fields and large-scale undulations in the evening sector of the diffuse auroral zone

    NASA Astrophysics Data System (ADS)

    Baishev, D. G.; Barkova, E. S.; Stepanov, A. E.; Rich, F.; Yumoto, K.

    2010-02-01

    The synchronous observations of strong electric fields and large-scale undulations observed on December 12, 2004, in the evening sector of the diffuse auroral zone 0900-1000 UT (~1700-1800 MLT) have been analyzed. The appearance of strong northward electric field at ~0900 UT was almost simultaneously registered at Tixie Bay ionospheric station (71.6° N, 128.9° E, L =, 5.6) and on the DMSP F15 satellite. At 0910-1000 UT, the all-sky TV camera at Tixie Bay and the DMSP satellites (F13, F14, and F15) registered eight undulations propagating westward at a velocity of 0.7—0.8 km/s. The undulation parameters registered during the TV observations agree with the satellite measurements. The distinctive feature of the analyzed event consists in that an intense electric field and undulations were localized within the diffuse zone in the region of increased precipitation of keV electrons. A comparison of the ground-based and satellite measurements made it possible to draw the conclusion on the necessary conditions for formation of diffuse undulations.

  5. Basic principles of static proton low-resolution spin diffusion NMR in nanophase-separated materials with mobility contrast.

    PubMed

    Schäler, Kerstin; Roos, Matthias; Micke, Peter; Golitsyn, Yury; Seidlitz, Anne; Thurn-Albrecht, Thomas; Schneider, Horst; Hempel, Günter; Saalwächter, Kay

    2015-11-01

    We review basic principles of low-resolution proton NMR spin diffusion experiments, relying on mobility differences in nm-sized phases of inhomogeneous organic materials such as block-co- or semicrystalline polymers. They are of use for estimates of domain sizes and insights into nanometric dynamic inhomogeneities. Experimental procedures and limitations of mobility-based signal decomposition/filtering prior to spin diffusion are addressed on the example of as yet unpublished data on semicrystalline poly(ϵ-caprolactone), PCL. Specifically, we discuss technical aspects of the quantitative, dead-time free detection of rigid-domain signals by aid of the magic-sandwich echo (MSE), and magic-and-polarization-echo (MAPE) and double-quantum (DQ) magnetization filters to select rigid and mobile components, respectively. Such filters are of general use in reliable fitting approaches for phase composition determinations. Spin diffusion studies at low field using benchtop instruments are challenged by rather short (1)H T1 relaxation times, which calls for simulation-based analyses. Applying these, in combination with domain sizes as determined by small-angle X-ray scattering, we have determined spin diffusion coefficients D for PCL (0.34, 0.19 and 0.032nm(2)/ms for crystalline, interphase and amorphous parts, respectively). We further address thermal-history effects related to secondary crystallization. Finally, the state of knowledge concerning the connection between D values determined locally at the atomic level, using (13)C detection and CP- or REDOR-based "(1)H hole burning" procedures, and those obtained by calibration experiments, is summarized. Specifically, the non-trivial dependence of D on the magic-angle spinning (MAS) frequency, with a minimum under static and a local maximum under moderate-MAS conditions, is highlighted. PMID:26404771

  6. BRCA2 diffuses as oligomeric clusters with RAD51 and changes mobility after DNA damage in live cells

    PubMed Central

    Reuter, Marcel; Zelensky, Alex; Smal, Ihor; Meijering, Erik; van Cappellen, Wiggert A.; de Gruiter, H. Martijn; van Belle, Gijsbert J.; van Royen, Martin E.; Houtsmuller, Adriaan B.; Essers, Jeroen; Kanaar, Roland

    2014-01-01

    Genome maintenance by homologous recombination depends on coordinating many proteins in time and space to assemble at DNA break sites. To understand this process, we followed the mobility of BRCA2, a critical recombination mediator, in live cells at the single-molecule level using both single-particle tracking and fluorescence correlation spectroscopy. BRCA2-GFP and -YFP were compared to distinguish diffusion from fluorophore behavior. Diffusive behavior of fluorescent RAD51 and RAD54 was determined for comparison. All fluorescent proteins were expressed from endogenous loci. We found that nuclear BRCA2 existed in oligomeric clusters, and exhibited heterogeneous mobility. DNA damage increased BRCA2 transient binding, presumably including binding to damaged sites. Despite its very different size, RAD51 displayed mobility similar to BRCA2, which indicates physical interaction between these proteins both before and after induction of DNA damage. We propose that BRCA2-mediated sequestration of nuclear RAD51 serves to prevent inappropriate DNA interactions and that all RAD51 is delivered to DNA damage sites in association with BRCA2. PMID:25488918

  7. Oscillation of electron mobility in parabolic double quantum well structure due to applied electric field

    SciTech Connect

    Sahoo, Narayan; Sahu, Trinath

    2014-12-15

    We show that oscillation of low temperature electron mobility μ can be obtained by applying an electric field F along the growth direction of the asymmetrically barrier delta doped Al{sub x}Ga{sub 1-x}As parabolic double quantum well structure. The drastic changes in the subband Fermi energies and distributions of subband wave functions as a function of F yield nonmonotonic intra- and intersubband scattering rate matrix elements mediated by intersubband effects. The oscillatory enhancement of μ, which is attributed to the subband mobilities governed by the ionized impurity scattering, magnifies with increase in well width and decrease in height of the parabolic structure potential. The results can be utilized for nanoscale low temperature device applications.

  8. Electrically active centers formed in silicon during the high-temperature diffusion of boron and aluminum

    SciTech Connect

    Sobolev, N. A.; Loshachenko, A. S.; Poloskin, D. S.; Shek, E. I.

    2013-02-15

    The parameters of electrically active centers formed during the high-temperature diffusion of boron and aluminum into silicon in various media are studied by the Hall method and capacitance spectroscopy. It is found that the variation in the resistivity of the n base of the structures with p-n junctions fabricated in the study is controlled by the formation of three donor levels Q1, E4, and Q3 with the energies E{sub c} - 0.31, E{sub c} - 0.27, and E{sub c} - 0.16 eV. Diffusion in a chlorine-containing atmosphere introduces only a single level E4, but its concentration is 2.5 times lower, compared with diffusion in air. The values of the ionization energy of the Q3 level, measured under equilibrium (Hall effect) and nonequilibrium (capacitance spectroscopy) conditions, almost coincide. The deepest level E1 with an energy of E{sub c} - 0.54 eV, formed upon diffusion in both media, has no effect on the resistivity in the n base of the structures.

  9. Computational studies of coarsening rates for the Cahn-Hilliard equation with phase-dependent diffusion mobility

    NASA Astrophysics Data System (ADS)

    Dai, Shibin; Du, Qiang

    2016-04-01

    We study computationally coarsening rates of the Cahn-Hilliard equation with a smooth double-well potential, and with phase-dependent diffusion mobilities. The latter is a feature of many materials systems and makes accurate numerical simulations challenging. Our numerical simulations confirm earlier theoretical predictions on the coarsening dynamics based on asymptotic analysis. We demonstrate that the numerical solutions are consistent with the physical Gibbs-Thomson effect, even if the mobility is degenerate in one or both phases. For the two-sided degenerate mobility, we report computational results showing that the coarsening rate is on the order of l ∼ ct 1 / 4, independent of the volume fraction of each phase. For the one-sided degenerate mobility, that is non-degenerate in the positive phase but degenerate in the negative phase, we illustrate that the coarsening rate depends on the volume fraction of the positive phase. For large positive volume fractions, the coarsening rate is on the order of l ∼ ct 1 / 3 and for small positive volume fractions, the coarsening rate becomes l ∼ ct 1 / 4.

  10. Diffusion-driven proton exchange membrane fuel cell for converting fermenting biomass to electricity.

    PubMed

    Malati, P; Mehrotra, P; Minoofar, P; Mackie, D M; Sumner, J J; Ganguli, R

    2015-10-01

    A membrane-integrated proton exchange membrane fuel cell that enables in situ fermentation of sugar to ethanol, diffusion-driven separation of ethanol, and its catalytic oxidation in a single continuous process is reported. The fuel cell consists of a fermentation chamber coupled to a direct ethanol fuel cell. The anode and fermentation chambers are separated by a reverse osmosis (RO) membrane. Ethanol generated from fermented biomass in the fermentation chamber diffuses through the RO membrane into a glucose solution contained in the DEFC anode chamber. The glucose solution is osmotically neutral to the biomass solution in the fermentation chamber preventing the anode chamber from drying out. The fuel cell sustains >1.3 mW cm(-2) at 47°C with high discharge capacity. No separate purification or dilution is necessary, resulting in an efficient and portable system for direct conversion of fermenting biomass to electricity. PMID:26208756

  11. Optical and electrical investigation of a cylindrical diffuse-discharge chamber

    SciTech Connect

    Teng, Yun; Li, Lee Cheng, Yong; Ma, Ning; Peng, Ming-yang; Liu, Ming-hai

    2015-03-15

    More and more attention has been attached to atmospheric-pressure air diffuse plasma due to its enormous potential applications. In this paper, we designed a large-scale, cylindrical diffuse-plasma chamber using wire electrodes and a repetitive nanosecond pulse generator. The plasma chamber can be completely exposed in the open air without any barrier dielectric, and the length of cylindrical plasma chamber was extensible. Using optical and electrical measurements, we investigated the effects of electrode distance, electrode length, pulse repetition frequency, and electrode angle on the uniformity of discharge space. Four discharge regions were distinguished based on different spectral characteristics. Additionally, it was found that the discharge uniformity was improved as the electrode distance decreases, but remained almost constant with the variations of electrode length and pulse repetition frequency. Both of the plasma uniformity and the power density increased significantly as the electrode angle reduced.

  12. Geospatial measurements of soil electrical conductivity to assess soil salinity and diffuse salt loading from irrigation

    NASA Astrophysics Data System (ADS)

    Rhoades, James D.; Corwin, Dennis L.; Lesch, Scott M.

    Irrigated agriculture is necessary to meet the food demands of the world, but excessive irrigation has wasted water and drainage from it has degraded the productivity and altered the ecology of vast areas of land. Irrigated agriculture also has polluted associated surface water and groundwater resources. The extent of soil degradation from salinization and waterlogging and, especially, the extent of water salinization resulting from excessive irrigation have not been well quantified. Additionally, the diffuse sources of deep percolation and salt loading from irrigation have not been well established. This paper describes basic principles of soil electrical conductivity, recent technology developed to assess the magnitude and distribution of soil salinity in fields, and ways to infer the areal sources and amounts of diffuse salt loading from irrigation.

  13. Development of a semiclassical method to compute mobility and diffusion coefficient of a Brownian particle in a nonequilibrium environment.

    PubMed

    Shit, Anindita; Ghosh, Pradipta; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray

    2011-03-01

    We explore the issue of a quantum-noise-induced directed transport of an overdamped Brownian particle that is allowed to move in a spatially periodic potential. The established system-reservoir model has been employed here to study the quantum-noise-induced transport of a Brownian particle in a periodic potential, where the reservoir is being modulated externally by a Gaussian-colored noise. The mobility of the Brownian particle in the linear response regime has been calculated. Then, using Einstein's relation, the analytical expression for the diffusion rate is evaluated for any arbitrary periodic potential for the high-temperature quantum regime. PMID:21517472

  14. The Invisible Hand: Governmental Influences on the Field of Play During the Production and Diffusion of Mobile TV

    NASA Astrophysics Data System (ADS)

    Lin, Su-Yi; Chiasson, Mike W.

    The purpose of this paper is to examine how government agencies alter the context around the production and diffusion of technologies, and how this strengthens or weakens particular ICT trajectories. An embedded case is conducted to address this question in Taiwan, as governmental actions affected the early production and diffusion of DVB-H technology and WiMAX technology, both of which enable mobile TV services. The context around and across these two technologies are analyzed from an institutional perspective, including the framework proposed by King et al (1994). The key lesson of this paper is that government agencies are capable of influencing the diffusion of nomadic technologies through their legitimating powers, specific national policies, the allocation of radio frequency spectrum, the implementation of regulations, and the allocation of financial resources. However, the ultimate effects are determined by mixed institutional factors and sometimes contradictory governmental interventions, stemming from historical differences and conflicts across the various government agencies involved. The implications for ICT diffusion research and governmental policy makers are discussed.

  15. An electrically-activated dynamic tissue-equivalent phantom for assessment of diffuse optical imaging systems.

    PubMed

    Hebden, Jeremy C; Brunker, Joanna; Correia, Teresa; Price, Ben D; Gibson, Adam P; Everdell, N L

    2008-01-21

    A novel design of solid dynamic phantom with tissue-like optical properties is presented, which contains variable regions of contrast which are activated electrically. Reversible changes in absorption are produced by localized heating of targets impregnated with thermochromic pigment. A portable, battery-operated prototype has been constructed, and its optical and temporal characteristics have been investigated. The phantom has been developed as a means of assessing the performance of diffuse optical imaging systems, such as those used to monitor haemodynamic changes in the brain and other tissues. Images of the phantom have been reconstructed using data acquired with a continuous wave optical topography system. PMID:18184989

  16. An electrically-activated dynamic tissue-equivalent phantom for assessment of diffuse optical imaging systems

    NASA Astrophysics Data System (ADS)

    Hebden, Jeremy C.; Brunker, Joanna; Correia, Teresa; Price, Ben D.; Gibson, Adam P.; Everdell, N. L.

    2008-01-01

    A novel design of solid dynamic phantom with tissue-like optical properties is presented, which contains variable regions of contrast which are activated electrically. Reversible changes in absorption are produced by localized heating of targets impregnated with thermochromic pigment. A portable, battery-operated prototype has been constructed, and its optical and temporal characteristics have been investigated. The phantom has been developed as a means of assessing the performance of diffuse optical imaging systems, such as those used to monitor haemodynamic changes in the brain and other tissues. Images of the phantom have been reconstructed using data acquired with a continuous wave optical topography system.

  17. Ultrawide electrical tuning of light matter interaction in a high electron mobility transistor structure

    PubMed Central

    Pal, Shovon; Nong, Hanond; Markmann, Sergej; Kukharchyk, Nadezhda; Valentin, Sascha R.; Scholz, Sven; Ludwig, Arne; Bock, Claudia; Kunze, Ulrich; Wieck, Andreas D.; Jukam, Nathan

    2015-01-01

    The interaction between intersubband resonances (ISRs) and metamaterial microcavities constitutes a strongly coupled system where new resonances form that depend on the coupling strength. Here we present experimental evidence of strong coupling between the cavity resonance of a terahertz metamaterial and the ISR in a high electron mobility transistor (HEMT) structure. The device is electrically switched from an uncoupled to a strongly coupled regime by tuning the ISR with epitaxially grown transparent gate. The asymmetric potential in the HEMT structure enables ultrawide electrical tuning of ISR, which is an order of magnitude higher as compared to an equivalent square well. For a single heterojunction with a triangular confinement, we achieve an avoided splitting of 0.52 THz, which is a significant fraction of the bare intersubband resonance at 2 THz. PMID:26578287

  18. Time-of-flight mobility of charge carriers in position-dependent electric field between coplanar electrodes

    NASA Astrophysics Data System (ADS)

    Pavlica, Egon; Bratina, Gvido

    2012-08-01

    Time-of-flight measurements of the photocurrent in thin organic semiconductor layers represent an effective way to extract charge carrier mobility. A common method to interpret the time-dependence of the photocurrent in these material systems assumes a position-independent electric field between two coplanar electrodes. In this letter, we compare time-dependence of the photocurrent, measured in the samples comprising thin layers of poly-3-hexylthiophene, with the Monte Carlo simulations. In the simulations, we have used both, a position-independent and a position-dependent electric field. We obtained a favorable agreement between the simulations and the measurements only in the case of position-dependent electric field. We demonstrate that the charge carrier mobility may be underestimated by more than one order of magnitude, if a position-independent electric field is used in the calculations of the mobility.

  19. Thermal diffusivity of Zn1-xBexSe crystals and it's correlation with electrical conductivity and optical absorption spectra

    NASA Astrophysics Data System (ADS)

    Bodzenta, J.; Firszt, F.; Kaźmierczak-Bałata, A.; Pyka, M.; Szperlich, P.; Szydłowski, M.; Zakrzewski, J.

    2008-01-01

    This article presents results obtained for mixed crystal of Zn{1-x}Be{x}Se. Samples with different Be contents were examined to determine their thermal, optical and electrical properties. The influence of composition of investigated mixed crystals on the value of thermal diffusivity, electrical resistivity and energy gap was checked. An interesting problem is a correlation between thermal properties and other physical parameters. In this work possible correlations between the thermal diffusivity and either the optical band gap determined from photothermal spectra or electrical conductivity are studied. The current investigation is a part of research projects: BK-269/RMF-1/2006 and 1 P03B 092 27.

  20. Terahertz Conductivity within Colloidal CsPbBr3 Perovskite Nanocrystals: Remarkably High Carrier Mobilities and Large Diffusion Lengths.

    PubMed

    Yettapu, Gurivi Reddy; Talukdar, Debnath; Sarkar, Sohini; Swarnkar, Abhishek; Nag, Angshuman; Ghosh, Prasenjit; Mandal, Pankaj

    2016-08-10

    Colloidal CsPbBr3 perovskite nanocrystals (NCs) have emerged as an excellent light emitting material in last one year. Using time domain and time-resolved THz spectroscopy and density functional theory based calculations, we establish 3-fold free carrier recombination mechanism, namely, nonradiative Auger, bimolecular electron-hole recombination, and inefficient trap-assisted recombination in 11 nm sized colloidal CsPbBr3 NCs. Our results confirm a negligible influence of surface defects in trapping charge carriers, which in turn results into desirable intrinsic transport properties, from the perspective of device applications, such as remarkably high carrier mobility (∼4500 cm(2) V(-1) s(-1)), large diffusion length (>9.2 μm), and high luminescence quantum yield (80%). Despite being solution processed and possessing a large surface to volume ratio, this combination of high carrier mobility and diffusion length, along with nearly ideal photoluminescence quantum yield, is unique compared to any other colloidal quantum dot system. PMID:27367476

  1. ELECTROKINETIC PHENOMENA : VI. RELATIONSHIP BETWEEN ELECTRIC MOBILITY, CHARGE, AND TITRATION OF PROTEINS.

    PubMed

    Abramson, H A

    1932-05-20

    1. By combining the theories of Smoluchowski, Debye and Hückel, and Henry it is possible to state explicitly (making necessary assumptions) under what conditions the following simple rule should be valid for proteins: In solutions of the same ionic strength, the electric mobilities of the same protein at different hydrogen ion activities should be proportional to the number of hydrogen (hydroxyl) ions bound. 2. Data of Tiselius and of the writer confirm this rule for (a) egg albumin, (b) serum albumin, (c) deaminized gelatin and gelatin, and (d) casein. 3. On the basis of the confirmed theory the titration curves of certain proteins are predicted from their mobilities. 4. It is shown that when certain proteins are adsorbed by quartz the apparent dissociation constant of the adsorbed protein is practically unchanged. The mass law must also be valid at the phase boundary. 5. The facts of paragraphs (1) to (4) are discussed in connection with the mechanism of (a) protein adsorption, (b) enzyme activity, (c) immune reactions, (d) the calculation of the electric charge of cells, and (e) criteria of surface similarity. PMID:19872668

  2. Innovators in Teacher Education: Diffusing Mobile Technologies in Teacher Preparation Curriculum

    ERIC Educational Resources Information Center

    Foulger, Teresa S.; Waker, Mary L.; Burke, Diane; Hansen, Randall; Williams, Mia Kim; Slykhuis, David A.

    2013-01-01

    The purpose of this study is to establish a snapshot of the extent to which teacher educators are preparing teacher candidates to use mobile learning technologies in PK-12 classrooms, with the goal of drawing more teacher credentialing institutions into the conversations surrounding this initiative. We used a questionnaire consisting of open-ended…

  3. Commercializing light-duty plug-in/plug-out hydrogen-fuel-cell vehicles: "Mobile Electricity" technologies and opportunities

    NASA Astrophysics Data System (ADS)

    Williams, Brett D.; Kurani, Kenneth S.

    Starting from the premise that new consumer value must drive hydrogen-fuel-cell-vehicle (H 2FCV) commercialization, a group of opportunities collectively called "Mobile Electricity" is characterized. Mobile Electricity (Me-) redefines H 2FCVs as innovative products able to import and export electricity across the traditional vehicle boundary. Such vehicles could provide home recharging and mobile power, for example for tools, mobile activities, emergencies, and electric-grid-support services. This study integrates and extends previous analyses of H 2FCVs, plug-in hybrids, and vehicle-to-grid (V2G) power. Further, it uses a new electric-drive-vehicle and vehicular-distributed-generation model to estimate zero-emission-power versus zero-emission-driving tradeoffs, costs, and grid-support revenues for various electric-drive vehicle types and levels of infrastructure service. By framing market development in terms of new consumer value flowing from Me-, this study suggests a way to move beyond the battery versus fuel-cell zero-sum game and towards the development of integrated plug-in/plug-out hybrid platforms. As one possible extension of this Me- product platform, H 2FCVs might supply clean, high-power, and profitable Me- services as the technologies and markets mature.

  4. Magmas, Mushes and Mobility: Thermal Histories of Magma Reservoirs from Combined U-Series and Diffusion Ages

    NASA Astrophysics Data System (ADS)

    Cooper, K. M.; Rubin, A. E.; Schrecengost, K.; Kent, A. J.; Huber, C.

    2014-12-01

    The thermal conditions of magma storage control many aspects of the dynamics of a magma reservoir system. For example, the temperature of magma storage directly relates to the crystallinity, and magmas stored at relatively low temperatures in a crystal mush (more than 40-50% crystalline) must be remobilized (e.g., by heating) before they can be erupted. A better understanding of the duration of magma storage at largely-liquid vs. largely-solid conditions is thus critical to understanding crustal magmatic processes such as magma mixing and for quantifying the hazard potential of a given volcano. Although mineral thermometry reflects the conditions of crystal growth or equilibration, these may not correspond to the thermal conditions of crystal storage. The duration of crystal storage at high temperatures can be quantified by comparing U-series crystal ages with the time scales over which disequilibrium trace-element profiles in the same crystals would be erased by diffusion. In the case of Mount Hood, OR, such a comparison for the two most recent eruptions shows that <12% of the total lifetime of plagioclase crystals (minimum 21 kyr) was spent at temperatures high enough that the magma would be easily mobilized. Partial data sets for other systems suggest such behavior is common, although the diffusion and U-series ages in these cases are from different samples and may not be directly comparable. We will present preliminary data combining U-series dating and diffusion timescales on the same samples for other volcanic systems (e.g., Lassen Volcanic Center, Mount St. Helens, Okataina Volcanic Center, New Zealand). Combining these data with numerical models offers additional insights into the controls on the conditions of storage. In addition, extension of this approach to combining U-Th ages with time scales of Li diffusion in zircon offers a promising new method to quantify thermal histories of silicic reservoir systems.

  5. An electric scooter simulation program for training the driving skills of stroke patients with mobility problems: a pilot study.

    PubMed

    Jannink, Michiel J A; Erren-Wolters, C Victorien; de Kort, Alexander C; van der Kooij, Herman

    2008-12-01

    This paper describes an electric scooter simulation program and a first evaluation study in which we explored if it is possible to train the driving skills of future users of electric mobility scooters by means of an electric scooter simulation program in addition to conventional electric scooter training. Within this explorative study,10 stroke survivors were randomly assigned to either the control (n=5) or the electric scooter simulation intervention group (n=5). Participants were assessed twice on the functional evaluating rating scale. During the followup measurement, subjective experiences regarding both forms of electric scooter training were elicited by a questionnaire. After a training period of 5 weeks, both groups improved on the Functional Evaluation Rating Scale. It can be concluded that the patients with stroke were satisfied with the electric scooter simulation training. PMID:18954289

  6. Diffusion in liquid metal systems. [information on electrical resistivity and thermal conductivity

    NASA Technical Reports Server (NTRS)

    Ukanwa, A. O.

    1975-01-01

    Physical properties of twenty liquid metals are reported; some of the data on such liquid metal properties as density, electrical resistivity, thermal conductivity, and heat capacity are summarized in graphical form. Data on laboratory handling and safety procedure are summarized for each metal; heat-transfer-correlations for liquid metals under various conditions of laminar and turbulent flow are included. Where sufficient data were available, temperature equations of properties were obtained by the method of least-squares fit. All values of properties given are valid in the given liquid phase ranges only. Additional tabular data on some 40 metals are reported in the appendix. Included is a brief description of experiments that were performed to investigate diffusion in liquid indium-gallium systems.

  7. Magnetically Diffused Radial Electric-Arc Air Heater Employing Water-Cooled Copper Electrodes

    NASA Technical Reports Server (NTRS)

    Mayo, R. F.; Davis, D. D., Jr.

    1962-01-01

    A magnetically rotated electric-arc air heater has been developed that is novel in that an intense magnetic field of the order of 10,000 to 25,000 gauss is employed. This field is supplied by a coil that is connected in series with the arc. Experimentation with this heater has shown that the presence of an intense magnetic field transverse to the arc results in diffusion of the arc and that the arc has a positive effective resistance. With the field coil in series with the arc, highly stable arc operation is obtained from a battery power supply. External ballast is not required to stabilize the arc when it is operating at maximum power level. The electrode erosion rate is so low that the airstream contamination is no more than 0.07 percent and may be substantially less.

  8. Electrical and materials characterization of tungsten-titanium diffusion barrier layers and alloyed silver metallization

    NASA Astrophysics Data System (ADS)

    Bhagat, Shekhar Kumar

    With the constant miniaturization of semiconductor devices, research is always ongoing to obtain the best materials and/or materials systems which fulfill all the requirements of an ideal interconnect. Silver (Ag) and silver based alloys are front runners among other metals and alloys being investigated. Ag has a low electrical resistivity (1.59 micro-ohm-centimeters for bulk), very high thermal conductivity (4.25 Watt per centimeters per Kelvin), and has better electromigration resistance than aluminum (Al). In the pure form, however, it has several drawbacks (e.g., a tendency to diffuse in silicon substrate at higher temperatures, inadequate adhesion to silicon dioxide, poor corrosion resistance, and agglomeration at higher temperatures). These drawbacks can be circumvented by the addition of diffusion barrier layers and/or alloying in silver. The present study investigates both routes to make silver a legitimate interconnect material. Initially this study focuses on thermal stability and behavior of tungsten-titanium (W-Ti) barrier layers for Ag metallization. It is shown that Ag thin films are thermally stable up to 650 degrees centigrade with the presence of W-Ti under layers. The effect of a W-Ti layer on the {111} texture formation in Ag thin film is also evaluated in detail. Insertion of a thin W-Ti over layer on Ag thin films is investigated with respect to their thermal stability. This research also evaluates the diffusion of Ag into silicon dioxide and W-Ti barriers. This project shows that W-Ti is an effective barrier layer for silver metallization. Later, the study investigates the effect of Cu addition in silver metallization and its impact on electromigration resistance. It is shown that Cu addition enhances the electromigration lifetime for silver metallization.

  9. Thermal relaxation, electrical conductivity, and charge diffusion in a hot QCD medium

    NASA Astrophysics Data System (ADS)

    Mitra, Sukanya; Chandra, Vinod

    2016-08-01

    The response of electromagnetic (EM) fields that are produced in noncentral heavy-ion collisions to electromagnetically charged quark gluon plasma can be understood in terms of charge transport and charge diffusion in the hot QCD medium. This article presents a perspective on these processes by investigating the temperature behavior of the related transport coefficients, viz. electrical conductivity and the charge diffusion coefficients along with charge susceptibility. In the process of estimating them, thermal relaxation times for quarks and gluons have been determined first. These transport coefficients have been studied by solving the relativistic transport equation in the Chapman-Enskog method. For the analysis, 2 →2 , quark-quark, quark-gluon and gluon-gluon scattering processes are taken into account along with an effective description of hot QCD equations of state (EOSs) in terms of temperature dependent effective fugacities of quasiquarks (antiquarks) and quasigluons. Both improved perturbative hot QCD EOSs at high temperature and a lattice QCD EOS are included for the analysis. The hot QCD medium effects entering through the quasiparticle momentum distributions along with an effective coupling, are seen to have significant impact on the temperature behavior of these transport parameters along with the thermal relaxation times for the quasigluons and quasiquarks.

  10. Measurement by nuclear magnetic resonance diffusion of the dimensions of the mobile lipid compartment in C6 cells.

    PubMed

    Pérez, Yolanda; Lahrech, Hana; Cabañas, Miquel E; Barnadas, Ramon; Sabés, Manel; Rémy, Chantal; Arús, Carles

    2002-10-15

    The (1)H spectrum of certain tumor cells, in vivo tumors, and their biopsies in vitro shows a narrow and intense resonance at 1.26 ppm, which has been assigned to the fatty acyl chain of triglycerides [nuclear magnetic resonance (NMR) visible mobile lipids, MLs]. We have used diffusion-weighted NMR spectroscopy to directly address the subcellular origin of MLs in the case of C6 cells in which lactate accumulation had been inhibited by prior iodoacetamide incubation. Borage oil and artificial lipid droplets were used as model systems of free and restricted diffusion, respectively. The characteristic diameter for the ML resonance compartment measured by NMR for the C6 cells was not significantly different from the one obtained with phase contrast microscopy (1.88 +/- 0.04 micro m from NMR versus 1.37 +/- 0.33 micro m from microscopy). We herewith provide direct and noninvasive evidence that the lipid signal at 1.26 ppm in C6 cells, which remains visible in long echo time (T(E) = 136 ms) experiments, mostly originates from subcellular structures with diameters of 1-2 micro m, which correspond to the cytosolic lipid droplets that can be detected in optical microscopy preparations of the same cells. PMID:12384523

  11. Drift-Diffusion Modeling of the Effects of Structural Disorder and Carrier Mobility on the Performance of Organic Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Finck, Benjamin Y.; Schwartz, Benjamin J.

    2015-09-01

    We probe the effects of structural disorder on the performance of organic photovoltaic (OPV) devices via drift-diffusion modeling. We utilize ensembles of spatially disordered one-dimensional mobility profiles to approximate the three-dimensional structural disorder present in actual devices. Each replica in our ensemble approximates one high-conductivity pathway through the three-dimensional network(s) present in a polymer-based bulk heterojunction solar cell, so that the ensemble-averaged behavior provides a good approximation to a full three-dimensional structurally disordered device. Our calculations show that the short-circuit current, fill factor, and power conversion efficiency of simulated devices are all negatively impacted by the inclusion of structural disorder, but that the open-circuit voltage is nearly impervious to structural defects. This is in contrast to energetic disorder, where previous studies found that spatial variation in the energy in OPV active layers causes a decrease in the open-circuit voltage. We also show that structural disorder causes the greatest detriment to device performance for feature sizes between 2 and 10 nm. Since this is on the same length scale as the fullerene crystallites in experimental devices, it suggests both that controlling structural disorder is critical to the performance of OPV devices and that the effects of structural disorder should be included in future drift-diffusion modeling studies of organic solar cells.

  12. Monitoring of dust emission on gravel roads: Development of a mobile methodology and examination of horizontal diffusion

    NASA Astrophysics Data System (ADS)

    Edvardsson, Karin; Magnusson, Rolf

    Traffic-generated fugitive dust on gravel roads impairs visibility and deposits on the adjacent environment. Particulate matter smaller than 10 μm in diameter (PM 10) is also associated with human health problems. Dust emission strength depends on the composition of granular material, road moisture, relative humidity, local climate (precipitation, wind velocity, etc.), and vehicle characteristics. The objectives of this study were to develop a reliable and rapid mobile methodology to measure dust concentrations on gravel roads, evaluate the precision and repeatability of the methodology and correspondence with the currently used visual assessment technique. Downwind horizontal diffusion was studied to evaluate the risk of exceeding the maximum allowed particulate matter concentration in ambient air near gravel roads according to European Council Directive [European Council Directive 1999/30/EC of 22 April 1999 relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. Official Journal of the European Communities. L163/41.]. A TSI DustTrak Aerosol Monitor was mounted on an estate car travelling along test sections treated with various dust suppressants. Measured PM 10 concentrations were compared to visual assessments performed at the same time. Airborne particles were collected in filters mounted behind the vehicle to compare the whole dust fraction with the PM 10 concentration. For measuring the horizontal diffusion, DustTraks were placed at various distances downwind of a dusty road section. The mobile methodology was vehicle and speed dependent but not driver dependent with pre-specified driving behaviours. A high linear correlation between PM 10 of different vehicles makes relative measurements of dust concentrations possible. The methodology gives continuous data series, mobility, and easy handling and provides fast, reliable and inexpensive measurements for estimating road conditions to

  13. Diffuse, non-polar electropermeabilization and reduced propidium uptake distinguish the effect of nanosecond electric pulses.

    PubMed

    Semenov, Iurii; Zemlin, Christian; Pakhomova, Olga N; Xiao, Shu; Pakhomov, Andrei G

    2015-10-01

    Ca2+ activation and membrane electroporation by 10-ns and 4-ms electric pulses (nsEP and msEP) were compared in rat embryonic cardiomyocytes. The lowest electric field which triggered Ca2+ transients was expectedly higher for nsEP (36 kV/cm) than for msEP (0.09 kV/cm) but the respective doses were similar (190 and 460 mJ/g). At higher intensities, both stimuli triggered prolonged firing in quiescent cells. An increase of basal Ca2+ level by >10 nM in cells with blocked voltage-gated Ca2+ channels and depleted Ca2+ depot occurred at 63 kV/cm (nsEP) or 0.14 kV/cm (msEP) and was regarded as electroporation threshold. These electric field values were at 150-230% of stimulation thresholds for both msEP and nsEP, notwithstanding a 400,000-fold difference in pulse duration. For comparable levels of electroporative Ca2+ uptake, msEP caused at least 10-fold greater uptake of propidium than nsEP, suggesting increased yield of larger pores. Electroporation by msEP started Ca2+ entry abruptly and locally at the electrode-facing poles of cell, followed by a slow diffusion to the center. In a stark contrast, nsEP evoked a "supra-electroporation" pattern of slower but spatially uniform Ca2+ entry. Thus nsEP and msEP had comparable dose efficiency, but differed profoundly in the size and localization of electropores. PMID:26112464

  14. Extrinsic and intrinsic causes of the electrical degradation of AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Yulong, Fang; Shaobo, Dun; Bo, Liu; Jiayun, Yin; Shujun, Cai; Zhihong, Feng

    2012-05-01

    Electrical stress experiments under different bias configurations for AlGaN/GaN high electron mobility transistors were performed and analyzed. The electric field applied was found to be the extrinsic cause for the device instability, while the traps were recognized as the main intrinsic factor. The effect of the traps on the device degradation was identified by recovery experiments and pulsed I-V measurements. The total degradation of the devices consists of two parts: recoverable degradation and unrecoverable degradation. The electric field induced traps combined with the inherent ones in the device bulk are mainly responsible for the recoverable degradation.

  15. Efficient Stem Cell Collection after Modified Cisplatin-Based Mobilization Chemotherapy in Patients with Diffuse Large B Cell Lymphoma.

    PubMed

    Lisenko, Katharina; Cremer, Martin; Schwarzbich, Mark-Alexander; Kriegsmann, Mark; Ho, Anthony D; Witzens-Harig, Mathias; Wuchter, Patrick

    2016-08-01

    In patients with relapsed or refractory diffuse large B cell lymphoma (DLBCL), R-DHAP (rituximab, dexamethasone, cytarabine, and cisplatin) is a commonly used regimen for salvage therapy and for mobilization of peripheral blood stem cells (PBSCs). At our center, a modified R-DHAP regimen with administration of 25 mg/m(2) cisplatin as a 3-hour infusion over 4 consecutive days, instead of a single infusion of 100 mg/m(2) over 24 hours, has been established. The aim of this study was to analyze the efficiency of this modified R-DHAP regimen plus G-CSF as a mobilization strategy. We retrospectively analyzed clinical characteristics, PBSC collection and autologous stem cell transplantation parameters, and hematologic reconstitution data for 65 patients with relapsed or refractory DLBCL who underwent PBSC collection after mobilization with the modified R-DHAP protocol at our institution between 2002 and 2013. Data were evaluated for the overall cohort and with regard to the number of R-DHAP cycles received before PBSC collection. PBSC collection was performed after the first R-DHAP course in 32 patients (49%), after the second course in 30 patients (46%), and after the third course in 3 patients (5%). Sixty-three patients (97%) achieved the collection goal of ≥2.0 × 10(6) CD34(+) cells/kg body weight. A significantly higher median CD34(+) cell collection yield was achieved when cells were collected after the first R-DHAP course compared with after the second course (P < .01). A peripheral blood leukocyte increase of ≥1.0 × 10(9)/L and a platelet increase of ≥20 × 10(9)/L were observed by 11 days after ASCT. In our cohort, the modified R-DHAP regimen proved safe and feasible, showed an overall response rate (complete response, complete response unconfirmed, and partial response) of 66%, and allowed efficient mobilization of CD34(+) cells for PBSC collection. PMID:27060439

  16. Thermal Diffusion Processes in Metal-Tip-Surface Interactions: Contact Formation and Adatom Mobility

    NASA Astrophysics Data System (ADS)

    Sørensen, Mads R.; Jacobsen, Karsten W.; Jónsson, Hannes

    1996-12-01

    We have carried out computer simulations to identify and characterize various thermally activated atomic scale processes that can play an important role in room temperature experiments where a metal tip is brought close to a metal surface. We find that contact formation between the tip and the surface can occur by a sequence of atomic hop and exchange processes which become active on a millisecond time scale when the tip is about 3-5 Å from the surface. Adatoms on the surface are stabilized by the presence of the tip and energy barriers for diffusion processes in the region under the tip are reduced. This can cause adatoms to follow the tip as it is moved over the surface.

  17. Study on electrical characteristics of barrier-free atmospheric air diffuse discharge generated by nanosecond pulses and long wire electrodes

    SciTech Connect

    Li, Lee Liu, Yun-Long; Teng, Yun; Liu, Lun; Pan, Yuan

    2014-07-15

    In room-temperature atmospheric air, the large-scale diffuse plasmas can be generated via high-voltage nanosecond pulses with short rise-time and wire electrodes. Diffuse discharge with the wire electrode length up to 110.0 cm and the discharge spacing of several centimeters has been investigated in this paper. Electrical characteristics of diffuse discharge have been analyzed by their optical photographs and measuring of the voltage and current waveforms. Experimental results show the electrode spacing, and the length of wire electrodes can influence the intensity and mode transition of diffuse discharge. The characteristic of current waveforms is that there are several current oscillation peaks at the time of applied pulsed voltage peak, and at the tail of applied pulse, the conduction current component will compensate the displacement one so that the measured current is unidirectional in diffuse discharge mode. The transition from diffuse discharge to arc discharge is always with the increasing of conduction current density. As for nanosecond pulses with long tail, the long wire electrodes are help for generating non-equilibrium diffuse plasmas.

  18. Satellite applications to electric-utility communications needs. [land mobile satellite service

    NASA Technical Reports Server (NTRS)

    Horstein, M.; Barnett, R.

    1981-01-01

    Significant changes in the Nation's electric power systems are expected to result from the integration of new technology, possible during the next decade. Digital communications for monitor and control, exclusive of protective relaying, are expected to double or triple current traffic. A nationwide estimate of 13 Mb/s traffic is projected. Of this total, 8 Mb/s is attributed to the bulk-power system as it is now being operated (4 Mb/s). This traffic could be accommodated by current communications satellites using 3- to 4.5-m-diameter ground terminals costing $35,000 to $70,000 each. The remaining 5-Mb/s traffic is attributed to new technology concepts integrated into the distribution system. Such traffic is not compatible with current satellite technology because it requires small, low-cost ground terminals. Therefore, a high effective isotropic radiated power satellite, such as the one being planned by NASA for the Land Mobile Satellite Service, is required.

  19. Midnight ionosphere collapse at Arecibo and its relationship to the neutral wind, electric field, and ambipolar diffusion

    NASA Astrophysics Data System (ADS)

    Gong, Yun; Zhou, Qihou; Zhang, Shaodong; Aponte, Nestor; Sulzer, Michael; Gonzalez, Sixto

    2012-08-01

    We report the analysis of "midnight collapse," a large drop in the F-layer peak height (HmF2) around midnight, observed at Arecibo during Jan. 14-22, 2010. During the nine nights of observations, the first four nights (Jan. 14-17) exhibited modest drops in HmF2 while the last five nights (Jan. 18-22) showed more severe drops. We examine the roles played by the meridional wind, electric field, and ambipolar diffusion in driving the vertical ion motion. The collapse process can be classified into three stages: preconditioning, initial descent, and sustained descent. Severe collapses occur when HmF2 is preconditioned high prior to the collapse. Ambipolar diffusion is most important during the initial descent. Neutral wind and electric field are responsible for sustaining the collapse. During Jan. 18-22, HmF2 was pushed high by the neutral wind before the collapse started. Neutral wind and electric field were in phase during the sustained severe collapses. The diurnal tide of the meridional wind provided the general condition for the collapses. The terdiurnal tide was most important to cause the difference between the two periods in our observation. Previous studies largely emphasized meridional wind being the dominant mechanism causing midnight collapse. Our study suggests that electric field and ambipolar diffusion also play an important role and the former can be the most dominant factor in some cases.

  20. Simultaneously improving electrical conductivity and thermopower of polyaniline composites by utilizing carbon nanotubes as high mobility conduits.

    PubMed

    Wang, Hong; Yi, Su-in; Pu, Xiong; Yu, Choongho

    2015-05-13

    Electrical conductivity and thermopower of isotropic materials typically have inversely proportional correlation because both are strongly affected in the opposite way by the electronic carrier concentration. This behavior has been one of the major hurdles in developing high-performance thermoelectrics whose figure-of-merit enhances with large thermopower and high electrical conductivity. Here we report a promising method of simultaneously improving both properties with polyaniline (PANI) composites filled by carbon nanotubes (CNTs). With addition of double-wall CNTs (DWCNTs), the electronic mobility of PANI doped with camphorsulfonic acid (PANI-CSA) was raised from ∼0.15 to ∼7.3 cm(2)/(V s) (∼50 time improvement) while the carrier concentration was decreased from ∼2.1 × 10(21) to ∼5.6 × 10(20) cm(-3) (∼4 time reduction). The larger increase of mobility increased electrical conductivity despite the carrier concentration reduction that enlarges thermopower. The improvement in the carrier mobility could be attributed to the band alignment that attracts hole carriers to CNTs whose mobility is much higher than that of PANI-CSA. The electrical conductivity of the PANI-CSA composites with 30-wt % DWCNTs was measured to be ∼610 S/cm with a thermopower value of ∼61 μV/K at room temperature, resulting in a power factor value of ∼220 μW/(m K(2)), which is more than two orders higher than that of PANI-CSA as well as the highest among those of the previously reported PANI composites. Further study may result in high performance thermoelectric organic composites uniquely offering mechanical flexibility, light weight, low toxicity, and easy manufacturing. unlike conventional inorganic semiconductors. PMID:25894982

  1. Survey on Different Samsung with Nokia Smart Mobile Phones in the Specific Absorption Rate Electrical Field of Head.

    PubMed

    Fakhri, Yadolah; Alinejad, Azim; Keramati, Hassan; Bay, Abotaleb; Avazpour, Moayed; Zandsalimi, Yahya; Moradi, Bigard; Rasouli Amirhajeloo, Leila; Mirzaei, Maryam

    2016-01-01

    The use of smart phones is increasing in the world. This excessive use, especially in the last two decades, has created too much concern on the effects of emitted electromagnetic fields and specific absorption rate on human health. In this descriptive-analytical study of the electric field resulting from smart phones of Samsung and Nokia by portable measuring device, electromagnetic field, Model HI-3603-VDT/VLF, were measured. Then, head absorption rate was calculated in these two mobiles by ICNIRP equation. Finally, the comparison of specific absorption rate, especially between Samsung and Nokia smart phones, was conducted by T-Test statistics analysis. The mean of electric field for Samsung and Nokia smart mobile phones was obtained 1.8 ±0.19 v/m  and 2.23±0.39 v/m , respectively, while the range of the electric field was obtained as 1.56-2.21 v/m and 1.69-2.89 v/m for them, respectively. The mean of specific absorption rate in Samsung and Nokia was obtained 0.002 ± 0.0005 W/Kg and 0.0041±0.0013 W/Kg at the frequency of 900 MHz and 0.004±0.001 W/Kg and 0.0062±0.0002 W/Kg at the frequency of 1800 MHz respectively. The ratio of mean electronic field to guidance in the Samsung mobile phone at the frequency of 900 MHz and 1800 MHz was 4.36% and 3.34%, while was 5.62% and 4.31% in the Nokia mobile phone, respectively. The ratio of mean head specific absorption rate in smart mobile phones of Samsung and Nokia in the guidance level at the frequency of 900 was 0.15% and 0.25%, respectively, while was 0.23 %and 0.38% at the frequency of 1800 MHz, respectively. The rate of specific absorption of Nokia smart  mobile phones at the frequencies of 900 and 1800 MHz  was significantly higher than Samsung (p value <0.05). Hence, we can say that in a fixed period, health risks of Nokia smart phones is higher than Samsung smart mobile phone. PMID:27157169

  2. Origin of the unidentified positive mobile ions causing the bias temperature instability in SiC MOSFETs and their diffusion process

    NASA Astrophysics Data System (ADS)

    Shirakawa, Hiroki; Kamiya, Katsumasa; Araidai, Masaaki; Watanabe, Heiji; Shiraishi, Kenji

    2016-06-01

    For SiC metal–oxide–semiconductor field-effect transistors (MOSFETs), it has been shown that unidentified positive mobile ions are generated in SiO2 after conventional hydrogen annealing, which leads to significant reliability degradation known as bias temperature instability (BTI). Discovering the origin of these mobile ions is important for fabricating highly reliable SiC MOSFETs. On the basis of first-principles calculations, we verified that the BTI of SiC MOSFETs is caused by hydrogen ions combining with CO3-like defects in SiO2. These hydrogen ions dissociate from the CO3-like defects and diffuse “as protons” in SiO2. These results indicate that the observed positive mobile ions are protons.

  3. Electrical mobility in organic thin-film transistors determined by noise spectroscopy

    NASA Astrophysics Data System (ADS)

    Bonavolontà, C.; Albonetti, C.; Barra, M.; Valentino, M.

    2011-11-01

    Organic field-effect transistors (OFET) based on both n-type (perylene derivative) and p-type (α-sexithiophene and pentacene) organic thin films are characterized using low-frequency noise spectroscopy to estimate the charge carrier mobility. The power spectral density shows that the exposure of OFET to air affects the thermal noise fluctuations and that the thermal noise RMS value depends on gate voltage. The power spectral density noise proves that the carrier mobility is gate-voltage dependent. Unlike the I-V measurements, the noise spectroscopy analysis demonstrates the dependence of the mobility on the carrier polarity. We discuss the charge mobility and transport mechanism of a pentacene device with and without electrodes functionalized by an octanethiol chain. The results show that in the functionalized device the carrier mobility is improved and does not depend on the high gate voltage.

  4. Theoretical examination of effective oxygen diffusion coefficient and electrical conductivity of polymer electrolyte fuel cell porous components

    NASA Astrophysics Data System (ADS)

    Inoue, Gen; Yokoyama, Kouji; Ooyama, Junpei; Terao, Takeshi; Tokunaga, Tomomi; Kubo, Norio; Kawase, Motoaki

    2016-09-01

    The reduction of oxygen transfer resistance through porous components consisting of a gas diffusion layer (GDL), microporous layer (MPL), and catalyst layer (CL) is very important to reduce the cost and improve the performance of a PEFC system. This study involves a systematic examination of the relationship between the oxygen transfer resistance of the actual porous components and their three-dimensional structure by direct measurement with FIB-SEM and X-ray CT. Numerical simulations were carried out to model the properties of oxygen transport. Moreover, based on the model structure and theoretical equations, an approach to the design of new structures is proposed. In the case of the GDL, the binder was found to obstruct gas diffusion with a negative effect on performance. The relative diffusion coefficient of the MPL is almost equal to that of the model structure of particle packing. However, that of CL is an order of magnitude less than those of the other two components. Furthermore, an equation expressing the relative diffusion coefficient of each component can be obtained with the function of porosity. The electrical conductivity of MPL, which is lower than that of the carbon black packing, is considered to depend on the contact resistance.

  5. Diffusion zone between high-chromium cast iron and high-manganese steel during electric-slag facing

    SciTech Connect

    Ponomarenko, V.P.; Shvartser, A.Y.; Stroganova, G.V.

    1986-05-01

    The authors investigate extending the service lives of components by the method of electric-slag facing of working surfaces. Steel 45 was used in the annealed state. Electric-slag remelting was the method used to determine the bending strength. Metallographic examinations were conducted under an MIM-8m microscope, while x-ray analysis of the built-up and base metals were performed on a DRON-2 diffractometer. BAsic alloying elements, chromium and manganese were studied on a ''Cameca MS-46'' microanalyzer. During the electri-slag facing of a high-chromium cast iron containing 8% of Mn on high-manganese steel 11OG13L diffusion equalization of the manganese content occurs in the fusion zone. Diffusion displacement of carbon, chromium, and manganese from high-chromium cast iron into the high-manganese steel during electric-slag facing gies rise to a smooth change in the structure of the metal in the fusion zone, and to increased strength of the joint between the unlike materials investigated.

  6. Variation in the electrical properties of 100 V/100 a rated mesh and stripe TDMOSFETs (Trench Double-Diffused MOSFETs) for motor drive applications

    NASA Astrophysics Data System (ADS)

    Na, Kyoung-Il; Kah, Dong-Ha; Kim, Sang-Gi; Koo, Jin-Gun; Kim, Jongdae; Yang, Yil-Suk; Lee, Jin-Ho

    2012-05-01

    The vertical power metal-oxide semiconductor field-effect transistors (MOSFETs) with deep trench structures are the most promising candidates to overcome the trade-off relationship between the ON-resistance (R ON ) and the blocking voltage (BV DS ). Especially, 100 V/100 A rated trench power MOSFETs are used in components of many power systems, such as motors and LED lighting drive ICs, DC-DC converters in electric vehicles, and so on. In this work, we studied variations of the electrical characteristics, such as threshold voltage (V TH ), BV DS , and drain current drivability, with p-well doping concentration via the SILVACO simulator. From simulation results, we found the BV DS and the drain current (I D ) as functions of the p-well doping concentration at an ion implantation energy of 80 keV. With increasing of p-well doping concentration in the guard ring region, both V TH and BV DS slowly increased, but I D decreased, because the boron lateral diffusion during the fabrication process below gate trench region affected the doping concentration of the p-body at the active region. Additionally, 100 V/100 A rated trench double-diffused MOSFETs (TDMOSFETs) with meshes and stripes were successfully developed by using a silicon deep etching process. The variations in the electrical properties, such as V TH , BV DS , and drain current drivability, of the two different kinds of fabricated devices, with cell design and density in TDMOSFETs were also studied. The BV DS and the V TH in the stripe-type TDMOSFET were 110 and 3 V, respectively. However, the V TH of mesh-type device was smaller 0.5 V than that of stripe-type because of corner effect. The BV DS improved about 20 V compared to stripe-type TDMOSFET due to edge termination, and the maximum drain current (I D.MAX ) was improved by about 10% due to an increase in the gate width at the same chip size. These effects were reflected in devices with different cell densities. When the cell density was increased, however

  7. The role of waves and DC electric fields for electron heating and acceleration in the diffusion region

    NASA Astrophysics Data System (ADS)

    Graham, Daniel; Khotyaintsev, Yuri; Vaivads, Andris; Norgren, Cecilia; Andre, Mats; Lindqvist, Per-Arne; Le Contel, Olivier; Ergun, Robert; Goodrich, Katherine; Torbert, Roy; Burch, James; Russell, Christopher; Magnes, Werner; Giles, Barbara; Pollock, Craig; Mauk, Barry; Fuselier, Stephen

    2016-04-01

    Magnetic reconnection is a fundamental process in solar and astrophysical plasmas. The processes operating at electron spatial-scales, which enable magnetic field lines to reconnect, are generally difficult to resolve and identify. However, the recently launched Magnetospheric Multiscale (MMS) mission is specifically designed to resolve electron spatial scales. We use the MMS spacecraft to investigate the process operating within the diffusion region to determine the causes of electron heating and acceleration. In particular, we investigate the type of electrostatic and electromagnetic waves that develop and how they affect the electron distributions. We also compare the roles of wave-particle interactions with DC electric fields to determine which is responsible for the electron heating observed in diffusion regions.

  8. Effect of Epidural Electrical Stimulation and Repetitive Transcranial Magnetic Stimulation in Rats With Diffuse Traumatic Brain Injury

    PubMed Central

    Yoon, Yong-Soon; Cho, Kang Hee; Kim, Eun-Sil; Lee, Mi-Sook

    2015-01-01

    Objective To evaluate the effects of epidural electrical stimulation (EES) and repetitive transcranial magnetic stimulation (rTMS) on motor recovery and brain activity in a rat model of diffuse traumatic brain injury (TBI) compared to the control group. Methods Thirty rats weighing 270-285 g with diffuse TBI with 45 kg/cm2 using a weight-drop model were assigned to one of three groups: the EES group (ES) (anodal electrical stimulation at 50 Hz), the rTMS group (MS) (magnetic stimulation at 10 Hz, 3-second stimulation with 6-second intervals, 4,000 total stimulations per day), and the sham-treated control group (sham) (no stimulation). They were pre-trained to perform a single-pellet reaching task (SPRT) and a rotarod test (RRT) for 14 days. Diffuse TBI was then induced and an electrode was implanted over the dominant motor cortex. The changes in SPRT success rate, RRT performance time rate and the expression of c-Fos after two weeks of EES or rTMS were tracked. Results SPRT improved significantly from day 8 to day 12 in the ES group and from day 4 to day 14 in the MS group (p<0.05) compared to the sham group. RRT improved significantly from day 6 to day 11 in ES and from day 4 to day 9 in MS compared to the sham group. The ES and MS groups showed increased expression of c-Fos in the cerebral cortex compared to the sham group. Conclusion ES or MS in a rat model of diffuse TBI can be used to enhance motor recovery and brain activity. PMID:26161348

  9. A study of electrically active traps in AlGaN/GaN high electron mobility transistor

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Cui, Sharon; Ma, T. P.; Hung, Ting-Hsiang; Nath, Digbijoy; Krishnamoorthy, Sriram; Rajan, Siddharth

    2013-10-01

    We have studied electron conduction mechanisms and the associated roles of the electrically active traps in the AlGaN layer of an AlGaN/GaN high electron mobility transistor structure. By fitting the temperature dependent I-V (Current-Voltage) curves to the Frenkel-Poole theory, we have identified two discrete trap energy levels. Multiple traces of I-V measurements and constant-current injection experiment all confirm that the main role of the traps in the AlGaN layer is to enhance the current flowing through the AlGaN barrier by trap-assisted electron conduction without causing electron trapping.

  10. Improvement of Electrical Properties of Silicon Quantum Dot Superlattice Solar Cells with Diffusion Barrier Layers

    NASA Astrophysics Data System (ADS)

    Yamada, Shigeru; Kurokawa, Yasuyoshi; Miyajima, Shinsuke; Konagai, Makoto

    2013-04-01

    We investigate the effects of a niobium-doped titanium dioxide (TiO2:Nb) diffusion barrier layer on the performance of silicon quantum dot superlattice (Si-QDSL) solar cells. The insertion of a 2-nm-thick TiO2:Nb layer significantly reduces phosphorus diffusion from a highly doped n-type layer into a Si-QDSL layer during thermal annealing at 900 °C. The phosphorous concentration in the Si-QDSL layer of the solar cell with the TiO2:Nb diffusion barrier layer was found to be less than 1018 cm-3, which is approximately two orders of magnitude lower than that of the solar cell without the diffusion barrier layer. The reduction in phosphorous concentration leads to the improvement of photo-generated carrier collection in the Si-QDSL layer. The short circuit current density of the solar cell with the diffusion barrier layer was dramatically improved to 1.6 mA/cm2 without the degradation of open circuit voltage and fill factor.

  11. Ambipolar diffusion in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Tzur, I.; Roble, R. G.

    1984-01-01

    In the middle atmosphere above 60 km, the electron concentration increases with altitude, reaching values of 10 to the 10th per cu m in the daytime ionospheric E region near 100 km. The electrons are more mobile than the ions and diffuse more rapidly through the neutral atmosphere. The electron diffusion polarizes the medium, causing an electric field to develop that acts to retard the electron diffusion and enhance the conduction current of ions. A global zonally averaged numerical model of atmosheric electricity from the ground to 100 km is used to examine the effect of ambipolar diffusion and the earth's geomagnetic field on the currents and fields in the middle atmosphere. The results show that above about 65 km, ambipolar diffusion generates local electric fields and conduction currents that balance electron diffusion currents. The electric fields and conduction currents are a few orders of magnitude larger than the vertical fields and currents calculated from the downward mapping of the ionospheric potential without taking electron diffusion into account. Ambipolar diffusion does not alter the total current flowing in the global circuit. It is a local effect where enhanced conduction currens flow to balance the electron diffusion current.

  12. ELECTROKINETIC PHENOMENA : X. ELECTRIC MOBILITY AND CHARGE OF PROTEINS IN ALCOHOL-WATER MIXTURES.

    PubMed

    Daniel, J

    1933-01-20

    1. The electrophoretic velocities of gelatin-, egg-albumin-, and gliadin-covered quartz particles in various alcohol-water solutions are, within the limits employed in usual experimental procedures, proportional to the field strength. 2. The electrophoretic mobilities of small, irregularly shaped quartz particles covered with an adsorbed film of protein in alcohol-water solutions are equal to the electroosmotic mobilities of the liquid past similarly coated flat surfaces. Hence the size and shape of such particles does not influence their mobilities, which depend entirely on the protein film. 3. The corrected mobility and hence presumably the charge of gelatin-covered quartz particles in solutions containing 35 per cent ethyl alcohol is proportional to the combining power of the gelatin; therefore the gelatin is adsorbed with the active groups oriented toward the liquid. The same is true in 60 per cent alcohol. 4. The charge calculated by means of the Debye-Henry approximation from the mobility of gelatin in solutions containing up to 35 per cent ethyl alcohol is, in the neighborhood of the isoelectric point, proportional to the combining power of the gelatin. Therefore the dielectric constant and the viscosity of the bulk of the medium may be used in the Debye-Henry approximation Q = 6 pi eta r v(m) (1 + kappa r) to predict changes in charge from mobility. 5. In the neighborhood of the isoelectric point gelatin is probably completely ionized in buffered ethyl alcohol-water mixtures up to 60 per cent alcohol. 6. In the presence of ethyl alcohol the isoelectric point of gelatin is shifted toward smaller hydrogen ion activities. This shift, like that caused by alcohol in the isoelectric points of certain amino acids, is approximately linearly related to the dielectric constant of the medium. PMID:19872717

  13. Low and moderate dose gamma-irradiation and annealing impact on electronic and electrical properties of AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Yadav, Anupama; Flitsiyan, Elena; Chernyak, Leonid; Hwang, Ya-Hsi; Hsieh, Yueh-Ling; Lei, Lei; Ren, Fan; Pearton, Stephen J.; Lubomirsky, Igor

    2015-05-01

    To understand the effects of 60Co gamma-irradiation, systematic studies were carried out on n-channel AlGaN/GaN high electron mobility transistors. Electrical testing, combined with electron beam-induced current measurements, was able to provide critical information on defects induced in the material as a result of gamma-irradiation. It was shown that at low gamma-irradiation doses, the minority carrier diffusion length in AlGaN/GaN exhibits an increase up to ∼300 Gy. The observed effect is due to longer minority carrier (hole) life time in the material's valence band as a result of an internal electron irradiation by Compton electrons. However, for larger doses of gamma irradiation (above 400 Gy), deteriorations in transport properties and device characteristics were observed. This is consistent with the higher density of deep traps in the material's forbidden gap induced by a larger dose of gamma-irradiation. Moderate annealing of device structures at 200°C for 25 min resulted in partial recovery of transport properties and device performance.

  14. Experimental and numerical modeling study of the electrical resistance of gas diffusion layer-less polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Tanaka, Shiro; Shudo, Toshio

    2015-03-01

    The gas diffusion layer (GDL)-less fuel cell composed of a corrugated-mesh shows low flooding performance even in the high current density region, since the gases are supplied more uniformly to the catalyst layer (CL) compared with the conventional fuel cells that utilize GDLs. On the other hand, the internal electrical resistance of the GDL-less fuel cell is higher than that of the conventional fuel cell, because the corrugated-mesh and the underlying microporous layer (MPL) have a low contact area with point contacts. This can greatly increase the resistance at the interface between the corrugated-mesh and MPL as well as that between the MPL and CL, compared to the conventional fuel cell where GDL can make a good contact with the MPL. In this study, the conductivities and the contact resistances of each material in the GDL-less fuel cell were measured under various mechanical compression pressures, and a coupled mechanical-electric-electrochemical model was developed to investigate the effect of electrical resistance on the fuel cell performance. We found that our model can simulate the GDL-less fuel cell well and the electric resistance contributes significantly to the polarization performance in the GDL-less fuel cell.

  15. ELECTROKINETIC PHENOMENA : VII. RELATIONSHIP BETWEEN ELECTRIC MOBILITY, CHARGE, TITRATION CURVE, AND OPTICAL ROTATION OF PROTEIN.

    PubMed

    Abramson, H A; Grossman, E B

    1932-05-20

    The specific rotation of egg albumin, gliadin, and gelatin (40 degrees C.) is discussed in connection with available data on (a) mobility, (b) titration curve, and (c) osmotic pressure. It seems likely that the change in specific rotation with pH of protein solutions is proportional to the change in net charge. PMID:19872669

  16. Structures, Hydration, and Electrical Mobilities of Bisulfate Ion-Sulfuric Acid-Ammonia/Dimethylamine Clusters: A Computational Study.

    PubMed

    Tsona, Narcisse T; Henschel, Henning; Bork, Nicolai; Loukonen, Ville; Vehkamäki, Hanna

    2015-09-17

    Despite the well-established role of small molecular clusters in the very first steps of atmospheric particle formation, their thermochemical data are still not completely available due to limitation of the experimental techniques to treat such small clusters. We have investigated the structures and the thermochemistry of stepwise hydration of clusters containing one bisulfate ion, sulfuric acid, base (ammonia or dimethylamine), and water molecules using quantum chemical methods. We found that water facilitates proton transfer from sulfuric acid or the bisulfate ion to the base or water molecules, and depending on the hydration level, the sulfate ion was formed in most of the base-containing clusters. The calculated hydration energies indicate that water binds more strongly to ammonia-containing clusters than to dimethylamine-containing and base-free clusters, which results in a wider hydrate distribution for ammonia-containing clusters. The electrical mobilities of all clusters were calculated using a particle dynamics model. The results indicate that the effect of humidity is negligible on the electrical mobilities of molecular clusters formed in the very first steps of atmospheric particle formation. The combination of the results of this study with those previously published on the hydration of neutral clusters by our group provides a comprehensive set of thermochemical data on neutral and negatively charged clusters containing sulfuric acid, ammonia, or dimethylamine. PMID:26304742

  17. Solution processing of transparent conducting epitaxial La:BaSnO3 films with improved electrical mobility

    NASA Astrophysics Data System (ADS)

    Wei, R. H.; Tang, X. W.; Hui, Z. Z.; Luo, X.; Dai, J. M.; Yang, J.; Song, W. H.; Chen, L.; Zhu, X. G.; Zhu, X. B.; Sun, Y. P.

    2015-03-01

    As a type of perovskite transparent conducting oxides, La-doped BaSnO3 is considered as a very important material to construct all transparent perovskite devices. The difficulty in achievement of large-area films with high electrical mobility has hindered the development of La-doped BaSnO3 films. Here, we report the results about chemical solution deposition of Ba0.92La0.08SnO3-δ (BLSO) films. The post-annealing and atmosphere as well as lattice mismatch have been investigated. Post-annealing at 1000 °C can obviously improve the performance due to the enhanced crystallization. Under post-annealing in N2 atmosphere the room-temperature resistivity and electrical mobility can achieve 3.25 mΩ cm and 11.09 cm2 V-1 s-1, respectively, for the BLSO on LaAlO3 single crystal substrates due to the enhanced oxygen deficiencies. BLSO films with different orientation can be easily obtained by selection of the substrates, showing isotropic physical properties. Furthermore, the room-temperature resistivity and mobility are optimized to 1.8 mΩ cm and 23.04 cm2 V-1 s-1 when SrTiO3 single crystal substrates with smaller lattice mismatch are used due to the decreased dislocation density. The results will provide an alternative route to fabricate large-area transparent conducting alkaline-earth stannate films with high performance using low-cost chemical solution deposition.

  18. Multi-Instrument Manager Tool for Data Acquisition and Merging of Optical and Electrical Mobility Size Distributions

    NASA Astrophysics Data System (ADS)

    Tritscher, Torsten; Koched, Amine; Han, Hee-Siew; Filimundi, Eric; Johnson, Tim; Elzey, Sherrie; Avenido, Aaron; Kykal, Carsten; Bischof, Oliver F.

    2015-05-01

    Electrical mobility classification (EC) followed by Condensation Particle Counter (CPC) detection is the technique combined in Scanning Mobility Particle Sizers(SMPS) to retrieve nanoparticle size distributions in the range from 2.5 nm to 1 μm. The detectable size range of SMPS systems can be extended by the addition of an Optical Particle Sizer(OPS) that covers larger sizes from 300 nm to 10 μm. This optical sizing method reports an optical equivalent diameter, which is often different from the electrical mobility diameter measured by the standard SMPS technique. Multi-Instrument Manager (MIMTM) software developed by TSI incorporates algorithms that facilitate merging SMPS data sets with data based on optical equivalent diameter to compile single, wide-range size distributions. Here we present MIM 2.0, the next-generation of the data merging tool that offers many advanced features for data merging and post-processing. MIM 2.0 allows direct data acquisition with OPS and NanoScan SMPS instruments to retrieve real-time particle size distributions from 10 nm to 10 μm, which we show in a case study at a fireplace. The merged data can be adjusted using one of the merging options, which automatically determines an overall aerosol effective refractive index. As a result an indirect and average characterization of aerosol optical and shape properties is possible. The merging tool allows several pre-settings, data averaging and adjustments, as well as the export of data sets and fitted graphs. MIM 2.0 also features several post-processing options for SMPS data and differences can be visualized in a multi-peak sample over a narrow size range.

  19. The effect of interfacial diffusion on the electrical resistivity of magnetron sputtered Al-Fe-Sn alloy thin film

    NASA Astrophysics Data System (ADS)

    Zhao, Guannan; Zhang, Qing; Zheng, Zeng; Zhang, Yong; Yan, Biao

    2016-03-01

    The effect of interfacial diffusion in post-deposition annealing on the electrical resistivity of AlFeSn alloy films was investigated for the first time. The microstructure of the film before and after annealing was characterized by Atomic Force Microscope and Transmission Electron Microscope. The temperature dependence of resistivity in the range from 30 to 300 K suggests the presence of electron localization in both as-deposited and annealed films. The electron localization in the as-deposited film could be attributed to structural discontinuity. However, the electron localization in the annealed samples could probably be attributed to the diffusion of Si atoms into the film. An electrical resistivity as low as 1.43 μΩ cm was achieved for a 60 nm thick sample, which is considerably lower than predicted and previously reported. We propose the supreme conductivity of the annealed films could be partly due to the contribution from the electron localization. Our results provide new insight into developing highly conductive metallic materials.

  20. Electrical effect of titanium diffusion on amorphous indium gallium zinc oxide

    SciTech Connect

    Choi, Seung-Ha; Jung, Woo-Shik; Park, Jin-Hong

    2012-11-19

    In this work, thermal diffusion phenomenon of Ti into amorphous indium gallium zinc oxide ({alpha}-IGZO) was carefully investigated with secondary ion mass spectroscopy, I-V, and R{sub s} measurement systems and HSC chemistry simulation tool. According to the experimental and simulated results, the diffused Ti atoms were easily oxidized due to its lowest oxidation free energy. Since oxygen atoms were decomposed from the {alpha}-IGZO during the oxidation of Ti, the number of oxygen vacancies working as electron-donating sites in {alpha}-IGZO was dramatically increased, contributing to the decrease of resistivity ({rho}) from 1.96 {Omega} cm (as-deposited {alpha}-IGZO) to 1.33 Multiplication-Sign 10{sup -3}{Omega} cm (350 Degree-Sign C annealed {alpha}-IGZO).

  1. Water-Rock Interaction Simulations of Iron Oxide Mobilization and Precipitation: Implications of Cross-diffusion Reactions for Terrestrial and Mars 'Blueberry' Hematite Concretions

    NASA Astrophysics Data System (ADS)

    Park, A. J.; Chan, M. A.; Parry, W. T.

    2005-12-01

    Modeling of how terrestrial concretions form can provide valuable insights into understanding water-rock interactions that led to the formation of hematite concretions at Meridiani Planum, Mars. Numerical simulations of iron oxide concretions in the Jurassic Navajo Sandstone of southern Utah provide physical and chemical input parameters for emulating conditions that may have prevailed on Mars. In the terrestrial example, iron oxide coatings on eolian sand grains are reduced and mobilized by methane or petroleum. Precipitation of goethite or hematite occurs as Fe interacts with oxygen. Conditions that produced Navajo Sandstone concretions can range from a regional scale that is strongly affected by advection of large pore volumes of water, to small sub-meter scale features that are dominantly controlled by diffusive processes. Hematite concretions are results of a small-scale cross-diffusional process, where Fe and oxygen are supplied from two opposite sides from the 'middle' zone of mixing where concretions precipitate. This is an ideal natural system where Liesegang banding and other self-organized patterns can evolve. A complicating variable here is the sedimentologic (both mineralogic and textural) heterogeneity that, in reality, may be the key factor controlling the nucleation and precipitation habits (including possible competitive growth) of hematite concretions. Sym.8 water-rock interaction simulator program was used for the Navajo Sandstone concretions. Sym.8 is a water-rock simulator that accounts for advective and diffusive mass-transfer, and equilibrium and kinetic reactions. The program uses a dynamic composite media texture model to address changing sediment composition and texture to be consistent with the reaction progress. Initial one-dimensional simulation results indicate precipitation heterogeneity in the range of sub-meters, e.g., possible banding and distribution of iron oxide nodules may be centimeters apart for published diffusivities and

  2. Physical properties of transparent perovskite oxides (Ba,La)SnO3 with high electrical mobility at room temperature

    NASA Astrophysics Data System (ADS)

    Kim, Hyung Joon; Kim, Useong; Kim, Tai Hoon; Kim, Jiyeon; Kim, Hoon Min; Jeon, Byung-Gu; Lee, Woong-Jhae; Mun, Hyo Sik; Hong, Kwang Taek; Yu, Jaejun; Char, Kookrin; Kim, Kee Hoon

    2012-10-01

    Transparent electronic materials are increasingly in demand for a variety of optoelectronic applications, ranging from passive transparent conductive windows to active thin-film transistors. BaSnO3 is a semiconducting oxide with a large band gap of more than 3.1 eV. Recently, we discovered that BaSnO3 doped with a few percent of La exhibits an unusually high electrical mobility of 320cm2V-1s-1 at room temperature and superior thermal stability at high temperatures [H. J. Kim , Appl. Phys. ExpressAPECE41882-077810.1143/APEX.5.061102 5, 061102 (2012)]. Following that paper, here, we report various physical properties of (Ba,La)SnO3 single crystals and epitaxial films including temperature-dependent transport and phonon properties, optical properties, and first-principles calculations. We find that almost doping-independent mobility of 200-300cm2V-1s-1 is realized in the single crystals in a broad doping range from 1.0×1019 to 4.0×1020 cm-3. Moreover, the conductivity of ˜104Ω-1cm-1 reached at the latter carrier density is comparable to the highest value previously reported in the transparent conducting oxides. We attribute the high mobility to several physical properties of (Ba,La)SnO3: a small effective mass coming from the ideal Sn-O-Sn bonding in a cubic perovskite network, small disorder effects due to the doping away from the SnO6 octahedra, and reduced carrier scattering due to the high dielectric constant. The observation of the reduced mobility of ˜70cm2V-1s-1 in the epitaxial films is mainly attributed to additional carrier scattering due to dislocations and grain boundaries, which are presumably created by the lattice mismatch between the substrate SrTiO3 and (Ba,La)SnO3. The main optical gap coming from the charge transfer from O 2p to Sn 5s bands in (Ba,La)SnO3 single crystals remained at about 3.33 eV, and the in-gap states only slightly increased, thus, maintaining optical transparency in the visible spectral region. Based on all these results, we

  3. Lifetime, mobility, and diffusion of photoexcited carriers in ligand-exchanged lead selenide nanocrystal films measured by time-resolved terahertz spectroscopy.

    PubMed

    Guglietta, Glenn W; Diroll, Benjamin T; Gaulding, E Ashley; Fordham, Julia L; Li, Siming; Murray, Christopher B; Baxter, Jason B

    2015-02-24

    Colloidal semiconductor nanocrystals have been used as building blocks for electronic and optoelectronic devices ranging from field-effect transistors to solar cells. Properties of the nanocrystal films depend sensitively on the choice of capping ligand to replace the insulating synthesis ligands. Thus far, ligands leading to the best performance in transistors result in poor solar cell performance, and vice versa. To gain insight into the nature of this dichotomy, we used time-resolved terahertz spectroscopy measurements to study the mobility and lifetime of PbSe nanocrystal films prepared with five common ligand-exchange reagents. Noncontact terahertz spectroscopy measurements of conductivity were corroborated by contacted van der Pauw measurements of the same samples. The films treated with different displacing ligands show more than an order of magnitude difference in the peak conductivities and a bifurcation of time dynamics. Inorganic chalcogenide ligand exchanges with sodium sulfide (Na2S) or ammonium thiocyanate (NH4SCN) show high mobilities but nearly complete decay of transient photocurrent in 1.4 ns. In contrast, ligand exchanges with 1,2-ethylenediamine (EDA), 1,2-ethanedithiol (EDT), and tetrabutylammonium iodide (TBAI) show lower mobilities but longer carrier lifetimes, resulting in longer diffusion lengths. This bifurcated behavior may explain the divergent performance of field-effect transistors and photovoltaics constructed from nanocrystal building blocks with different ligand exchanges. PMID:25644854

  4. Negative Ion Drift Velocity and Longitudinal Diffusion in Mixtures of Carbon Disulfide and Methane

    NASA Technical Reports Server (NTRS)

    Dion, Michael P.; Son, S.; Hunter, S. D.; deNolfo, G. A.

    2011-01-01

    Negative ion drift velocity and longitudinal diffusion has been measured for gas mixtures of carbon disulfide (CS2) and methane (CH4)' Measurements were made as a function of total pressure, CS2 partial pressure and electric field. Constant mobility and thermal-limit longitudinal diffusion is observed for all gas mixtures tested. Gas gain for some of the mixtures is also included.

  5. Electrical detection of biomaterials using AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Kang, B. S.; Wang, H. T.; Ren, F.; Pearton, S. J.

    2008-08-01

    Chemical sensors can be used to analyze a wide variety of environmental and biological gases and liquids and may need to be able to selectively detect a target analyte. Different methods, including gas chromatography, chemiluminescence, selected ion flow tube, and mass spectroscopy, have been used to measure biomarkers. These methods show variable results in terms of sensitivity for some applications and may not meet the requirements for a handheld biosensor. A promising sensing technology utilizes AlGaN/GaN high electron mobility transistors (HEMTs). HEMT structures have been developed for use in microwave power amplifiers due to their high two dimensional electron gas (2DEG) mobility and saturation velocity. The conducting 2DEG channel of AlGaN/GaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. HEMT sensors can be used for detecting gases, ions, pH values, proteins, and DNA. In this paper we review recent progress on functionalizing the surface of HEMTs for specific detection of glucose, kidney marker injury molecules, prostate cancer, and other common substances of interest in the biomedical field.

  6. Spatio-temporal modelling of electrical supply systems to optimize the site planning process for the "power to mobility" technology

    NASA Astrophysics Data System (ADS)

    Karl, Florian; Zink, Roland

    2016-04-01

    The transformation of the energy sector towards decentralized renewable energies (RE) requires also storage systems to ensure security of supply. The new "Power to Mobility" (PtM) technology is one potential solution to use electrical overproduction to produce methane for i.e. gas vehicles. Motivated by these fact, the paper presents a methodology for a GIS-based temporal modelling of the power grid, to optimize the site planning process for the new PtM-technology. The modelling approach is based on a combination of the software QuantumGIS for the geographical and topological energy supply structure and OpenDSS for the net modelling. For a case study (work in progress) of the city of Straubing (Lower Bavaria) the parameters of the model are quantified. The presentation will discuss the methodology as well as the first results with a view to the application on a regional scale.

  7. General electrokinetic model for concentrated suspensions in aqueous electrolyte solutions: Electrophoretic mobility and electrical conductivity in static electric fields.

    PubMed

    Carrique, Félix; Ruiz-Reina, Emilio; Roa, Rafael; Arroyo, Francisco J; Delgado, Ángel V

    2015-10-01

    In recent years different electrokinetic cell models for concentrated colloidal suspensions in aqueous electrolyte solutions have been developed. They share some of its premises with the standard electrokinetic model for dilute colloidal suspensions, in particular, neglecting both the specific role of the so-called added counterions (i.e., those released by the particles to the solution as they get charged), and the realistic chemistry of the aqueous solution on such electrokinetic phenomena as electrophoresis and electrical conductivity. These assumptions, while having been accepted for dilute conditions (volume fractions of solids well below 1%, say), are now questioned when dealing with concentrated suspensions. In this work, we present a general electrokinetic cell model for such kind of systems, including the mentioned effects, and we also carry out a comparative study with the standard treatment (the standard solution only contains the ions that one purposely adds, without ionic contributions from particle charging or water chemistry). We also consider an intermediate model that neglects the realistic aqueous chemistry of the solution but accounts for the correct contribution of the added counterions. The results show the limits of applicability of the classical assumptions and allow one to better understand the relative role of the added counterions and ions stemming from the electrolyte in a realistic aqueous solution, on electrokinetic properties. For example, at low salt concentrations the realistic effects of the aqueous solution are the dominant ones, while as salt concentration is increased, it is this that progressively takes the control of the electrokinetic response for low to moderate volume fractions. As expected, if the solids concentration is high enough the added counterions will play the dominant role (more important the higher the particle surface charge), no matter the salt concentration if it is not too high. We hope this work can help in

  8. Comparison of Three E-Beam Techniques for Electric Field Imaging and Carrier Diffusion Length Measurement on the Same Nanowires.

    PubMed

    Donatini, F; de Luna Bugallo, Andres; Tchoulfian, Pierre; Chicot, Gauthier; Sartel, Corinne; Sallet, Vincent; Pernot, Julien

    2016-05-11

    Whereas nanowire (NW)-based devices offer numerous advantages compared to bulk ones, their performances are frequently limited by an incomplete understanding of their properties where surface effect should be carefully considered. Here, we demonstrate the ability to spatially map the electric field and determine the exciton diffusion length in NW by using an electron beam as the single excitation source. This approach is performed on numerous single ZnO NW Schottky diodes whose NW radius vary from 42.5 to 175 nm. The dominant impact of the surface on the NW properties is revealed through the comparison of three different physical quantities recorded on the same NW: electron-beam induced current, cathodoluminescence, and secondary electron signal. Indeed, the space charge region near the Schottky contact exhibits an unusual linear variation with reverse bias whatever the NW radius. On the contrary, the exciton diffusion length is shown to be controlled by the NW radius through surface recombination. This systematic comparison performed on a single ZnO NW demonstrates the power of these complementary techniques in understanding NW properties. PMID:27105083

  9. Measurement of effective bulk and contact resistance of gas diffusion layer under inhomogeneous compression - Part I: Electrical conductivity

    NASA Astrophysics Data System (ADS)

    Vikram, Ajit; Chowdhury, Prabudhya Roy; Phillips, Ryan K.; Hoorfar, Mina

    2016-07-01

    This paper describes a measurement technique developed for the determination of the effective electrical bulk resistance of the gas diffusion layer (GDL) and the contact resistance distribution at the interface of the GDL and the bipolar plate (BPP). The novelty of this study is the measurement and separation of the bulk and contact resistance under inhomogeneous compression, occurring in an actual fuel cell assembly due to the presence of the channels and ribs on the bipolar plates. The measurement of the electrical contact resistance, contributing to nearly two-third of the ohmic losses in the fuel cell assembly, shows a non-linear distribution along the GDL/BPP interface. The effective bulk resistance of the GDL under inhomogeneous compression showed a decrease of nearly 40% compared to that estimated for homogeneous compression at different compression pressures. Such a decrease in the effective bulk resistance under inhomogeneous compression could be due to the non-uniform distribution of pressure under the ribs and the channels. This measurement technique can be used to identify optimum GDL, BPP and channel-rib structures based on minimum bulk and contact resistances measured under inhomogeneous compression.

  10. The study of electrical conductivity and diffusion behavior of water-based and ferro/ferricyanide-electrolyte-based alumina nanofluids.

    PubMed

    Liu, Chang; Lee, Hyeonseok; Chang, Ya-Huei; Feng, Shien-Ping

    2016-05-01

    Nanofluids are liquids containing suspensions of solid nanoparticles and have attracted considerable attention because they undergo substantial mass transfer and have many potential applications in energy technologies. Most studies on nanofluids have used low-ionic-strength solutions, such as water and ethanol. However, very few studies have used high-ionic-strength solutions because the aggregation and sedimentation of nanoparticles cause a stability problem. In this study, a stable water-based alumina nanofluid was prepared using stirred bead milling and exhibits a high electrical conductivity of 2420 μS/cm at 23 °C and excellent stability after five severe freezing-melting cycles. We then developed a process for mixing the water-based nanofluid with a high-ionic-strength potassium ferro/ferricyanide electrolyte and sodium dodecyl sulfate by using stirred bead milling and ultrasonication, thus forming a stable electrolyte-based nanofluid. According to the rotating disk electrode study, the electrolyte-based alumina nanofluid exhibits an unusual increase in the limiting current at high angular velocities, resulting from a combination of local percolation behavior and shear-induced diffusion. The electrolyte-based alumina nanofluid was demonstrated in a possible thermogalvanic application, since it is considered to be an alternative electrolyte for thermal energy harvesters because of the increased electrical conductivity and confined value of thermal conductivity. PMID:26866885

  11. Electrical Mobility of Protons and Proton-Holes in Pure Water Characterized by Physics-Based Water Model

    NASA Astrophysics Data System (ADS)

    Jie, Binbin; Sah, Chihtang

    Pure water has been characterized empirically for nearly a century, as dissociation into hydronium (H3O)1+ and hydroxide (HO)1- ions. Last March, we reported that the ~40 year experimental industrial standard of chemical equilibrium reaction constant, the ion product, can be accounted for by a statistical-physics-based concentration product of two electrical charge carriers, the positively charged protons, p+, and the negatively charged proton holes or prohols, p-, with a thermal activation energy or proton trapping well depth of Ep + / p - = 576 meV, in the 0-100OC pure liquid water. We now report that the empirically fitted industrial standard experimental data (1985, 1987, 2005) of the two dc ion mobilities in liquid water, can also be accounted for by trapping-limited drift of protons and prohols through proton channels of lower proton electrical potential valleys, Ep+/0 <= Ep-/0 <(Ep + / p -/3), in the tetrahedrally-directed electron-pair-bonded oxygen ions, O2-, in hexagonal lattice based on the 1935 Pauling statistical model using the 1933 Bernal-Fowler water rule.

  12. Diffused and Sustained Inhibitory Effects of Intestinal Electrical Stimulation on Intestinal Motility Mediated via Sympathetic Pathway

    PubMed Central

    Zhao, Xiaotuan; Yin, Jieyun; Wang, Lijie; Chen, J D Z

    2013-01-01

    Objective The aims was to investigate the energy-dose response effect of IES on small bowel motility, to compare the effect of forward and backward IES; to explore the possibility of using intermittent IES and mechanism of IES on intestinal motility. Material and Methods Five dogs implanted with a duodenal cannula and one pair of intestinal serosal electrodes were studied in 5 sessions: 1) energy-dose response study; 2) forward IES; 3) backward IES; 4) intermittent IES vs. continuous IES; 5) administration of guanethidine. The contractile activity and tonic pressure of the small intestine were recorded. The duration of sustained effect after turning off IES was manually calculated. Results 1) IES with long pulses energy-dose dependently inhibited contractile activity and tonic pressure of the small intestine (p < 0.001). 2) The duration of sustained inhibitory effect of IES on the small intestine depended on the energy of IES delivered (p < 0.001). 3) The potency of the inhibitory effect was the same between forward and backward IES. 4) The efficacy of intermittent IES was the same as continuous IES in inhibiting motility of the small intestine. 5) Guanethidine blocked the inhibitory effect of IES on intestinal motility. Conclusions IES with long pulses inhibits small intestinal motility; the effect is energy-dose dependent, diffused and sustained. Intermittent IES has the same efficacy as the continuous IES in inhibiting small intestinal motility. Forward and backward IES have similar inhibitory effects on small bowel motility. This IES-induced inhibitory effect is mediated via the sympathetic pathway. PMID:23924055

  13. New Technology for Microfabrication and Testing of a Thermoelectric Device for Generating Mobile Electrical Power

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Taylor, Patrick J.; Trivedi, Sudhir B.; Kutcher, Susan

    2012-01-01

    Thermoelectric (TE) power generation is an increasingly important power generation technology. Major advantages include: no moving parts, low-weight, modularity, covertness/silence, high power density, low amortized cost, and long service life with minimum or no required maintenance. Despite low efficiency of power generation, there are many specialized needs for electrical power that TE technologies can uniquely and successfully address. Recent advances in thermoelectric materials technology have rekindled acute interest in thermoelectric power generation. We have developed single crystalline n- and p- type PbTe crystals and are also, developing PbTe bulk nanocomposites using PbTe nano powders and emerging filed assisted sintering technology (FAST). We will discuss the materials requirements for efficient thermoelectric power generation using waste heat at intermediate temperature range (6500 to 8500 K). We will present our recent results on production of n- and p- type PbTe crystals and their thermoelectric characterization. Relative characteristics and performance of PbTe bulk single crystals and nano composites for thermoelectric power generation will be discussed.

  14. Rapid mapping of soil electrical conductivity by remote sensing: implication for landmine detection and vehicle mobility

    NASA Astrophysics Data System (ADS)

    Katsube, T. J.; McNairn, H.; Das, Y.; Gauthier, E.; Holt, R. M.; Singhroy, V.; DiLabio, R.; Connell-Madore, S.; Dyke, L.

    2005-06-01

    Many soil physical and chemical properties interfere with landmine detection signals. Since prior knowledge of these property distributions would allow appropriate technology selection and efficient demining operations, rapid mapping of these properties over wide areas are considered for meeting military and economic constraints. As soil electrical conductivity (EC) interferes with widely used detection systems, such as metal detectors and ground penetrating radar, we have started with developing a rapid mapping technique for EC using remote sensing. Electromagnetic surveys are proven methods for mapping EC, but do not provide all information required for demining. Therefore, EC prediction by imaging of soil moisture change using radar satellite imagery acquired by RADARSAT is being tested in eastern Alberta, Canada; northern Mississippi (U.S.A.). Areas of little soil moisture change with time are associated with high moisture retention and high clay content, suggesting higher EC. These soil characteristics are also associated with trafficability. RADARSAT soil moisture change detection images for eastern Alberta identified five areas with possible high moisture retention characteristics. Validation by soil and trafficability maps verified the predictions for more than half of the areas. Lack of some prediction accuracy is considered due to image acquisition timing and lack of physical property knowledge of some soil constituents.

  15. New Technology for Microfabrication and Testing of a Thermoelectric Device for Generating Mobile Electrical Power

    NASA Technical Reports Server (NTRS)

    Prasad, Narashimha S.; Taylor, Patrick J.; Trivedi, Sudhir B.; Kutcher, Susan

    2010-01-01

    We report the results of fabrication and testing of a thermoelectric power generation module. The module was fabricated using a new "flip-chip" module assembly technique that is scalable and modular. This technique results in a low value of contact resistivity ( < or = 10(exp 5) Ohms-sq cm). It can be used to leverage new advances in thin-film and nanostructured materials for the fabrication of new miniature thermoelectric devices. It may also enable monolithic integration of large devices or tandem arrays of devices on flexible or curved surfaces. Under mild testing, a power of 22 mW/sq cm was obtained from small (<100 K) temperature differences. At higher, more realistic temperature differences, approx.500 K, where the efficiency of these materials greatly improves, this power density would scale to between 0.5 and 1 Watt/cm2. These results highlight the excellent potential for the generation and scavenging of electrical power of practical and usable magnitude for remote applications using thermoelectric power generation technologies.

  16. Making tuba in the Torres Strait Islands: the cultural diffusion and geographic mobility of an alcoholic drink.

    PubMed

    Brady, Maggie; McGrath, Vic

    2010-01-01

    There is relatively scant evidence of the Indigenous production and consumption of intoxicating drinks on the Australian mainland prior to the arrival of outsiders. Although Australian Aboriginal peoples had mastered fermentation in some regions, the Indigenous manufacture of much stronger drinks by distillation was unknown on the Australian mainland. However, following contact with Pacific Island and Southeast Asian peoples in the 19th century, Islanders in the Torres Strait adopted techniques for fermenting and distilling what became a quasi-indigenous alcoholic drink known as tuba. This paper discusses the historical process of the diffusion of this substance as a result of labour migration and internationalisation in the Strait, and provides present-day accounts of tuba production from Torres Strait Islanders. PMID:21280393

  17. Surface Exchange and Bulk Diffusivity of LSCF as SOFC Cathode: Electrical Conductivity Relaxation and Isotope Exchange Characterizations

    SciTech Connect

    Li, Yihong; Gerdes, Kirk; Horita, Teruhisa; Liu, Xingbo

    2013-05-05

    The oxygen diffusion coefficient (D) and surface exchange coefficient (k) of a typical SOFC cathode material, La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-δ} (LSCF) were characterized by both electrical conductivity relaxation (ECR) and oxygen isotope exchange (IE) methods. Conductivity relaxation experiments were conducted at 800°C for small step changes in partial pressure of oxygen (P{sub O{sub 2}} ), both decreasing and increasing, from 0.02 atm to 0.20 atm. The results revealed P{sub O{sub 2}} dependent hysteresis with the reduction process requiring more equilibration time than oxidation. Analysis of the experimental data indicated that the surface exchange coefficient is a function of the final oxygen partial pressure in an isothermal system. In addition, both forward and backward oxygen reduction reaction constants, which are vital for the fundamental understanding of SOFC cathode reaction mechanisms, are investigated based on the relationship between surface exchange coefficient and P{sub O{sub 2}} . The direct comparisons between the results from both ECR and IE were presented and the possible experimental errors in both methods were discussed.

  18. Evaluation of mobility in thin Bi2Se3 Topological Insulator for prospects of Local Electrical Interconnects

    PubMed Central

    Gupta, Gaurav; Jalil, Mansoor Bin Abdul; Liang, Gengchiau

    2014-01-01

    Three-dimensional (3D) topological insulator (TI) has been conjectured as an emerging material to replace copper (Cu) as an interconnect material because of the suppression of elastic scattering from doping and charge impurities for carrier transport on TI surface. We, therefore via full real-space simulation, examine the feasibility of using thin 3D-TI (Bi2Se3) wire for the local electrical interconnects in the presence of edge roughness, vacancies, acoustic phonons and charge impurities across temperature and Fermi-level by simulating quantum transport through Non-Equilibrium Green Function algorithm. We found that because of the scattering induced by the acoustic phonons, the mobility reduces considerably at the room temperature which complemented with the low density of states near Dirac-point does not position Bi2Se3 3D-TI as a promising material to replace Cu for local interconnects. Properties required in suitable TI material for this application have also been discussed. PMID:25354476

  19. Electrical Muscle Stimulation: An Effective Form of Exercise and Early Mobilization to Preserve Muscle Strength in Critically Ill Patients

    PubMed Central

    Karatzanos, Eleftherios; Gerovasili, Vasiliki; Zervakis, Dimitrios; Tripodaki, Elli-Sophia; Apostolou, Kleovoulos; Vasileiadis, Ioannis; Papadopoulos, Emmanouil; Mitsiou, Georgios; Tsimpouki, Dimitra; Routsi, Christina; Nanas, Serafim

    2012-01-01

    Purpose. This is a secondary analysis of previously published data to investigate the effects of electrical muscle stimulation (EMS) on strength of various muscle groups in critically ill patients. Methods. One hundred forty-two consecutive patients, with APACHE II score ≥ 13, were randomly assigned to the EMS or the control group. EMS sessions were applied daily on vastus lateralis, vastus medialis, and peroneus longus of both lower extremities. Various muscle groups were evaluated with the Medical Research Council (MRC) scale for muscle strength. Handgrip strength assessment was also employed. Results. Twenty four patients in the EMS group and 28 patients in the control group were finally evaluated. EMS patients achieved higher MRC scores than controls (P ≤ 0.05) in wrist flexion, hip flexion, knee extension, and ankle dorsiflexion. Collectively, the EMS group performed higher (P < 0.01) in the legs and overall. Handgrip strength correlated (P ≤ 0.01) with the upper and lower extremities' muscle strength and the overall MRC scores. Conclusions. EMS has beneficial effects on the strength of critically ill patients mainly affecting muscle groups stimulated, while it may also affect muscle groups not involved presenting itself as a potential effective means of muscle strength preservation and early mobilization in this patient population. PMID:22545212

  20. Scanning and mobile multi-axis DOAS measurements of SO2 and NO2 emissions from an electric power plant in Montevideo, Uruguay

    NASA Astrophysics Data System (ADS)

    Frins, E.; Bobrowski, N.; Osorio, M.; Casaballe, N.; Belsterli, G.; Wagner, T.; Platt, U.

    2014-12-01

    In March 2012 the emissions of NO2 and SO2 from a power station located on the east side of Montevideo Bay (34° 53‧ 10″ S, 56° 11‧ 49″ W) were quantified by simultaneously using mobile and scanning multi-axis differential optical absorption spectroscopy (in the following mobile DOAS and scanning DOAS, respectively). The facility produces electricity by means of two technologies: internal combustion motors and steam generators. The motors are powered with centrifuged heavy oil and produce a maximum power of 80 MW approximately. The steam generators produce approximately 305 MW and are powered with heavy fuel oil. We compare the emissions obtained from the measured slant column densities (mobile DOAS and scanning DOAS) with the emissions estimated from fuel mass balance. On one occasion it was possible to distinguish between the two types of sources, observing two plumes with different SO2 and NO2 emission rates. During the period of the campaign the mean SO2 emission flux was determined to be 0.36 (±0.12) kg s-1 and 0.26 (±0.09) kg s-1 retrieved from mobile and scanning DOAS respectively, while the calculated SO2 flux from the sulphur content of the fuel was 0.34 (±0.03) kg s-1. The average NO2 flux calculated from mobile DOAS was determined to be 11 (±3) × 10-3 kg s-1. Using the scanning DOAS approach a mean NO2 flux of 5.4 (±1.7) × 10-3 kg s-1 was obtained, which is significantly lower than by the mobile measurements. The differences between the results of mobile MAX-DOAS measurements and scanning DOAS measurements are most probably caused by the variability and the limited knowledge of the wind speed and direction.

  1. Ion mobility sensor system

    DOEpatents

    Xu, Jun; Watson, David B.; Whitten, William B.

    2013-01-22

    An ion mobility sensor system including an ion mobility spectrometer and a differential mobility spectrometer coupled to the ion mobility spectrometer. The ion mobility spectrometer has a first chamber having first end and a second end extending along a first direction, and a first electrode system that generates a constant electric field parallel to the first direction. The differential mobility spectrometer includes a second chamber having a third end and a fourth end configured such that a fluid may flow in a second direction from the third end to the fourth end, and a second electrode system that generates an asymmetric electric field within an interior of the second chamber. Additionally, the ion mobility spectrometer and the differential mobility spectrometer form an interface region. Also, the first end and the third end are positioned facing one another so that the constant electric field enters the third end and overlaps the fluid flowing in the second direction.

  2. A simple method for assessment and minimization of errors in determination of electrophoretic or electroosmotic mobilities and velocities associated with the axial electric field distortion.

    PubMed

    Nowak, Paweł Mateusz; Woźniakiewicz, Michał; Kościelniak, Paweł

    2015-12-01

    It is commonly accepted that the modern CE instruments equipped with efficient cooling system enable accurate determination of electrophoretic or electroosmotic mobilities. It is also often assumed that velocity of migration in a given buffer is constant throughout the capillary length. It is simultaneously neglected that the noncooled parts of capillary produce extensive Joule heating leading to an axial electric field distortion, which contributes to a difference between the effective and nominal electric field potentials and between velocities in the cooled and noncooled parts of capillary. This simplification introduces systematic errors, which so far were however not investigated experimentally. There was also no method proposed for their elimination. We show a simple and fast method allowing for estimation and elimination of these errors that is based on combination of a long-end and short-end injections. We use it to study the effects caused by variation of temperature, electric field, capillary length, and pH. PMID:26383237

  3. Measurement of Fine Particles From Mobile and Stationary Sources, and Reducing the Air Conditioner Power Consumption in Hybrid Electric Vehicles

    NASA Astrophysics Data System (ADS)

    Brewer, Eli Henry

    We study the PM2.5and ultrafine exhaust emissions from a new natural gas-fired turbine power facility to better understand air pollution in California. To characterize the emissions from new natural gas turbines, a series of tests were performed on a GE LMS100 gas turbine. These tests included PM2.5 and wet chemical tests for SO2/SO 3 and NH3, as well as ultrafine (less than 100 nm in diameter) particulate matter measurements. The turbine exhaust had an average particle number concentration that was 2.3x103 times higher than ambient air. The majority of these particles were nanoparticles; at the 100 nm size, stack particle concentrations were about 20 times higher than ambient, and increased to 3.9x104 times higher on average in the 2.5 - 3 nm particle size range. This study also found that ammonia emissions were higher than expected, but in compliance with permit conditions. This was possibly due to an ammonia imbalance entering the catalyst, some flue gas bypassing the catalyst, or not enough catalyst volume. SO3 accounted for an average of 23% of the total sulfur oxides emissions measured. Some of the SO3 is formed in the combustion process, it is likely that the majority formed as the SO2 in the combustion products passed across the oxidizing CO catalyst and SCR catalyst. The 100 MW turbine sampled in this study emitted particle loadings similar to those previously measured from turbines in the SCAQMD area, however, the turbine exhaust contained far more particles than ambient air. The power consumed by an air conditioner accounts for a significant fraction of the total power used by hybrid and electric vehicles especially during summer. This study examined the effect of recirculation of cabin air on power consumption of mobile air conditioners both in-lab and on-road. Real time power consumption and vehicle mileage were recorded by an On Board Diagnostic monitor and carbon balance method. Vehicle mileage improved with increased cabin air recirculation. The

  4. Soil phosphorus mobility and solid-to-solution phase resupply studied by diffusive gradients in thin films: background soil properties driving their variation

    NASA Astrophysics Data System (ADS)

    Menezes-Blackburn, Daniel; Zhang, Hao; Giles, Courtney; George, Timothy; Shand, Charlie; Lumsdon, David; Cooper, Patricia; Wendler, Renate; Brown, Lawrie; Stutter, Marc; Blackwell, Martin; Darch, Tegan; Wearing, Catherine; Philip, Haygarth

    2015-04-01

    The mobility and resupply of inorganic phosphorus (P) from the solid phase was studied in 32 representative soils from the UK. The objective was to identify the background soil properties driving the variation of soil inorganic P desorption kinetics across different soil types. Diffusive gradients in thin films (DGT), diffusive equilibration in thin films (DET) and the DGT-induced fluxes in sediments model (DIFS) were used as tools for exploring solid-to-solution desorption kinetics. Previously characterized physicochemical properties of the same soils were used for correlation analysis. On average and across soil types, the inorganic P maximum distance of depletion was 0.42±0.10 cm, the equilibration time (Tc) was 3.63 h, the desorption rate constant (k-1) was 0.0046 h-1, and the desorption rate was 4.71 nmol l-1 s-1. The correlation between P in Olsen extractcs (POlsen) with PDGT, PDET and phosphorus effective concentration (PE) was enhanced when similar soils were isolated and used in the comparison, clearly showing that these parameters are affected differently by soil types. The PE was better correlated to Ptot, POlsen, PFeO, and PNaOH/EDTA than PDGT. This may indicate that PE is a better representation of P availability across soil types than PDGT. While the relative DGT-induced inorganic P flux in the first hour is mainly a function of soil wetting properties and % Corg, at longer times it is a function of the resupply capacity (R-Rdiff) of the soil solid phase. In general, resupply of P from the solid phase was less than that for other chemical elements, as shown by high Tc and low k-1 values. Desorption rates and resupply from the solid phase were fundamentally influenced by P saturation status, as reflected by their strong correlation with P concentration in water, FeO strips, Olsen and NaOH-EDTA extracts. Soil pH and particle size distribution had little or no effect on the evaluated parameters. The DGT and DET techniques, along with the DIFS model

  5. Long-term exposure to mobile communication radiation: an analysis of time-variability of electric field level in GSM900 downlink channels.

    PubMed

    Miclaus, Simona; Bechet, Paul; Gheorghevici, Marius

    2013-04-01

    Interest for knowing long-term human exposure levels due to mobile communications has increased in the last years. It has been shown that short-term exposure assessment made under standard procedural restrictions is not reliable when it comes to conclusions on long-term exposure levels. The present work is the result of a several week analysis of time variability of electric field level inside traffic and control channels of the GSM900 mobile communication downlink band and it indicates that a temporal model to allow future predictions of exposure on the long run is obtainable. Collecting, processing and statistically analysing the data provide expression of the maximum and weighted field strengths and their evolution in time. Specific electromagnetic footprints of the channels have been extracted, differentiations between their characteristics have been emphasised and practical advice is provided, with the scope of contributing to the development of reliable procedures for long-term exposure assessment. PMID:22908352

  6. Precise determination of the chemical diffusion coefficient of calcium-doped lanthanum chromites by means of electrical conductivity relaxation

    SciTech Connect

    Yasuda, Isamu; Hikita, Tomoji . Fundamental Technology Research Lab.)

    1994-05-01

    Chemical relaxation experiments were conducted on sintered samples of calcium-doped lanthanum chromites by abruptly changing the oxygen partial pressure in the atmosphere and following the time change of conductivity. The re-equilibration kinetics was analyzed by fitting the relaxation data to the solutions of Fick's second law for appropriate boundary conditions. The diffusion equation ignoring the effect of surface reaction failed to describe the transient behavior especially for the initial stage, while that taking the surface effect into account gave a satisfactory interpretation of the overall relaxation process and allowed a precise determination of the two kinetic parameters: oxygen chemical diffusion coefficient and surface reaction rate constant. The chemical diffusion coefficients increased with a decrease of the oxygen partial pressure due to the corresponding change in the concentration of the moving species. The activation energy was similar to that of oxygen vacancy diffusion coefficients in other monocrystalline perovskites, suggesting that the measured diffusion coefficients were attributable to lattice diffusion. The surface reaction rate constant increased with a decrease of the oxygen partial pressure similarly to the reported oxygen nonstoichiometry, which implies that the presence of oxygen vacancies plays an important role in the surface reaction kinetics.

  7. One sign ion mobile approximation

    NASA Astrophysics Data System (ADS)

    Barbero, G.

    2011-12-01

    The electrical response of an electrolytic cell to an external excitation is discussed in the simple case where only one group of positive and negative ions is present. The particular case where the diffusion coefficients of the negative ions, Dm, is very small with respect to that of the positive ions, Dp, is considered. In this framework, it is discussed under what conditions the one mobile approximation, in which the negative ions are assumed fixed, works well. The analysis is performed by assuming that the external excitation is sinusoidal with circular frequency ω, as that used in the impedance spectroscopy technique. In this framework, we show that there exists a circular frequency, ω*, such that for ω > ω*, the one mobile ion approximation works well. We also show that for Dm ≪ Dp, ω* is independent of Dm.

  8. Self-consistent modeling for estimation of the reduced electric field in a DC excited diffusion controlled CW CO2 laser

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Bhagat, M. S.; Biswas, A. K.; Rana, L. B.; Pakhare, Jagdish; Rawat, B. S.; Kukreja, L. M.

    2016-07-01

    The results of a numerical simulation method that estimate various discharge parameters in the positive column of a DC glow discharge controlled by ambipolar diffusion are presented. The parameters like reduced electric field (E/N), electron temperature, ionization rates, ambipolar diffusion losses and the average gas temperature were numerically evaluated for several mixtures of CO2, N2 and He in low pressure regime. The estimated E/N value which is a primary governing parameter of positive column was verified experimentally using a double probe in diffusion controlled CW CO2 laser for a variety of CO2, N2 and He mixtures. The role of auxiliary ionization source like pulser used for pre-ionization and its effect on the steady state E/N value was also studied. A reasonably good agreement was found between the theoretical and the experimental results. Based on the results of this simulation a zigzag folded, diffusion-cooled, 500 W CW CO2 laser has been designed and developed for research in gas phase nanoparticle synthesis.

  9. A study of the properties of beryllium doped silicon with particular emphasis on diffusion mechanisms: Profiles of depth dependent conductivity as determined by electrical surface probes

    NASA Technical Reports Server (NTRS)

    Franks, R. K.; Robertson, J. B.

    1972-01-01

    Very large diffusion coefficients were encountered and required the determination of impurity profiles for samples approximately 1 cm thick. Since conductivity values are readily converted into concentrations of electrically active impurities, the major problem became that of accurately determining the conductivity profiles of beryllium diffused silicon samples. Four-point probe measurements on samples having depth conductivities are interpreted in terms of conductivity profiles, based on an exact solution of the problem of exponentially depth dependent conductivity. Applications include surface conductivity determination where the form of the conductivity profile is known, and conductivity profile determination from probe measurements taken as the sample surface is progressively lapped away. The application is limited to samples having conductivity monotonically decreasing with depth from the probed surface.

  10. Electrical properties of magnesium oxide layers with different surface pretreatment on high mobility Ge1-xSnx and Ge MOS capacitors

    NASA Astrophysics Data System (ADS)

    Su, Chen-Yi; Lieten, Ruben; Bakalov, Petar; Tseng, Wei-Jhih; Dillemans, Leander; Menghini, Mariela; Smets, Tomas; Seo, Jin Won; Locquet, Jean-Pierre

    2014-02-01

    Germanium based channels are interesting for high performance CMOS devices because of their high carrier mobility. In this study, the electrical properties of MgO on both GeSn and Ge MOS capacitors have been investigated. The low equivalent oxide thickness (EOT) of 2.1 nm for MgO on GeSn with a Ge cap layer indicates the high potential for MOSFET applications. A surface treatment prior to oxide deposition is found essential to reduce the gate leakage. It is shown that HCl and H2O2 dipping followed by ozone treatment improves the leakage and leads to good capacitance-voltage (C-V) behavior.

  11. Diffusion of hydrogen interstitials in the near-surface region of Pd(111) under the influence of surface coverage and external static electric fields

    SciTech Connect

    Blanco-Rey, M.; Tremblay, J. C.

    2015-04-21

    Past scanning tunneling microscopy (STM) experiments of H manipulation on Pd(111), at low temperature, have shown that it is possible to induce diffusion of surface species as well as of those deeply buried under the surface. Several questions remain open regarding the role of subsurface site occupancies. In the present work, the interaction potential of H atoms with Pd(111) under various H coverage conditions is determined by means of density functional theory calculations in order to provide an answer to two of these questions: (i) whether subsurface sites are the final locations for the H impurities that attempt to emerge from bulk regions, and (ii) whether penetration of the surface is a competing route of on-surface diffusion during depletion of surface H on densely covered Pd(111). We find that a high H coverage has the effect of blocking resurfacing of H atoms travelling from below, which would otherwise reach the surface fcc sites, but it hardly alters deeper diffusion energy barriers. Penetration is unlikely and restricted to high occupancies of hcp hollows. In agreement with experiments, the Pd lattice expands vertically as a consequence of H atoms being blocked at subsurface sites, and surface H enhances this expansion. STM tip effects are included in the calculations self-consistently as an external static electric field. The main contribution to the induced surface electric dipoles originates from the Pd substrate polarisability. We find that the electric field has a non-negligible effect on the H-Pd potential in the vicinity of the topmost Pd atomic layer, yet typical STM intensities of 1-2 VÅ{sup −1} are insufficient to invert the stabilities of the surface and subsurface equilibrium sites.

  12. Diffusion of hydrogen interstitials in the near-surface region of Pd(111) under the influence of surface coverage and external static electric fields

    NASA Astrophysics Data System (ADS)

    Blanco-Rey, M.; Tremblay, J. C.

    2015-04-01

    Past scanning tunneling microscopy (STM) experiments of H manipulation on Pd(111), at low temperature, have shown that it is possible to induce diffusion of surface species as well as of those deeply buried under the surface. Several questions remain open regarding the role of subsurface site occupancies. In the present work, the interaction potential of H atoms with Pd(111) under various H coverage conditions is determined by means of density functional theory calculations in order to provide an answer to two of these questions: (i) whether subsurface sites are the final locations for the H impurities that attempt to emerge from bulk regions, and (ii) whether penetration of the surface is a competing route of on-surface diffusion during depletion of surface H on densely covered Pd(111). We find that a high H coverage has the effect of blocking resurfacing of H atoms travelling from below, which would otherwise reach the surface fcc sites, but it hardly alters deeper diffusion energy barriers. Penetration is unlikely and restricted to high occupancies of hcp hollows. In agreement with experiments, the Pd lattice expands vertically as a consequence of H atoms being blocked at subsurface sites, and surface H enhances this expansion. STM tip effects are included in the calculations self-consistently as an external static electric field. The main contribution to the induced surface electric dipoles originates from the Pd substrate polarisability. We find that the electric field has a non-negligible effect on the H-Pd potential in the vicinity of the topmost Pd atomic layer, yet typical STM intensities of 1-2 VÅ-1 are insufficient to invert the stabilities of the surface and subsurface equilibrium sites.

  13. Surface morphology and electrical transport of rapid thermal annealed chromium-doped indium zinc oxides: The influence of zinc interstitials and out-diffusion

    SciTech Connect

    Hsu, C. Y.

    2013-12-09

    We investigate the complex impedance (CI) spectra of chromium-doped indium zinc oxide (CIZO) films with different rapid thermal annealing (RTA) temperatures. The CI spectra drawn from the impedance contributions of Zn-O and In-O bondings in CIZO films were analyzed by two sets of parallel resistance and capacitance components in series. The result demonstrates that zinc interstitials controls electron concentration and transition of electrical transport from semiconducting to metallic. At higher RTA temperature, high-density zinc interstitial promotes Zn atom diffusion from the surface, modifying surface morphology.

  14. Surface morphology and electrical transport of rapid thermal annealed chromium-doped indium zinc oxides: The influence of zinc interstitials and out-diffusion

    NASA Astrophysics Data System (ADS)

    Hsu, C. Y.

    2013-12-01

    We investigate the complex impedance (CI) spectra of chromium-doped indium zinc oxide (CIZO) films with different rapid thermal annealing (RTA) temperatures. The CI spectra drawn from the impedance contributions of Zn-O and In-O bondings in CIZO films were analyzed by two sets of parallel resistance and capacitance components in series. The result demonstrates that zinc interstitials controls electron concentration and transition of electrical transport from semiconducting to metallic. At higher RTA temperature, high-density zinc interstitial promotes Zn atom diffusion from the surface, modifying surface morphology.

  15. Albany Interim Landfill gas extraction and mobile power system: Using landfill gas to produce electricity. Final report

    SciTech Connect

    1997-06-01

    The Albany Interim Landfill Gas Extraction and Mobile Power System project served three research objectives: (1) determination of the general efficiency and radius of influence of horizontally placed landfill gas extraction conduits; (2) determination of cost and effectiveness of a hydrogen sulfide gas scrubber utilizing Enviro-Scrub{trademark} liquid reagent; and (3) construction and evaluation of a dual-fuel (landfill gas/diesel) 100 kW mobile power station. The horizontal gas extraction system was very successful; overall, gas recovery was high and the practical radius of influence of individual extractors was about 50 feet. The hydrogen sulfide scrubber was effective and its use appears feasible at typical hydrogen sulfide concentrations and gas flows. The dual-fuel mobile power station performed dependably and was able to deliver smooth power output under varying load and landfill gas fuel conditions.

  16. Electrical Mobility Spectrometer Using a Diethylene Glycol Condensation Particle Counter for Measurement of Aerosol Size Distributions Down to 1 nm

    SciTech Connect

    Jiang, J.; Kuang, C.; Chen, M.; Attoui, M.; McMurry, P. H.

    2011-02-01

    We report a new scanning mobility particle spectrometer (SMPS) for measuring number size distributions of particles down to {approx}1 nm mobility diameter. This SMPS includes an aerosol charger, a TSI 3085 nano differential mobility analyzer (nanoDMA), an ultrafine condensation particle counter (UCPC) using diethylene glycol (DEG) as the working fluid, and a conventional butanol CPC (the 'booster') to detect the small droplets leaving the DEG UCPC. The response of the DEG UCPC to negatively charged sodium chloride particles with mobility diameters ranging from 1-6 nm was measured. The sensitivity of the DEG UCPC to particle composition was also studied by comparing its response to positively charged 1.47 and 1.70 nm tetra-alkyl ammonium ions, sodium chloride, and silver particles. A high resolution differential mobility analyzer was used to generate the test particles. These results show that the response of this UCPC to sub-2 nm particles is sensitive to particle composition. The applicability of the new SMPS for atmospheric measurement was demonstrated during the Nucleation and Cloud Condensation Nuclei (NCCN) field campaign (Atlanta, Georgia, summer 2009). We operated the instrument at saturator and condenser temperatures that allowed the efficient detection of sodium chloride particles but not of air ions having the same mobility. We found that particles as small as 1 nm were detected during nucleation events but not at other times. Factors affecting size distribution measurements, including aerosol charging in the 1-10 nm size range, are discussed. For the charger used in this study, bipolar charging was found to be more effective for sub-2 nm particles than unipolar charging. No ion induced nucleation inside the charger was observed during the NCCN campaign.

  17. Simplification of physics-based electrochemical model for lithium ion battery on electric vehicle. Part I: Diffusion simplification and single particle model

    NASA Astrophysics Data System (ADS)

    Han, Xuebing; Ouyang, Minggao; Lu, Languang; Li, Jianqiu

    2015-03-01

    Now the lithium ion batteries are widely used in electrical vehicles (EV). The battery modeling and state estimation is of great significance. The rigorous physic based electrochemical model is too complicated for on-line simulation in vehicle. In this work, the simplification of physics-based model lithium ion battery for application in battery management system (BMS) on real electrical vehicle is proposed. Approximate method for solving the solid phase diffusion and electrolyte concentration distribution problems is introduced. The approximate result is very close to the rigorous model but fewer computations are needed. An extended single particle model is founded based on these approximated results and the on-line state of charge (SOC) estimation algorithm using the extended Kalman filter with this single particle model is discussed. This SOC estimation algorithm could be used in the BMS in real vehicle.

  18. Commercializing light-duty plug-in/plug-out hydrogen-fuel-cell vehicles: "Mobile electricity" technologies, early California household markets, and innovation management

    NASA Astrophysics Data System (ADS)

    Williams, Brett David

    Starting from the premise that new consumer value must drive hydrogen-fuel-cell-vehicle (H2FCV) commercialization, a group of opportunities collectively called "Mobile Electricity" (Me-) is characterized. Me- redefines H2 FCVs as innovative products able to provide home recharging and mobile power, for example for tools, mobile activities, emergencies, and electric-grid-support services. To characterize such opportunities, this study first integrates and extends previous analyses of H2FCVs, plug-in hybrids, and vehicle-to-grid (V2G) power. It uses a new model to estimate zero-emission-power vs. zero-emission-driving tradeoffs, costs, and grid-support revenues for various electric-drive vehicle types and levels of infrastructure service. Next, the initial market potential for Me- enabled vehicles, such as H2FCVs and plug-in hybrids, is estimated by eliminating unlikely households from consideration for early adoption. 5.2 million of 33.9 million Californians in the 2000 Census live in households pre-adapted to Me-, 3.9 million if natural gas is required for home refueling. The possible sales base represented by this population is discussed. Several differences in demographic and other characteristics between the target market and the population as a whole are highlighted, and two issues related to the design of H2FCVs and their supporting infrastructure are discussed: vehicle range and home hydrogen refueling. These findings argue for continued investigation of this and similar target segments-which represent more efficient research populations for subsequent study by product designers and other decision-makers wishing to understand the early market dynamics facing Me- innovations. Next, Me-H2FCV commercialization issues are raised from the perspectives of innovation, product development, and strategic marketing. Starting with today's internalcombustion hybrids, this discussion suggests a way to move beyond the battery vs. fuel-cell zero-sum game and towards the

  19. Relativistic diffusion

    NASA Astrophysics Data System (ADS)

    Haba, Z.

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  20. Relativistic diffusion.

    PubMed

    Haba, Z

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed. PMID:19391727

  1. The effect of electric field geometry on the performance of electromembrane extraction systems: footprints of a third driving force along with migration and diffusion.

    PubMed

    Moazami, Hamid Reza; Hosseiny Davarani, Saied Saeed; Mohammadi, Jamil; Nojavan, Saeed; Abrari, Masoud

    2015-09-01

    The distribution of electric field vectors was first calculated for electromembrane extraction (EME) systems in classical and cylindrical electrode geometries. The results showed that supported liquid membrane (SLM) has a general field amplifying effect due to its lower dielectric constant in comparison with aqueous donor/acceptor solutions. The calculated norms of the electric field vector showed that a DC voltage of 50 V can create huge electric field strengths up to 64 kV m(-1) and 111 kV m(-1) in classical and cylindrical geometries respectively. In both cases, the electric field strength reached its peak value on the inner wall of the SLM. In the case of classical geometry, the field strength was a function of the polar position of the SLM whereas the field strength in cylindrical geometry was angularly uniform. In order to investigate the effect of the electrode geometry on the performance of real EME systems, the analysis was carried out in three different geometries including classical, helical and cylindrical arrangements using naproxen and sodium diclofenac as the model analytes. Despite higher field strength and extended cross sectional area, the helical and cylindrical geometries gave lower recoveries with respect to the classical EME. The observed decline of the signal was proved to be against the relations governing migration and diffusion processes, which means that a third driving force is involved in EME. The third driving force is the interaction between the radially inhomogeneous electric field and the analyte in its neutral form. PMID:26388374

  2. Dielectric Properties and Ion Mobility in Erythrocytes

    PubMed Central

    Pauly, H.; Schwan, H. P.

    1966-01-01

    The impedance of erythrocytes of man, cattle, sheep, dog, cat, rabbit, and chicken was measured in the range from 0.5 to 250 Mc. The dielectric constant of the red cell interior is 50 at 250 Mc, varies but little with species, and can readily be accounted for by the cells' hemoglobin content. The electrical conductivity of the red cell interior was determined between 70 and 100 Mc. The values differ from species to species within the rather limited range from 4.4 to 5.3 mmho/cm. Removal of the cell membranes does not affect the conductivity. Hence, the cell interior behaves, from an electrical point of view, like a highly concentrated hemoglobin solution. A theoretical value for the electrical conductivity of erythrocyte interiors, which is calculated on the basis of the salt content of the cell, ion mobility, and the volume concentration of the hemoglobin, is roughly twice as large as the measured value. This discrepancy is typical not only of the red blood cell. Pertinent measurements show that it is probably caused by hydrodynamic and possibly by electrostatic effects also, which lower the mobility of the ions. From the lower electrical mobility it appears that a lowered diffusion constant of the electrolytes and nonelectrolytes within the cell is indicated. PMID:5970566

  3. A mobile Sn nanowire inside a β-Ga2 O3 tube: a practical nanoscale electrically/thermally driven switch.

    PubMed

    Zou, Rujia; Zhang, Zhenyu; Tian, Qiwei; Ma, Guanxing; Song, Guosheng; Chen, Zhigang; Hu, Junqing

    2011-12-01

    Nanoelectromechanical system switches are seen as key devices for fast switching in communication networks since they can be switched between transmitting and receiving states with an electrostatic command. Herein, the fabrication of practical, nanoscale electrically/thermally driven switches is reported based on a mobile Sn nanowire inside a β-Ga2 O3 tube. The melting point of Sn inside the Ga2 O3 tube is found to be as low as 58 °C-far below the value of bulk Sn (231.89 °C)-and its crystal phase (β-Sn) remains unchanged even at temperatures as low as -170 °C. Thus a miniaturization of the unique wide-temperature-range thermometer based on the linear thermal expansion of liquid Sn fillings in the Ga2 O3 tube is realized. In addition, the electrical properties of the Sn-nanowire-filled β-Ga2 O3 tubes are carefully determined: importantly, the resistance demonstrates a sudden drop (rise) when two Sn nanowires contact (separate), due to the thermally driven motion of the liquid Sn fillings inside the tube. Thus this structure can be switched between its on and off states by controlling the motion, merging or splitting, of the Sn nanowires inside the tube, either electrically, by applying a current, or thermally, at a predetermined temperature. PMID:21972087

  4. In Situ XPS Chemical Analysis of MnSiO3 Copper Diffusion Barrier Layer Formation and Simultaneous Fabrication of Metal Oxide Semiconductor Electrical Test MOS Structures.

    PubMed

    Byrne, Conor; Brennan, Barry; McCoy, Anthony P; Bogan, Justin; Brady, Anita; Hughes, Greg

    2016-02-01

    Copper/SiO2/Si metal-oxide-semiconductor (MOS) devices both with and without a MnSiO3 barrier layer at the Cu/SiO2 interface have been fabricated in an ultrahigh vacuum X-ray photoelectron spectroscopy (XPS) system, which allows interface chemical characterization of the barrier formation process to be directly correlated with electrical testing of barrier layer effectiveness. Capacitance voltage (CV) analysis, before and after tube furnace anneals of the fabricated MOS structures showed that the presence of the MnSiO3 barrier layer significantly improved electric stability of the device structures. Evidence of improved adhesion of the deposited copper layer to the MnSiO3 surface compared to the clean SiO2 surface was apparent both from tape tests and while probing the samples during electrical testing. Secondary ion mass spectroscopy (SIMS) depth profiling measurements of the MOS test structures reveal distinct differences of copper diffusion into the SiO2 dielectric layers following the thermal anneal depending on the presence of the MnSiO3 barrier layer. PMID:26732185

  5. CsSnI3: Semiconductor or metal? High electrical conductivity and strong near-infrared photoluminescence from a single material. High hole mobility and phase-transitions.

    PubMed

    Chung, In; Song, Jung-Hwan; Im, Jino; Androulakis, John; Malliakas, Christos D; Li, Hao; Freeman, Arthur J; Kenney, John T; Kanatzidis, Mercouri G

    2012-05-23

    CsSnI(3) is an unusual perovskite that undergoes complex displacive and reconstructive phase transitions and exhibits near-infrared emission at room temperature. Experimental and theoretical studies of CsSnI(3) have been limited by the lack of detailed crystal structure characterization and chemical instability. Here we describe the synthesis of pure polymorphic crystals, the preparation of large crack-/bubble-free ingots, the refined single-crystal structures, and temperature-dependent charge transport and optical properties of CsSnI(3), coupled with ab initio first-principles density functional theory (DFT) calculations. In situ temperature-dependent single-crystal and synchrotron powder X-ray diffraction studies reveal the origin of polymorphous phase transitions of CsSnI(3). The black orthorhombic form of CsSnI(3) demonstrates one of the largest volumetric thermal expansion coefficients for inorganic solids. Electrical conductivity, Hall effect, and thermopower measurements on it show p-type metallic behavior with low carrier density, despite the optical band gap of 1.3 eV. Hall effect measurements of the black orthorhombic perovskite phase of CsSnI(3) indicate that it is a p-type direct band gap semiconductor with carrier concentration at room temperature of ∼ 10(17) cm(-3) and a hole mobility of ∼585 cm(2) V(-1) s(-1). The hole mobility is one of the highest observed among p-type semiconductors with comparable band gaps. Its powders exhibit a strong room-temperature near-IR emission spectrum at 950 nm. Remarkably, the values of the electrical conductivity and photoluminescence intensity increase with heat treatment. The DFT calculations show that the screened-exchange local density approximation-derived band gap agrees well with the experimentally measured band gap. Calculations of the formation energy of defects strongly suggest that the electrical and light emission properties possibly result from Sn defects in the crystal structure, which arise

  6. Review and recent advances in battery health monitoring and prognostics technologies for electric vehicle (EV) safety and mobility

    NASA Astrophysics Data System (ADS)

    Rezvanizaniani, Seyed Mohammad; Liu, Zongchang; Chen, Yan; Lee, Jay

    2014-06-01

    As hybrid and electric vehicle technologies continue to advance, car manufacturers have begun to employ lithium ion batteries as the electrical energy storage device of choice for use in existing and future vehicles. However, to ensure batteries are reliable, efficient, and capable of delivering power and energy when required, an accurate determination of battery performance, health, and life prediction is necessary. This paper provides a review of battery prognostics and health management (PHM) techniques, with a focus on major unmet needs in this area for battery manufacturers, car designers, and electric vehicle drivers. A number of approaches are presented that have been developed to monitor battery health status and performance, as well as the evolution of prognostics modeling methods. The goal of this review is to render feasible and cost effective solutions for dealing with battery life issues under dynamic operating conditions.

  7. Multiple mobility edges in a 1D Aubry chain with Hubbard interaction in presence of electric field: Controlled electron transport

    NASA Astrophysics Data System (ADS)

    Saha, Srilekha; Maiti, Santanu K.; Karmakar, S. N.

    2016-09-01

    Electronic behavior of a 1D Aubry chain with Hubbard interaction is critically analyzed in presence of electric field. Multiple energy bands are generated as a result of Hubbard correlation and Aubry potential, and, within these bands localized states are developed under the application of electric field. Within a tight-binding framework we compute electronic transmission probability and average density of states using Green's function approach where the interaction parameter is treated under Hartree-Fock mean field scheme. From our analysis we find that selective transmission can be obtained by tuning injecting electron energy, and thus, the present model can be utilized as a controlled switching device.

  8. ESHAP + fixed dose G-CSF as autologous peripheral blood stem cell mobilization regimen in patients with relapsed or refractory diffuse large cell and Hodgkin's lymphoma: a single institution result of 127 patients.

    PubMed

    Akhtar, S; Tbakhi, A; Humaidan, H; El Weshi, A; Rahal, M; Maghfoor, I

    2006-02-01

    From 1996 to November 2004, 131 consecutive patients with relapsed or refractory diffuse large cell lymphoma (DLCL) and Hodgkin's lymphoma (HD) received ESHAP as mobilization chemotherapy before autologous peripheral blood stem cell transplant (ASCT). Patients received fixed dose G-CSF 300 microg SC bid starting 24-36 h after finishing mobilizing ESHAP. In all, four patients failed mobilization and are excluded. Characteristics of 127 patients: 68 males: 59 females. DLCL 49: HD 78. Initial stage I:II:III:IV:unknown was 15:34:33:42:3. Median age at ASCT 26 years. Median prior chemotherapy cycles were six [<6 (17 patients), 6-8 (90 patients), >8 (20 patients)]. Median ESHAP cycle used as mobilizer was third. Patients required 1, 2, 3, 4 apheresis were 93:25:8:1. Median total CD34+ cells/kg collected were 6.9 x 10(6) (DLCL 5.17 x 10(6) and HD 7.6 x 10(6)), patients weighing < or = 70 kg (93 patients) 6.54 x 10(6) and >70 kg (34 patients) 7.44 x 10(6) (P = 0.59), one apheresis (93 patients) 8.6 x 10(6)/kg and >1 apheresis (34 patients) 4.5 x 10(6) (P = 0.001). We conclude that ESHAP and G-CSF 300 microg SC bid is an effective mobilizing regimen even in patients >70 kg and most patients require only 1-2 apheresis. PMID:16400345

  9. Electric field induced oscillating electron mobility in asymmetric wide GaAs/Al{sub x}Ga{sub 1−x}As quantum well structure

    SciTech Connect

    Sahoo, Narayan; Sahu, Trinath

    2014-07-28

    For the first time, we show that an oscillatory enhancement of low temperature electron mobility μ can be achieved in an asymmetric GaAs/Al{sub x}Ga{sub 1−x}As wide quantum well structure by applying an external electric field F perpendicular to the interface plane. We show that the oscillating nature of μ as a function of F is mostly due to the contribution of the higher subband through intersubband effects when there is double subband occupancy. We further show that the wavy nature of μ can be enhanced by increasing the well width, surface electron density, and also by considering a double quantum well structure. Our results can be utilized for low temperature device applications.

  10. Global properties and propensity to dimerization of the amyloid-beta (12-28) peptide fragment through the modeling of its monomer and dimer diffusion coefficients and electrophoretic mobilities.

    PubMed

    Deiber, Julio A; Peirotti, Marta B; Piaggio, Maria V

    2015-03-01

    Neuronal activity loss may be due to toxicity caused mainly by amyloid-beta (1-40) and (1-42) peptides forming soluble oligomers. Here the amyloid-beta (12-28) peptide fragment (monomer) and its dimer are characterized at low pH through the modeling of their diffusion coefficients and effective electrophoretic mobilities. Translational diffusion coefficient experimental values of monomer and dimer analogs of this peptide fragment and monomer and dimer mixtures at thermodynamic equilibrium are used as reported in the literature for different monomer initial concentrations. The resulting electrokinetic and hydrodynamic global properties are employed to evaluate the amyloid-beta (12-28) peptide fragment propensity to dimerization through a thermodynamic theoretical framework. Therefore equilibrium constants are considered at pH 2.9 to elucidate one of the amyloidogenic mechanisms involving the central hydrophobic region LVFFA of the peptide spanning residues 17-21 associated with phenylalanine at positions 19 and 20 in the amino acid sequence of amyloid-beta peptides. An analysis demonstrating that peptide aggregation is a concentration-dependent process is provided, where both pair and intraparticle charge regulation phenomena become relevant. It is shown that the modeling of the effective electrophoretic mobility of the amyloid-beta (12-28) peptide fragment is crucial to understand the effect of hydrophobic region LVFFA in the amyloidogenic process. PMID:25403948

  11. Electrical detection of kidney injury molecule-1 with AlGaN/GaN high electron mobility transistors

    SciTech Connect

    Wang, H. T.; Kang, B. S.; Ren, F.; Pearton, S. J.; Johnson, J. W.; Rajagopal, P.; Roberts, J. C.; Piner, E. L.; Linthicum, K. J.

    2007-11-26

    AlGaN/GaN high electron mobility transistors (HEMTs) were used to detect kidney injury molecule-1 (KIM-1), an important biomarker for early kidney injury detection. The gate region consisted of 5 nm gold deposited onto the AlGaN surface. The gold was conjugated to highly specific KIM-1 antibodies through a self-assembled monolayer of thioglycolic acid. The HEMT source-drain current showed a clear dependence on the KIM-1 concentration in phosphate-buffered saline solution. The limit of detection was 1 ng/ml using a 20x50 {mu}m{sup 2} gate sensing area. This approach shows potential for both preclinical and clinical kidney injury diagnosis with accurate, rapid, noninvasive, and high throughput capabilities.

  12. Specific absorption rate and electric field measurements in the near field of six mobile phone base station antennas.

    PubMed

    Toivonen, Tommi; Toivo, Tim; Puranen, Lauri; Jokela, Kari

    2009-05-01

    In this article, the exposure to radio frequency electromagnetic fields was studied in close proximity (distances of 10, 100, 300, and 600 mm) to six base station antennas. The specific absorption rate (SAR) in 800 mm x 500 mm x 200 mm box phantom as well as unperturbed electric field (E) in air was measured. The results were used to determine whether the measurement of local maximum of unperturbed electric field can be used as a compliance check for local exposure. Also, the conservativeness of this assessment method compared to the ICNIRP basic restriction was studied. Moreover, the assessment of whole-body exposure was discussed and the distance ranges presented in which the ICNIRP limit for local exposure could be exceeded before the limit for whole-body SAR. These results show that the electric field measurement alone can be used for easy compliance check for the local exposure at all distances and for all antenna types studied. However, in some cases when the local peak value of E was compared directly to the ICNIRP reference level for unperturbed E, the exposure was overestimated only very slightly (by factor 1.1) compared to the basic restriction for localized SAR in a human, and hence these results can not be generalized to all antenna types. Moreover, it was shown that the limit for localized exposure could be exceeded before the limit for the whole-body average SAR, if the distance to the antenna was less than 240 mm. PMID:19194889

  13. Hall mobility, electrical resistivity, and dielectric properties of reduced La0.01Ba0.99TiO3

    NASA Astrophysics Data System (ADS)

    Ali, Ahmed. I.; Abdel Moez, A.; Kim, Yong Soo

    2013-04-01

    The La0.01Ba0.99TiO3 sample was reduced at 1380 °C under about a 10-14-atmosphere oxygen partial pressure. After the sample had been reduced under these conditions, the resistivity and the Hall mobility of the reduced La0.01Ba0.99TiO3 were investigated experimentally within a temperature range of 300 to 600 K. The electrical resistivity decreased linearly with increasing measurement temperature, indicating that the conduction mechanism in this system was thermally activated. Evidence of an excess of charge carriers was observed at high temperatures. The dielectric property data showed that the known phase-transition temperature shifted to a higher temperature (425 K). Thus the reduction of the sample has an influence on both the dielectric constant and the transition temperature. In-situ high-temperature electrical-conductivity and Hall measurements are useful tools for establishing the donor-doping effect in perovskite La0.01Ba0.99TiO3 and for screening it for more industrial applications.

  14. Fixed Electrical Charges and Mobile Ions Affect the Measurable Mechano-Electrochemical Properties of Charged-Hydrated Biological Tissues: The Articular Cartilage Paradigm

    PubMed Central

    Wan, Leo Q.; Miller, Chester; Guo, X. Edward; Mow, Van C.

    2009-01-01

    The triphasic constitutive law [Lai, Hou and Mow (1991)] has been shown in some special 1D cases to successfully model the deformational and transport behaviors of charged-hydrated, porous-permeable, soft biological tissues, as typified by articular cartilage. Due to nonlinearities and other mathematical complexities of these equations, few problems for the deformation of such materials have ever been solved analytically. Using a perturbation procedure, we have linearized the triphasic equations with respect to a small imposed axial compressive strain, and obtained an equilibrium solution, as well as a short-time boundary layer solution for the mechano- electrochemical (MEC) fields for such a material under a 2D unconfined compression test. The present results show that the key physical parameter determining the deformational behaviors is the ratio of the perturbation of osmotic pressure to elastic stress, which leads to changes of the measurable elastic coefficients. From the short-time boundary layer solution, both the lateral expansion and the applied load are found to decrease with the square root of time. The predicted deformations, flow fields and stresses are consistent with the analysis of the short time and equilibrium biphasic (i.e., the solid matrix has no attached electric charges) [Armstrong, Lai and Mow (1984)]. These results provide a better understanding of the manner in which fixed electric charges and mobile ions within the tissue contribute to the observed material responses. PMID:16783948

  15. Electrical and structural degradation of GaN high electron mobility transistors under high-power and high-temperature Direct Current stress

    SciTech Connect

    Wu, Y. Alamo, J. A. del; Chen, C.-Y.

    2015-01-14

    We have stressed AlGaN/GaN HEMTs (High Electron Mobility Transistors) under high-power and high-temperature DC conditions that resulted in various levels of device degradation. Following electrical stress, we conducted a well-established three-step wet etching process to remove passivation, gate and ohmic contacts so that the device surface can be examined by SEM and AFM. We have found prominent pits and trenches that have formed under the gate edge on the drain side of the device. The width and depth of the pits under the gate edge correlate with the degree of drain current degradation. In addition, we also found visible erosion under the full extent of the gate. The depth of the eroded region averaged along the gate width under the gate correlated with channel resistance degradation. Both electrical and structural analysis results indicate that device degradation under high-power DC conditions is of a similar nature as in better understood high-voltage OFF-state conditions. The recognition of a unified degradation mechanism provides impetus to the development of a degradation model with lifetime predictive capabilities for a broad range of operating conditions spanning from OFF-state to ON-state.

  16. Propagation of Epileptiform Activity Can Be Independent of Synaptic Transmission, Gap Junctions, or Diffusion and Is Consistent with Electrical Field Transmission

    PubMed Central

    Zhang, Mingming; Ladas, Thomas P.; Qiu, Chen; Shivacharan, Rajat S.; Gonzalez-Reyes, Luis E.

    2014-01-01

    The propagation of activity in neural tissue is generally associated with synaptic transmission, but epileptiform activity in the hippocampus can propagate with or without synaptic transmission at a speed of ∼0.1 m/s. This suggests an underlying common nonsynaptic mechanism for propagation. To study this mechanism, we developed a novel unfolded hippocampus preparation, from CD1 mice of either sex, which preserves the transverse and longitudinal connections and recorded activity with a penetrating microelectrode array. Experiments using synaptic transmission and gap junction blockers indicated that longitudinal propagation is independent of chemical or electrical synaptic transmission. Propagation speeds of 0.1 m/s are not compatible with ionic diffusion or pure axonal conduction. The only other means of communication between neurons is through electric fields. Computer simulations revealed that activity can indeed propagate from cell to cell solely through field effects. These results point to an unexpected propagation mechanism for neural activity in the hippocampus involving endogenous field effect transmission. PMID:24453330

  17. Dielectric Dispersion, Diffuse Phase Transition, and Electrical Properties of BCT-BZT Ceramics Sintered at a Low-Temperature

    NASA Astrophysics Data System (ADS)

    Tian, Yongshang; Gong, Yansheng; Meng, Dawei; Li, Yuanjian; Kuang, Boya

    2015-08-01

    Lead-free ceramics 0.50Ba0.9Ca0.1TiO3-0.50BaTi1- x Zr x O3 (BCT-BZT) were prepared via sintering BCT and BZT nanoparticles, which were synthesized using a modified Pechini polymeric precursor method, at a low temperature of 1260°C. The relative densities of the ceramics prepared with different zirconium contents ( x) were all above 95.3%, reaching a maximum of 97% when x = 0.08. X-ray diffraction results confirmed the onset of phase transformation from orthorhombic to rhombohedral symmetry with increasing zirconium contents, and the polymorphic phase transition was observed at x = 0.10. The dielectric dispersion, diffuse phase transition (DPT), and relaxor-like ferroelectric characteristics as a function of zirconium content were thoroughly studied. Optimum physical properties, remnant polarization ( P r) = 16.4 μC/cm2, piezoelectric constant ( d 33) = ~240 pC/N, and electromechanical coupling factor ( k p) = 0.22, were obtained at x = 0.10. The findings of the current DPT behavior study of BCT-BZT ceramics are believed to be insightful to the development of ferroelectric materials.

  18. The combined influence of stretch, mobility and electrical stimulation in the prevention of muscle fiber atrophy caused hypokinesia and hypodynamia

    NASA Technical Reports Server (NTRS)

    Goldspink, G.; Goldspink, D.; Loughna, P.

    1984-01-01

    The morphological and biochemical changes which occur in the hind limb muscles of the rat in response to hypokinesia and hypodynamia were investigated. Hind limb cast fixation and suspension techniques were employed to study the musclar atrophy after five days of hypokinesia and hypodynamia induced by suspension, appreciable muscular atrophy was apparent, particularly in the anti-gravity muscles. The effect of passive stretching and electrical stimulation on muscle atrophy was studied. Changes in muscle protein mass were assessed with spectrophotometric and radioactive techniques. Passive stretch is shown to counteract muscle disuse atrophy. The change in the numbers of specific muscle fibers in atrophied muscles is discussed.

  19. Chiral selection and frequency response of spiral waves in reaction-diffusion systems under a chiral electric field.

    PubMed

    Li, Bing-Wei; Cai, Mei-Chun; Zhang, Hong; Panfilov, Alexander V; Dierckx, Hans

    2014-05-14

    Chirality is one of the most fundamental properties of many physical, chemical, and biological systems. However, the mechanisms underlying the onset and control of chiral symmetry are largely understudied. We investigate possibility of chirality control in a chemical excitable system (the Belousov-Zhabotinsky reaction) by application of a chiral (rotating) electric field using the Oregonator model. We find that unlike previous findings, we can achieve the chirality control not only in the field rotation direction, but also opposite to it, depending on the field rotation frequency. To unravel the mechanism, we further develop a comprehensive theory of frequency synchronization based on the response function approach. We find that this problem can be described by the Adler equation and show phase-locking phenomena, known as the Arnold tongue. Our theoretical predictions are in good quantitative agreement with the numerical simulations and provide a solid basis for chirality control in excitable media. PMID:24832300

  20. Chiral selection and frequency response of spiral waves in reaction-diffusion systems under a chiral electric field

    NASA Astrophysics Data System (ADS)

    Li, Bing-Wei; Cai, Mei-Chun; Zhang, Hong; Panfilov, Alexander V.; Dierckx, Hans

    2014-05-01

    Chirality is one of the most fundamental properties of many physical, chemical, and biological systems. However, the mechanisms underlying the onset and control of chiral symmetry are largely understudied. We investigate possibility of chirality control in a chemical excitable system (the Belousov-Zhabotinsky reaction) by application of a chiral (rotating) electric field using the Oregonator model. We find that unlike previous findings, we can achieve the chirality control not only in the field rotation direction, but also opposite to it, depending on the field rotation frequency. To unravel the mechanism, we further develop a comprehensive theory of frequency synchronization based on the response function approach. We find that this problem can be described by the Adler equation and show phase-locking phenomena, known as the Arnold tongue. Our theoretical predictions are in good quantitative agreement with the numerical simulations and provide a solid basis for chirality control in excitable media.

  1. Instrument and method to determine the electrophoretic mobility of nanoparticles and proteins by combining electrical and flow field-flow fractionation.

    PubMed

    Johann, Christoph; Elsenberg, Stephan; Schuch, Horst; Rösch, Ulrich

    2015-04-21

    A new FFF method is presented which combines asymmetrical flow-FFF (AF4) and electrical FFF (ElFFF) in one channel to electrical asymmetrical flow-FFF (EAF4) to overcome the restrictions of pure ElFFF. It allows for measuring electrophoretic mobility (μ) as a function of size. The method provides an absolute value and does not require calibration. Results of μ for two particle standards are in good agreement with values determined by phase analysis light scattering (PALS). There is no requirement for low ionic strength carriers with EAF4. This overcomes one of the main limitations of ElFFF, making it feasible to measure proteins under physiological conditions. EAF4 has the capability to determine μ for individual populations which are resolved into separate peaks. This is demonstrated for a mixture of three polystyrene latex particles with different sizes as well as for the monomer and dimer of BSA and an antibody. The experimental setup consists of an AF4 channel with added electrodes; one is placed beneath the frit at the bottom wall and the other covers the inside of the upper channel plate. This design minimizes contamination from the electrolysis reactions by keeping the particles distant from the electrodes. In addition the applied voltage range is low (1.5-5 V), which reduces the quantity of gaseous electrolysis products below a threshold that interferes with the laminar flow profile or detector signals. Besides measuring μ, the method can be useful to improve the separation between sample components compared to pure flow-FFF. For two proteins (BSA and a monoclonal antibody), enhanced resolution of the monomer and dimer is achieved by applying an electric field. PMID:25789885

  2. Integrated architecture for the electrical detection of plasmonic resonances based on high electron mobility photo-transistors

    NASA Astrophysics Data System (ADS)

    Sammito, Davide; de Salvador, Davide; Zilio, Pierfrancesco; Biasiol, Giorgio; Ongarello, Tommaso; Massari, Michele; Ruffato, Gianluca; Morpurgo, Margherita; Silvestri, Davide; Maggioni, Gianluigi; Bovo, Gianluca; Gaio, Michele; Romanato, Filippo

    2014-01-01

    We report the design of an integrated platform for on-chip electrical transduction of the surface plasmon resonance supported by a nanostructured metal grating. The latter is fabricated on the active area of a GaAs/AlGaAs photo-HEMT and simultaneously works as the electronic gate of the device. The gold plasmonic crystal has a V-groove profile and has been designed by numerical optical simulations. By showing that the numerical models accurately reproduce the phototransistors experimental response, we demonstrate that the proposed architecture is suitable for the development of a new class of compact and scalable SPR sensors.We report the design of an integrated platform for on-chip electrical transduction of the surface plasmon resonance supported by a nanostructured metal grating. The latter is fabricated on the active area of a GaAs/AlGaAs photo-HEMT and simultaneously works as the electronic gate of the device. The gold plasmonic crystal has a V-groove profile and has been designed by numerical optical simulations. By showing that the numerical models accurately reproduce the phototransistors experimental response, we demonstrate that the proposed architecture is suitable for the development of a new class of compact and scalable SPR sensors. Electronic supplementary information (ESI) available: HEMTs optical response, device fabrication flow chart, estimate of device resolution based on numerical simulations, synthesis of thiolated biotin, biotin functionalization and avidin binding procedure. See DOI: 10.1039/c3nr04666d

  3. Exciton diffusion in disordered small molecules for organic photovoltaics: insights from first-principles simulations.

    PubMed

    Li, Z; Zhang, X; Lu, G

    2014-05-01

    Exciton diffusion in small molecules 3,6-bis(5-(benzofuran-2-yl)thiophen-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione [DPP(TBFu)2] is studied using first-principles simulations. We have examined dependence of exciton diffusion on structure disorder, temperature and exciton energy. We find that exciton diffusion length and diffusivity increase with structural order, temperature and the initial exciton energy. Compared to conjugated polymer poly(3-hexylthiophene) (P3HT), DPP(TBFu)2 small molecules exhibit a much higher exciton diffusivity, but a shorter lifetime. The exciton diffusion length in DPP(TBFu)2 is 50% longer than that in P3HT, yielding a higher exciton harvesting efficiency; the physical origin behind these differences is discussed. The time evolutions of exciton energy, electron-hole distance, and exciton localization are explored, and the widely speculated exciton diffusion mechanism is confirmed theoretically. The connection between exciton diffusion and carrier mobilities is also studied. Finally we point out the possibility to estimate exciton diffusivity by measuring carrier mobilities under AC electric fields. PMID:24759042

  4. Study of mechanisms of electric field-induced DNA transfection. I. DNA entry by surface binding and diffusion through membrane pores.

    PubMed

    Xie, T D; Sun, L; Tsong, T Y

    1990-07-01

    A study of mechanisms of electrotransfection using Escherichia coli (JM 105) and the plasmid DNA pBR322 as model system is reported. pBR322 DNA carries an ampicillin resistance gene: E. coli transformants are conveniently assayed by counting colonies in a selection medium containing 50 micrograms/ml ampicillin and 25 micrograms/ml streptomycin. Samples not exposed to the electric field showed no transfection. In the absence of added cations, the plasmid DNA remains in solution and the efficiency of the transfection was 2 x 10(6)/micrograms DNA for cells treated with a 8-kV/cm, 1-ms electric pulse (square wave). DNA binding to the cell membrane greatly enhanced the efficiency of the transfection and this binding was increased by milimolar concentrations of CaCl2, MgCl2, or NaCl (CaCl2 greater than MgCl2 greater than NaCl). For example, in the presence of 2.5 mM CaCl2, 55% of the DNA added bound to E. coli and the transfection efficiency was elevated by two orders of magnitude (2 x 10(8)/micrograms DNA). These ions did not cause cell aggregation. With a low ratio of DNA to cells (less than 1 copy/cell), transfection efficiency correlated with the amount of DNA bound to the cell surface irrespective of salts. When the DNA binding ratio approached zero, the transfection efficiency was reduced by two to three orders, indicating that DNA entry by diffusion through the bulk solution was less than 1%. Square pulses of up to 12 kV/cm and 1 ms were used in the electrotransfection experiments. When cell concentration was 1 x 1010 cell/ml and DNA was added before the pulse, a transfection efficiency of up to 5 x 108/ microg DNA was obtained under optimum conditions (a single pulse of 8 kV/cm, 1 ms, in the presence of 5 mM CaCl2). When DNA was added to E. coli after the electric pulse, the efficiency of the transfection was dramatically reduced owing to the resealing of pores. Transfection was reduced to zero when DNA was added 2 h after the electroporation. However

  5. Measuring the Effect of Ion-Induced Drift-Gas Polarization on the Electrical Mobilities of Multiply-Charged Ionic Liquid Nanodrops in Air

    NASA Astrophysics Data System (ADS)

    Fernández-García, Juan; Fernández de la Mora, Juan

    2013-12-01

    The electrical mobilities of multiply-charged nanodrops of the ionic liquid 1-ethyl, 3-methylimidazolium dicyanamide (EMI-N[CN]2) were accurately measured in air at 20 °C for mass-selected clusters of composition [EMI-N[CN]2] n [EMI+] z , with 2 ≤ n ≤ 369 and 1 ≤ z ≤ 10. We confirm prior reports that the mobility Z of a globular ion of mass m is given approximately by the modified Stokes-Millikan law for spheres, Z = Z SM, mod ( d m + d g , z, m), where d m = (6 m/ πρ)1/3 is the nanodrop mass-diameter based on the density ρ of the liquid (corrected for the capillary compression and electrostatic deformation of the nanodrop), and d g is an effective air molecule diameter. There is however a measurable (up to 7 %) and systematic z-dependent departure of Z from Z SM,mod . As theoretically expected at small ɛ * , this effect is accurately described by a simple correction factor of the form Z/ Z SM, mod = δ(1 - βɛ *), where kTɛ * is the potential energy due to the ion-induced dipole ( polarization) attraction between a perfectly-conducting charged nanodrop and a polarized neutral gas-molecule at a distance ( d m + d g )/2 from its center. An excellent fit of this model to hundreds of data points is found for d g ≈ 0.26 nm, β ≈ 0.36, and δ ≈ 0.954. Accounting for the effect of polarization decreases d g considerably with respect to values inferred from earlier nanodrop measurements that ignored this effect. In addition, and in spite of ambiguities in the mobility calibration scale, the measured constant δ smaller than unity increases Millikan's drag enhancement factor from the accepted value ξ m ≈ 1.36 to the new value ξ ≈ ξ m / δ ≈ 1.42 ± 0.03.

  6. Measuring the effect of ion-induced drift-gas polarization on the electrical mobilities of multiply-charged ionic liquid nanodrops in air.

    PubMed

    Fernández-García, Juan; Fernández de la Mora, Juan

    2013-12-01

    The electrical mobilities of multiply-charged nanodrops of the ionic liquid 1-ethyl, 3-methylimidazolium dicyanamide (EMI-N[CN]2) were accurately measured in air at 20 °C for mass-selected clusters of composition [EMI-N[CN]2] n [EMI(+)] z , with 2 ≤ n ≤ 369 and 1 ≤ z ≤ 10. We confirm prior reports that the mobility Z of a globular ion of mass m is given approximately by the modified Stokes-Millikan law for spheres, Z  =  Z SM,mod (d m   +  d g , z, m), where d m   =  (6m/πρ)(1/3) is the nanodrop mass-diameter based on the density ρ of the liquid (corrected for the capillary compression and electrostatic deformation of the nanodrop), and d g is an effective air molecule diameter. There is however a measurable (up to 7%) and systematic z-dependent departure of Z from Z SM,mod . As theoretically expected at small ε (*) , this effect is accurately described by a simple correction factor of the form Z/Z SM,mod   =  δ(1  -  βε (*)), where kTε (*) is the potential energy due to the ion-induced dipole (polarization) attraction between a perfectly-conducting charged nanodrop and a polarized neutral gas-molecule at a distance (d m   +  d g )/2 from its center. An excellent fit of this model to hundreds of data points is found for d g ≈ 0.26 nm, β ≈ 0.36, and δ ≈ 0.954. Accounting for the effect of polarization decreases d g considerably with respect to values inferred from earlier nanodrop measurements that ignored this effect. In addition, and in spite of ambiguities in the mobility calibration scale, the measured constant δ smaller than unity increases Millikan's drag enhancement factor from the accepted value ξ m ≈ 1.36 to the new value ξ ≈ ξ m /δ ≈ 1.42  ± 0.03. PMID:24048890

  7. Study of mechanisms of electric field-induced DNA transfection. I. DNA entry by surface binding and diffusion through membrane pores

    SciTech Connect

    Xie, T.D.; Sun, L.; Tsong, T.Y. )

    1990-07-01

    A study of mechanisms of electrotransfection using Escherichia coli (JM 105) and the plasmid DNA pBR322 as model system is reported. pBR322 DNA carries an ampicillin resistance gene: E. coli transformants are conveniently assayed by counting colonies in a selection medium containing 50 micrograms/ml ampicillin and 25 micrograms/ml streptomycin. Samples not exposed to the electric field showed no transfection. In the absence of added cations, the plasmid DNA remains in solution and the efficiency of the transfection was 2 x 10(6)/micrograms DNA for cells treated with a 8-kV/cm, 1-ms electric pulse (square wave). DNA binding to the cell membrane greatly enhanced the efficiency of the transfection and this binding was increased by milimolar concentrations of CaCl2, MgCl2, or NaCl (CaCl2 greater than MgCl2 greater than NaCl). For example, in the presence of 2.5 mM CaCl2, 55% of the DNA added bound to E. coli and the transfection efficiency was elevated by two orders of magnitude (2 x 10(8)/micrograms DNA). These ions did not cause cell aggregation. With a low ratio of DNA to cells (less than 1 copy/cell), transfection efficiency correlated with the amount of DNA bound to the cell surface irrespective of salts. When the DNA binding ratio approached zero, the transfection efficiency was reduced by two to three orders, indicating that DNA entry by diffusion through the bulk solution was less than 1%. Square pulses of up to 12 kV/cm and 1 ms were used in the electrotransfection experiments.

  8. DNA electrophoresis in agarose gels: Effects of electric field and gel concentration on the exponential dependence of reciprocal mobility on DNA length

    NASA Astrophysics Data System (ADS)

    Beheshti, Afshin; van Winkle, David; Randolph, Rill

    2002-03-01

    Electrophoresis was performed on double stranded DNA fragments ranging in length from 200 bp to 48502 bp at agarose gel concentrations T = 0.5% - 1.5% and electric fields E = 0.71 V/cm to 5 V/cm. A wide range of electric fields and gel concentrations were used to find what range of conditions work with the new interpolation equation, 1/μ(L) = 1/μl - (1/μl - 1/μ_s)e^-L/γ. The equation fit extremely well (\\chi^2 >= 0.999) to data with E = 2.5 V/cm to 5 V/cm and for lower fields (E < 2.5 V/cm) at low gel concentrations (T = 0.5% and 0.7%). This exponential relation seemed to hold when there is a smooth transition from the Ogston sieving regime to the reptation regime when looking at the “reptation plots” (plotting 3μL/μo vs. L) (Rousseau, J., Drouin, G., and Slater, G. W., Phys Rev Lett. 1997, 79, 1945-1948). For separations of single-stranded DNA in polyacrylamide, similar reptation plots have a region with a negative slope between the Ogston sieving regime and the reptation regime which has been interpreted as the signature of entropic trapping. When separating double-stranded DNA in agarose it was observed that fits deviate from the data when three different slopes are observed in the reptation plots. Failure of the simple exponential relationship between reciprocal mobility and DNA length appears to be the consequence of entropic trapping.

  9. Direct label-free electrical immunodetection of transplant rejection protein biomarker in physiological buffer using floating gate AlGaN/GaN high electron mobility transistors.

    PubMed

    Tulip, Fahmida S; Eteshola, Edward; Desai, Suchita; Mostafa, Salwa; Roopa, Subramanian; Evans, Boyd; Islam, Syed Kamrul

    2014-06-01

    Monokine induced by interferon gamma (MIG/CXCL9) is used as an immune biomarker for early monitoring of transplant or allograft rejection. This paper demonstrates a direct electrical, label-free detection method of recombinant human MIG with anti-MIG IgG molecules in physiologically relevant buffer environment. The sensor platform used is a biologically modified GaN-based high electron mobility transistor (HEMT) device. Biomolecular recognition capability was provided by using high affinity anti-MIG monoclonal antibody to form molecular affinity interface receptors on short N-hydroxysuccinimide-ester functionalized disulphide (DSP) self-assembled monolayers (SAMs) on the gold sensing gate of the HEMT device. A floating gate configuration has been adopted to eliminate the influences of external gate voltage. Preliminary test results with the proposed chemically treated GaN HEMT biosensor show that MIG can be detected for a wide range of concentration varying from 5 ng/mL to 500 ng/mL. PMID:24803243

  10. Improved electrical mobility in highly epitaxial La:BaSnO3 films on SmScO3(110) substrates

    NASA Astrophysics Data System (ADS)

    Wadekar, P. V.; Alaria, J.; O'Sullivan, M.; Flack, N. L. O.; Manning, T. D.; Phillips, L. J.; Durose, K.; Lozano, O.; Lucas, S.; Claridge, J. B.; Rosseinsky, M. J.

    2014-08-01

    Heteroepitaxial growth of BaSnO3 and Ba1-xLaxSnO3 (x = 7%) lanthanum doped barium stannate thin films on different perovskite single crystal (SrTiO3 (001) and SmScO3 (110)) substrates has been achieved by pulsed laser deposition under optimized deposition conditions. X-ray diffraction measurements indicate that the films on either of these substrates are relaxed due to the large mismatch and present a high degree of crystallinity with narrow rocking curves and smooth surface morphology while analytical quantification by proton induced X-ray emission confirms the stoichiometric La transfer from a polyphasic target, producing films with measured La contents above the bulk solubility limit. The films show degenerate semiconducting behavior on both substrates, with the observed room temperature resistivities, Hall mobilities, and carrier concentrations of 4.4 mΩ cm, 10.11 cm2 V-1 s-1, and 1.38 × 1020 cm-3 on SmScO3 and 7.8 mΩ cm, 5.8 cm2 V-1 s-1, and 1.36 × 1020 cm-3 on SrTiO3 ruling out any extrinsic contribution from the substrate. The superior electrical properties observed on the SmScO3 substrate are attributed to reduction in dislocation density from the lower lattice mismatch.

  11. Mobile Genetic Elements Related to the Diffusion of Plasmid-Mediated AmpC β-Lactamases or Carbapenemases from Enterobacteriaceae: Findings from a Multicenter Study in Spain

    PubMed Central

    Zamorano, L.; Miró, E.; Juan, C.; Gómez, L.; Bou, G.; González-López, J. J.; Martínez-Martínez, L.; Aracil, B.; Conejo, M. C.; Oliver, A.

    2015-01-01

    We examined the genetic context of 74 acquired ampC genes and 17 carbapenemase genes from 85 of 640 Enterobacteriaceae isolates collected in 2009. Using S1 pulsed-field gel electrophoresis and Southern hybridization, 37 of 74 blaAmpC genes were located on large plasmids of different sizes belonging to six incompatibility groups. We used sequencing and PCR mapping to investigate the regions flanking the acquired ampC genes. The blaCMY-2-like genes were associated with ISEcp1; the surrounding blaDHA genes were similar to Klebsiella pneumoniae plasmid pTN60013 associated with IS26 and the psp and sap operons; and the blaACC-1 genes were associated with IS26 elements inserted into ISEcp1. All of the carbapenemase genes (blaVIM-1, blaIMP-22, and blaIMP-28) were located in class 1 integrons. Therefore, although plasmids are the main cause of the rapid dissemination of ampC genes among Enterobacteriaceae, we need to be aware that other mobile genetic elements, such as insertion sequences, transposons, or integrons, can be involved in the mobilization of these genes of chromosomal origin. Additionally, three new integrons (In846 to In848) are described in this study. PMID:26077249

  12. Mobile genetic elements related to the diffusion of plasmid-mediated AmpC β-lactamases or carbapenemases from Enterobacteriaceae: findings from a multicenter study in Spain.

    PubMed

    Zamorano, L; Miró, E; Juan, C; Gómez, L; Bou, G; González-López, J J; Martínez-Martínez, L; Aracil, B; Conejo, M C; Oliver, A; Navarro, F

    2015-09-01

    We examined the genetic context of 74 acquired ampC genes and 17 carbapenemase genes from 85 of 640 Enterobacteriaceae isolates collected in 2009. Using S1 pulsed-field gel electrophoresis and Southern hybridization, 37 of 74 bla AmpC genes were located on large plasmids of different sizes belonging to six incompatibility groups. We used sequencing and PCR mapping to investigate the regions flanking the acquired ampC genes. The bla CMY-2-like genes were associated with ISEcp1; the surrounding bla DHA genes were similar to Klebsiella pneumoniae plasmid pTN60013 associated with IS26 and the psp and sap operons; and the bla ACC-1 genes were associated with IS26 elements inserted into ISEcp1. All of the carbapenemase genes (bla VIM-1, bla IMP-22, and bla IMP-28) were located in class 1 integrons. Therefore, although plasmids are the main cause of the rapid dissemination of ampC genes among Enterobacteriaceae, we need to be aware that other mobile genetic elements, such as insertion sequences, transposons, or integrons, can be involved in the mobilization of these genes of chromosomal origin. Additionally, three new integrons (In846 to In848) are described in this study. PMID:26077249

  13. CO/sub 2/ laser processing of diffusion induced lattice imperfections in silicon: Experiment and theory

    SciTech Connect

    James, R.B.; Geist, G.A.; Young, R.T.; Christie, W.H.; Greulich, F.A.

    1987-10-01

    The high-temperature diffusion of phosphorus into crystalline silicon causes the formation of electrically inactive phosphorus-rich precipitates near the surface. These precipitates decrease the carrier lifetime and mobility in the diffused layer, and thus lead to less than optimal diode characteristics of electrical junctions formed by diffusion of phosphorus into a p-type substrate. We show that the free-carrier absorption of a CO/sub 2/ laser pulse can be used to completely dissolve the precipitates and remove dislocations in the diffused layer. Furthermore, we find that there are distinct advantages in depositing the pulse energy by way of free-carrier transitions, since the energy can be preferentially deposited in either confined doped layers or diffusion wells that are surrounded by lightly doped material. Our transmission electron microscopy results show that the annealing of the extended lattice defects is caused by melting of the near-surface region and subsequent liquid-phase epitaxial regrowth. Van der Pauw measurements are used to study the carrier concentration, mobility, and sheet resistivity of the samples before and after laser irradiation. The results of the electrical measurements show that there is a large increase in the carrier concentrations and a corresponding drop in the sheet resistivities of the laser irradiated samples. Using a Fourier transform

  14. Ion-cage interpretation for the structural and dynamic changes of ionic liquids under an external electric field.

    PubMed

    Shi, Rui; Wang, Yanting

    2013-05-01

    In many applications, ionic liquids (ILs) work in a nonequilibrium steady state driven by an external electric field. However, how the electric field changes the structure and dynamics of ILs and its underlying mechanism still remain poorly understood. In this paper, coarse-grained molecular dynamics simulations were performed to investigate the structure and dynamics of 1-ethyl-3-methylimidazolium nitrate ([EMIm][NO3]) under a static electric field. The ion cage structure was found to play an essential role in determining the structural and dynamic properties of the IL system. With a weak or moderate electric field (0-10(7) V/m), the external electric field is too weak to modify the ion cage structure in an influential way and thus the changes of structural and dynamic properties are negligible. With a strong electric field (10(7)-10(9) V/m) applied, ion cages expand and deform apparently, leading to the increase of ion mobility and self-diffusion coefficient with electric field, and the self-diffusion of ions along the electric field becomes faster than the other two directions due to the anisotropic deformation of ion cages. In addition, the Einstein relation connecting diffusion and mobility breaks down at strong electric fields, and it also breaks down for a single ion species even at moderate electric fields (linear-response region). PMID:23557150

  15. Effect of OFF-state stress induced electric field on trapping in AlGaN/GaN high electron mobility transistors on Si (111)

    SciTech Connect

    Anand, M. J. E-mail: eging@ntu.edu.sg; Ng, G. I. E-mail: eging@ntu.edu.sg; Syamal, B.; Zhou, X.; Arulkumaran, S.; Manoj Kumar, C. M.; Ranjan, K.; Vicknesh, S.; Foo, S. C.

    2015-02-23

    The influence of electric field (EF) on the dynamic ON-resistance (dyn-R{sub DS[ON]}) and threshold-voltage shift (ΔV{sub th}) of AlGaN/GaN high electron mobility transistors on Si has been investigated using pulsed current-voltage (I{sub DS}-V{sub DS}) and drain current (I{sub D}) transients. Different EF was realized with devices of different gate-drain spacing (L{sub gd}) under the same OFF-state stress. Under high-EF (L{sub gd} = 2 μm), the devices exhibited higher dyn-R{sub DS[ON]} degradation but a small ΔV{sub th} (∼120 mV). However, at low-EF (L{sub gd} = 5 μm), smaller dyn-R{sub DS[ON]} degradation but a larger ΔV{sub th} (∼380 mV) was observed. Our analysis shows that under OFF-state stress, the gate electrons are injected and trapped in the AlGaN barrier by tunnelling-assisted Poole-Frenkel conduction mechanism. Under high-EF, trapping spreads towards the gate-drain access region of the AlGaN barrier causing dyn-R{sub DS[ON]} degradation, whereas under low-EF, trapping is mostly confined under the gate causing ΔV{sub th}. A trap with activation energy 0.33 eV was identified in the AlGaN barrier by I{sub D}-transient measurements. The influence of EF on trapping was also verified by Silvaco TCAD simulations.

  16. Improved electrical mobility in highly epitaxial La:BaSnO{sub 3} films on SmScO{sub 3}(110) substrates

    SciTech Connect

    Wadekar, P. V.; O'Sullivan, M.; Flack, N. L. O.; Manning, T. D.; Claridge, J. B.; Rosseinsky, M. J.; Alaria, J.; Phillips, L. J.; Durose, K.; Lozano, O.; Lucas, S.

    2014-08-04

    Heteroepitaxial growth of BaSnO{sub 3} and Ba{sub 1−x}La{sub x}SnO{sub 3} (x = 7%) lanthanum doped barium stannate thin films on different perovskite single crystal (SrTiO{sub 3} (001) and SmScO{sub 3} (110)) substrates has been achieved by pulsed laser deposition under optimized deposition conditions. X-ray diffraction measurements indicate that the films on either of these substrates are relaxed due to the large mismatch and present a high degree of crystallinity with narrow rocking curves and smooth surface morphology while analytical quantification by proton induced X-ray emission confirms the stoichiometric La transfer from a polyphasic target, producing films with measured La contents above the bulk solubility limit. The films show degenerate semiconducting behavior on both substrates, with the observed room temperature resistivities, Hall mobilities, and carrier concentrations of 4.4 mΩ cm, 10.11 cm{sup 2} V{sup −1} s{sup −1}, and 1.38 × 10{sup 20} cm{sup −3} on SmScO{sub 3} and 7.8 mΩ cm, 5.8 cm{sup 2} V{sup −1} s{sup −1}, and 1.36 × 10{sup 20} cm{sup −3} on SrTiO{sub 3} ruling out any extrinsic contribution from the substrate. The superior electrical properties observed on the SmScO{sub 3} substrate are attributed to reduction in dislocation density from the lower lattice mismatch.

  17. Mobile Learning Using Mobile Phones

    ERIC Educational Resources Information Center

    Vicente, Paula

    2013-01-01

    The participation in mobile learning programs is conditioned by having/using mobile communication technology. Those who do not have or use such technology cannot participate in mobile learning programs. This study evaluates who are the most likely participants of mobile learning programs by examining the demographic profile and mobile phone usage…

  18. Electric field-induced deformation of polyelectrolyte gels

    SciTech Connect

    Adolf, D.; Hance, B.G.

    1995-08-01

    Water-swollen polyelectrolyte gels deform in an electric field. We observed that the sign and magnitude of the deformation is dependent on the nature of the salt bath in which the gel is immersed and electrocuted. These results are compatible with a deformation mechanism based upon creation of ion density gradients by the field which, in turn, creates osmotic pressure gradients within the gel. A consistent interpretation results only if gel mobility is allowed as well as free ion diffusion and migration.

  19. 63. Mobile Learning in Developing Nations

    ERIC Educational Resources Information Center

    Motlik, Scott

    2008-01-01

    This paper looks at the diffusion and applications of mobile phone technology in Asia and Africa, compared with North America. It indicates that Asian distance education can be the global leader in the development of educational uses for the mobile phone; and it considers the potential for mobile learning in Africa and other developing regions.…

  20. Drift and diffusion of spin and charge density waves in a two-dimensional electron gas

    NASA Astrophysics Data System (ADS)

    Yang, Luyi; Koralek, J. D.; Orenstein, J.; Tibbetts, D. R.; Reno, J. L.; Lilly, M. P.

    2011-03-01

    We use transient grating spectroscopy (TGS) to study the persistent spin helix (PSH) state and electron-hole density wave (EHDW) in a 2D electron gas in the presence of an in-plane electric field parallel to the wavevector of the PSH or EHDW. By directly measuring the phase, we can measure the PSH and EHDW displacement with 10 nm spatial and sub-picosecond time resolution. We obtain both the spin diffusion and mobility and ambipolar diffusion and mobility from the TGS measurements of PSH and EHDW, respectively. The spin transresistivity extracted from the spin diffusion is in excellent agreement with the RPA theory of spin Coulomb drag (SCD). The spin mobility data indicate that SCD may also play a role in the spin wave drifting process. From the ambipolar diffusion and mobility, we obtain the transresistivity of electrons and holes in the same layer, which is much stronger than is typically seen in the conventional Coulomb drag experiments on coupled quantum wells.

  1. Development of a mobile magnetic resonance imaging system for outdoor tree measurements

    NASA Astrophysics Data System (ADS)

    Kimura, Takeshi; Geya, Yuto; Terada, Yasuhiko; Kose, Katsumi; Haishi, Tomoyuki; Gemma, Hiroshi; Sekozawa, Yoshihiko

    2011-05-01

    By combining a 0.3 T permanent magnet with flexible rotation and translation mechanism, a probe with a local electromagnetic shielding, several electrical units, a mobile lift, and an electric wagon, a mobile magnetic resonance imaging (MRI) system was developed for outdoor tree measurements. 2D cross-sectional images of normal and diseased branches of a pear tree were acquired for measurements of T1, T2, proton density, and apparent diffusion constant (ADC). The ADC map clearly differentiated diseased from normal branches. A whole-day measurement of the ADC map demonstrated that microscopic water flow in the normal branch changed proportionally with solar radiation. Therefore, we have concluded that our mobile MRI system is a powerful tool for studies of plants in outdoor environments.

  2. Real space mapping of ionic diffusion and electrochemical activity in energy storage and conversion materials

    DOEpatents

    Kalinin, Sergei V; Balke, Nina; Kumar, Amit; Dudney, Nancy J; Jesse, Stephen

    2014-05-06

    A method and system for probing mobile ion diffusivity and electrochemical reactivity on a nanometer length scale of a free electrochemically active surface includes a control module that biases the surface of the material. An electrical excitation signal is applied to the material and induces the movement of mobile ions. An SPM probe in contact with the surface of the material detects the displacement of mobile ions at the surface of the material. A detector measures an electromechanical strain response at the surface of the material based on the movement and reactions of the mobile ions. The use of an SPM tip to detect local deformations allows highly reproducible measurements in an ambient environment without visible changes in surface structure. The measurements illustrate effective spatial resolution comparable with defect spacing and well below characteristic grain sizes of the material.

  3. The influence of orientations and external electric field on charge carrier mobilities in CuPc and F16CuPc films on highly ordered pyrolytic graphite and octane-1-thiol terminated Au(111) substrates.

    PubMed

    Chen, Shuang; Ma, Jing

    2010-10-14

    The lying-down and standing-up CuPc and F(16)CuPc films on HOPG (highly ordered pyrolytic graphite) and C8-SAM/Au(111) (octane-1-thiol terminated Au(111)) substrates are investigated by using a hybrid strategy combing the molecular dynamic (MD) simulations with density functional theory (DFT) calculations, in order to understand the influence of packing orientation on charge carrier mobilities. On the basis of the periodic slab model and consistent-valence force field, MD simulations show the populations of various packing configurations and radial distribution of intermolecular distance in the films at room temperature. It is also demonstrated that the external electric field (parallel or perpendicular to the substrate) perturbs the intermolecular distances in CuPc and F(16)CuPc films, especially for the slipped edge-to-face stackings. DFT calculations are then used to evaluate two key charge-transfer parameters, reorganization energy and transfer integral. An electrostatics embedding model is employed to approximately consider the external electrostatics contributions to reorganization energy. The thermal-averaged mobility is consequently estimated by taking account of both electronic structures of charge-hopping pairs and dynamic fluctuations in film morphologies under various experimental conditions. It is found that CuPc has smaller reorganization energy and larger hole (electron) mobilities than F(16)CuPc. Under the external electric field of 10(4)-10(7) V cm(-1), both hole and electron mobilities of CuPc and F(16)CuPc films would decrease to 1-3 orders of magnitude. CuPc (F(16)CuPc) films show substantial orientation dependence of mobilities on the ratio of standing-up versus lying-down orientations falling in the range of 10-1000. PMID:20714578

  4. Molecular modeling of diffusion coefficient and ionic conductivity of CO2 in aqueous ionic solutions.

    PubMed

    Garcia-Ratés, Miquel; de Hemptinne, Jean-Charles; Bonet Avalos, Josep; Nieto-Draghi, Carlos

    2012-03-01

    Mass diffusion coefficients of CO(2)/brine mixtures under thermodynamic conditions of deep saline aquifers have been investigated by molecular simulation. The objective of this work is to provide estimates of the diffusion coefficient of CO(2) in salty water to compensate the lack of experimental data on this property. We analyzed the influence of temperature, CO(2) concentration,and salinity on the diffusion coefficient, the rotational diffusion, as well as the electrical conductivity. We observe an increase of the mass diffusion coefficient with the temperature, but no clear dependence is identified with the salinity or with the CO(2) mole fraction, if the system is overall dilute. In this case, we notice an important dispersion on the values of the diffusion coefficient which impairs any conclusive statement about the effect of the gas concentration on the mobility of CO(2) molecules. Rotational relaxation times for water and CO(2) increase by decreasing temperature or increasing the salt concentration. We propose a correlation for the self-diffusion coefficient of CO(2) in terms of the rotational relaxation time which can ultimately be used to estimate the mutual diffusion coefficient of CO(2) in brine. The electrical conductivity of the CO(2)-brine mixtures was also calculated under different thermodynamic conditions. Electrical conductivity tends to increase with the temperature and salt concentration. However, we do not observe any influence of this property with the CO(2) concentration at the studied regimes. Our results give a first evaluation of the variation of the CO(2)-brine mass diffusion coefficient, rotational relaxation times, and electrical conductivity under the thermodynamic conditions typically encountered in deep saline aquifers. PMID:22292779

  5. Electricity in the Atmosphere.

    ERIC Educational Resources Information Center

    Sampath, S.; Kumar, V. Sasi

    1991-01-01

    The theory of the atmospheric electric circuit and a discussion of the fair-weather electrical are presented. The ion concentration, mobility, conductivity, and electric field altitudinal profiles are explained. An outline of the electrical processes inside thunderstorms along with a description of the lightning strike are included. (Author)

  6. Electrical characterization of fluorinated benzothiadiazole based conjugated copolymer – a promising material for high-performance solar cells

    SciTech Connect

    Toušek, J. Toušková, J.; Chomutová, R.; Remeš, Z.; Čermák, J.; Helgesen, M.; Carlé, J. E.; Krebs, F. C.

    2015-12-15

    Measurements of electrical conductivity, electron work function, carrier mobility of holes and the diffusion length of excitons were performed on samples of conjugated polymers relevant to polymer solar cells. A state of the art fluorinated benzothiadiazole based conjugated copolymer (PBDT{sub THD} − DTBTff) was studied and benchmarked against the reference polymer poly-3-hexylthiophene (P3HT). We employed, respectively, four electrode conductivity measurements, Kelvin probe work function measurements, carrier mobility using charge extraction by linearly increasing voltage (CELIV) measurements and diffusion length determinaton using surface photovoltage measurements.

  7. Limits of social mobilization

    PubMed Central

    Rutherford, Alex; Cebrian, Manuel; Dsouza, Sohan; Moro, Esteban; Pentland, Alex; Rahwan, Iyad

    2013-01-01

    The Internet and social media have enabled the mobilization of large crowds to achieve time-critical feats, ranging from mapping crises in real time, to organizing mass rallies, to conducting search-and-rescue operations over large geographies. Despite significant success, selection bias may lead to inflated expectations of the efficacy of social mobilization for these tasks. What are the limits of social mobilization, and how reliable is it in operating at these limits? We build on recent results on the spatiotemporal structure of social and information networks to elucidate the constraints they pose on social mobilization. We use the DARPA Network Challenge as our working scenario, in which social media were used to locate 10 balloons across the United States. We conduct high-resolution simulations for referral-based crowdsourcing and obtain a statistical characterization of the population recruited, geography covered, and time to completion. Our results demonstrate that the outcome is plausible without the presence of mass media but lies at the limit of what time-critical social mobilization can achieve. Success relies critically on highly connected individuals willing to mobilize people in distant locations, overcoming the local trapping of diffusion in highly dense areas. However, even under these highly favorable conditions, the risk of unsuccessful search remains significant. These findings have implications for the design of better incentive schemes for social mobilization. They also call for caution in estimating the reliability of this capability. PMID:23576719

  8. Limits of social mobilization.

    PubMed

    Rutherford, Alex; Cebrian, Manuel; Dsouza, Sohan; Moro, Esteban; Pentland, Alex; Rahwan, Iyad

    2013-04-16

    The Internet and social media have enabled the mobilization of large crowds to achieve time-critical feats, ranging from mapping crises in real time, to organizing mass rallies, to conducting search-and-rescue operations over large geographies. Despite significant success, selection bias may lead to inflated expectations of the efficacy of social mobilization for these tasks. What are the limits of social mobilization, and how reliable is it in operating at these limits? We build on recent results on the spatiotemporal structure of social and information networks to elucidate the constraints they pose on social mobilization. We use the DARPA Network Challenge as our working scenario, in which social media were used to locate 10 balloons across the United States. We conduct high-resolution simulations for referral-based crowdsourcing and obtain a statistical characterization of the population recruited, geography covered, and time to completion. Our results demonstrate that the outcome is plausible without the presence of mass media but lies at the limit of what time-critical social mobilization can achieve. Success relies critically on highly connected individuals willing to mobilize people in distant locations, overcoming the local trapping of diffusion in highly dense areas. However, even under these highly favorable conditions, the risk of unsuccessful search remains significant. These findings have implications for the design of better incentive schemes for social mobilization. They also call for caution in estimating the reliability of this capability. PMID:23576719

  9. Diffusion-Barrier Contacts For Solar Cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Pool, Frederick S.; Nicolet, Marc; Iles, Peter A.

    1996-01-01

    Electrically conductive diffusion barriers of TaSiN prevent diffusion of metal from overlying metal contacts into underlying silicon during processing at high temperature, improving performance during subsequent use in low-intensity light at low temperature.

  10. Mg dopant in Cu2ZnSnSe4: An n-type former and a promoter of electrical mobility up to 120 cm2 V-1 s-1

    NASA Astrophysics Data System (ADS)

    Kuo, Dong-Hau; Wubet, Walelign

    2014-07-01

    Mg-doped Cu2ZnSnSe4 (CZTSe) bulk materials with the (Cu2-xMgx)ZnSnSe4 formula at x=0, 0.1, 0.2, 0.3, and 0.4 were prepared at 600 °C for 2 h with soluble sintering aids of Sb2S3 and Te. Defect chemistry was studied by measuring structural and electrical properties of Mg-doped CZTSe as a function of dopant concentration. Except at x=0, all Mg-doped CZTSe pellets showed an n-type behavior. The Mg-doped CZTSe pellets showed an n-type behavior. n-Type Mg-CZTSe pellets at x=0.1 showed the highest electrical conductivity of 24.6 S cm-1 and the net hole mobility of 120 cm2 V-1 s-1, while they were 11.8 S cm-1 and 36.5 cm2 V-1 s-1 for the undoped p-type CZTSe. Mg dopant is a strong promoter of electrical mobility. Mg dopant behaves as a donor defect in CZTSe at a 5% doping content, but is also used as an acceptor at a high content above 5%. Mg doping has further developed CZTSe into a promising semiconductor.