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Sample records for 3-4 day kelvin

  1. Unraveling nanoscale conduction and work function in a poly(3,4-ethylenedioxypyrrole)/carbon nanotube composite by Kelvin probe force microscopy and conducting atomic force microscopy

    Highlights: ► Counter ion effect on the nanoscale conduction of poly(3,4-ethylenedioxypyrrole) films. ► Local work function at nanometric spatial resolution by Kelvin probe force microscopy. ► Interconnected high current domains prevail in films with sulfonated carbon nanotubes. ► Enhanced redox activity and electrochromic contrast in carbon nanotube based films. ► Low work function of PEDOP/carbon nanotube film promotes uninhibited charge propagation. - Abstract: Poly(3,4-ethylenedioxypyrrole) or PEDOP films doped with triflate ions, dodecyl sulfate ions and benzyl sulfonate functionalized multiwalled carbon nanotubes (MWCNTs) have been synthesized by oxidative electropolymerization. The dynamic variation of local work function at the nanoscale has been followed by Kelvin probe force microscopy (KPFM) and the measure of heterogeneity of dopant distribution was assessed from the distinctive disparities in the current maps, using conductive atomic force microscopy (C-AFM). The surface potential profiles revealed a smaller work function for PEDOP-(MWCNT)SO3− film, and the current images showed a remarkably larger current sustaining capacity for this film, in contrast to PEDOP-CF3SO3− and PEDOP-C12H25)OSO3− films which, is a consequence of widespread interconnects between localized conducting domains of the polymer coated with carbon nanotubes. Functionalized nanotubes offer the prospect of conducting both electrons and ions, and therefore an almost seamless charge transport across PEDOP and (MWCNT)SO3− species is realized. Such an unhindered movement of charge is not realized in PEDOP films doped by the insulating triflate or dodecyl sulfate ions. Averaged point contact nanoscale I–V profiles confirmed this claim, as the PEDOP-(MWCNT)SO3− film showed carrier conductivity greater by four orders of magnitude, as compared to the PEDOP-CF3SO3− film. The enhanced electronic function and the reduced band gap of PEDOP-(MWCNT)SO3− film (0.19 eV) in

  2. Climatology of the ∼5-day Rossby and ∼6-day Kelvin waves seen in the SABER/TIMED temperatures (2002-2007)

    Complete text of publication follows. The presentation is focused on the global spatial (altitude and latitude) structure, seasonal and interannual variability of the ∼5-day Rossby (W1) and ∼6-day Kelvin (E1) waves derived from the SABER/TIMED temperature measurements for full 6 years (January 2002-December 2007). The latitude structure of the ∼5-day W1 wave is related to the gravest symmetric wave number 1 Rossby wave, i.e. the (1,1) mode. Its seasonal behavior is dominated by equinoctial amplifications; in the NH the wave amplifies in March-April and September, while in the SH - in March and November. The vertical structure of the ∼5-day Rossby wave amplitude revealed double-peaked maxima centered at ∼80-90 km in the mesosphere and ∼105-110 km in the lower thermosphere, as the lower thermospheric maximum is at least two times stronger than the mesospheric one. This is a vertically propagating wave from the stratosphere up to 120 km altitude with a mean vertical wavelength of ∼50-60 km. The ∼5-day Rossby wave at middle latitudes (40 deg) revealed some interannual variability and at least part of it is connected with the effect of QBO. The ∼6-day E1 wave is equatorially trapped wave located between 20 deg N and 20 deg S. Its seasonal behavior indicated some equinoctial and June solstice amplifications. The altitude structure of the ∼6-day Kelvin wave phase indicated that this is a vertically propagating wave up to 110 km altitude. The mean vertical wavelength in the stratosphere and mesosphere is ∼25 km, however above 95 km altitude the vertical wavelength shortened to 15 km. The ∼6-day Kelvin wave indicated significant SAO and QBO variability.

  3. PREFACE: Kelvin and Ireland

    Flood, Raymond; McCartney, Mark; Whitaker, Andrew

    2009-07-01

    Sir Joseph Larmor unveiling the Kelvin memorial in the Botanic Gardens, Belfast on a rainy day in 1913 Sir Joseph Larmor unveiling the Kelvin memorial in the Botanic Gardens, Belfast on a rainy day in 1913 © The Ulster Museum: Hogg collection William Thomson, later Lord Kelvin, was born in Belfast in 1824, and his family had lived near Ballynahinch in the north of Ireland, quite close to Belfast, from the seventeenth century. At the time of Kelvin's birth, James Thomson, his father, was Professor of Mathematics at the Belfast Royal Academical Institution (Inst). However, following the death of his wife in 1830, James took up a new position as Professor at the University of Glasgow, and he and his children moved there in 1832. Apart from three years studying at Cambridge, and a very brief period immediately afterwards travelling and teaching in Cambridge, Kelvin was to spend the rest of his life in Glasgow, where he occupied the Chair of Natural Philosophy (or Physics) for 53 years. The natural assumption might be that his birth in Ireland was irrelevant to Kelvin's life and work, and that the fine monument erected in his honour in Belfast's Botanic Gardens, which is pictured on the front cover of this volume, was more a demonstration of civic pride than a recognition of an aspect of Kelvin's life which was important to him. The purpose of the meeting was to demon strate that this was not the case, that, great Glaswegian as he undoubtedly became, Kelvin always delighted in the title of Irishman. The influence of his father, very much an Ulsterman, was immense, and Kelvin and his siblings were to follow his non-sectarian and reforming approach. Also important for Kelvin was his Christian upbringing, which began in Belfast, and his beliefs were to play a role of importance in his life and indeed in much of his most important work, in particular that on thermodynamics. Two of his siblings returned to Belfast and spent much of their lives there, and Kelvin was a

  4. Leapfrogging Kelvin waves

    Hietala, N; Salman, H; Barenghi, C F

    2016-01-01

    Two vortex rings can form a localized configuration whereby they continually pass through one another in an alternating fashion. This phenomenon is called leapfrogging. Using parameters suitable for superfluid helium-4, we describe a recurrence phenomenon that is similar to leapfrogging which occurs for two coaxial straight vortex filaments with the same Kelvin wave mode. For small amplitude Kelvin waves we demonstrate that our full Biot-Savart simulations closely follow predictions obtained from a simpified model that provides an analytical approximation developed for nearly parallel vortices. Our results are also relevant to thin-cored helical vortices in classical fluids.

  5. Lord Kelvin and Liberal Unionism

    Hutchison, Iain

    2009-04-01

    Kelvin had been a staunch Liberal until Gladstone's Irish Home Rule Bill of 1886 made him a Liberal Unionist. He believed the measure would damage Ireland's best interests and would create economic and social instability. He also rejected it on constitutional grounds. Concern for the position of Ulster's Protestants was, however, not a major issue for Kelvin. Between 1886 and 1890 he was the most prominent Liberal Unionist in the West of Scotland, and under his leadership, the party was highly effective in the region. It is likely that, to a certain extent, his peerage was a reward for his political work. After 1890, Kelvin became more of a party figurehead, while his views on many political issues drew him closer to those of the Conservatives.

  6. Pitfalls in Kelvin probe measurements

    We report on the interpretation of thickness-dependent surface potential profiles in insulators on metal substrates measured by Kelvin probe method. The electrical potentials are calculated within a self-consistent model taking both the conductive substrate and the insulator into account. It is shown that interpreting the Kelvin potentials for different layer thicknesses as the prevailing potential profile of a thick insulator film is generally wrong. Even more controversially, the reconstruction of the potential profile in a thick insulator layer on the basis of layer-thickness-dependent Kelvin measurements alone is per se impossible. This will be demonstrated exemplarily on the basis of doped and undoped organic films on conductive substrates.

  7. 3.4 Radiotherapy

    Kramer, H.-M.; Selbach, H.-J.; Vatnitsky, S.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Section '3.4 Radiotherapy' of the Chapter '3 Dosimetry in Diagnostic Radiology and Radiotherapy' with the contents:

  8. Ultrasound estimation and FE analysis of elastic modulus of Kelvin foam

    Kim, Nohyu; Yang, Seung Yong [School of Mechatronics Engineering, Korea University of Technology and Education, Cheonan (Korea, Republic of)

    2016-02-15

    The elastic modulus of a 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam with 3 mm unit cell is designed and printed layer upon layer to fabricate a Kelvin foam plate of 14 mm thickness with a 3D CAD/printer using ABS plastic. The Kelvin foam plate is completely filled with paraffin wax for impedance matching, so that the acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF) method and is used to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity. Finite element method (FEM) and micromechanics is applied to the Kelvin foam plate to calculate the theoretical elastic modulus using a non-isotropic tetrakaidecahedron model. The predicted elastic modulus of the Kelvin foam plate from FEM and micromechanics model is similar, which is only 3-4% of the bulk material. The experimental value of the elastic modulus from the ultrasonic method is approximately twice as that of the numerical and theoretical methods because of the flexural deformation of the cell edges neglected in the ultrasonic method.

  9. Caustic graphene plasmons with Kelvin angle

    Shi, Xihang; Gao, Fei; Xu, Hongyi; Yang, Zhaoju; Zhang, Baile

    2015-01-01

    A century-long argument made by Lord Kelvin that all swimming objects have an effective Mach number of 3, corresponding to the Kelvin angle of 19.5 degree for ship waves, has been recently challenged with the conclusion that the Kelvin angle should gradually transit to the Mach angle as the ship velocity increases. Here we show that a similar phenomenon can happen for graphene plasmons. By analyzing the caustic wave pattern of graphene plasmons stimulated by a swift charged particle moving uniformly above graphene, we show that at low velocities of the charged particle, the caustics of graphene plasmons form the Kelvin angle. At large velocities of the particle, the caustics disappear and the effective semi-angle of the wave pattern approaches the Mach angle. Our study introduces caustic wave theory to the field of graphene plasmonics, and reveals a novel physical picture of graphene plasmon excitation during electron energy-loss spectroscopy measurement.

  10. Kelvin-Helmholtz instabilities with Godunov SPH

    Cha, Seung-Hoon; Inutsuka, Shu-Ichiro; Nayakshin, Sergei

    2009-01-01

    Numerical simulations for the non-linear development of Kelvin-Helmholtz instability in two different density layers have been performed with the particle-based method (Godunov SPH) developed by Inutsuka (2002). The Godunov SPH can describe the Kelvin-Helmholtz instability even with a high density contrast, while the standard SPH shows the absence of the instability across a density gradient (Agertz et al. 2007). The interaction of a dense blob with a hot ambient medium has been performed als...

  11. Ship wakes: Kelvin or Mach angle?

    Rabaud, Marc

    2013-01-01

    From the analysis of a set of airborne images of ship wakes, we show that the wake angles decrease as $U^{-1}$ at large velocities, in a way similar to the Mach cone for supersonic airplanes. This previously unnoticed Mach-like regime is in contradiction with the celebrated Kelvin prediction of a constant angle of $19.47\\degree$ independent of the ship's speed. We propose here a model, confirmed by numerical simulations, in which the finite size of the disturbance explains this transition between the Kelvin and Mach regimes at a Froude number $Fr = U/\\sqrt{gL} \\simeq 0.5$, where $L$ is the hull ship length.

  12. Kelvin wake pattern at large Froude numbers

    Darmon, Alexandre; Benzaquen, Michael; Raphaël, Elie

    2013-01-01

    Gravity waves generated by an object moving at constant speed at the water surface form a specific pattern commonly known as the Kelvin wake. It was proved by Lord Kelvin that such a wake is delimited by a constant angle $\\simeq 19.47^\\circ$. However a recent study by Rabaud and Moisy based on the observation of airborne images showed that the wake angle seems to decrease as the Froude number $Fr$ increases, scaling as $Fr^{-1}$ for large Froude numbers. To explain such observations the autho...

  13. Ship wakes: Kelvin or Mach angle?

    Rabaud, Marc; Moisy, Frédéric

    2013-05-24

    From the analysis of a set of airborne images of ship wakes, we show that the wake angles decrease as U(-1) at large velocities, in a way similar to the Mach cone for supersonic airplanes. This previously unnoticed Mach-like regime is in contradiction with the celebrated Kelvin prediction of a constant angle of 19.47° independent of the ship's speed. We propose here a model, confirmed by numerical simulations, in which the finite size of the disturbance explains this transition between the Kelvin and Mach regimes at a Froude number Fr=U/√[gL]~/=0.5, where L is the hull ship length. PMID:23745883

  14. Extended Kelvin theorem in relativistic magnetohydrodynamics

    Bekenstein, Jacob D.; Oron, Asaf

    2000-01-01

    We prove the existence of a generalization of Kelvin's circulation theorem in general relativity which is applicable to perfect isentropic magnetohydrodynamic flow. The argument is based on a new version of the Lagrangian for perfect magnetohydrodynamics. We illustrate the new conserved circulation with the example of a relativistic magnetohydrodynamic flow possessing three symmetries.

  15. Kelvin's Canonical Circulation Theorem in Hall Magnetohydrodynamics

    Shivamoggi, B K

    2016-01-01

    The purpose of this paper is to show that, thanks to the restoration of the legitimate connection between the current density and the plasma flow velocity in Hall magnetohydrodynamics (MHD), Kelvin's Circulation Theorem becomes valid in Hall MHD. The ion-flow velocity in the usual circulation integral is now replaced by the canonical ion-flow velocity.

  16. Periodic homogenization for Kelvin-Voigt viscoelastic media with a Kelvin-Voigt viscoelastic interphase

    Daridon, Loic; Licht, Christian; Orankitjaroen, Somsak; Pagano, Stéphane

    2016-01-01

    International audience We studied the effective behavior of a composite made of a periodic distribution of inclusions linked to a matrix by a very thin layer, with the three components being of linear Kelvin-Voigt viscoelastic type. The effective behavior, derived by a rigorous mathematical homogenization method, is not of Kelvin-Voigt type but instead involves an additional fading memory term. The influence of various parameters of the composite were numerically analyzed through a finite ...

  17. Radiochemistry days

    This document provides the 44 papers (transparencies used during the presentations and posters) presented at the Radiochemistry Days, held September 3-4, 1998 in Nantes, France. The main studied topics were problematic questions concerning the nuclear fuel cycle and in particular the management, storage of radioactive wastes and the environmental impact. (O.M.)

  18. Analysis of Kelvin Probe Operational Models

    Popescu, Eugeniu M.

    2011-01-01

    We present a study of several models on which Kelvin Probe instruments with flat and spherical tips rely for operation and for the determination of the contact potential difference. Using covariance analysis, we have investigated the precision limits of each model as imposed by the Cramer-Rao bound. Where the situation demanded, we have evaluated the bias introduced by the method in the estimation of the contact potential difference.

  19. Automatic kelvin probe compatible with ultrahigh vacuum

    Baikie, I.D.; Werf, van der, M.J.; Oerbekke, H.; Broeze, J.; Silfhout, van, A.

    1989-01-01

    This article describes a new type of in situ ultrahigh‐vacuum compatible kelvin probe based on a voice‐coil driving mechanism. This design exhibits several advantages over conventional mechanical feed‐through and (in situ) piezoelectric devices in regard to the possibility of multiple probe geometry, flexibility of probe geometry, amplitude of oscillation, and pure parallel vibration. Automatic setup and constant spacing features are achieved using a digital‐to‐analog converter (DAC) steered ...

  20. Heating a Plasma to 100 Million Kelvin

    Fröberg, Gunnar; Nygren, Thomas

    2014-01-01

    In this work techniques for heating the fusion reactor ITER to thermonuclear temperatures, over 100 million kelvin, is investigated. The temperature is numerically computed for different heating configurations. The heat leakage is modeled to occur only via diffusion. The diffusion is assumed to be a combination of Bohm and gyro-Bohm diffusion. Basic conditions for a fusion reactor has been studied. The power needed for the different heat sources for the plasma to ignite is computed. Plots of ...

  1. Kelvin-Helmholtz instabilities with Godunov SPH

    Cha, Seung-Hoon; Nayakshin, Sergei

    2009-01-01

    Numerical simulations for the non-linear development of Kelvin-Helmholtz instability in two different density layers have been performed with the particle-based method (Godunov SPH) developed by Inutsuka (2002). The Godunov SPH can describe the Kelvin-Helmholtz instability even with a high density contrast, while the standard SPH shows the absence of the instability across a density gradient (Agertz et al. 2007). The interaction of a dense blob with a hot ambient medium has been performed also. The Godunov SPH describes the formation and evolution of the fingers due to the combinations of Rayleigh-Taylor, Richtmyer-Meshkov, and Kelvin-Helmholtz instabilities. The blob test result coincides well with the results of the grid-based codes. An inaccurate handling of a density gradient in the standard SPH has been pointed out as the direct reason of the absence of the instabilities. An unphysical force happens at the density gradient even in a pressure equilibrium, and repulses particles from the initial density di...

  2. Kelvin Helmholtz Instability in Planetary Magnetospheres

    Johnson, Jay R.; Wing, Simon; Delamere, Peter A.

    2014-11-01

    Kelvin-Helmholtz instability plays a particularly important role in plasma transport at magnetospheric boundaries because it can control the development of a turbulent boundary layer, which governs the transport of mass, momentum, and energy across the boundary. Waves generated at the interface can also couple into body modes in the plasma sheet and inner magnetosphere where they can play an important role in plasma sheet transport and particle energization in the inner magnetosphere. Kinetic and electron-scale effects are important for the development of K-H instability, leading to secondary instabilities and plasma mixing. The development of vortices that entwine magnetosheath field lines with magnetospheric field lines also allows reconnection and the interchange of plasma blobs from open to closed field lines. Dawn-dusk asymmetries in Kelvin-Helmholtz development at planetary boundary layers may result from several effects including plasma corotation, kinetic effects, magnetic geometry, or asymmetric distribution of plasma. Examples are provided throughout the solar system illustrating the pervasive effects of the Kelvin-Helmholtz instability on plasma transport.

  3. N-(3,4-Dimethylphenylbenzamide

    B. Thimme Gowda

    2008-01-01

    Full Text Available The conformation of the NH bond in the structure of the title compound (N34DMPBA, C15H15NO, is anti to the meta-methyl substituent in the aniline ring, similar to that observed with respect to the meta-chloro substituent in N-(3,4-dichlorophenylbenzamide (N34DCPBA, but in contrast to the syn conformation observed with respect to the meta-methyl substituent in N-(3,4-dimethylphenylacetamide. The bond parameters in N34DMPBA are similar to those in N34DCPBA and other benzanilides. The molecules in N34DMPBA are packed into a column-like structure in the direction of the a axis through N—H...O hydrogen bonds.

  4. Kelvin probe’s stray capacitance and noise simulation

    Danyluk, S.; Dubanevich, A. V.; O. K. Gusev; A. I. Svistun; Tyavlovsky, A. K.; K. L. Tyavlovsky; R. I. Vorobey; A. L. Zharin

    2014-01-01

    Stray capacitance effects and their influence on Kelvin probe’s performance are studied using mathematical and computer simulation. Presence of metal surface, even grounded, in vicinity of vibrating Kelvin probe produces the additional stray signal of complex harmonic character. Mean value and amplitude of this stray signal depends mostly on the ratio of stray and measurement vibrating capacitors gaps d1/d0. The developed model can be used for theoretical analysis of Kelvin probe configuratio...

  5. Vertical propagation of baroclinic Kelvin waves along the west coast of India

    D Nethery; D Shankar

    2007-08-01

    A linear, continuously stratified ocean model is used to investigate vertical propagation of remotely forced, baroclinic Kelvin waves along the Indian west coast. The extent of vertical propagation over the length of the coast is found to be an increasing function of the forcing frequency. Simulations show that, over the length of the Indian west coast, vertical propagation is limited at annual and semi-annual periods, but significant at periods shorter than about 120 days. This has two major consequences. First, the depth of subsurface currents associated with these frequencies varies substantially along the coast. Second, baroclinic Kelvin waves generated in the Bay of Bengal at periods shorter than about 120 days have negligible influence on surface currents along the north Indian west coast.

  6. Equatorial atmospheric Kelvin waves during El Niño episodes and their effect on stratospheric QBO.

    Das, Uma; Pan, C J

    2016-02-15

    Equatorial atmospheric Kelvin waves are investigated during a positive El Niño Southern Oscillation (ENSO) episode using temperature data retrieved from GPS Radio Occultation (RO) observations of FORMOSAT-3/COSMIC during the period from August 2006 to December 2013. Enhanced Kelvin wave amplitudes are observed during the El Niño episode of 2009-2010 and it is also observed that these amplitudes correlate with the Niño 3.4 index and also with outgoing longwave radiation and trade wind index. This study indicates that the enhanced equatorial atmospheric Kelvin wave amplitudes might be produced by geophysical processes that were involved in the onset and development of the El Niño episode. Further, easterly winds above the tropopause during this period favored the vertically upward propagation of these waves that induced a fast descending westerly regime by the end of 2010, where the zero-wind line is observed to take only 5 months to descend from 10 to 50 hPa. The current study presents observational evidence of enhanced Kelvin wave amplitudes during El Niño that has affected the stratospheric quasi-biennial oscillation (QBO) through wave-mean flow interactions. Earlier El Niño episodes of 1987 and 1998 are also qualitatively investigated, using reanalysis data. It is found that there might have been an enhancement in the equatorial Kelvin wave amplitudes during almost all El Niño episodes, however, an effect of a fast descending westerly is observed in the QBO only when the ambient zonal winds in the lower stratosphere favor the upward propagation of the Kelvin waves and consequently they interact with the mean flow. This study indicates that the El Niño and QBO are not linearly related and wave mean flow interactions play a very important role in connecting these two geophysical phenomena. PMID:26771207

  7. High-resolution Kelvin probe microscopy in corrosion science: Scanning Kelvin probe force microscopy (SKPFM) versus classical scanning Kelvin probe (SKP)

    With the introduction of a Kelvin probe mode to atomic force microscopy, the so called scanning Kelvin probe force microscopy (SKPFM), the Kelvin probe technique finds application in a steadily increasing number of different fields, from corrosion science to microelectronics and biosciences. For many of these applications, high resolution is required as the relevant information lies in the sub-microscopic distribution of work functions or potentials, which explains the increasing interest in SKPFM. However, compared to the standard scanning Kelvin probe (SKP) technique SKPFM is prone to much more artefacts, which are often not taken into account in the interpretation of the results, as is also the case with the real physical nature of the measured data. A critical discussion of possible artefacts and on the interpretation of the data is presented in this paper, with the main focus on application in corrosion science

  8. CFD simulation of Kelvin-Helmholtz instability

    Kelvin-Helmholtz instability appears in stratified two-fluid flow at surface. When the relative velocity is higher than the critical relative velocity, the growth of waves occurs. The experiment of Thorpe [1] used as a benchmark in the present paper, is made in a rectangular glass tube filled with two immiscible fluids of various densities. We simulated the growth of instability with CFX-5.7 code and compared simulation with analytical solution. It was found that surface tension force, which stabilizes growth of waves, actually has a destabilizing effect in simulation, unless very small timestep and residual is used. In CFX code system of nonlinear Navier-Stokes equations is linearised and solved iterative in each timestep, until prescribed residual is achieved. On the other hand, simulation without surface tension force is more stable than analytical result predicts. (author)

  9. Automatic kelvin probe compatible with ultrahigh vacuum

    Baikie, I. D.; van der Werf, K. O.; Oerbekke, H.; Broeze, J.; van Silfhout, A.

    1989-05-01

    This article describes a new type of in situ ultrahigh-vacuum compatible kelvin probe based on a voice-coil driving mechanism. This design exhibits several advantages over conventional mechanical feed-through and (in situ) piezoelectric devices in regard to the possibility of multiple probe geometry, flexibility of probe geometry, amplitude of oscillation, and pure parallel vibration. Automatic setup and constant spacing features are achieved using a digital-to-analog converter (DAC) steered offset potential. The combination of very low driver noise pick-up and data-acquisition system (DAS) signal processing techniques results in a work function (wf ) resolution, under optimal conditions, of analysis techniques this design has numerous applications in surface studies, e.g., adsorption kinetics, sample topography and homogeneity, sputter profiles, etc. For semiconductor specimens the high wf resolution makes it eminently suitable for surface photovoltage (SPV) spectroscopy.

  10. KELVIN PROBE’S STRAY CAPACITANCE AND NOISE SIMULATION

    S. Danyluk

    2015-03-01

    Full Text Available Stray capacitance effects and their influence on Kelvin probe’s performance are studied using mathematical and computer simulation. Presence of metal surface, even grounded, in vicinity of vibrating Kelvin probe produces the additional stray signal of complex harmonic character. Mean value and amplitude of this stray signal depends mostly on the ratio of stray and measurement vibrating capacitors gaps d1/d0. The developed model can be used for theoretical analysis of Kelvin probe configuration and probe electrometer’s input circuit. 

  11. Ultrasonic Measurement of Elastic Modulus of Kelvin Foam

    Oh Sukwon

    2016-01-01

    Full Text Available Elastic modulus of 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam of 3 mm unit cell is designed and printed layer upon layer to fablicate a Kelvin foam plate of 14mm thickness by 3D CAD/printer using ABS plastic. The Kelvin foam plate is filled completely with paraffin wax for impedance matching, so that acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF method to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity.

  12. Observations of Equatorial Kelvin Wave Modes in FORMOSAT-3/COSMIC GPS RO Temperature Profiles

    Potula Sree Brahmanandam

    2010-01-01

    Full Text Available In this study, we analyze FORMOSAT-3/COSMIC (F3/C GPS radio occultation (RO derived temperature components for the period September 2006 to February 2008. Results show the presence of slow Kelvin waves (wave period > 10 days with higher zonal wavenumbers (either one or two in the upper troposphere and lower stratosphere (UTLS. The vertical wavelengths of these waves are found to be in the range of 5 - 12 km. The predominant Kelvin waves observed in the temperature fluctuations are in the altitude range between 15 and 28 km and centered on the tropical tropopause. The downward phase progression of these waves suggests that the derived waves are propagating upward, with the source region located at lower altitudes possibly due to tropical convective heating. The zonal winds retrieved using radiosonde observations over Singapore _ _ during this period show a periodicity of ~24 - 26 months in the stratosphere, and quasi-biennial oscillation (QBO characteristics with eastward zonal winds from March 2006 to May 2007 and westward winds from June 2007 to July 2008 respectively. Our results further show that the Kelvin wave characteristics are enhanced during the westward phase of QBO and diminish during the eastward phase, in line with the previous reported results. Furthermore, an examination of outgoing longwave radiation (OLR data shows that deep convection activity is developed episodically over the Indonesian archipelago during the observation period, thereby indicating that the Kelvin wave events observed in temperature fluctuations are either driven by convective activity (convectively coupled waves or by a broad spectrum of convective variability (free waves over the Indonesian region.

  13. Object size effect on the contact potential difference measured by scanning Kelvin probe method

    Polyakov, B.; Krutokhvostov, R.; Kuzmin, A.; Tamanis, E.; Muzikante, I.; Tale, I.

    2010-01-01

    Abstract Contact potential difference (CPD) was measured by macroscopic Kelvin probe instrument and scanning Kelvin probe microscope on Al, Ni and Pt on ITO substrates at ambient conditions. CPD values measured by scanning Kelvin probe microscope and macroscopic Kelvin probe are close within the error of about 10?30% for large studied objects, whereas scanning Kelvin probe microscope signal decreases, when the object size becomes smaller than 1.4 ?m. CPD and...

  14. A Validated Nonlinear Kelvin-Helmholtz Benchmark for Numerical Hydrodynamics

    Lecoanet, Daniel; Quataert, Eliot; Burns, Keaton J; Vasil, Geoffrey M; Oishi, Jeffrey S; Brown, Benjamin P; Stone, James M; O'Leary, Ryan M

    2015-01-01

    The nonlinear evolution of the Kelvin-Helmholtz instability is a popular test for code verification. To date, most Kelvin-Helmholtz problems discussed in the literature are ill-posed: they do not converge to any single solution with increasing resolution. This precludes comparisons among different codes and severely limits the utility of the Kelvin-Helmholtz instability as a test problem. The lack of a reference solution has led various authors to assert the accuracy of their simulations based on ad-hoc proxies, e.g., the existence of small-scale structures. This paper proposes well-posed Kelvin-Helmholtz problems with smooth initial conditions and explicit diffusion. We show that in many cases numerical errors/noise can seed spurious small-scale structure in Kelvin-Helmholtz problems. We demonstrate convergence to a reference solution using both Athena, a Godunov code, and Dedalus, a pseudo-spectral code. Problems with constant initial density throughout the domain are relatively straightforward for both cod...

  15. Multi-Scale Kelvin-Helmholtz Vortices Along Mercury's Magnetopause

    Gershman, D. J.; Raines, J. M.; Slavin, J. A.; Zurbuchen, T.; Sundberg, T.; Boardsen, S. A.; Anderson, B. J.; Korth, H.; Solomon, S. C.

    2014-12-01

    Data from the Fast Imaging Plasma Spectrometer (FIPS) and Magnetometer (MAG) sensors on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft have revealed stark differences in the Kelvin-Helmholtz (K-H) instability at Mercury compared with that at Earth. Although K-H vortices have been documented in planetary magnetospheres at the interface of magnetosheath and magnetospheric plasmas, such features at Mercury have been observed exclusively on the dusk side. From a survey of 58 K-H events, we find that these vortices have two distinct sets of behavior separated by the dusk terminator. On the dayside, the wave frequencies measured by MAG are nearly constant at ~0.025 Hz (~40 s period) under a variety of magnetosheath conditions, whereas the wave frequency measured on the nightside is correlated with the strength of the magnetic field near the magnetopause and matches the local Na+ gyrofrequency. The polarization of these waves inside the magnetosphere is distinctly right-handed, consistent with non-linear roll-up of K-H vortices as opposed to the left-handed ion-cyclotron wave mode. During these events, measurements from FIPS reveal strong (~30%) concentrations of Na+ in the nightside plasma sheet adjacent to the magnetopause. The keV energies of these planetary ions provide them with gyroradii that are ~500-1000 km, a scale at which a kinetic description of the K-H instability may be appropriate at Mercury. These data suggest a transition from fluid-scale to kinetic scale K-H vortices from day to night along Mercury's duskside magnetopause.

  16. Characterization of interfacial bonding using a scanning Kelvin probe

    Interfaces play a crucial role in determining the ultimate properties and service life of coating and film materials. However, the characterization and measurement of interfacial bonding, in particular of the local strength, is difficult. The high sensitivity of the electron work function (EWF) to surface conditions has attracted increasing interest in applications of the Kelvin probing technique to investigate the mechanical behavior of materials. In this study, the Kelvin method was used to characterize the interfacial bond formed between pure copper and brass after annealing in argon gas. It was demonstrated that low EWF values, small EWF fluctuations, and narrow fluctuation ranges in interfacial regions corresponded to good bonding. Furthermore, there was a strong correlation between the EWF and the interfacial strength determined by the microindentation method using a universal microtribometer. The Kelvin probing technique could be a powerful tool for studying the local property and structure of interfaces

  17. AFM tip characterization by Kelvin probe force microscopy

    Reliable determination of the surface potential with spatial resolution is key for understanding complex interfaces that range from nanostructured surfaces to molecular systems to biological membranes. In this context, Kelvin probe force microscopy (KPFM) has become the atomic force microscope (AFM) method of choice for mapping the local electrostatic surface potential as it changes laterally due to variations in the surface work function or surface charge distribution. For reliable KPFM measurements, the influence of the tip on the measured electrostatic surface potential has to be understood. We show here that the mean Kelvin voltage can be used for a straightforward characterization of the electrostatic signature of neutral, charged and polar tips, the starting point for quantitative measurements and for tip-charge control for AFM manipulation experiments. This is proven on thin MgO(001) islands supported on Ag(001) and is supported by theoretical modeling, which shows that single ions or dipoles at the tip apex dominate the mean Kelvin voltage.

  18. A solution to the Kelvin wake angle controversy

    Darmon, Alexandre; Raphaël, Elie

    2014-01-01

    Gravity waves generated by an object moving at constant speed at the water surface form a specific pattern commonly known as the Kelvin wake. It was proved by Lord Kelvin that such a wake is delimited by a constant angle = 19.47{\\deg}. However a recent study by Rabaud and Moisy based on the observation of airborne images showed that the wake angle seems to decrease as the Froude number Fr increases, scaling as 1/Fr for large Froude numbers. To explain such observations the authors make the strong hypothesis that an object of size b cannot generate wavelengths larger than b thus leading to unrealistic pressure fields to model the object. With no need of such an assumption, we here analytically show that the angle corresponding to the maximum amplitude of the waves scales as 1/Fr for large Froude numbers whereas the Kelvin angle remains constant for all Fr.

  19. Nuclear order in silver at pico-Kelvin temperature

    Siemensmeyer, K.; Clausen, K.N.; Lefmann, K.;

    1997-01-01

    Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 μT. The entropy-field phase diagram was determined using the spin-dependent absorption.......Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 μT. The entropy-field phase diagram was determined using the spin-dependent absorption....

  20. Nuclear order in silver at pico-Kelvin temperature

    Siemensmeyer, K.; Clausen, K.N.; Lefmann, K.; Lounasmaa, O.V.; Metz, A.; Nummila, K.K.; Rasmussen, F.B.; Steiner, M.; Tuoriniemi, J.T.; Vuorinen, R.T.

    Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 mu T. The entropy-field phase diagram was determined using the spin-dependent absorption.......Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 mu T. The entropy-field phase diagram was determined using the spin-dependent absorption....

  1. Nuclear order in silver at pico-Kelvin temperature

    Siemensmeyer, K.; Clausen, K.N.; Lefmann, K.;

    1997-01-01

    Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 mu T. The entropy-field phase diagram was determined using the spin-dependent absorption.......Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 mu T. The entropy-field phase diagram was determined using the spin-dependent absorption....

  2. Kelvin-Helmholtz and Buckling Instabilities for a Viscoelastic Liquid

    Keshavarz, Bavand

    2012-01-01

    In this fluid dynamics video prepared for the APS-DFD Gallery of Fluid Motion we study the Kelvin-Helmholtz instability for both Newtonian and viscoelastic jets. The nonlinear dynamics of the jet motion are slowed down by orders of magnitude using a synchronized strobe effect coupled with precise timing control of perturbation frequencies. Our results show that at high wave-numbers the imposed perturbations initially grow linearly with time and the jet axis remains straight while the Kelvin-Helmholtz wave amplitude grows and rolls up into bags that encapsulate the central jet within themselves. At low wave-numbers (long wave-lengths) the jet axis buckles under the action of viscous stresses and a coupling between the Kelvin-Helmholtz instability and bending of the jet leads to new concertina or chevron modes which grow with time as they move downstream. Addition of viscoelasticity to the jet leads to the pronounced inhibition of the Kelvin-Helmholtz instability as the jet perturbation amplitude grows and larg...

  3. Work function of colloidal semiconducting nanocrystals measured by Kelvin probe

    Colloidal suspensions of CdS, PbS, Cu2S, Ag2S and ZnO nanocrystals were prepared by chemical route in presence of organic capping ligands. The formation of nanocrystals was studied by using UV-visible absorption spectroscopy. Kelvin probe measurements of work function were performed on nanocrystals thin film on ITO (indium tin oxide) coated glass.

  4. 3,4-methylenedioxymethamphetamine (MDMA: current perspectives

    Meyer JS

    2013-11-01

    Full Text Available Jerrold S Meyer Department of Psychology, Neuroscience and Behavior Program, University of Massachusetts, Amherst, MA, USA Abstract: Ecstasy is a widely used recreational drug that usually consists primarily of 3,4-methylenedioxymethamphetamine (MDMA. Most ecstasy users consume other substances as well, which complicates the interpretation of research in this field. The positively rated effects of MDMA consumption include euphoria, arousal, enhanced mood, increased sociability, and heightened perceptions; some common adverse reactions are nausea, headache, tachycardia, bruxism, and trismus. Lowering of mood is an aftereffect that is sometimes reported from 2 to 5 days after a session of ecstasy use. The acute effects of MDMA in ecstasy users have been attributed primarily to increased release and inhibited reuptake of serotonin (5-HT and norepinephrine, along with possible release of the neuropeptide oxytocin. Repeated or high-dose MDMA/ecstasy use has been associated with tolerance, depressive symptomatology, and persisting cognitive deficits, particularly in memory tests. Animal studies have demonstrated that high doses of MDMA can lead to long-term decreases in forebrain 5-HT concentrations, tryptophan hydroxylase activity, serotonin transporter (SERT expression, and visualization of axons immunoreactive for 5-HT or SERT. These neurotoxic effects may reflect either a drug-induced degeneration of serotonergic fibers or a long-lasting downregulation in 5-HT and SERT biosynthesis. Possible neurotoxicity in heavy ecstasy users has been revealed by neuroimaging studies showing reduced SERT binding and increased 5-HT2A receptor binding in several cortical and/or subcortical areas. MDMA overdose or use with certain other drugs can also cause severe morbidity and even death. Repeated use of MDMA may lead to dose escalation and the development of dependence, although such dependence is usually not as profound as is seen with many other drugs of abuse

  5. The metabolite 3,4,3',4'-tetrachloroazobenzene (TCAB) exerts a higher ecotoxicity than the parent compounds 3,4-dichloroaniline (3,4-DCA) and propanil.

    Xiao, Hongxia; Kuckelkorn, Jochen; Nüßer, Leonie Katharina; Floehr, Tilman; Hennig, Michael Patrick; Roß-Nickoll, Martina; Schäffer, Andreas; Hollert, Henner

    2016-05-01

    3,4,3',4'-tetrachloroazobenzene (TCAB) is not commercially manufactured but formed as an unwanted by-product in the manufacturing of 3,4-dichloroaniline (3,4-DCA) or metabolized from the degradation of chloranilide herbicides, like propanil. While a considerable amount of research has been done concerning the toxicological and ecotoxicological effects of propanil and 3,4-DCA, limited information is available on TCAB. Our study examined the toxicity of TCAB in comparison to its parent compounds propanil and 3,4-DCA, using a battery of bioassays including in vitro with aryl hydrocarbon receptor (AhR) mediated activity by the 7-ethoxyresorufin-O-deethylase (EROD) assay and micro-EROD, endocrine-disrupting activity with chemically activated luciferase gene expression (CALUX) as well as in vivo with fish embryo toxicity (FET) assays with Danio rerio. Moreover, the quantitative structure activity response (QSAR) concepts were applied to simulate the binding affinity of TCAB to certain human receptors. It was shown that TCAB has a strong binding affinity to the AhR in EROD and micro-EROD induction assay, with the toxic equivalency factor (TEF) of 8.7×10(-4) and 1.2×10(-5), respectively. TCAB presented to be a weak endocrine disrupting compound with a value of estradiol equivalence factor (EEF) of 6.4×10(-9) and dihydrotestosterone equivalency factor (DEF) of 1.1×10(-10). No acute lethal effects of TCAB were discovered in FET test after 96h of exposure. Major sub-lethal effects detected were heart oedema, yolk malformation, as well as absence of blood flow and tail deformation. QSAR modelling suggested an elevated risk to environment, particularly with respect to binding to the AhR. An adverse effect potentially triggering ERβ, mineralocorticoid, glucocorticoid and progesterone receptor activities might be expected. Altogether, the results obtained suggest that TCAB exerts a higher toxicity than both propanil and 3,4-DCA. This should be considered when assessing the

  6. Wave fluxes of equatorial Kelvin waves and QBO zonal wind forcing derived from SABER and ECMWF temperature space-time spectra

    M. Ern

    2009-03-01

    Full Text Available The quasi-biennial oscillation (QBO of the zonal mean zonal wind is one of the most important processes in the dynamics of the middle atmosphere in the tropics. Influences of the QBO can even be found at mid and high latitudes. It is widely accepted that the phase descent of alternating tropical easterlies and westerlies is driven by atmospheric waves of both global scale (equatorial wave modes like Kelvin, equatorial Rossby, Rossby-gravity, or inertia-gravity waves, as well as mesoscale gravity waves. However, the relative distribution of the different types of waves to the forcing of the QBO winds is highly uncertain. This is the case because until recently there were no high resolution long-term global measurements in the stratosphere. In our study we estimate Kelvin wave momentum flux and the contribution of zonal wind forcing by Kelvin waves based on space-time spectra determined from both Sounding of the Atmosphere using Broadband Emission Radiometry (SABER temperature measurements as well as temperatures from European Centre for Medium-Range Weather Forecasts (ECMWF operational analyses. Peak values of total Kelvin wave zonal wind forcing found are about 0.2 m/s/day. There is good agreement between SABER and ECMWF results. Global distributions are shown and the results are compared to the total wave forcing required to balance the background atmosphere. Sometimes Kelvin wave forcing is sufficient to explain almost the whole total wave forcing required for the momentum balance during the transition from QBO easterly to westerly winds. This is especially the case during the later parts of the periods of westerly wind shear at the equator between 20 and 35 km altitude. During other phases of the westerly wind shear periods, however, the contribution of Kelvin waves can be comparably low and the missing wave forcing, which is often attributed to mesoscale gravity waves or intermediate scale waves, can be the by far dominant contribution of

  7. Magnetic moments of lanthanide 3-, 4-nitrobenzoates and 3,4-dinitrobenzoates

    The magnetic moments for lanthanide 3-nitro and 4-nitrobenzoates were determined at 298 K and those for 3,4-dinitrobenzoates of rare earth elements over the temperature range 77 - 296 K. The complexes of 3,4-dinitrobenzoates of rare earth were found to obey the Curie-Weiss law. The values of μ calculated for all complexes (except that for europium 3,4-dinitrobenzoates) are close to those obtained for Ln3+ ions by Hund and Van Vleck. The results reveal that irrespective of the kind of ligands (3-nitro, 4-nitro or 3,4-dinitrobenzoates) no influence of their field on lanthanide ions occurs. (author)

  8. Determination of the yield locus using a Kelvin probing method

    The high sensitivity of the electron work function (EWF) to surface condition has attracted increasing interest from materials scientists. In this study, application of a Kelvin probe, which is used to measure the EWF, for determination of the material's yielding under multiaxial plane stresses was explored. Yielding of copper was investigated using the EWF as an indicator of plastic deformation. It was demonstrated that the yield point of copper determined using this method was consistent with those given respectively by von Mises and Tresca yield criteria. Furthermore, the experimental results indicated that yielding was easier under a tensile stress than under a compressive stress. The Kelvin probing method is promising and could be very suitable for determining yield onset of materials under complex loading conditions

  9. Kelvin-Helmholtz instabilities in tokamak edge plasmas

    The parallel Kelvin-Helmholtz instability is investigated as a possible explanation for poloidal asymmetries of density fluctuations which reverse with the plasma current direction. It is shown that these modes are localised around the position where the radial gradient of parallel velocity is maximum. Two mechanisms lead to unstable Kelvin-Helmholtz modes: the acceleration of ions in a presheath and the anomalous Stringer spin-up due to asymmetries of the particle flux. Up-down asymmetries are explained by combining these two effects. Depending on the limiter configuration, the Stringer effect amplifies or weakens the flow due to presheath acceleration. This type of asymmetry reverses with the plasma current direction. (authors)

  10. Dense magnetospheric plasma and Kelvin-Helmholtz waves

    Walsh, B.

    2015-12-01

    The coupling of energy between the solar wind and a planetary magnetosphere is a function of the plasma parameters on both sides of the planet's magnetopause. Scientists routinely monitor the changing conditions in the solar wind in efforts to predict the dynamics at the magnetopause, but there can also be significant changes within the magnetosphere that play a role. On the magnetospheric side, the plasma density can change by several orders of magnitude (0.1cm-3 to 50cm-3). The current study investigates the role of dense magnetospheric plasma in the formation of Kelvin-Helmholtz waves at the magnetopause boundary. Spacecraft observations and SuperDARN radar measurements are presented showing the occurrence of Kelvin-Helmholtz waves on the dayside magnetopause under relatively low shear flows in the presence of a dense plasmaspheric plume.

  11. Charged-state dynamics in Kelvin probe force microscopy

    Ondráček, Martin; Hapala, Prokop; Jelínek, Pavel

    2016-01-01

    We present a numerical model which allows us to study the Kelvin force probe microscopy response to the charge switching in quantum dots at various time scales. The model provides more insight into the behavior of frequency shift and dissipated energy under different scanning conditions measuring a temporarily charged quantum dot on surface. Namely, we analyze the dependence of the frequency shift, its fluctuation and of the dissipated energy, on the resonance frequency of tip and electron tu...

  12. Noise performance of frequency modulation Kelvin force microscopy

    Heinrich Diesinger; Dominique Deresmes; Thierry Mélin

    2014-01-01

    Noise performance of a phase-locked loop (PLL) based frequency modulation Kelvin force microscope (FM-KFM) is assessed. Noise propagation is modeled step by step throughout the setup using both exact closed loop noise gains and an approximation known as “noise gain” from operational amplifier (OpAmp) design that offers the advantage of decoupling the noise performance study from considerations of stability and ideal loop response. The bandwidth can be chosen depending on how much noise is acc...

  13. AFM tip characterization by Kelvin probe force microscopy

    Barth, C.; Hynninen, T.; Bieletzki, M.; Henry, C.R.; Foster, Adam S.; Esch, F; Heiz, U.

    2010-01-01

    Reliable determination of the surface potential with spatial resolution is key for understanding complex interfaces that range from nanostructured surfaces to molecular systems to biological membranes. In this context, Kelvin probe force microscopy (KPFM) has become the atomic force microscope (AFM) method of choice for mapping the local electrostatic surface potential as it changes laterally due to variations in the surface work function or surface charge distribution. For reliable KPFM meas...

  14. The effect of sample resistivity on Kelvin probe force microscopy

    Weymouth, Alfred Jay; Giessibl, Franz J.

    2012-01-01

    Kelvin probe force microscopy (KPFM) is a powerful technique to probe the local electronic structure of materials with atomic force microscopy. One assumption often made is that the applied bias drops fully in the tip-sample junction. We have recently identified an effect, the Phantom force, which can be explained by an ohmic voltage drop near the tip-sample junction causing a reduction of the electrostatic attraction when a tunneling current is present. Here, we demonstrate the strong effect...

  15. High Spatial Resolution Kelvin Probe Force Microscopy With Coaxial Probes

    Westervelt, Robert M.; Brown, Keith A.; Satziner, Kevin J.

    2012-01-01

    Kelvin probe force microscopy (KPFM) is a widely used technique to measure the local contact potential difference (CPD) between an AFM probe and the sample surface via the electrostatic force. The spatial resolution of KPFM is intrinsically limited by the long range of the electrostatic interaction, which includes contributions from the macroscopic cantilever and the conical tip. Here, we present coaxial AFM probes in which the cantilever and cone are shielded by a conducting shell, confining...

  16. Visualisation of Local Charge Densities with Kelvin Probe Force Microscopy

    Milde, Peter

    2011-01-01

    For the past decades, Kelvin probe force microscopy (KPFM) developed from a sidebranch of atomic force microscopy to a widely used standard technique. It allows to measure electrostatic potentials on any type of sample material with an unprecedented spatial resolution. While the technical aspects of the method are well understood, the interpretation of measured data remains object of intense research. This thesis intends to prove an advanced view on how sample systems which are typical for ul...

  17. Quantitative Kelvin probe force microscopy of current-carrying devices

    Fuller, EJ; Pan, D; Corso, BL; Tolga Gul, O; Gomez, JR; Collins, PG

    2013-01-01

    Kelvin probe force microscopy (KPFM) should be a key tool for characterizing the device physics of nanoscale electronics because it can directly image electrostatic potentials. In practice, though, distant connective electrodes interfere with accurate KPFM potential measurements and compromise its applicability. A parameterized KPFM technique described here determines these influences empirically during imaging, so that accurate potential profiles can be deduced from arbitrary device geometri...

  18. Kelvin Probe Studies of Cesium Telluride Photocathode for AWA Photoinjector

    Wisniewski, Eric; Velazquez, Daniel; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff; Harkay, Katherine

    2012-01-01

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (~50 nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin Probe technique. The study incl...

  19. Kelvin Probe Force Microscopy in liquid using Electrochemical Force Microscopy

    Liam Collins; Stephen Jesse; Kilpatrick, Jason I.; Alexander Tselev; M. Baris Okatan; Kalinin, Sergei V.; Rodriguez, Brian J

    2015-01-01

    Conventional closed loop-Kelvin probe force microscopy (KPFM) has emerged as a powerful technique for probing electric and transport phenomena at the solid–gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe–sample...

  20. Kelvin-Helmholtz wave generation beneath hovercraft skirts

    Sullivan, P. A.; Walsh, C.; Hinchey, M. J.

    1993-05-01

    When a hovercraft is hovering over water, the air flow beneath its skirts can interact with the water surface and generate waves. These, in turn, can cause the hovercraft to undergo violent self-excited heave motions. This note shows that the wave generation is due to the classical Kelvin-Helmholtz mechanism where, beyond a certain air flow rate, small waves at the air water interface extract energy from the air stream and grow.

  1. The survival of interstellar clouds against Kelvin-Helmholtz instabilities

    Vietri, Mario; Ferrara, Andrea; Miniati, Francesco

    1997-01-01

    We consider the stability of clouds surrounded by a hotter confining medium with respect to which they are in motion, against Kelvin-Helmholtz instabilities (KHI). In the presence of cooling, sound waves are damped by dissipation. Whenever cooling times are shorter than sound crossing times, as they are in the normal interstellar medium, this implies that the instability generated at the interface of the two media cannot propagate far from the interface itself. To study how this influences th...

  2. KELVIN rare gas time-of-flight program

    The purpose of this appendix is to explain in detail the procedure for performing time-of-flight (TOF) calibration measurements. The result of the calibration measurements is to assign a correct length (L) to the path the molecules travel in a particular experimental configuration. In conjunction with time information (t) a velocity distribution (L/t) can then be determined. The program KELVIN is listed

  3. Cavitation and bubble dynamics: the Kelvin impulse and its applications.

    Blake, John R; Leppinen, David M; Wang, Qianxi

    2015-10-01

    Cavitation and bubble dynamics have a wide range of practical applications in a range of disciplines, including hydraulic, mechanical and naval engineering, oil exploration, clinical medicine and sonochemistry. However, this paper focuses on how a fundamental concept, the Kelvin impulse, can provide practical insights into engineering and industrial design problems. The pathway is provided through physical insight, idealized experiments and enhancing the accuracy and interpretation of the computation. In 1966, Benjamin and Ellis made a number of important statements relating to the use of the Kelvin impulse in cavitation and bubble dynamics, one of these being 'One should always reason in terms of the Kelvin impulse, not in terms of the fluid momentum…'. We revisit part of this paper, developing the Kelvin impulse from first principles, using it, not only as a check on advanced computations (for which it was first used!), but also to provide greater physical insights into cavitation bubble dynamics near boundaries (rigid, potential free surface, two-fluid interface, flexible surface and axisymmetric stagnation point flow) and to provide predictions on different types of bubble collapse behaviour, later compared against experiments. The paper concludes with two recent studies involving (i) the direction of the jet formation in a cavitation bubble close to a rigid boundary in the presence of high-intensity ultrasound propagated parallel to the surface and (ii) the study of a 'paradigm bubble model' for the collapse of a translating spherical bubble, sometimes leading to a constant velocity high-speed jet, known as the Longuet-Higgins jet. PMID:26442141

  4. KELVIN rare gas time-of-flight program

    Vernon, M.

    1981-03-01

    The purpose of this appendix is to explain in detail the procedure for performing time-of-flight (TOF) calibration measurements. The result of the calibration measurements is to assign a correct length (L) to the path the molecules travel in a particular experimental configuration. In conjunction with time information (t) a velocity distribution (L/t) can then be determined. The program KELVIN is listed.

  5. Radiochemistry days; Journees radiochimie

    NONE

    1998-09-01

    This document provides the 44 papers (transparencies used during the presentations and posters) presented at the Radiochemistry Days, held September 3-4, 1998 in Nantes, France. The main studied topics were problematic questions concerning the nuclear fuel cycle and in particular the management, storage of radioactive wastes and the environmental impact. (O.M.)

  6. 3,4-methylenedioxymethamphetamine (MDMA): current perspectives

    Meyer JS

    2013-01-01

    Jerrold S Meyer Department of Psychology, Neuroscience and Behavior Program, University of Massachusetts, Amherst, MA, USA Abstract: Ecstasy is a widely used recreational drug that usually consists primarily of 3,4-methylenedioxymethamphetamine (MDMA). Most ecstasy users consume other substances as well, which complicates the interpretation of research in this field. The positively rated effects of MDMA consumption include euphoria, arousal, enhanced mood, increased sociability, and heighten...

  7. The application of the Kelvin probe in materials science

    This thesis reports on the application of the Kelvin probe in materials science and in particular on the study of metal and semiconductor surfaces in both ambient and UHV environments. The concept of the work function φ and its importance as a parameter in materials science is discussed in the context of novel technological applications. The various methods to determine the work function are reviewed. The main measurement technique used here - the Kelvin probe - is described in detail. The Kelvin probe measures local work function differences between a conducting sample and a reference tip in a non-contact, truly non-invasive way over a wide temperature range. However, it is an inherently relative technique and does not provide an absolute work function if the work function of the tip (φtip) is not known. Therefore, a novel technique has been developed to measure φtip with the Kelvin probe via the photoelectric effect, thus combining the advantages of both methods to provide the absolute work function of the sample surface. High and low work function surfaces were generated as target materials for a novel ion source based on hyperthermal surface ionisation: oxidised rhenium exhibits the highest work function of 7.15eV at a temperature of ∼900K whereas the lowest work function of ∼2.54eV was measured on lanthanum hexaboride, LaB6. The process of thermal and hyperthermal surface ionisation (SI, HSI) as well as the generation of hyperthermal molecular beams is discussed and a model of the surface ionisation process is developed to estimate its efficiency. Experimental data of SI and HSI are presented. The application of the Kelvin probe for the detection of defects and impurities in semiconductors, namely iron contamination, is demonstrated via two methods based on the measurement of the surface photovoltage. We find that both methods yield a lower surface potential and surface charge for iron contaminated wafers compared to a clean sample and therefore can be

  8. A Review Paper: Contributions from the Gravity and the Kelvin Modes for the Vertical Motion Response.

    Julio Buchmann

    2009-10-01

    Full Text Available In earlier papers of a series of real data integrations of the National Center for Atmospheric Research (NCAR Community Climate Model (CCM with tropical heat anomalies display regions of pronounced subsidence and drying located several thousand kilometers westward poleward of the heating for cases of tropical Atlantic heating and tropical east Pacific heating. This highly predictable sinking response is established within the first five days of these integrations. The normal-modes of a set of nonlinear primitive equations for an atmosphere: Adiabatic, hydrostatic, incompressible, dry, without friction and viscosity are linearized about a basic state at rest and used to partition model response into gravity-inertia and Rossby modes. The emphasis of this review is given upon the contributions of the gravity and Kelvin modes for the vertical motion response.

  9. Sleeping body temperatures in 3-4 month old infants.

    Wailoo, M P; Petersen, S A; Whittaker, H.; Goodenough, P

    1989-01-01

    Rectal, skin, and ambient temperatures were continuously recorded overnight from 3-4 month old normal infants in their home cots under conditions of room temperature and wrapping chosen freely by parents. It was found that rectal temperature was above 37 degrees C when infants were put down, but fell rapidly to 36.4 degrees C within one and a half hours, then stabilised for a few hours before rising steadily. This pattern was tied more closely to the time of putting down than time of day. The...

  10. May Day

    王芳

    2009-01-01

    For Teacher: May Day occurs in May 1 and refers to any of several public holidays.In many countries, May Day is synonymous(同义词的)with International Workers' Day, or Labor Day, which celebrates the social and economic achievements(成就)of the labor movement.

  11. MATHEMATICAL MODELING OF A DISTANCE DEPENDENCE OF A SCANNING KELVIN PROBE LATERAL RESOLUTION

    Tyavlovsky, A. K.

    2015-01-01

    A mathematical model of cylindrical shaped plane-ended scanning Kelvin probe output signal is proposed considering the case of an infinite plane sample's surface with local defects represented by dot charges. Modeling results were obtained for the case of two closely situated dot charges anddifferent combinations of scanning Kelvin probe tip's diameter and sample-to-probe gap. It was found that the most effective way to improve the lateral resolution of a scanning Kelvin probe is to reduce th...

  12. May Day

    王芳

    2009-01-01

    For Teachers: May Day occurs on May 1 and refers to any of several public holidays. In many coun- tries, May Day is synonymous (同义词的) with International Workers' Day, or Labor Day, which celebrates the social and economic achievements (成就) of the labor movement. As a day of celebration, the holiday has an- cient origins (起源), and it can relate to many customs that have survived into modem times.

  13. 3, 4-methylenedioximethamphetamin reverses anxiety induced by chronic mild stress

    Laura Andrea León A

    2013-01-01

    Full Text Available Here we report the effects of subchronic 3, 4 methylenedioximethamphetamine (MDMA on the elevated plusmaze, a widely used animal model of anxiety. Rats exposed to a mild chronic stress (MCS protocol received intracerebroventricular microinjections of the selective serotonin reuptake inhibitor (SSRI – fluoxetine (2.0 ug/ul or MDMA, (2.0 ug/ul for seven days. On the eighth day rats were tested in the elevated plus-maze. Our results showed that sub chronic MDMA interacted with MCS leading to a decrease in anxiety related behaviors including: percentage of open arms entries (F [2, 26] = 4.00; p = 0.031, time spent in the open arms (F [2, 26] = 3.656; p = 0.040 and time spent in the open arms extremities (F [2, 26] = 5.842; p = 0.008. These results suggest a potential effect of MDMA in the reversion of the emotional significance of aversive stimuli.

  14. Noise performance of frequency modulation Kelvin force microscopy

    Heinrich Diesinger

    2014-01-01

    Full Text Available Noise performance of a phase-locked loop (PLL based frequency modulation Kelvin force microscope (FM-KFM is assessed. Noise propagation is modeled step by step throughout the setup using both exact closed loop noise gains and an approximation known as “noise gain” from operational amplifier (OpAmp design that offers the advantage of decoupling the noise performance study from considerations of stability and ideal loop response. The bandwidth can be chosen depending on how much noise is acceptable and it is shown that stability is not an issue up to a limit that will be discussed. With thermal and detector noise as the only sources, both approaches yield PLL frequency noise expressions equal to the theoretical value for self-oscillating circuits and in agreement with measurement, demonstrating that the PLL components neither modify nor contribute noise. Kelvin output noise is then investigated by modeling the surrounding bias feedback loop. A design rule is proposed that allows choosing the AC modulation frequency for optimized sharing of the PLL bandwidth between Kelvin and topography loops. A crossover criterion determines as a function of bandwidth, temperature and probe parameters whether thermal or detector noise is the dominating noise source. Probe merit factors for both cases are then established, suggesting how to tackle noise performance by probe design. Typical merit factors of common probe types are compared. This comprehensive study is an encouraging step toward a more integral performance assessment and a remedy against focusing on single aspects and optimizing around randomly chosen key values.

  15. Kelvin-Helmholtz instabilities with Godunov smoothed particle hydrodynamics

    Cha, Seung-Hoon; Inutsuka, Shu-Ichiro; Nayakshin, Sergei

    2010-04-01

    Numerical simulations for the non-linear development of Kelvin-Helmholtz instability in two different density layers have been performed with the particle-based method (Godunov SPH) developed by Inutsuka. The Godunov SPH can describe the Kelvin-Helmholtz instability even with a high-density contrast, while the standard SPH shows the absence of the instability across a density gradient. The interaction of a dense blob with a hot ambient medium has been performed also. The Godunov SPH describes the formation and evolution of the fingers due to the combinations of Rayleigh-Taylor, Richtmyer-Meshkov and Kelvin-Helmholtz instabilities. The blob test result coincides well with the results of the grid-based codes. An inaccurate handling of a density gradient in the standard SPH has been pointed out as the direct reason of the absence of the instabilities. An unphysical force happens at the density gradient even in a pressure equilibrium, and repulses particles from the initial density discontinuity. Therefore, the initial perturbation damps, and a gap form at the discontinuity. The unphysical force has been studied in terms of the consistency of a numerical scheme. Contrary to the standard SPH, the momentum equation of the Godunov SPH does not use the particle approximation, and has been derived from the kernel convolution or a new Lagrangian function. The new Lagrangian function used in the Godunov SPH is more analogous to the real Lagrangian function for continuum. The momentum equation of the Godunov SPH has much better linear consistency, so the unphysical force is greatly reduced compared to the standard SPH in a high density contrast.

  16. 29 CFR 3.4 - Submission of weekly statements and the preservation and inspection of weekly payroll records.

    2010-07-01

    ... inspection of weekly payroll records. 3.4 Section 3.4 Labor Office of the Secretary of Labor CONTRACTORS AND... STATES § 3.4 Submission of weekly statements and the preservation and inspection of weekly payroll... subcontractor, within seven days after the regular payment date of the payroll period, to a representative of...

  17. Strain analysis of nonlocal viscoelastic Kelvin bar in tension

    ZHAO Xue-chuan; LEI Yong-jun; ZHOU Jian-ping

    2008-01-01

    Based on viscoelastic Kelvin model and nonlocal relationship of strain and stress, a nonlocal constitutive relationship of viscoelasticity is obtained and the strain response of a bar in tension is studied. By transforming governing equation of the strain analysis into Volterra integration form and by choosing a symmetric exponential form of kernel function and adapting Neumann series, the closed-form solution of strain field of the bar is obtained. The creep process of the bar is presented. When time approaches infinite, the strain of bar is equal to the one of nonlocal elasticity.

  18. Open-loop band excitation Kelvin probe force microscopy

    A multidimensional scanning probe microscopy approach for quantitative, cross-talk free mapping of surface electrostatic properties is demonstrated. Open-loop band excitation Kelvin probe force microscopy (OL BE KPFM) probes the full response-frequency-potential surface at each pixel at standard imaging rates. The subsequent analysis reconstructs work function, tip–surface capacitance gradient and resonant frequency maps, obviating feedback-related artifacts. OL BE KPFM imaging is demonstrated for several materials systems with topographic, potential and combined contrast. This approach combines the features of both frequency and amplitude KPFM and allows complete decoupling of topographic and voltage contributions to the KPFM signal. (paper)

  19. Temperature calibration for diffusion experiments to sub-Kelvin precision.

    Zaum, Christopher; Bertram, Cord; Meyer Auf der Heide, Kastur M; Mehlhorn, Michael; Morgenstern, Karina

    2016-05-01

    Arrhenius plots are often used to determine energy barriers and prefactors of thermally activated processes. The precision of thus determined values depends crucially on the precision of the temperature measurement at the sample surface. We line out a procedure to determine the absolute temperature of a metal sample in a cryogenic scanning tunneling microscope between 5 K and 50 K with sub-Kelvin precision. We demonstrate the dependence of prefactor and diffusion energy on this calibration for diffusion of CO on Cu(111) and on Ag(100) measured in the temperature range from 30 K to 38 K and 19 K to 23 K, respectively. PMID:27250437

  20. Kelvin-Helmholtz instability and vortices in magnetized plasma

    Analytic theory and implicit particle simulations are used to describe the evolution of the Kelvin-Helmholtz instability and the plasma vortices driven by a nonuniform E x B flow velocity. Formulas for plasma convection arising from the self-consistent plasma electric field give the rate of anomalous momentum transport across the magnetic field. The momentum transport is shown to be controlled by the tilting angle of the elliptical vortex with respect to the direction of the parallel flow. Three stages of evolution are investigated and formulas for the final vortex state are given

  1. Kelvin--Helmholtz instability in an active region jet observed with \\emph{Hinode}

    Zhelyazkov, I; Srivastava, A K

    2015-01-01

    Over past ten years a variety of jet-like phenomena were detected in the solar atmosphere, including plasma ejections over a range of coronal temperatures being observed as extreme ultraviolet (EUV) and X-ray jets. We study the possibility for the development of Kelvin--Helmholtz (KH) instability of transverse magnetohydrodynamic (MHD) waves traveling along an EUV jet situated on the west side of NOAA AR 10938 and observed by three instruments on board Hinode on 2007 January 15/16 (Chifor et al., Astron. Astrophys.481, L57 (2008)). The jet was observed around LogT_e = 6.2 with up-flow velocities exceeded 150 km/s. Using Fe XII lambda186 and lambda195 line ratios, the measured densities were found to be above LogN_e = 11. We have modeled that EUV jet as a vertically moving magnetic flux tube (untwisted and weakly twisted) and have studied the propagation characteristics of the kink (m=1) mode and the higher m modes with azimuthal mode numbers m=2,3,4. It turns out that all these MHD waves can become unstable a...

  2. The influence of surface topography on Kelvin probe force microscopy

    Long-range electrostatic forces govern the imaging mechanism in electrostatic force microscopy as well as in Kelvin probe force microscopy. To improve the analysis of such images, simulations of the electrostatic field distribution have been performed in the past using a flat surface and a cone-shaped tip. However, the electrostatic field distribution between a tip and a sample depends strongly on the surface topography, which has been neglected in previous studies. It is therefore of general importance to study the influence of sample topography features on Kelvin probe force microscopy images, which we address here by performing finite element simulations. We show how the surface potential measurement is influenced by surface steps and surface grooves, considering potential variations in the form of a potential peak and a potential step. The influence of the topography on the measurement of the surface potential is found to be rather small compared to a typical experimental resolution. Surprisingly, in the case of a coinciding topography and potential step an improvement of the potential profile due to the inclusion of the topography is observed. Finally, based on the obtained results, suggestions for the realization of KPFM measurement are given.

  3. 3.4 Environmental impacts: energy industry

    The subchapter 3.4 'Environmental impact of the energy industry' of the 7th state of the environment report analyzes the current situation in Austria and briefly describes the following aspects: environmental policy targets, uniform taxation of energy, use of renewable energy sources, efficient use of energy, energy input, electricity supply and input, energy input into space heating and air conditioning systems, and renewable energy. In 2002, the input of final energy was risen by about 5 % in comparison to 1998. During this period, the largest increments in final energy inputs were recorded in the mobility sector with + 9.4 %, and in the private households sector with + 8.3 % . The goods production sector showed a slight decrease of about 1.3 % between 1998 and 2002. The 'goods production', 'mobility' and 'private households' sectors combined require about 87 % of the total final energy input. The final energy input for space heating and hot water in 2001 was 5.7 % above the input in 1998. Energy supply from renewable energy sources rose by about 13.8 % in 2002 compared to 1998. Domestic electricity consumption (excluding consumption for pumped-storage systems) in 2002 was about 10.5 % above consumption in 1998. Physical imports and physical exports in 2002 increased about 32 % and 8.6 % correspondingly compared to 1999. (nevyjel)

  4. The Lord Kelvin Project: Middle School Science for the 21st Century.

    Foti, Sebastian; Ledbetter, Ric; Taylor, Fred; Al-Kazemi, Ebraheem

    This paper introduces and reports upon lessons learned during the development phase of the Lord Kelvin Middle School Science Program. For the past two years, a set of tools to help middle school students learn science in a way that uses the full power of today's technology has been under development. Lord Kelvin is a robust collection of science…

  5. SDI Days

    Željko Hećimović

    2012-12-01

    Full Text Available NSDI and INSPIRE Days and Cartography and Geoinformation Conferences are traditionally organized every year. Three NSDI and INSPIRE Days and Cartography and Geoinformation Conferences have been organized so far: Varaždin (2009, Opatija (2010 and Split (2011. The Regional INSPIRE Training and Forum organized by EU INSPIRATION Project was also included this year. SDI Days were held in the Hotel International in Zagreb, September 25th – 29th, 2012.

  6. CEMI Days

    None

    2015-07-01

    CEMI Days are an important channel of engagement between DOE and the manufacturing industry to identify challenges and opportunities for increasing U.S. manufacturing competitiveness. CEMI Days that are held at manufacturing companies’ facilities can include tours of R&D operations or other points of interest determined by the host company.

  7. Effects of 3,4-Dichloroaniline on Testicle Enzymes as Biological Markers in Rats

    Bo ZHANG; SEN LIN

    2009-01-01

    Objective To investigate the effects of 3,4-dichlomaniline (3,4-DCA) on activities of testicle enzymes as biological markers in rats. Methods Fifty male rats were randomly divided into 5 groups (n=10). One group was left untreated and used as a solvent control (administered orally by corn oil), while the other 4 groups were treated with 3, 4-DCA. Corn oil was used as a solvent, and 3,4-DCA was diluted into tested concentrations (39, 81, 170, and 357 mg/kg). All the groups orally administered 3,4-DCA or corn oil, once a day for 4 weeks. The testicle tissue was homogenized in a 0.1 mol/L potassium phosphate buffer (0.1 mol/L, pH 7.2). The crude homogenate was centrifuged at 6000 rpm for 5 rain at 4 ℃. The supematant obtained was used as an enzyme extract for determination of the enzyme activities. Results Compared with the control, the activities of ALP, ACE and SDH were increased significantly at a lower level of 3,4-DCA, and decreased at a higher level of 3, 4-DCA, whreas the activities of LDH, LDH-X, and G6PDH were inhibited significantly with the increased 3,4-DCA concentration. Organ coefficient "organ weight/total body weight × 100" of testis, liver, and spleen increased significantly with the increased 3,4-DCA concentration. These results suggest that 3,4-DCA toxicity to the male reproductive system was associated with the activities of testicular enzymes which are the sensitive biochemical endpoints reflecting 3,4-DCA toxicity to the male reproductive system. Conclusion 3,4-DCA has toxicity to the reproductive system in male rats.

  8. High spatial resolution Kelvin probe force microscopy with coaxial probes

    Kelvin probe force microscopy (KPFM) is a widely used technique to measure the local contact potential difference (CPD) between an AFM probe and the sample surface via the electrostatic force. The spatial resolution of KPFM is intrinsically limited by the long range of the electrostatic interaction, which includes contributions from the macroscopic cantilever and the conical tip. Here, we present coaxial AFM probes in which the cantilever and cone are shielded by a conducting shell, confining the tip–sample electrostatic interaction to a small region near the end of the tip. We have developed a technique to measure the true CPD despite the presence of the shell electrode. We find that the behavior of these probes agrees with an electrostatic model of the force, and we observe a factor of five improvement in spatial resolution relative to unshielded probes. Our discussion centers on KPFM, but the field confinement offered by these probes may improve any variant of electrostatic force microscopy. (paper)

  9. Band excitation Kelvin probe force microscopy utilizing photothermal excitation

    A multifrequency open loop Kelvin probe force microscopy (KPFM) approach utilizing photothermal as opposed to electrical excitation is developed. Photothermal band excitation (PthBE)-KPFM is implemented here in a grid mode on a model test sample comprising a metal-insulator junction with local charge-patterned regions. Unlike the previously described open loop BE-KPFM, which relies on capacitive actuation of the cantilever, photothermal actuation is shown to be highly sensitive to the electrostatic force gradient even at biases close to the contact potential difference (CPD). PthBE-KPFM is further shown to provide a more localized measurement of true CPD in comparison to the gold standard ambient KPFM approach, amplitude modulated KPFM. Finally, PthBE-KPFM data contain information relating to local dielectric properties and electronic dissipation between tip and sample unattainable using conventional single frequency KPFM approaches

  10. Reconstruction of surface potential from Kelvin probe force microscopy images

    We present an algorithm for reconstructing a sample surface potential from its Kelvin probe force microscopy (KPFM) image. The measured KPFM image is a weighted average of the surface potential underneath the tip apex due to the long-range electrostatic forces. We model the KPFM measurement by a linear shift-invariant system where the impulse response is the point spread function (PSF). By calculating the PSF of the KPFM probe (tip+cantilever) and using the measured noise statistics, we deconvolve the measured KPFM image to obtain the surface potential of the sample.The reconstruction algorithm is applied to measurements of CdS-PbS nanorods measured in amplitude modulation KPFM (AM-KPFM) and to graphene layers measured in frequency modulation KPFM (FM-KPFM). We show that in the AM-KPFM measurements the averaging effect is substantial, whereas in the FM-KPFM measurements the averaging effect is negligible. (paper)

  11. Kelvin Probe Studies of Cesium Telluride Photocathode for AWA Photoinjector

    Wisniewski, Eric; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff; Harkay, Katherine

    2012-01-01

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (~50 nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating.

  12. The survival of interstellar clouds against Kelvin-Helmholtz instabilities

    Vietri, M; Miniati, F; Vietri, Mario; Ferrara, Andrea; Miniati, Francesco

    1997-01-01

    We consider the stability of clouds surrounded by a hotter confining medium with respect to which they are in motion, against Kelvin-Helmholtz instabilities (KHI). In the presence of cooling, sound waves are damped by dissipation. Whenever cooling times are shorter than sound crossing times, as they are in the normal interstellar medium, this implies that the instability generated at the interface of the two media cannot propagate far from the interface itself. To study how this influences the overall stability, first we derive an analytic dispersion relation for cooling media, separated by a shear layer. The inclusion of dissipation does not heal the instability, but it is shown that only a small volume around the interface is affected, the perturbation decaying exponentially with distance from the surface; this is confirmed by numerical simulations. Numerical simulations of spherical clouds moving in a surrounding intercloud medium by which they are pressure confined show that these clouds develop a core/ha...

  13. Kelvin-Helmholtz instability in non-Newtonian complex plasma

    Banerjee, D.; Garai, S.; Janaki, M. S.; Chakrabarti, N. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

    2013-07-15

    The Kelvin-Helmholtz (KH) instability is studied in a non-Newtonian dusty plasma with an experimentally verified model [Phys. Rev. Lett. 98, 145003 (2007)] of shear flow rate dependent viscosity. The shear flow profile used here is a parabolic type bounded flow. Both the shear thinning and shear thickening properties are investigated in compressible as well as incompressible limits using a linear stability analysis. Like the stabilizing effect of compressibility on the KH instability, the non-Newtonian effect in shear thickening regime could also suppress the instability but on the contrary, shear thinning property enhances it. A detailed study is reported on the role of non-Newtonian effect on KH instability with conventional dust fluid equations using standard eigenvalue analysis.

  14. Analysis and simulation of the operation of a Kelvin probe

    Reasenberg, Robert D; Phillips, James D

    2013-01-01

    Experiments that measure extremely small gravitational forces are often hampered by the presence of non-gravitational forces that can neither be calculated nor separately measured. Among these spurious forces is electrostatic attraction between a test mass and its surroundings due to the presence of spatially varying surface potential known as the "patch effect." In order to make surfaces with small surface potential variation, it is necessary to be able to measure it. A Kelvin probe (KP) measures contact potential difference (CPD), using the time-varying capacitance between the sample and a vibrating tip that is biased with a backing potential. Assuming that the tip remains constant, this measures the sample's surface potential variation. We examine the operation of the KP from the perspective of parameter estimation in the presence of noise. We show that, when the CPD is estimated from measurements at two separate backing potentials, the standard deviation of the optimal estimate depends on the total observ...

  15. MATHEMATICAL MODELING OF A DISTANCE DEPENDENCE OF A SCANNING KELVIN PROBE LATERAL RESOLUTION

    A. K. Tyavlovsky

    2015-04-01

    Full Text Available A mathematical model of cylindrical shaped plane-ended scanning Kelvin probe output signal is proposed considering the case of an infinite plane sample's surface with local defects represented by dot charges. Modeling results were obtained for the case of two closely situated dot charges anddifferent combinations of scanning Kelvin probe tip's diameter and sample-to-probe gap. It was found that the most effective way to improve the lateral resolution of a scanning Kelvin probe is to reduce the sample-to-probe gap in line with the reduction of sensor's vibration amplitude.

  16. Compensating electrostatic forces by single-scan Kelvin probe force microscopy

    We describe a novel method of single-scan Kelvin probe force microscopy, operating simultaneously with amplitude-modulation distance control in ambient air. A separate Kelvin probe feedback control loop compensates for potential differences between tip and sample by minimizing electrostatic forces. As a result, electrostatically induced height errors in topography are automatically cancelled. To prevent crosstalk from topography or errors in distance control, the Kelvin probe feedback employs phase information resulting from a combination of mechanical and electrical excitation of the cantilever at its second flexural eigenmode. The feedback for amplitude-modulation distance control operates as usual close to the first eigenfrequency

  17. Characterization of photovoltage evolution of ZnO films using a scanning Kelvin probe system

    Work function (WF) and surface photovoltage evolution of films can be measured using the Kelvin probe technique, and further analysis of the photoelectronic behavior can provide information on the energy level structure. In this paper, a theoretical analysis to measure surface photovoltage using Kelvin probe technique is presented. Based on this analysis, the surface photovoltage and its time-resolved evolution process as well as the energy level structure of ZnO films are determined using a scanning Kelvin probe. The present study therefore provides a simple and practical methodology for the characterization of the electronic behavior of films.

  18. MAY DAY

    李佳

    2009-01-01

    @@ May 1 is Intemational Labour Day.It is a great holiday for the working class.On this day working people all over the world demonstrate(显示)their power and solidarity(团结).It has its origins(起因,起源)in the struggle for shorter working hours.In 1884,eight Labour Unions of the United States and Canada held a convention(集会)in Chicago(芝加哥).Here it was decided to wage(开展)a united struggle to win the eight-hour day.A resolution(决议) was adopted (通过)fixing May1,1886,for a great nationwide(全国性的)demonstration(示威).

  19. 21 CFR 3.4 - Designated agency component.

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Designated agency component. 3.4 Section 3.4 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PRODUCT JURISDICTION Assignment of Agency Component for Review of Premarket Applications § 3.4 Designated...

  20. 40 CFR 257.3-4 - Ground water.

    2010-07-01

    ... to sewage sludge that is not used or disposed through a practice regulated in 40 CFR part 503 may... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Ground water. 257.3-4 Section 257.3-4... and Practices § 257.3-4 Ground water. (a) A facility or practice shall not contaminate an...

  1. 34 CFR 3.4 - Use of the seal.

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Use of the seal. 3.4 Section 3.4 Education Office of the Secretary, Department of Education OFFICIAL SEAL § 3.4 Use of the seal. (a) Use by any person or...) Requests by any person or organization outside of the Department for permission to use the Seal must...

  2. Mathematical justification of Kelvin-Voigt beam models by asymptotic methods

    Rodríguez-Arós, Á. D.; Viaño, J. M.

    2012-06-01

    The authors derive and justify two models for the bending-stretching of a viscoelastic rod by using the asymptotic expansion method. The material behaviour is modelled by using a general Kelvin-Voigt constitutive law.

  3. The Crossroads between the Galactic Disk and Interstellar Space, Ablaze in 3/4 keV Light

    Shelton, Robin L.

    2016-04-01

    The halo is the crossroads between the Galactic disk and intergalactic space. This region is inhabited by hot gas that has risen from the disk, gas heated in situ, and hot material that has fallen in from intergalactic space. Owing to high spectral resolution observations made by by XMM-Newton, Suzaku, and Chandra of the hot plasma's 3/4 keV emission and absorption, increasingly sophisticated and CPU intensive computer modeling, and an awareness that charge exchange can contaminate 3/4 keV observations, we are now better able to understand the hot halo gas than ever before.Spectral analyses indicate that the 3/4 keV emission comes from T ~ 2.2 million Kelvin gas. Although observations suggest that the gas may be convectively unstable and the spectra's temperature is similar to that predicted by recent sophisticated models of the galactic fountain, the observed emission measure is significantly brighter than that predicted by fountain models. This brightness disparity presents us with another type of crossroads: should we continue down the road of adding physics to already sophisticated modeling or should we seek out other sources? In this presentation, I will discuss the galactic fountain crossroads, note the latitudinal and longitudinal distribution of the hot halo gas, provide an update on charge exchange, and explain how shadowing observations have helped to fine tune our understanding of the hot gas.

  4. Experiments R285-3/4/5 (ILAS 3/4/5). Activity calculations

    In the irradiation experiments ILAS 3/4/5 a number of different austenitic stainless steel types and three types of vanadium samples for advanced nuclear systems will be irradiated at a temperature of 300 C up to dpa (displacements per atom) levels of 2.5 dpa for the steel samples and up to 6 dpa for the vanadium samples. In this report the results of the activity calculations of the sample holder material and of the different types of sample materials are presented. The activity of the holder material is calculated for the vertical average of the irradiation position. The activities of the sample materials are given for the vertical maximum of the irradiation position. A relation is given to convert these data to any vertical sample position. Also the changes in chemical composition of the different sample materials, due to nuclide transmutation, are given in this report. (orig.)

  5. Stabilization of nonhomogeneous beam by embedding patch of Kelvin-Voigt viscoelasticity%嵌有Kelvin-Voigt阻尼片的非均质梁的镇定

    陈叔平; 司守奎

    2003-01-01

    With the help of operator semigroup theory, the frequency domain method and the multiplier techniques wereapplied. When the Kelvin-Voigt damping was distributed locally on any subinterval of the region, the energy of the nonhomoge-neous Euler-Bernoulli beam was proved to decay uniformly exponentially.%借助于算子半群理论.应用频域方法和乘子技巧,证明了具有局部Kelvin-Voigt阻尼的非均质Euler-Bernoulli梁的能量是指数衰减的.

  6. Understanding the Atomic-Scale Contrast in Kelvin Probe Force Microscopy

    Nony, Laurent; Foster, Adam S.; Bocquet, Franck; Loppacher, Christian

    2009-01-01

    A numerical analysis of the origin of the atomic-scale contrast in Kelvin probe force microscopy is presented. Atomistic simulations of the tip-sample interaction force field have been combined with a noncontact atomic force microscope simulator including a Kelvin module. The implementation mimics recent experimental results on the (001) surface of a bulk alkali halide crystal for which simultaneous atomic-scale topographical and contact potential difference contrasts were reported. The local...

  7. Applying the Kelvin Probe to biological tissues: Theoretical and computational analyses

    Ahn, Andrew C; Gow, Brian J.; Martinsen, Ørjan G.; Zhao, Min; Grodzinsky, Alan J.; Baikie, Iain D.

    2012-01-01

    The Kelvin Probe measures surface electrical potential without making physical contact with the specimen. It relies on capacitive coupling between an oscillating metal tip that is normal to a specimen’s surface. Kelvin Probes have been increasingly used to study surface and electrical properties of metals and semiconductors and are capable of detecting material surface potentials with sub-millivolt resolution at a micrometer spatial scale. Its capability for measuring electrical potential wit...

  8. Determination of surface recombination velocities of organic monolayers on silicon through Kelvin probe

    Alderman, Nicholas; Adib Ibrahim, Mohd; Danos, Lefteris; Martin C. Grossel; Markvart, Tom

    2013-01-01

    We report the determination of the surface recombination velocity of electron-hole pairs for silicon samples passivated with organic monolayers using the Kelvin probe. The recombination velocity was determined from the surface photovoltage and incident photon flux. By scanning of the Kelvin probe tip over the sample, the change in surface recombination velocity can be measured allowing recombination lifetime mapping. Organic monolayers with different chain lengths and exhibiting various recom...

  9. KELVIN PROBE SELF-CALIBRATION MODE FOR SEMICONDUCTOR WAFERS PROPERTIES MONITORING

    R. I. Vorobey; O. K. Gusev; A. L. Zharin; A. N. Petlitsky; V. A. Pilipenko; A. S. Turtsevitch; Tyavlovsky, A. K.

    2015-01-01

    Improvement of repeatability and reliability of semiconductor wafers properties monitoring with a probe charge-sensitive methods is achieved by realization of Kelvin probe self-calibration mode using a wafer’s surface itself as a reference sample. Results of wafer surface scanning are visualized in the form of parameter distribution color map. A method of measurements based on Kelvin probe self-calibration mode is realized in a measurement installation for non-destructive non-contact monitori...

  10. Interaction and decay of Kelvin waves in the Gross-Pitaevskii model

    Proment, Davide; Barenghi, Carlo F.; Onorato, Miguel

    2013-01-01

    By solving numerically the governing Gross-Pitaevskii equation, we study the dynamics of Kelvin waves on a superfluid vortex. After determining the dispersion relation, we monitor the turbulent decay of Kelvin waves with energy initially concentrated at large length scales. At intermediate length scales, we find that the decay is consistent with scaling predictions of theoretical models. Finally we report the unexpected presence of large-length scale phonons in the system.

  11. A 10 Kelvin 3 Tesla Magnet for Space Flight ADR Systems

    Tuttle, Jim; Shirron, Peter; Canavan, Edgar; DiPirro, Michael; Riall, Sara; Pourrahimi, Shahin

    2003-01-01

    Many future space flight missions are expected to use adiabatic demagnetization refrigerators (ADRs) to reach detector operating temperatures well below one Kelvin. The goal is to operate each ADR with a mechanical cooler as its heat sink, thus avoiding the use of liquid cryogens. Although mechanical coolers are being developed to operate at temperatures of 6 Kelvin and below, there is a large efficiency cost associated with operating them at the bottom of their temperature range. For the multi-stage ADR system being developed at Goddard Space Flight Center, the goal is to operate with a 10 Kelvin mechanical cooler heat sink. With currently available paramagnetic materials, the highest temperature ADR stage in such a system will require a magnetic field of approximately three Tesla. Thus the goal is to develop a small, lightweight three Tesla superconducting magnet for operation at 10 Kelvin. It is important that this magnet have a low current/field ratio. Because traditional NbTi magnets do not operate safely above about six Kelvin, a magnet with a higher Tc is required. The primary focus has been on Nb3Sn magnets. Since standard Nb3Sn wire must be coated with thick insulation, wound on a magnet mandrel and then reacted, standard Nb,Sn magnets are quite heavy and require high currents Superconducting Systems developed a Nb3Sn wire which can be drawn down to small diameter, reacted, coated with thin insulation and then wound on a small diameter coil form. By using this smaller wire and operating closer to the wire s critical current, it should be possible to reduce the mass and operating current of 10 Kelvin magnets. Using this "react-then-wind" technology, Superconducting Systems has produced prototype 10 Kelvin magnets. This paper describes the development and testing of these magnets and discusses the outlook for including 10 Kelvin magnets on space-flight missions.

  12. Kelvin-Helmholtz Instabilities in Smoothed Particle Hydrodynamics

    Valcke, S.; de Rijcke, S.; Röediger, E.

    2011-07-01

    We have investigated whether Smoothed Particle Hydrodynamics (SPH), equipped with artificial conductivity, is able to capture the physics of density/energy discontinuities in the case of the so-called shearing layers test, a test for examining Kelvin-Helmholtz (KH) instabilities. We can trace back each failure of SPH to show KH rolls to two causes: i) shock waves travelling in the simulation box and ii) particle clumping, or more generally, particle noise. The probable cause of shock waves is the Local Mixing Instability (LMI), previously identified in the literature. Particle noise on the other hand is a problem because it introduces a large error in the SPH momentum equation. We show that setting up initial conditions with a suitably smoothed density gradient dramatically improves results. Particle clumping is easy to overcome, the most straightforward method being the use of a suitable smoothing kernel with non-zero first central derivative. We present results to that effect using a new smoothing kernel: the LInear Quartic (LIQ) kernel. Furthermore, we present new Artificial Conductivity signal velocities that lead to less diffusion. The effects of the shock waves and of particle disorder become less important as the time-scale of the physical problem (for the shearing layers problem: lower density contrast and higher Mach numbers) decreases. At the resolution of current galaxy formation simulations mixing is probably not important. However, mixing could become crucial for next-generation simulations.

  13. Kelvin probe studies of cesium telluride photocathode for AWA photoinjector

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (≈50nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating. -- Highlights: ► The correlation between Quantum Efficiency (QE) and work function. ► How QE and work function evolve together. ► Rejuvenation of the photocathode via heating and the effect on work function. ► The effects on the work function due to exposure to UV light

  14. Scanning Kelvin probe study of metal/polymer interfaces

    A scanning Kelvin probe was used to study the metal/polymer contacts for models of epoxy, alkyd and polyaniline coatings. It was shown that the potential drop across the electrical double layer of oriented ionic dipoles at the metal/polymer interface contributes a major part of the measured Volta potentials. The Broensted acid/base interactions are responsible for the charge separation and the creation of a double electric layer. Polyaniline (an electron-conducting polymer) accepts electrons from the metal to its own Fermi level, thus producing a Schottky barrier. In this case, the Volta potential of the contact does not depend on the metal, but follows the polyaniline flat band potential. Exposure in water vapor neutralizes the potential drop at the interface due to water dipole orientation in a direction opposite to the intrinsic electric field. The kinetics of potential change during water uptake follow Fick's and Nernst's equations. After hydrolysis of the interfacial bonds, activation of the metal surface can takes place

  15. Kelvin probe studies of cesium telluride photocathode for AWA photoinjector

    Wisniewski, Eric E., E-mail: ewisniew@anl.gov [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Velazquez, Daniel [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Yusof, Zikri, E-mail: zyusof@hawk.iit.edu [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Spentzouris, Linda; Terry, Jeff [Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Sarkar, Tapash J. [Rice University, 6100 Main, Houston, TX 77005 (United States); Harkay, Katherine [Accelerator Science Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States)

    2013-05-21

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (≈50nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating. -- Highlights: ► The correlation between Quantum Efficiency (QE) and work function. ► How QE and work function evolve together. ► Rejuvenation of the photocathode via heating and the effect on work function. ► The effects on the work function due to exposure to UV light.

  16. Kelvin--Helmholtz instability in solar H-alpha surges

    Zhelyazkov, I; Chandra, R; Srivastava, A K; Mishonov, T

    2015-01-01

    We study the evolutionary conditions for Kelvin--Helmholtz (KH) instability in a H-alpha solar surge observed in NOAA AR 8227 on 1998 May 30. The jet with speeds in the range of 45--50 km/s, width of 7 Mm, and electron number density of 3.83 x 10^{10} cm^{-3} is assumed to be confined in a twisted magnetic flux tube embedded in a magnetic field of 7 G. The temperature of the plasma flow is of the order of 10^5 K while that of its environment is taken to be 2 x 10^6 K. The electron number density of surrounding magnetized plasma has a typical for the TR/lower corona region value of 2 x 10^{9} cm^{-3}. Under these conditions, the Alfven speed inside the jet is equal to 78.3 km/s. We model the surge as a moving magnetic flux tube for two magnetic field configurations: (i) a twisted tube surrounded by plasma with homogeneous background magnetic field, and (ii) a twisted tube which environment is plasma with also twisted magnetic field. The magnetic field twist in given region is characterized by the ratio of azim...

  17. KELVIN-HELMHOLTZ INSTABILITY OF A CORONAL STREAMER

    Shear-flow-driven instability can play an important role in energy transfer processes in coronal plasma. We present for the first time the observation of a kink-like oscillation of a streamer that is probably caused by the streaming kink-mode Kelvin-Helmholtz instability (KHI). The wave-like behavior of the streamer was observed by the Large Angle and Spectrometric Coronagraph Experiment C2 and C3 on board the SOlar and Heliospheric Observatory. The observed wave had a period of about 70-80 minutes, and its wavelength increased from 2 R☉ to 3 R☉ in about 1.5 hr. The phase speeds of its crests and troughs decreased from 406 ± 20 to 356 ± 31 km s–1 during the event. Within the same heliocentric range, the wave amplitude also appeared to increase with time. We attribute the phenomena to the MHD KHI, which occurs at a neutral sheet in a fluid wake. The free energy driving the instability is supplied by the sheared flow and sheared magnetic field across the streamer plane. The plasma properties of the local environment of the streamer were estimated from the phase speed and instability threshold criteria

  18. Kelvin probe force and scanning capacitance microscopy on MOS structures

    Baumgart, Christine; Helm, Manfred; Schmidt, Heidemarie [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, Dresden (Germany); Jaensch, Stefan [ElKiDo, Skjern (Denmark)

    2009-07-01

    As the size of semiconductor devices is decreasing permanently, new techniques are required to probe their dopant profile reliably on a nanometer scale. Kelvin probe force microscopy (KPFM) and scanning capacitance microscopy (SCM) are the most promising techniques for this demand. KPFM (LevelAFM from Anfatec) enables the detection of the contact potential difference (CPD) between tip and sample and SCM (DI3100 from Veeco Instruments) probes the capacitance of the metal oxide structures formed in contact. In order to demonstrate the complementary information obtained by KPFM and SCM measurements, we used the pn junction in a static random access memory integrated circuit device where the n-well with a donor concentration of 2.10{sup 17} cm{sup -3} has been fabricated by implanting the p-epi with a nominal acceptor concentration of 2.10{sup 16} cm{sup -3} with P{sup +} ions of energy 900 keV and a fluence of 1.7.10{sup 13} cm{sup -2}. As expected, KPFM yields a smooth variation of the CPD between the p-epi and the n-well amounting to 230 meV. SCM clearly shows the boxlike doping profile of this pn junction. The CPD variation can be modelled by assuming a partially compensated donor concentration in the n-well.

  19. MESSENGER observations of multiscale Kelvin-Helmholtz vortices at Mercury

    Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Sundberg, Torbjörn; Boardsen, Scott A.; Anderson, Brian J.; Korth, Haje; Solomon, Sean C.

    2015-06-01

    Observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in Mercury's magnetotail demonstrate for the first time that Na+ ions exert a dynamic influence on Mercury's magnetospheric system. Na+ ions are shown to contribute up to ~30% of the ion thermal pressure required to achieve pressure balance in the premidnight plasma sheet. High concentrations of planetary ions should lead to Na+ dominance of the plasma mass density in these regions. On orbits with northward-oriented interplanetary magnetic field and high (i.e., >1 cm-3) Na+ concentrations, MESSENGER has often recorded magnetic field fluctuations near the Na+ gyrofrequency associated with the Kelvin-Helmholtz (K-H) instability. These nightside K-H vortices are characteristically different from those observed on Mercury's dayside that have a nearly constant wave frequency of ~0.025 Hz. Collectively, these observations suggest that large spatial gradients in the hot planetary ion population at Mercury may result in a transition from a fluid description to a kinetic description of vortex formation across the dusk terminator, providing the first set of truly multiscale observations of the K-H instability at any of the diverse magnetospheric environments explored in the solar system.

  20. Kelvin Notation for Stabilizing Elastic-Constant Inversion Notation Kelvin pour stabiliser l'inversion de constantes élastiques

    Dellinger J.

    2006-12-01

    Full Text Available Inverting a set of core-sample traveltime measurements for a complete set of 21 elastic constants is a difficult problem. If the 21 elastic constants are directly used as the inversion parameters, a few bad measurements or an unfortunate starting guess may result in the inversion converging to a physically impossible solution . Even given perfect data, multiple solutions may exist that predict the observed traveltimes equally well. We desire the inversion algorithm to converge not just to a physically possible solution, but to the best(i. e. most physically likely solution of all those allowed. We present a new parameterization that attempts to solve these difficulties. The search space is limited to physically realizable media by making use of the Kelvin eigenstiffness-eigentensor representation of the 6 x 6 elastic stiffness matrix. Instead of 21 stiffnesses, there are 6 eigenstiffness parametersand 15 rotational parameters . The rotational parameters are defined using a Lie-algebra representation that avoids the artificial degeneracies and coordinate-system bias that can occur with standard polar representations. For any choice of these 21 real parameters, the corresponding stiffness matrix is guaranteed to be physically realizable. Furthermore, all physically realizable matrices can be represented in this way. This new parameterization still leaves considerable latitude as to which linear combinations of the Kelvin parameters to use, and how they should be ordered. We demonstrate that by careful choice and ordering of the parameters, the inversion can be relaxedfrom higher to lower symmetry simply by adding a few more parameters at a time. By starting from isotropy and relaxing to the general result in stages (isotropy, transverse isotropy, orthorhombic, general, we expect that the method should find the solution that is closest to isotropy of all those that fit the data. L'inversion d'un ensemble de mesures du temps de parcours d

  1. Complexing 7,3',4'-tryoxiflavonol with cell phosphatidylcholine

    Nusratullin V. M.; Fahretdinova E. R.; Nasibullin R. S.; Galeeva R. I.

    2010-01-01

    Aim. To investigate the complex formation of 7,3',4'-try-oxyflavonol of flavonoids group with cellular phosphatidylcholine. Methods. Semi-empirical quantum chemistry, spectroscopy NMR. Results. The changes in conformational status of 7,3',4'-tryoxy- flavonol at complex formation have been shown. Conclusions. The conformational changes in phosphatidylcholine take place under the 7,3',4'-tryoxyflavonol/phosphatidylcholine complex formation.

  2. 基于分数阶微积分的Kelvin-Voigt流变模型%The Kelvin-Voigt Rheological Model Based on Fractional Calculus

    郭佳奇; 乔春生; 徐冲; 黄山秀

    2009-01-01

    为研究岩土材料的应力、应变和时间的关系,基于分数阶微积分理论,定义含分数阶导数的力学元件(FC元件),推导FC元件的蠕变柔量和松弛模量.与牛顿体元件相比,FC元件能更好地反映流变问题的非线性渐变过程.借鉴经典元件组合模型的建模思路,用FC元件取代整数阶微积分Kelvin-Voigt流变模型中的牛顿体元件,形成基于分数阶微积分的Kelvin-Voigt流变模型.应用离散化求Laplace逆变换的方法以及H-Fox函数,得出分数阶微积分Kelvin-Voigt流变模型的本构方程、蠕变方程、松弛方程、蠕变柔量及松弛模量的解析表达式.采用整数阶微积分Kelvin-Voigt流变模型、整数阶5参数开尔文流变模型和分数阶微积分Kelvin-Voigt流变模型对试验数据拟合的结果表明,分数阶微积分Kelvin-Voigt流变模型不但拟合精度高,能够克服整数阶微积分Kelvin-Voigt流变模型在蠕变初期及蠕变曲线拐点附近与试验数据不能很好吻合的弊端,而且能够在保证拟合精度的条件下,减少本构模型中的参数.

  3. Analysis and simulation of the operation of a Kelvin probe

    Experiments that measure extremely small gravitational forces are often hampered by the presence of non-gravitational forces that can neither be calculated nor separately measured. Among these spurious forces is electrostatic attraction between a test mass and its surroundings due to the presence of spatially varying surface potential known as the ‘patch effect’. In order to make surfaces with small surface potential variation, it is necessary to be able to measure it. A Kelvin probe (KP) measures contact potential difference (CPD), using the time-varying capacitance between the sample and a vibrating tip that is biased with a backing potential. Assuming that the tip remains constant, this measures the sample's surface potential variation. We examine the operation of the KP from the perspective of parameter estimation in the presence of noise. We show that, when the CPD is estimated from measurements at two separate backing potentials, the standard deviation of the optimal estimate depends on the total observing time. Further, the observing time may be unevenly divided between the two backing potentials, provided the values of those potentials are correspondingly set. We simulate a two-stage KP data analysis, including a sub-optimal estimator with advantages for real-time operation. Based on the real-time version, we present a novel approach to stabilizing the average distance of the tip from the sample. We also present the results of a series of covariance analyses that validate and bound the applicability of the suboptimal estimator, make a comparison with the results of an optimal estimator and guide the user. We discuss the application of the KP to the Laser Interferometer Space Antenna and to a test of the weak equivalence principle. (paper)

  4. Kelvin probe force microscopy in liquid using electrochemical force microscopy

    Liam Collins

    2015-01-01

    Full Text Available Conventional closed loop-Kelvin probe force microscopy (KPFM has emerged as a powerful technique for probing electric and transport phenomena at the solid–gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe–sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present. Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl and ionically-inactive (non-polar decane liquids by electrochemical force microscopy (EcFM, a multidimensional (i.e., bias- and time-resolved spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids, KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions. EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid–liquid interface.

  5. Kelvin probe force microscopy in liquid using electrochemical force microscopy.

    Collins, Liam; Jesse, Stephen; Kilpatrick, Jason I; Tselev, Alexander; Okatan, M Baris; Kalinin, Sergei V; Rodriguez, Brian J

    2015-01-01

    Conventional closed loop-Kelvin probe force microscopy (KPFM) has emerged as a powerful technique for probing electric and transport phenomena at the solid-gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid-liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe-sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present). Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl) and ionically-inactive (non-polar decane) liquids by electrochemical force microscopy (EcFM), a multidimensional (i.e., bias- and time-resolved) spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids), KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD) values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions). EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid-liquid interface. PMID:25671164

  6. 机织建筑膜材料的广义Kelvin-Voigt蠕变模型%General Kelvin-Voigt creep model of fabric architectural membrane

    张伍连; 丁辛; 杨旭东

    2011-01-01

    The uniaxial tension creep tests of PVC coating membrane with plain architectural are experimented along the warp and weft direction at five different stresses. The general Kelvin -Voigt creep formulas are given. The experimental data are studied through the use of these creep formulas with three, five and seven parameters. The result shows: As the number of the parameters grew, prediction complexity is increased with grade. When the parameter is seven, the coefficients of determination are over 99.9% at different stresses. This shows that the general Kelvin-Voigt creep model with seven parameters can well predict creeping behavior of fabric architectural membrane.%对平纹组织为基布的PVC涂层膜材料进行了经纬两方向各自5种不同应力条件下的单轴向拉伸蠕变试验,给出了广义Kelvin-Voigt模型的具体蠕变方程,并利用广义三参数、五参数与七参数Kelvin-Voigt的蠕变方程对实验数据进行了分析.结果显示:随着模型参数个数的增加,预测效果也呈现出递增趋势;当模型参数为7个时,各应力拟合的确定系数均在99.9%以上,表明七参数广义Kelvin-Voigt蠕变模型已可以很好地预测膜材料的蠕变特性.

  7. Anthracen-9-ylmethylene-(3,4-dimethylisoxazol-5-ylamine

    Abdullah M. Asiri

    2011-09-01

    Full Text Available The title compound, anthracen-9-ylmethylene-(3,4-dimethylisoxazol-5-ylamine (3, was synthesized in high yield by reaction of anthracene-9-carbaldehyde and 5-amino-3,4-dimethyl­isoxazole in ethanol. The structure of this new compound was confirmed by elemental analysis, IR, 1H NMR, 13C NMR and GC-MS spectral analysis.

  8. Gyroresonance of Kelvin-Helmholtz vortices with Na+ in Mercury's magnetotail

    Gingell, Peter; Sundberg, Torbjorn; Burgess, David

    2015-04-01

    Observations of Mercury's plasma environment by the MESSENGER spacecraft have revealed that the planet hosts a strongly asymmetric magnetosphere as a result of an off-axis internal magnetic field, and significant finite Larmor radius effects at the boundary layer between magnetospheric and solar wind plasma environments. Linear analysis and global hybrid simulations suggest asymmetric growth of the Kelvin-Helmholtz instability between the dusk and dawn flanks of the magnetopause, and indeed Kelvin-Helmholtz waves have been observed almost exclusively at the dusk flank during northward IMF. A previous study has shown that Kelvin-Helmholtz waves at the dusk flank are observed predominantly at scales associated with the gyration of hot sodium ions - a population originating at the dayside exosphere, and distributed preferentially at the dusk flank. This suggests that a resonance may occur between sodium ion gyration and Kelvin-Helmholtz vortex growth. Using two- and three-dimensional local hybrid simulations of dusk and dawn boundaries, with varying magnetospheric sodium ion density, we have reproduced the main observational features: we see a strong peak in the Kelvin-Helmholtz wave spectra at sodium gyro scales at the dusk boundaries, and suppression of the growth of vortices at the dawn boundaries. We examine the mechanism of the resonant interaction between counter-gyrating sodium ions and K-H vortices using test particle simulations. Finally, we discuss the effect of the sodium ion population on cross-boundary particle transport.

  9. 3,4-Methylenedioxymethamphetamine facilitates fear extinction learning.

    Young, M B; Andero, R; Ressler, K J; Howell, L L

    2015-01-01

    Acutely administered 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') has been proposed to have long-term positive effects on post-traumatic stress disorder (PTSD) symptoms when combined with psychotherapy. No preclinical data support a mechanistic basis for these claims. Given the persistent nature of psychotherapeutic gains facilitated by MDMA, we hypothesized that MDMA improves fear extinction learning, a key process in exposure-based therapies for PTSD. In these experiments, mice were first exposed to cued fear conditioning and treated with drug vehicle or MDMA before extinction training 2 days later. MDMA was administered systemically and also directly targeted to brain structures known to contribute to extinction. In addition to behavioral measures of extinction, changes in mRNA levels of brain-derived neurotrophic factor (Bdnf) and Fos were measured after MDMA treatment and extinction. MDMA (7.8 mg kg(-1)) persistently and robustly enhanced long-term extinction when administered before extinction training. MDMA increased the expression of Fos in the amygdala and medial prefrontal cortex (mPFC), whereas increases in Bdnf expression were observed only in the amygdala after extinction training. Extinction enhancements were recapitulated when MDMA (1 μg) was infused directly into the basolateral complex of the amygdala (BLA), and enhancement was abolished when BDNF signaling was inhibited before extinction. These findings suggest that MDMA enhances fear memory extinction through a BDNF-dependent mechanism, and that MDMA may be a useful adjunct to exposure-based therapies for PTSD and other anxiety disorders characterized by altered fear learning. PMID:26371762

  10. Impact of atmospheric convectively coupled equatorial Kelvin waves on upper ocean variability

    Baranowski, Dariusz B.; Flatau, Maria K.; Flatau, Piotr J.; Matthews, Adrian J.

    2016-03-01

    Convectively coupled Kelvin waves (CCKWs) are atmospheric weather systems that propagate eastward along the equatorial wave guide with phase speeds between 11 and 14 m s-1. They are an important constituent of the convective envelope of the Madden-Julian oscillation (MJO), for which ocean-atmosphere interactions play a vital role. Hence, ocean-atmosphere interactions within CCKWs may be important for MJO development and prediction and for tropical climate, in general. Although the atmospheric structure of CCKWs has been well studied, their impact on the underlying ocean is unknown. In this paper, the ocean-atmosphere interactions in CCKWs are investigated by a case study from November 2011 during the CINDY/DYNAMO field experiment, using in situ oceanographic measurements from an ocean glider. The analysis is then extended to a 15 year period using precipitation data from the Tropical Rainfall Measuring Mission and surface fluxes from the TropFlux analysis. A methodology is developed to calculate trajectories of CCKWs. CCKW events are strongly controlled by the MJO, with twice as many CCKWs observed during the convectively active phase of the MJO compared to the suppressed phase. Coherent ocean-atmosphere interaction is observed during the passage of a CCKW, which lasts approximately 4 days at any given longitude. Surface wind speed and latent heat flux are enhanced, leading to a transient suppression of the diurnal cycle of sea surface temperature (SST) and a sustained decrease in bulk SST of 0.1°C. Given that a typical composite mean MJO SST anomaly is of the order of 0.3°C, and more than one CCKW can occur during the active phase of a single MJO event, the oceanographic impact of CCKWs is of major importance to the MJO cycle.

  11. Force gradient sensitive detection in lift-mode Kelvin probe force microscopy

    We demonstrate frequency modulation Kelvin probe force microscopy operated in lift-mode under ambient conditions. Frequency modulation detection is sensitive to force gradients rather than forces as in the commonly used amplitude modulation technique. As a result there is less influence from electric fields originating from the tip's cone and cantilever, and the recorded surface potential does not suffer from the large lateral averaging observed in amplitude modulated Kelvin probe force microscopy. The frequency modulation technique further shows a reduced dependence on the lift-height and the frequency shift can be used to map the second order derivative of the tip-sample capacitance which gives high resolution material contrast of dielectric sample properties. The sequential nature of the lift-mode technique overcomes various problems of single-scan techniques, where crosstalk between the Kelvin probe and topography feedbacks often impair the correct interpretation of the recorded data in terms of quantitative electric surface potentials.

  12. Determination of Contact Potential Difference by the Kelvin Probe (Part I I. Basic Principles of Measurements

    Vilitis O.

    2016-04-01

    Full Text Available Determination of electric potential difference using the Kelvin probe, i.e. vibrating capacitor technique, is one of the most sensitive measuring procedures in surface physics. Periodic modulation of distance between electrodes leads to changes in capacitance, thereby causing current to flow through the external circuit. The procedure of contactless, non-destructive determination of contact potential difference between an electrically conductive vibrating reference electrode and an electrically conductive sample is based on precise control measurement of Kelvin current flowing through a capacitor. The present research is devoted to creation of a new low-cost miniaturised measurement system to determine potential difference in real time and at high measurement resolution. Furthermore, using the electrode of a reference probe, the Kelvin method leads to both the indirect measurement of an electronic work function, or a contact potential of sample, and of a surface potential for insulator type samples.

  13. A validated non-linear Kelvin-Helmholtz benchmark for numerical hydrodynamics

    Lecoanet, D.; McCourt, M.; Quataert, E.; Burns, K. J.; Vasil, G. M.; Oishi, J. S.; Brown, B. P.; Stone, J. M.; O'Leary, R. M.

    2016-02-01

    The non-linear evolution of the Kelvin-Helmholtz instability is a popular test for code verification. To date, most Kelvin-Helmholtz problems discussed in the literature are ill-posed: they do not converge to any single solution with increasing resolution. This precludes comparisons among different codes and severely limits the utility of the Kelvin-Helmholtz instability as a test problem. The lack of a reference solution has led various authors to assert the accuracy of their simulations based on ad hoc proxies, e.g. the existence of small-scale structures. This paper proposes well-posed two-dimensional Kelvin-Helmholtz problems with smooth initial conditions and explicit diffusion. We show that in many cases numerical errors/noise can seed spurious small-scale structure in Kelvin-Helmholtz problems. We demonstrate convergence to a reference solution using both ATHENA, a Godunov code, and DEDALUS, a pseudo-spectral code. Problems with constant initial density throughout the domain are relatively straightforward for both codes. However, problems with an initial density jump (which are the norm in astrophysical systems) exhibit rich behaviour and are more computationally challenging. In the latter case, ATHENA simulations are prone to an instability of the inner rolled-up vortex; this instability is seeded by grid-scale errors introduced by the algorithm, and disappears as resolution increases. Both ATHENA and DEDALUS exhibit late-time chaos. Inviscid simulations are riddled with extremely vigorous secondary instabilities which induce more mixing than simulations with explicit diffusion. Our results highlight the importance of running well-posed test problems with demonstrated convergence to a reference solution. To facilitate future comparisons, we include as supplementary material the resolved, converged solutions to the Kelvin-Helmholtz problems in this paper in machine-readable form.

  14. Pump-probe Kelvin-probe force microscopy: Principle of operation and resolution limits

    Knowledge on surface potential dynamics is crucial for understanding the performance of modern-type nanoscale devices. We describe an electrical pump-probe approach in Kelvin-probe force microscopy that enables a quantitative measurement of dynamic surface potentials at nanosecond-time and nanometer-length scales. Also, we investigate the performance of pump-probe Kelvin-probe force microscopy with respect to the relevant experimental parameters. We exemplify a measurement on an organic field effect transistor that verifies the undisturbed functionality of our pump-probe approach in terms of simultaneous and quantitative mapping of topographic and electronic information at a high lateral and temporal resolution

  15. The work function of doped polyaniline nanoparticles observed by Kelvin probe force microscopy

    The work function of polyaniline nanoparticles in the emeraldine base state was determined by Kelvin probe force microscopy to be ∼270 meV higher than that of similar nanoparticles in the emeraldine salt state. Normal tapping mode atomic force microscopy could not be used to distinguish between the particles due to their similar morphologies and sizes. Moreover, other potential measurement systems, such as using zeta potentials, were not suitable for the measurement of surface charges of doped nanoparticles due to their encapsulation by interfering chemical groups. Kelvin probe force microscopy can be used to overcome these limitations and unambiguously distinguish between the bare and doped polyaniline nanoparticles. (paper)

  16. KELVIN PROBE SELF-CALIBRATION MODE FOR SEMICONDUCTOR WAFERS PROPERTIES MONITORING

    R. I. Vorobey

    2015-03-01

    Full Text Available Improvement of repeatability and reliability of semiconductor wafers properties monitoring with a probe charge-sensitive methods is achieved by realization of Kelvin probe self-calibration mode using a wafer’s surface itself as a reference sample. Results of wafer surface scanning are visualized in the form of parameter distribution color map. A method of measurements based on Kelvin probe self-calibration mode is realized in a measurement installation for non-destructive non-contact monitoring of semiconductor wafer defects. Method can be used to define defects’ physical properties including minority carrier diffusion length and lifetime, trapped charge density and energy distribution etc.

  17. Pump-probe Kelvin-probe force microscopy: Principle of operation and resolution limits

    Murawski, J.; Graupner, T.; Milde, P., E-mail: peter.milde@tu-dresden.de; Raupach, R.; Zerweck-Trogisch, U.; Eng, L. M. [Institute of Applied Physics, Technische Universität Dresden, D-01062 Dresden (Germany)

    2015-10-21

    Knowledge on surface potential dynamics is crucial for understanding the performance of modern-type nanoscale devices. We describe an electrical pump-probe approach in Kelvin-probe force microscopy that enables a quantitative measurement of dynamic surface potentials at nanosecond-time and nanometer-length scales. Also, we investigate the performance of pump-probe Kelvin-probe force microscopy with respect to the relevant experimental parameters. We exemplify a measurement on an organic field effect transistor that verifies the undisturbed functionality of our pump-probe approach in terms of simultaneous and quantitative mapping of topographic and electronic information at a high lateral and temporal resolution.

  18. Conductimetric immunosensor based on poly(3,4-ethylenedioxythiophene).

    Kanungo, Mandakini; Srivastava, Divesh N; Kumar, Anil; Contractor, A Q

    2002-04-01

    A conductimetric reagentless immunosensor using the biospecific binding pair of goat antirabbit IgG and rabbit IgG has been designed and fabricated using poly (3,4-ethylenedioxythiophene) as the immobilization matrix-cumtransducer. PMID:12119672

  19. The influence of microstructure on the corrosion behaviour of AZ91D studied by scanning Kelvin probe force microscopy and scanning Kelvin probe

    β-Mg17Al12, η-Al8Mn5 and an α-magnesium phase have been synthesized from pure components by controlled solidification procedures. These phases have been studied using different electrochemical techniques including the scanning Kelvin probe (SKP). From the results, it was possible to determine the nobility and the rate of the cathodic reaction of the different phases. Measurements have also been made on an AZ91D Mg-alloy using scanning Kelvin probe force microscopy (SKPFM) and field emission gun scanning electron microscopy (FEG-SEM). The results show that the Volta potentials measured with the scanning Kelvin probe (SKP) on bulk intermetallics are comparable with those recorded with the SKPFM on the AZ91D alloy. It is shown that SKPFM provides information on the local nobility of the different intermetallic particles and phases on the submicron scale. Both the η-Al8Mn5 phase and the β-Mg17Al12 phase in AZ91D showed a more noble potential than the α-magnesium phase. It is also shown that the aluminium-rich coring along the grain boundaries results in measurable changes in the Volta potential. Finally, the role of the β-Mg17Al12 phase and the η-Al8Mn5 phase in the corrosion behaviour of AZ91D is discussed in term of local nobility, surface coverage of the cathode and the cathodic activity of the different phases

  20. The subchronic effects of 3,4-methylendioxymethamphetamine on oxidative stress in rat brain

    Simić Ivan

    2014-01-01

    Full Text Available The aim of the present study was to evaluate the subchronic effects of 3,4-methylenedioxymethamphetamine on several oxidative stress markers: index of lipid peroxidation (ILP, superoxide dismutase (SOD activity, superoxide radical (O2.- levels, and reduced glutathione (GSH levels in the frontal cortex, striatum and hippocampus of the rat. The study included 64 male Wistar rats (200-250g. The animals were treated per os with of 5, 10, or 20 mg/kg of 3,4-methylenedioxymethamphetamine (MDMA every day for 15 days. The subchronic administration of MDMA resulted in an increase in ILP, SOD and O2.-, and a decrease in GSH, from which we conclude that oxidative stress was induced in rat brain.

  1. Preliminary evidence of motor impairment among polysubstance 3,4-methylenedioxymethamphetamine users with intact neuropsychological functioning

    Bousman, Chad A.; Cherner, Mariana; Emory, Kristen T; BARRON, DANIEL; Grebenstein, Patricia; Atkinson, J. Hampton; Heaton, Robert K.; Grant, Igor

    2010-01-01

    Neuropsychological disturbances have been reported in association with use of the recreational drug “ecstasy,” or 3,4-methylenedioxymethamphetamine (MDMA), but findings have been inconsistent. We performed comprehensive neuropsychological testing examining seven ability domains in 21 MDMA users (MDMA+) and 21 matched control participants (MDMA−). Among MDMA+ participants, median [interquartile range] lifetime MDMA use was 186 [111, 516] doses, with 120 [35–365] days of abstinence. There were ...

  2. Comment on ``Are there internal Kelvin waves in Lake Tanganyika?'' by Jaya Naithani and Eric Deleersnijder

    Antenucci, Jason P.

    2005-11-01

    Recent numerical modelling efforts have demonstrated the presence of Kelvin waves in Lake Tanganyika (Naithani and Deleersnijder, 2004), however it is claimed that these waves should not appear according to classical scaling arguments. Based on existing classical scaling arguments, supported by laboratory and field investigations, I will show why they can, and apparently do, appear in Lake Tanganyika.

  3. Characterization of interfacial strength of dissimilar metallic joints using a scanning Kelvin probe

    It is very important to understand the interfacial behavior for effective evaluation of welding quality. This letter reports a simple nondestructive characterization method of the interfacial strength of dissimilar metallic joints. Using a scanning Kelvin probe, the electron work function of Cu–steel joints was measured and a strong correlation between the electron work function and the interfacial tensile strength was found.

  4. Kelvin-Voigt均匀黏弹性介质中传播的地震波

    苑春方; 彭苏萍; 张中杰; 刘振宽

    2005-01-01

    研究了在小扰动的情况下, 地震波在Kelvin-Voigt均匀黏弹性介质中传播时的瞬态响应以及对应的三阶偏微分方程的解析解. 获得了在脉冲震源条件下Kelvin-Voigt均匀黏弹性三阶波动方程的平面波解. 运用脉冲叠加原理, 获得了在任意震源条件下Kelvin-Voigt均匀黏弹性三阶波动方程的平面波解. 讨论了地震波在Kelvin-Voigt均匀黏弹性介质中的传播速度和衰减, 推导出了地震波的衰减系数和传播速度与介质的密度、弹性模量和黏滞系数之间的精确关系. 这些结果能够用于地震勘探中黏弹性岩性参数的反演.

  5. Seismic wave propagating in Kelvin-Voigt homogeneous visco-elastic media

    2006-01-01

    This paper studies, under a small disturbance, the responses of seismic transient wave in the visco-elastic media and the analytic solution of the corresponding third-order partial differential equation. A plane wave solution of Kelvin-Voigt homogeneous visco-elastic third-order partial differential equation with a pulse source is obtained. By the principle of pulse stacking of particle vibration, the result is extended to the solution of Kelvin-Voigt homogeneous visco-elastic third-order partial differential equation with any source. The velocities of seismic wave propagating and the attenuation of seismic wave in Kelvin-Voigt homogeneous visco-elastic media are discussed. The velocities of seismic wave propagating and the coefficient of attenuation of seismic wave in Kelvin-Voigt homogeneous visco-elastic media are derived, expressed as functions of density of the media, elastic modulus and visco-elastic coefficient. These results can be applied in inversing lithology parameters in geophysical prospecting.

  6. EIGEN THEORY OF VISCOELASTIC DYNAMICS BASED ON THE KELVIN-VOIGT MODEL

    郭少华

    2004-01-01

    Using the eigen theory of solid mechanics, the eigen properties of anisotropic viscoelastic bodies with Kelvin-Voigt model were studied, and the generalized Stokes equation of anisotropic viscoelastic dynamics was obtained, which gives the threedimensional pattern of viscoelastical waves. The laws of viscoelastical waves of different anisotropical bodies were discussed. Several new conclusiones are given.

  7. Exponential stability of an elastic string with local Kelvin-Voigt damping

    Zhang, Qiong

    2010-12-01

    This paper is devoted to analyzing an elastic string with local Kelvin-Voigt damping. We prove the exponential stability of the system when the material coefficient function near the interface is smooth enough. Our method is based on the frequency method and semigroup theory.

  8. 169 kelvin cryogenic microcooler empoying a condenser, evaporator, flow restriction and counterflow heat exchangers

    Burger, Johannes; Holland, Harry; Berenschot, Erwin; Seppenwolde, Jan-Henry; Brake, ter Marcel; Gardeniers, Han; Elwenspoek, Miko

    2001-01-01

    This paper presents the first cryogenic micromachined cooler that is suitable to cool from ambient temperature to 169 kelvin and below. The cooler operates with the vapor compression cycle. It consists of a silicon micromachined condenser, a flow restriction/evaporator and two miniature glass-tube c

  9. Reproductive solutions for the g-Navier-Stokes and g-Kelvin-Voight equations

    Luis Friz

    2016-01-01

    Full Text Available This article presents the existence of reproductive solutions of g-Navier-Stokes and g-Kelvin-Voight equations. In this way, for weak solutions, we reach basically the same result as for classic Navier-Stokes equations.

  10. Extension of SGTE data for pure elements to zero Kelvin temperature - A case study

    Vřešťál, Jan; Štrof, J.; Pavlů, Jana

    2012-01-01

    Roč. 37, JUN (2012), s. 37-48. ISSN 0364-5916 R&D Projects: GA ČR(CZ) GAP108/10/1908 Institutional support: RVO:68081723 Keywords : Gibbs energy * Pure elements * Zero Kelvin * SGTE data * Heat capacity Subject RIV: BJ - Thermodynamics Impact factor: 1.433, year: 2012

  11. Vertical propagation of baroclinic Kelvin waves along the west coast of India

    Nethery, D.; Shankar, D.

    -1 Vertical propagation of baroclinic Kelvin waves along the west coast of India DNethery1,2,asteriskmath and D Shankar1 1National Institute of Oceanography, Goa 403 004, India. 2Ecole Normale Sup?erieure, Paris, France. asteriskmathe-mail: daniel...

  12. Evaluation of Bcl-2 Family Gene Expression in Hippocampus of 3, 4-methylenedioxymethamphetamine Treated Rats

    Hamed Hashemi-Nasl; Mohammad Taghi Joghataei; Alireza Samzadeh-Kermani; Seyed Behnamedin Jameie; Mansoure Soleimani; Ali Samadikuchaksaraei; Mohammad Hassan Farhadi; Kazem Mousavizadeh; Sara Soleimani Asl; Mehdi Mehdizadeh

    2012-01-01

    Objective: 3,4-methylenedioxymethamphetamine (MDMA) is an illicit, recreational drug that causes cellular death and neurotoxicity. This study evaluates the effects of different doses of MDMA on the expression of apoptosis–related proteins and genes in the hippocampus of adult rats. Materials and Methods: In this expremental study,a total of 20 male Sprague Dawley rats (200-250 g ) were treated with MDMA (0, 5, 10, 20 mg/kg i.p. twice daily) for 7 days. Seven days after the last administration...

  13. Kelvin-Helmholtz instability at the magnetotail boundary: MHD simulation and comparison with Geotail observations

    Otto, A.; Fairfield, D. H.

    2000-09-01

    On March 24, 1995, the Geotail spacecraft observed large fluctuations of the magnetic field and plasma properties in the low-latitude boundary layer about 15 RE tailward of the dusk meridian. Although the magnetospheric and magnetosheath magnetic fields were strongly northward, the Bz component showed strong short-duration fluctuations in which Bz could even reach negative values. We have used two-dimensional magnetohydrodynamic simulations with magnetospheric and magnetosheath input parameters specifically chosen for this Geotail event to identify the processes which cause the observed boundary properties. It is shown that these fluctuations can be explained by the Kelvin-Helmholtz instability if the k vector of the instability has a component along the magnetic field direction. The simulation results show many of the characteristic properties of the Geotail observations. In particular, the quasi-periodic strong fluctuations are well explained by satellite crossings through the Kelvin-Helmholtz vortices. It is illustrated how the interior structure of the Kelvin-Helmholtz vortices leads to the rapid fluctuations in the Geotail observations. Our results suggest an average Kelvin-Helmholtz wavelength of about 5 RE, with a vortex size of close to 2 RE for an average repetition time of 2.5 min. The growth time for these waves implies a source region of about 10-16 RE upstream from the location of the Geotail spacecraft (i.e., near the dusk meridian). The results also indicate a considerable mass transport of magnetosheath material into the magnetosphere by magnetic reconnection in the Kelvin-Helmholtz vortices.

  14. Squaroglitter: A 3,4-Connected Carbon Net

    Prasad, Dasari L. V. K.

    2013-08-13

    Theoretical calculations are presented on a new hypothetical 3,4-connected carbon net (called squaroglitter) incorporating 1,4 cyclohexadiene units. The structure has tetragonal space group P4/mmm (No. 123) symmetry. The optimized geometry shows normal distances, except for some elongated bonds in the cyclobutane ring substructures in the network. Squaroglitter has an indirect bandgap of about 1.0 eV. The hypothetical lattice, whose density is close to graphite, is more stable than other 3,4-connected carbon nets. A relationship to a (4,4)nanotube is explored, as is a potential threading of the lattice with metal needles. © 2013 American Chemical Society.

  15. ANTIMICROBIAL ACTIVITIES OF 1,3,4-OXADIAZOLE : A REVIEW

    Bachwani Mukesh

    2011-06-01

    Full Text Available 1, 3, 4-Oxadiazole is a highly privileged structure the derivatives of which exhibit a wide range of biological activities including antibacterial, antitubercular, vasodialatory, antifungal, cytotoxic, anti-inflammatory and analgesic, hypolipidemic, anticancer and ulcerogenic activities. Resistance to number of antimicrobial agents among a variety of clinically significant species of bacteria is becoming increasingly important global problem. The search for new antimicrobial agents will consequently always remain as an important and challenging task for medicinal chemists. This Review has basic information about 1,3,4-oxadiazole and its antimicrobial activity work for further development in this field.

  16. A Characterization of the SPARC T3-4 System

    van Tol, Michiel W

    2011-01-01

    This technical report covers a set of experiments on the 64-core SPARC T3-4 system, comparing it to two similar AMD and Intel systems. Key characteristics as maximum integer and floating point arithmetic throughput are measured as well as memory throughput, showing the scalability of the SPARC T3-4 system. The performance of POSIX threads primitives is characterized and compared in detail, such as thread creation and mutex synchronization. Scalability tests with a fine grained multithreaded runtime are performed, showing problems with atomic CAS operations on such physically highly parallel systems.

  17. Direct comparison of photoemission spectroscopy and in situ Kelvin probe work function measurements on indium tin oxide films

    The work function of commercially available indium tin oxide (ITO) films on glass substrates was measured using photoemission spectroscopy (PES) and ultra-high vacuum (UHV) Kelvin probe in direct comparison. Absolute Kelvin probe work function values were determined via calibration of the measured contact potential difference (CPD) using an in situ sputtered Au reference sample. The Kelvin probe data confirmed that ultraviolet photoemission spectroscopy (UPS) measurements change the work function of ITO surfaces previously exposed to ambient environment, when measured without in situ surface cleaning procedures. The results also demonstrate that both Kelvin probe and PES yield virtually identical work function values, as long as the Kelvin probe data are calibrated against a known standard. As a consequence, previously reported higher work function values determined with Kelvin probe as compared to values obtained with UPS on similar samples are likely related to a photochemically generated surface dipole during UPS measurements. Comparison between Kelvin probe and low intensity X-ray photoemission spectroscopy (LIXPS) work function measurements demonstrated that accurate work function measurements on ITO previously exposed to the ambient are possible with PES

  18. Synthesis of Novel Biologically Active s-Triazolo[3,4-b]-1,3,4-thiadiazole Derivatives

    SUN,Yi-Feng

    2004-01-01

    @@ Heterocycles bearing a symmetrical triazole or 1,3,4-thiadiazole ring system are reported to show a broad spectrum of biological activities.[1,2] The 1,2,4-triazole nucleus has been recently incorporated into a wide variety of therapeutically interesting drugs including H1/H2 histamine receptor blockers, cholinesterase active agents, CNS stimulants, antianxiety and sedatives[3] Coumarins are nowadays an important group of organic compounds that used as bactericides, fungicides,anti-inflammatory, anticoagulant, anti-HIV and antitumour agents.[4,5] Keeping in view the biological importance of the above mentioned heterocyclic compounds and in continuation of our search for biologically active nitrogen and sulphur heterocycles, a series of s-triazolo[3,4-b]-1,3,4-thiadiazole derivatives was synthesized.

  19. Poly(3,4-ethylenedioxythiophene)-based glucose biosensors

    Kros, A.; Nolte, R.J.M. [Nijmegen Univ. (Netherlands). Dept. of Organic Chemistry; Hoevell, S.W.F.M. van [TNO Nutrition and Food Research Inst., Zeist (Netherlands); Sommerdijk, N.A.J.M. [Eindhoven Univ. of Technology (Netherlands). Lab. of Macromolecular and Organic Chemistry

    2001-10-16

    Amperometric biosensors for the recognition of glucose oxidase (GOx) based on poly(3,4-ethylenedioxythiophene) (PEDOT) have for the first time been fabricated and are presented in this communication. This biosensor has potential applications for long-term glucose measurements, e.g., in the treatment of diabetes. (orig.)

  20. 20 TO 30-DAY AND 30 TO 60-DAY OSCILLATIONS IN ASSIMILATED GLOBAL DATASETS USING TRMM RAINFALL OBSERVATIONS

    TAO Li; Song YANG; LU Wei-song

    2010-01-01

    The influences of Tropical Rainfall Measuring Mission (TRMM) precipitation products on the structure and underlying physics of intraseasonal oscillation (ISO) are investigated with the U.S. National Aeronautics and Space Administration Goddard Earth Observing System model version 3 (GEOS-3) data assimilation system (DAS). The strong ISO phase in the 1998 summer is apparently located in the Asian monsoon region and the east equatorial Pacific region. The eastward propagation is a dominant feature for the tropical ISO at 20 to 30-day oscillation while the northeastward propagation is the salient ISO at 30 to 60-day oscillation over the 10°N to 25°N belt region. It appears that the Kelvin wave structure is for the tropical 20 to 30-day oscillation. The tropical 30 to 60-day oscillation has the characteristics of the Kelvin-Rossby wave. The impact of satellite-derived precipitation (and its associated latent heating) on the ISO intensity is limited in the GEOS-3 assimilation system. However, its impact on the ISO spatial structures is obvious. Overall, the results demonstrate a better eastward propagation and a northward propagation of ISO with the TRMM precipitation simulation, indicating that latent heating is very important in exciting the equatorial ISO.

  1. Synthesis and Crystal Structure of 3-(4-Ethoxyphenyl)-6-(phenoxymethyl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole

    LEI Xin-Xiang; LIU Miao-Chang; XIAO Hong-Ping; ZHANG An-Jiang; ZHANG Li-Xue

    2007-01-01

    The title compound C18H16N4O2S has been synthesized by the reaction of 4-amino-3-(4-ethoxyphenyl)-5-mercapto-1,2,4-triazole with phenoxyacetic acid in phospho- rus oxychloride, and characterized by IR, NMR spectra and elemental analysis. Its structure was determined by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 1.4903(3), b = 1.5230(2), c = 0.9615(16) nm, Z = 4, V = 1.7769(5) nm3, Dc = 1.317 g/cm3, ( = 0.201 mm-1, F(000) = 736, R = 0.0795 and wR = 0.2233. In the title compound, all rings are essentially planar.

  2. Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system

    Drozdov, A. P.; Eremets, M. I.; Troyan, I. A.; Ksenofontov, V.; Shylin, S. I.

    2015-09-01

    A superconductor is a material that can conduct electricity without resistance below a superconducting transition temperature, Tc. The highest Tc that has been achieved to date is in the copper oxide system: 133 kelvin at ambient pressure and 164 kelvin at high pressures. As the nature of superconductivity in these materials is still not fully understood (they are not conventional superconductors), the prospects for achieving still higher transition temperatures by this route are not clear. In contrast, the Bardeen-Cooper-Schrieffer theory of conventional superconductivity gives a guide for achieving high Tc with no theoretical upper bound--all that is needed is a favourable combination of high-frequency phonons, strong electron-phonon coupling, and a high density of states. These conditions can in principle be fulfilled for metallic hydrogen and covalent compounds dominated by hydrogen, as hydrogen atoms provide the necessary high-frequency phonon modes as well as the strong electron-phonon coupling. Numerous calculations support this idea and have predicted transition temperatures in the range 50-235 kelvin for many hydrides, but only a moderate Tc of 17 kelvin has been observed experimentally. Here we investigate sulfur hydride, where a Tc of 80 kelvin has been predicted. We find that this system transforms to a metal at a pressure of approximately 90 gigapascals. On cooling, we see signatures of superconductivity: a sharp drop of the resistivity to zero and a decrease of the transition temperature with magnetic field, with magnetic susceptibility measurements confirming a Tc of 203 kelvin. Moreover, a pronounced isotope shift of Tc in sulfur deuteride is suggestive of an electron-phonon mechanism of superconductivity that is consistent with the Bardeen-Cooper-Schrieffer scenario. We argue that the phase responsible for high-Tc superconductivity in this system is likely to be H3S, formed from H2S by decomposition under pressure. These findings raise hope for the

  3. 具有Kelvin-Voigt阻尼的弱耦合系统的能量衰减估计%Energy decay estimates for the weakly coupled systems with Kelvin-Voigt damping

    樊美丽; 章春国; 谷尚武

    2014-01-01

    This paper studies the weakly coupled systems with Kelvin-Voigt damping. First, under the appro-priate hypothesis, we prove the well-posedness of the system by using the theory of linear operator semigroup. And then, we show that the energy of the weakly coupled system with Kelvin-Voigt damping is uniform expo-nential decay by applying the frequency domain result on Hilbert space.%研究具有 Kelvin-Voigt 阻尼的弱耦合系统。首先在合适的假设条件下,应用线性算子半群理论证明了系统的适定性;进而运用线性算子半群的频域定理证明了具有Kelvin-Voigt阻尼的弱耦合梁―弦系统的能量是一致指数衰减的。

  4. Study on the Synthesisof 3,4, 5-Trimethoxytol uene

    2001-01-01

    The 3,4,5-trimethoxytoluene(TMT) was systhesized using p-cresol by three steps including bromina-tion, methoxylation, and methylation with an overall yield of 84%. The structure of TMT was identified byNMR, GC/MS and IR. “One-pot”method was used in methoxylation and methylation for economical and conve-nient consideration. The mechanism for the methoxylation of 2,6-dibromo-4-methylphenol was discussed.

  5. Photoinduced 1,2,3,4-tetrahydropyridine ring conversions.

    Turovska, Baiba; Lund, Henning; Lūsis, Viesturs; Lielpētere, Anna; Liepiņš, Edvards; Beljakovs, Sergejs; Goba, Inguna; Stradiņš, Jānis

    2015-01-01

    Stable heterocyclic hydroperoxide can be easily prepared as a product of fast oxidation of a 1,2,3,4-tetrahydropyridine by (3)O2 if the solution is exposed to sunlight. The driving force for the photoinduced electron transfer is calculated from electrochemical and spectroscopic data. The outcome of the reaction depends on the light intensity and the concentration of O2. In the solid state the heterocyclic hydroperoxide is stable; in solution it is involved in further reactions. PMID:26664638

  6. Photoisomerization of azobenzene containing self-assembled monolayers investigated by Kelvin probe work function measurements

    Photoisomerization of asymmetric azobenzene disulfide self-assembled monolayer (SAM) on gold was characterized by the Kelvin probe work function measurements in ambient atmosphere. The reversible changes in work function between trans and cis azobenzene SAMs are reasonably interpreted by the molecular dipole moments normal to the surface based on the molecular conformational models. The different para-substituents of azobenzene with electron donating and electron-withdrawing properties induce opposite responses in work function against UV-vis photoirradiation, which is a direct evidence of functional SAMs being effective for the energy-level alignment at the organic/electrode interface. The Kelvin probe measurements in atmosphere eventually provide the work function value equivalent to that determined by ultraviolet photoelectron spectroscopy (UPS) in ultrahigh vacuum in our previous study.

  7. Heterojunction Effect in Weak Epitaxy Growth Thin Films Investigated by Kelvin Probe Force Microscopy

    We investigate the heterojunction effect between para-sexiphenyl (p-6P) and copper phthalocyanine (CuPc) using Kelvin probe force microscopy. CuPc films are grown on the inducing layer p-6P by a weak epitaxy growth technique. The surface potential images of Kelvin probe force microscopy indicate the band bending in CuPc, which reduces grain boundary barriers and lead to the accumulation of holes in the CuPc layer. The electrical potential distribution on the surface of heterojunction films shows negligible grain boundary barriers in the CuPc layers. The relation between band bending and grain boundary barrier in the weak epitaxy growth thin films is revealed. (condensed matter: structure, mechanical and thermal properties)

  8. Kelvin probe force microscopy of C60 on metal substrates: towards molecular resolution

    Surface workfunction changes upon C60 adsorption onto different metal single crystals are investigated by Kelvin probe force microscopy (KPFM). Literature values for similar metal/organic systems, showing a broad variation for both the measured metal workfunction and workfunction change, are compared to the acquired KPFM values. Good agreement is found between nanoscopic KPFM results and macroscopic photoelectron spectroscopy or Kelvin probe literature data. The model of a linear dependence between the metal substrate workfunction and the C60-induced workfunction change is confirmed. Former numerical simulations predicted a lateral quantitative KPFM resolution in the range of 10 nm, in this work results are published that show the achievement of this resolution with Cr coated, sharp tips. Furthermore, numerical simulations are presented that show the possibility of molecular contrast for KPFM

  9. Kelvin Probe Measurements on Solar Cells and Other Thin Film Devices

    Delk, John; Dils, D. W.; Lush, G. B.; Mackey, Willie R. (Technical Monitor)

    2001-01-01

    The Kelvin Probe (KP) has been used for years to measure the surface potential of metals and semiconductors. The KP is an elegantly simple but powerful tool invented by Lord Kelvin around the turn of the century. Using changes in surface potentials as a result of changing the intensity and wavelength of illumination, the KP returns data on material parameters such as band gap energies and the energy levels of interface states. We have employed the KP in the study of CdTe-based solar cells and quantum dot-based solar cells, as well as other thin-film devices. We hope eventually that the KP will be used as an in-line testing station for a fabrication process so that unfinished devices that will not meet requirements can be thrown out before the processing is completed, thus saving resources. Results of these studies will be presented.

  10. Numerical simulations of Kelvin-Helmholtz instability: a two-dimensional parametric study

    Tian, Chunlin

    2016-01-01

    Using two-dimensional simulations, we numerically explore the dependences of Kelvin-Helmholtz instability upon various physical parameters, including viscosity, width of sheared layer, flow speed, and magnetic field strength. In most cases, a multi-vortex phase exists between the initial growth phase and final single-vortex phase. The parametric study shows that the evolutionary properties, such as phase duration and vortex dynamics, are generally sensitive to these parameters except in certain regimes. An interesting result is that for supersonic flows, the phase durations and saturation of velocity growth approach constant values asymptotically as the sonic Mach number increases. We confirm that the linear coupling between magnetic field and Kelvin-Helmholtz modes is negligible if the magnetic field is weak enough. The morphological behaviour suggests that the multi-vortex coalescence might be driven by the underlying wave-wave interaction. Based on these results, we make a preliminary discussion about seve...

  11. THE DYNAMIC BEHAVIORS OF VISCOELASTIC PIPE CONVEYING FLUID WITH THE KELVIN MODEL

    Wang Zhongmin; Zhao Fengqun; Feng Zhenyu; Liu Hongzhao

    2000-01-01

    Based on the differential constitutive relationship of linear viscoelastic material, a solid-liquid coupling vibration equation for viscoelastic pipe conveying fluid is derived by the D'Alembert's principle. The critical flow velocities and natural frequencies of the cantilever pipe conveying fluid with the Kelvin model ( flutter instability) are calculated with the modified finite difference method in the form of the recurrence for mula. The curves between the complex frequencies of the first, second and third mode and flow velocity of the pipe are plotted. On the basis of the numerical calculation results, the dynamic behaviors and stability of the pipe are discussed. It should be pointed out that the delay time of viscoelastic material with the Kelvin model has a remarkable effect on the dynamic characteristics and stability behaviors of the cantilevered pipe conveying fluid, which is a gyroscopic non-conservative system.

  12. Sub-Kelvin refrigeration with dry-coolers on a rotating system

    Oguri, S; Choi, J; Kawai, M; Tajima, O

    2014-01-01

    We developed a cryogenic system on a rotating table that achieves sub-Kelvin conditions. The cryogenic system consists of a helium sorption cooler and a pulse tube cooler in a cryostat mounted on a rotating table. Two rotary-joint connectors for electricity and helium gas circulation enable the coolers to be operated and maintained with ease. We performed cool-down tests under a condition of continuous rotation at 20 rpm. We obtained a temperature of 0.23 K with a holding time of more than 24 hours, thus complying with catalog specifications. We monitored the system's performance for four weeks; two weeks with and without rotation. A few-percent difference in conditions was observed between these two states. Most applications can tolerate such a slight difference. The technology developed is useful for various scientific applications requiring sub-Kelvin conditions on rotating platforms.

  13. The effect of patch potentials in Casimir force measurements determined by heterodyne Kelvin probe force microscopy

    Garrett, Joseph L.; Somers, David; Munday, Jeremy N.

    2015-06-01

    Measurements of the Casimir force require the elimination of the electrostatic force between the surfaces. However, due to electrostatic patch potentials, the voltage required to minimize the total force may not be sufficient to completely nullify the electrostatic interaction. Thus, these surface potential variations cause an additional force, which can obscure the Casimir force signal. In this paper, we inspect the spatially varying surface potential of e-beamed, sputtered, sputtered and annealed, and template stripped gold surfaces with Heterodyne amplitude modulated Kelvin probe force microscopy (HAM-KPFM). It is demonstrated that HAM-KPFM improves the spatial resolution of surface potential measurements compared to amplitude modulated Kelvin probe force microscopy. We find that patch potentials vary depending on sample preparation, and that the calculated pressure can be similar to the pressure difference between Casimir force calculations employing the plasma and Drude models.

  14. On Advantages of the Kelvin Mapping in Finite Element Implementations of Deformation Processes

    Nagel, Thomas; Moerman, Kevin M; Kolditz, Olaf

    2016-01-01

    Classical continuum mechanical theories operate on three-dimensional Eu-clidian space using scalar, vector, and tensor-valued quantities usually up to the order of four. For their numerical treatment, it is common practice to transform the relations into a matrix-vector format. This transformation is usually performed using the so-called Voigt mapping. This mapping does not preserve tensor character leaving significant room for error as stress and strain quantities follow from different mappings and thus have to be treated differently in certain mathematical operations. Despite its conceptual and notational difficulties having been pointed out, the Voigt mapping remains the foundation of most current finite element programmes. An alternative is the so-called Kelvin mapping which has recently gained recognition in studies of theoretical mechanics. This article is concerned with benefits of the Kelvin mapping in numerical modelling tools such as finite element software. The decisive difference to the Voigt mapp...

  15. Why Was Kelvin's Estimate of the Earth's Age Wrong?

    Lovatt, Ian; Syed, M. Qasim

    2014-01-01

    This is a companion to our previous paper in which we give a published example, based primarily on Perry's work, of a graph of ln "y" versus "t" when "y" is an exponential function of "t". This work led us to the idea that Lord Kelvin's (William Thomson's) estimate of the Earth's age was…

  16. High-resolution superconducting single-flux quantum comparator for sub-Kelvin temperatures

    Savin, A. M.; Pekola, Jukka P.; Holmqvist, T.; Hassel, J.; Grönberg, L.; Helistö, P.; Kidiyarova-Shevchenko, A.

    2006-01-01

    A design of sub-Kelvin single-flux quantum (SFQ) circuits with reduced power dissipation and additional cooling of shunt resistors has been developed and characterized. The authors demonstrate operation of SFQ comparators with current resolution of 40nA at 2GHz sampling rate. Due to improved cooling the electron temperature in shunt resistors of a SFQ comparator is below 50mK when the bath temperature is about 30mK.

  17. Altimetric observations and model simulations of coastal Kelvin waves in the Bay of Bengal

    Nienhaus, M.J.; Subrahmanyam, B; Murty, V.S.N.

    , Columbia, SC 29208 1,2Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC 29208 3National Institute of Oceanography Regional Center (CSIR), Visakhapatnam 530 017, India Contact Information: Matthew J. Nienhaus, E...-mail: mnienhaus@geol.sc.edu Abstract Kelvin waves originating in the equatorial Indian Ocean propagate along the equatorial wave guide until reaching the Sumatra coast and follow the coastal waveguide counter clockwise around the perimeter of the Bay...

  18. The Kelvin-Helmholtz instability in weakly ionised plasmas II: multifluid effects in molecular clouds

    Jones, A. C.; Downes, T. P

    2011-01-01

    We present a study of the Kelvin-Helmholtz instability in a weakly ionised, multifluid MHD plasma with parameters matching those of a typical molecular cloud. The instability is capable of transforming well-ordered flows into disordered flows. As a result, it may be able to convert the energy found in, for example, bowshocks from stellar jets into the turbulent energy found in molecular clouds. As these clouds are weakly ionised, the ideal magnetohydrodynamic approximation does not apply at s...

  19. Local charge trapping in conjugated polymers resolved by scanning Kelvin probe microscopy

    Hallam, T.; Lee, M.; N. Zhao; Nandhakumar, I; Kemerink, M Martijn; Heeney, M.; McCulloch, I; Sirringhaus, H.

    2009-01-01

    The microstructure of conjugated polymers is heterogeneous on the length scale of individual polymer chains, but little is known about how this affects their electronic properties. Here we use scanning Kelvin probe microscopy with resolution-enhancing carbon nanotube tips to study charge transport on a 100 nm scale in a chain-extended, semicrystalline conjugated polymer. We show that the disordered grain boundaries between crystalline domains constitute preferential charge trapping sites and ...

  20. Simulating and interpreting Kelvin probe force microscopy images on dielectrics with boundary integral equations

    Shen, Yongxing; Barnett, David M.; Pinsky, Peter M.

    2008-01-01

    Kelvin probe force microscopy KPFM is designed for measuring the tip-sample contact potential differences by probing the sample surface, measuring the electrostatic interaction, and adjusting a feedback circuit. However, for the case of a dielectric insulating sample, the contact potential difference may be ill defined, and the KPFM probe may be sensing electrostatic interactions with a certain distribution of sample trapped charges or dipoles, leading to difficulty in interpr...

  1. Kelvin probe force microscopy of nanocrystalline TiO2 photoelectrodes

    Alex Henning; Gino Günzburger; Res Jöhr; Yossi Rosenwaks; Biljana Bozic-Weber; Housecroft, Catherine E.; Constable, Edwin C.; Ernst Meyer; Thilo Glatzel

    2013-01-01

    Dye-sensitized solar cells (DSCs) provide a promising third-generation photovoltaic concept based on the spectral sensitization of a wide-bandgap metal oxide. Although the nanocrystalline TiO2 photoelectrode of a DSC consists of sintered nanoparticles, there are few studies on the nanoscale properties. We focus on the microscopic work function and surface photovoltage (SPV) determination of TiO2 photoelectrodes using Kelvin probe force microscopy in combination with a tunable illumination sys...

  2. PREPARATIONS OF ZINC OXIDES AND CHARACTERIZATION OF THE PHOTOVOLTAIC BEHAVIOR USING A SCANNING KELVIN PROBE

    He, Y.; Zhi, W.; B. O. ZHOU

    2010-01-01

    Surface photovoltage of semiconductors depend strongly on their electronic structures, in particular, their Fermi energy level. This offers a possibility to characterize photoelectronic behavior using the Kelvin probe structure by measurements of work function (WF). In this paper, ZnO films were prepared using the CVD method and their microstructures and morphology were characterized using the XRD and SEM. Furthermore, photovoltage evolution and WF of selected ZnO samples were measured using ...

  3. Atomic force microscope based Kelvin probe measurements : application to an electrochemical reaction

    Böhmisch, Mathias; Burmeister, Frank; Rettenberger, Armin; Zimmermann, Jörg; Boneberg, Johannes; Leiderer, Paul

    1997-01-01

    An atomic force microscope (AFM) was utilized as a Kelvin probe to determine work functions of several metals and semiconductors quantitarively. Most of the experimental data show excellent agreement with published values measured by photoemission. Variations in work functions as low as 5 mV could be detected with a typical lateral resolution of 20 nm. This method allowed us to analyze and explain the energetics of an electrochemical reaction on the surface of WSe2, which could be in situ ind...

  4. Understanding the atomic-scale contrast in Kelvin Probe Force Microscopy

    Nony, Laurent; Foster, Adam; Bocquet, Franck; Loppacher, Christian

    2009-01-01

    A numerical analysis of the origin of the atomic-scale contrast in Kelvin probe force microscopy (KPFM) is presented. Atomistic simulations of the tip-sample interaction force field have been combined with a non-contact Atomic Force Microscope/KPFM simulator. The implementation mimics recent experimental results on the (001) surface of a bulk alkali halide crystal for which simultaneous atomic-scale topographical and Contact Potential Difference (CPD) contrasts were reported. The local CPD do...

  5. Determination of the electrostatic lever arm of carbon nanotube field effect transistors using Kelvin Force Microscopy

    Brunel, David; Deresmes, Dominique; Melin, Thierry

    2009-01-01

    We use Kelvin Force Microscopy (KFM) to study the electrostatic properties of single-walled Carbon Nanotube Field Effect Transistor devices (CNTFETs) with backgate geometry at room temperature. We show that KFM maps recorded as a function of the device backgate polarization enable a complete phenomenological determination of the averaging effects associated with the KFM probe side capacitances, and thus, to obtain KFM measurements with quantitative character. The value of the electrostatic le...

  6. High resolution investigation of localized corrosion by in-situ Scanning Kelvin Probe Force Microscopy

    Senöz, Ceylan

    2011-01-01

    In dieser Arbeit wurde die Möglichkeit zur Nutzung der Scanning Kelvin Probe Force Microscopy (SKPFM) in der Korrosionforschung untersucht. Ein wesentlicher Nachteil dieser Technik ist die mangelnde Fähigkeit der Abbildbarkeit durch organische Beschichtungen hindurch. In dieser Arbeit wurde die Methodik zur Nutzung von SKPFM so weiter entwickelt, dass auch in-situ Untersuchungen in zwei verschiedenen Anwendungsfeldern möglich sind. Eine dieser Anwendungen beinhaltet den zugrunde l...

  7. Facile Preparation of a Platinum Silicide Nanoparticle-Modified Tip Apex for Scanning Kelvin Probe Microscopy

    Lin, Chun-Ting; Chen, Yu-Wei; Su, James; Wu, Chien-Ting; Hsiao, Chien-Nan; Shiao, Ming-Hua; Chang, Mao-Nan

    2015-01-01

    In this study, we propose an ultra-facile approach to prepare a platinum silicide nanoparticle-modified tip apex (PSM tip) used for scanning Kelvin probe microscopy (SKPM). We combined a localized fluoride-assisted galvanic replacement reaction (LFAGRR) and atmospheric microwave annealing (AMA) to deposit a single platinum silicide nanoparticle with a diameter of 32 nm on the apex of a bare silicon tip of atomic force microscopy (AFM). The total process was completed in an ambient environment...

  8. Electrical Potential of Acupuncture Points: Use of a Noncontact Scanning Kelvin Probe

    Gow, Brian J.; Cheng, Justine L.; Baikie, Iain D.; Ørjan G. Martinsen; Min Zhao; Stephanie Smith; Ahn, Andrew C

    2012-01-01

    Objective. Acupuncture points are reportedly distinguishable by their electrical properties. However, confounders arising from skin-to-electrode contact used in traditional electrodermal methods have contributed to controversies over this claim. The Scanning Kelvin Probe is a state-of-the-art device that measures electrical potential without actually touching the skin and is thus capable of overcoming these confounding effects. In this study, we evaluated the electrical potential profiles of ...

  9. Dual harmonic Kelvin probe force microscopy at the graphene-liquid interface

    Collins, Liam; Kilpatrick, J. I.; Vlassiouk, Ivan V.; Weber, Stefan A. L.; Rodriguez, Brian J; et al.

    2014-01-01

    Kelvin probe force microscopy (KPFM) is a powerful technique for the determination of the contact potential difference (CPD) between an atomic force microscope tip and a sample under ambient and vacuum conditions. However, for many energy storage and conversion systems, including graphene-based electrochemical capacitors, understanding electrochemical phenomena at the solid¿liquid interface is paramount. Despite the vast potential to provide fundamental insight for energy storage materials at...

  10. The Importance of Cantilever Dynamics in the Interpretation of Kelvin Probe Force Microscopy

    Brown, Keith A.; Westervelt, Robert M.; Satzinger, Kevin J.

    2012-01-01

    A realistic interpretation of the measured contact potential difference (CPD) in Kelvin probe force microscopy (KPFM) is crucial in order to extract meaningful information about the sample. Central to this interpretation is a method to include contributions from the macroscopic cantilever arm, as well as the cone and sharp tip of a KPFM probe. Here, three models of the electrostatic interaction between a KPFM probe and a sample are tested through an electrostatic simulation and compared with ...

  11. The role of the cantilever in Kelvin probe force microscopy measurements

    George Elias; Thilo Glatzel; Ernst Meyer; Alex Schwarzman; Amir Boag; Yossi Rosenwaks

    2011-01-01

    The role of the cantilever in quantitative Kelvin probe force microscopy (KPFM) is rigorously analyzed. We use the boundary element method to calculate the point spread function of the measuring probe: Tip and cantilever. The calculations show that the cantilever has a very strong effect on the absolute value of the measured contact potential difference even under ultra-high vacuum conditions, and we demonstrate a good agreement between our model and KPFM measurements in ultra-high vacuum of ...

  12. Kelvin probe study of laterally inhomogeneous dielectric charging and charge diffusion in RF MEMS capacitive switches

    Herfst, R.W.; Steeneken, P. G.; Schmitz, J; Mank, A.J.G.; Gils, van, S.H.

    2008-01-01

    In this paper we use scanning Kelvin probe microscopy (SKPM) to detect charge in the dielectric of RF MEMS capacitive switches. We observe a laterally inhomogeneous distribution. Laterally inhomogeneous dielectric charging leads to a narrowing of the C-V curve [1], and can lead to stiction of the membrane. The measurements show that trapped charges slowly diffuse, which reduces the inhomogeneity and shows that charge is vertically confined. From these measurements we estimate the lateral diff...

  13. Surface Potential Analysis of Nanoscale Biomaterials and Devices Using Kelvin Probe Force Microscopy

    Hyungbeen Lee; Wonseok Lee; Jeong Hoon Lee; Dae Sung Yoon

    2016-01-01

    In recent years, Kelvin probe force microscopy (KPFM) has emerged as a versatile toolkit for exploring electrical properties on a broad range of nanobiomaterials and molecules. An analysis using KPFM can provide valuable sample information including surface potential and work function of a certain material. Accordingly, KPFM has been widely used in the areas of material science, electronics, and biomedical science. In this review, we will briefly explain the setup of KPFM and its measuring pr...

  14. Determination of Contact Potential Difference by the Kelvin Probe (Part I) I. Basic Principles of Measurements

    Vilitis O.; Rutkis M.; Busenberg J.; Merkulov D.

    2016-01-01

    Determination of electric potential difference using the Kelvin probe, i.e. vibrating capacitor technique, is one of the most sensitive measuring procedures in surface physics. Periodic modulation of distance between electrodes leads to changes in capacitance, thereby causing current to flow through the external circuit. The procedure of contactless, non-destructive determination of contact potential difference between an electrically conductive vibrating reference electrode and an electrical...

  15. Sample preparation for scanning Kelvin probe microscopy studies on cross sections of organic solar cells

    Michael Scherer; Rebecca Saive; Dominik Daume; Michael Kröger; Wolfgang Kowalsky

    2013-01-01

    We prepared cross sections of P3HT:PCBM bulk heterojunction (BHJ) organic solar cells (OSCs) for the characterization of their potential distribution with scanning Kelvin probe microscopy. We compared results of samples obtained by microtome cutting of OSCs on plastic substrates, cleaving of OSCs on glass substrates, and milling with a focused ion beam. Their potential distributions were in good agreement with each other. Under short circuit conditions, potential gradients were detected in vi...

  16. Kelvin probe measurements of microcrystalline silicon on a nanometer scale using SFM

    Breymesser, A.; Schlosser, V.; Peiró, D.; Voz Sánchez, Cristóbal; Bertomeu i Balagueró, Joan; Andreu i Batallé, Jordi; Summhammer, J.

    2001-01-01

    Work function measurements on cross-sectioned microcrystalline pin silicon solar cells deposited by Hot-Wire CVD are presented. The experiment is realized by combining a modified Kelvin probe experiment and a scanning force microscope. The measured surface potential revealed that the built-in electric drift field is weak in the middle of the compensated intrinsic layer. A graded donor distribution and a constant boron compensation have to be assumed within the intrinsic layer in order to obta...

  17. Kelvin probe force microscopy for local characterisation of active nanoelectronic devices

    Tino Wagner; Hannes Beyer; Patrick Reissner; Philipp Mensch; Heike Riel; Bernd Gotsmann; Andreas Stemmer

    2015-01-01

    Frequency modulated Kelvin probe force microscopy (FM-KFM) is the method of choice for high resolution measurements of local surface potentials, yet on coarse topographic structures most researchers revert to amplitude modulated lift-mode techniques for better stability. This approach inevitably translates into lower lateral resolution and pronounced capacitive averaging of the locally measured contact potential difference. Furthermore, local changes in the strength of the electrostatic inter...

  18. Observation of equatorial Kelvin solitary waves in a slowly varying thermocline

    Zheng, Q; R. D. Susanto; X.-H. Yan; W. T. Liu; C.-R. Ho

    1998-01-01

    TOPEX/POSEIDON (T/P) sea level deviation (SLD) time series from 3 October 1992 to 15 May 1997 combined with upper ocean thermal structures are used to observe the characteristics and analyze the dynamics of equatorial waves in the Pacific Ocean. The evolution of the Kelvin wave propagating along an eastward shoaling thermocline in the equatorial Pacific is investigated. The behaviour of this wave as it propagates eastward can be approximately described with the solutions of the perturbed Kort...

  19. Two competing interpretations of Kelvin Probe Force Microscopy on semiconductors put to test

    Polak, Leo; Wijngaarden, Rinke J.

    2016-01-01

    Kelvin probe force microscopy (KPFM) is a popular tool for studying properties of semiconductors. However, the interpretation of its results is complicated by the possibility of so-called band bending and the presence of surface charges. In this work we study two different interpretations for KPFM on semiconductors: the contact potential difference (CPD) interpretation, which interprets the measured potential as the work function difference between the sample and the probe, and a newer, alter...

  20. Measuring Method of a Surface Property inside the Pore: Application of Kelvin's equation

    Amano, Ken-ichi

    2015-01-01

    Surface analyses inside the nanopore, micropore, and a very narrow pipe are important topics for development of the chemical engineering. Here, we propose a measuring method which evaluates the surface coverage of the chemically modified pore surface and the corrosion rate of the inner surface of the narrow pipe, etc. The method uses Kelvin's equation that expresses saturated vapor pressure of a liquid in the pore (pipe). The surface coverage and the corrosion rate are calculated by measuring...

  1. The dynamics of beltramized flows and its relation with the Kelvin waves

    Gonzalez, Rafael [Instituto de Desarrollo Humano, Universidad Nacional de General Sarmiento Pcia. de Buenos Aires, Argentina and Depto. de Fisica FCEyN, Universidad de Buenos Aires, Buenos Aires (Argentina); Santini, E Sergio, E-mail: rgonzale@ungs.edu.ar [Instituto de Ciencias, Universidad Nacional de General Sarmiento Pcia. de Buenos Aires (Argentina) and ICRA-BR, Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro (Brazil)

    2011-05-01

    We define the beltramized flow as the sum of an uniform translation and an uniform rotation with a Beltrami flow. Some of their features are studied by solving the Euler equations, for different geometries, taking into account the boundary conditions, and for different symmetries. We show that the Kelvin waves are beltramized flows. Finally, we show that the variational principle found in a previous work, remains valid for the beltramized flow.

  2. Kelvin-Tkachenko waves of few-vortex arrays in trapped Bose-Einstein condensates

    We have calculated the low-lying elementary excitations of three-dimensional few-vortex arrays in trapped Bose-Einstein condensates. The number of different Kelvin-Tkachenko vortex wave branches found matches the number of vortices in the condensate. The lowest odd-parity modes exhibit superfluid gyroscopic vortex motion. Experimentally, these modes could be excited and observed individually or in connection with the formation and decay of quantum turbulence.

  3. Global Regular Solutions to a Kelvin-Voigt Type Thermoviscoelastic System

    Pawlow, Irena

    2011-01-01

    A classical 3-D thermoviscoelastic system of Kelvin-Voigt type is considered. The existence and uniqueness of a global regular solution is proved without small data assumption. The existence proof is based on the successive approximation method. The crucial part constitute a priori estimates on an arbitrary finite time interval, which are derived with the help of the theory of anisotropic Sobolev spaces with a mixed norm.

  4. Approximate Kelvin-Voigt Fluid Driven by an External Force Depending on Velocity with Distributed Delay

    Yantao Guo

    2015-01-01

    Full Text Available We consider the approximate 3D Kelvin-Voigt fluid driven by an external force depending on velocity with distributed delay. We investigate the long time behavior of solutions to Navier-Stokes-Voigt equation with a distributed delay external force depending on the velocity of fluid on a bounded domain. By a prior estimate and a contractive function, we give a sufficient condition for the existence of pullback attractor of NSV equation.

  5. Quantitative dopant profiling in semiconductors: A new approach to Kelvin probe force microscopy

    Baumgart, Christine

    2013-01-01

    Failure analysis and optimization of semiconducting devices request knowledge of their electrical properties. To meet the demands of today’s semiconductor industry, an electrical nanometrology technique is required which provides quantitative information about the doping profile and which enables scans with a lateral resolution in the sub-10 nm range. In the presented work it is shown that Kelvin probe force microscopy (KPFM) is a very promising electrical nanometrology technique to face this...

  6. Synthesis of 4-aryl-3,4-dihydrocoumarin derivatives catalyzed by NbCl{sub 5}; Sintese de derivados 4-aril-3,4-di-hidrocuraminicos catalisada por NbCl{sub 5}

    Santos, Willian Henrique dos; Siqueira, Mayara de Souza; Silva-Filho, Luiz Carlos da, E-mail: lcsilva@fc.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Bauru, SP (Brazil). Faculdade de Ciencias

    2013-11-01

    Multicomponent reactions between phenols, {beta}-diesters and benzaldehydes for the synthesis of 4-aryl-3,4-dihydrocoumarin derivatives were carried out under mild conditions (room temperature) and presented moderate yields (38-88%) and reasonable reaction times (2-4 days), using niobium pentachloride as a catalyst. (author)

  7. Evaluation of the oral subchronic toxicity of AHTN (7-Acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene) in the rat.

    Api, Anne Marie; Smith, Robert L; Pipino, Sandra; Marczylo, Timothy; De Matteis, Francesco

    2004-05-01

    7-Acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) is used as a fragrance material in a wide variety of consumer products. Because of its widespread exposure, a 90-day oral feeding study, with 4-week recovery periods for selected rats, was conducted. AHTN was added to the diet of rats at levels calculated to result in mean daily doses of 1.5, 5, 15 or 50 mg AHTN/kg body weight/day. On completion of the treatment period, 3 males and 3 females from each of the high dose groups and controls were maintained for a treatment free period of 4 weeks. There were no adverse effects revealed upon clinical examination or following extensive histopathological examinations. Histopathological examination of the prostate, seminal vesicles, mammary gland and testes of males and ovaries, mammary gland, uterus and vagina of females, undertaken on all animals in all test groups, revealed no evidence of hormonal effects of AHTN. A statistically significant decrease in body weight gain was observed in both sexes in the high dose group only. Statistically significant effects were observed in hematology and blood chemistry, although these effects were all within the range for historical controls and were not proportional to dose. A green to dark brown coloration in the livers and mesenteric lymph nodes was also seen in high dose animals. At the end of the treatment-free period, the color change was almost completely reversed; one high dose male still had green colored lymph nodes, but the liver appeared normal. A green coloration of the lacrimal glands in females, but not males, was also seen in 8/12, 4/15 and in 1 female given 50, 15 and 5 mg/kg body weight/day, respectively. This green color was still present in 2/3 of the high dose females after the treatment-free period. Microscopic examination of unstained sections of frozen livers under UV illumination did not reveal any fluorescence that might have been consistent with porphyrin accumulation. These findings were

  8. Kelvin probe force microscopy on electrically inhomogeneous Fe/W(001) films

    Noncontact scanning force microscopy can give information about the real topography of the sample. However, this is valid only when the dominant tip-sample interaction is due to the van der Waals force. If the sample is electrically inhomogeneous, e.g., the sample has an inhomogeneous electric charge distribution, it causes additional electrostatic forces between tip and sample, which prevent real topography measurement. To nullify the electrostatic effect, the tip bias can be regulated with a special feedback scheme called Kelvin probe force microscopy. Here we applied Kelvin probe force microscopy to the pseudomorphic Fe thin film grown on W(001). In this highly strained film, the electric properties depend on the number of layers, yielding different contact potentials in each layer. The samples were prepared and measured in-situ under ultra high vacuum condition without exposing them to the atmospheric environment. When the tip bias was not regulated, the apparent step height of the film changed depending on the tip-sample bias, and a reliable measurement of topography was impossible. With Kelvin probe force microscopy, the contact potentials different in each layer could be compensated, and the real topography image could be obtained

  9. A simultaneous Kelvin Probe and Raman spectroscopy approach for in situ surface and interface analysis

    A two-channel excitation and detection probe head for Raman spectroscopy was installed in the sample chamber of a height-regulated Kelvin Probe (KP). The beam of a 532 nm laser could be thereby focused on the sample area directly beneath the KP needle. Scattered light from the sample surface was collected by the Raman probe head and sent to a detector system via fiber optics. This allowed a simultaneous detection of surface potentials and Raman spectra for a localized investigation of the properties of oxide covered metal substrates in atmospheres of different relative humidity and oxygen partial pressure. Initial testing of the assembled setup revealed that both analytical methods can be operated independently of each other as long as the laser is not hitting the Kelvin Probe needle. The KP detected reversible and irreversible laser-induced drying, photoelectric and structural rearrangement effects that were correlated to equivalent Raman spectra recorded on bare steel sheets, steel covered with a powdery oxide layer and after that layer was wiped off. This showed that the combined Kelvin Probe–Raman spectroscopy approach can give additional information that is not available by each technique separately. As it has the potential to provide contributions to sophisticated analytical surface and interface studies, possible applications of this experimental tool are also discussed.

  10. Determination of Contact Potential Difference by the Kelvin Probe (Part I) I. Basic Principles of Measurements

    Vilitis, O.; Rutkis, M.; Busenberg, J.; Merkulov, D.

    2016-04-01

    Determination of electric potential difference using the Kelvin probe, i.e. vibrating capacitor technique, is one of the most sensitive measuring procedures in surface physics. Periodic modulation of distance between electrodes leads to changes in capacitance, thereby causing current to flow through the external circuit. The procedure of contactless, non-destructive determination of contact potential difference between an electrically conductive vibrating reference electrode and an electrically conductive sample is based on precise control measurement of Kelvin current flowing through a capacitor. The present research is devoted to creation of a new low-cost miniaturised measurement system to determine potential difference in real time and at high measurement resolution. Furthermore, using the electrode of a reference probe, the Kelvin method leads to both the indirect measurement of an electronic work function, or a contact potential of sample, and of a surface potential for insulator type samples. In the article, the first part of the research, i.e., the basic principles and prerequisites for establishment of such a measurement system are considered.

  11. Comparison of mobility equivalent diameter with Kelvin-Thomson diameter using ion mobility data

    Mäkelä, Jyrki M.; Riihelä, Marko; Ukkonen, Ari; Jokinen, Vilho; Keskinen, Jorma

    1996-07-01

    Mobility distributions of both positive and negative cluster ions were studied in nitrogen gas enriched by ethanol, isopropanol, n-butanol and acetone vapours, respectively. The ions were generated into the system by a radioactive source normally used as a bipolar aerosol charger. The ion mobility distributions were measured with a time-of-flight mobility spectrometer (TOF). The measured ion mobility can be used to estimate the mobility equivalent diameter via conventional Millikan-Fuchs formula based on Stokes law corrected by molecule slip effects. When the vapour concentration is increased the cluster ions will get larger due to enhanced molecule attachment onto ions. Here the vapour concentration is assumed to be high enough so that the chemical tracer effects would become of minor importance. Therefore the Kelvin-Thomson equation for ion induced nucleation is first assumed to be valid. The Kelvin-Thomson diameter of the ions in all cases was found to be systematically smaller than the corresponding mobility equivalent diameter according to Millikan-Fuchs, indicating of inconsistencies between the formulas based on macroscopic quantities at 1 nm size range. Thereafter, other available mobility vs diameter relationships were surveyed. The closest agreement between mobility equivalent and Kelvin-Thomson diameters at this size was obtained using the relationship given by Tammet [J. Aerosol Sci. 26, 459 (1995)].

  12. Impact of MHD shock physics on magnetosheath asymmetry and Kelvin-Helmholtz instability

    Nykyri, K.

    2013-08-01

    We have performed 13 three-dimensional global magnetohydrodynamic (MHD) simulations of the magnetosheath plasma and magnetic field properties for Parker spiral (PS) and ortho-Parker spiral interplanetary magnetic field (IMF) orientations corresponding to a wide range of solar wind plasma conditions. To study the growth of the Kelvin-Helmholtz instability on the dawn and dusk flank magnetopause, we have performed 26 local two-dimensional MHD simulations, with the initial conditions taken from global simulations on both sides of the velocity shear layer at the dawn-dusk terminator. These simulations indicate that while the MHD physics of the fast shocks does not directly lead to strong asymmetry of the magnetosheath temperature for typical solar wind conditions, the magnetosheath on the quasi-parallel shock side has a smaller tangential magnetic field along the magnetosheath flow which enables faster growth of the Kelvin-Helmholtz instability (KHI). Because the IMF is statistically mostly in the PS orientation, the KHI formation may statistically favor the dawnside flank. For all the 26 simulations, the growth rates of the KHI correlated well with the ratio of the velocity shear and Alfvén speed along the wave vector, k. Dynamics of the KHI may subsequently lead to formation of kinetic Alfvén waves and reconnection in the Kelvin-Helmholtz vortices which can lead to particle energization. This may partly help to explain the observed plasma sheet asymmetry of cold-component ions, which are heated more on the dawnside plasma sheet.

  13. Properties of the average distribution of equatorial Kelvin waves investigated by ray tracing techniques

    M. Ern

    2009-06-01

    Full Text Available Kelvin waves excited by tropospheric convection are considered to be one of the main drivers of the stratospheric quasi-biennial oscillation (QBO. In this paper we combine several measured data sets with the Gravity wave Regional Or Global RAy Tracer (GROGRAT in order to study the forcing and vertical propagation of Kelvin waves. Launch distributions for the ray tracer at tropospheric altitudes are deduced from space-time spectra of European Centre for Medium-Range Weather Forecasts (ECMWF operational analyses, as well as outgoing longwave radiation (OLR and rainfall data measured by the Tropical Rainfall Measuring Mission (TRMM satellite. The resulting stratospheric Kelvin wave spectra are compared to ECMWF operational analyses and temperature measurements of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER satellite instrument. Questions addressed are: the relative importance of source variability versus wind modulation, the relative importance of radiative and turbulent damping versus wave breaking, and the minimum altitude where freely propagating waves dominate the spectrum.

  14. Impurities in Illicit Drug Preparations: 3,4-(Methylenedioxy)amphetamine and 3,4-(Methylenedioxy)methylamphetamine.

    Verweij, A M

    1992-12-01

    Attention is given here to the mass spectral data of impurities present in illicit drug preparations of 3,4-(methylenedioxy)amphetamine and 3,4-(methylenedioxy)methylamphetamine. These "designer" drugs, having emphatic properties, were synthesized following well-known procedures such as the reductive amination route, the Leuckart reaction, and the nitropropene and the bromopropane routes. Based on the structure elucidation of impurities - especially those so-called "route specific" ones - present in these illicit drug preparations conclusions can be drawn about the method of preparation of a drug sample. Furthermore, on the basis of this kind of information methods can be developed for the comparison of drug samples, by which questions about the origin of drug samples can be solved (commonly known as the signature method). PMID:26267375

  15. Developmental Effects of ±3,4-Methylenedioxymethamphetamine on Spatial Versus Path Integration Learning: Effects of Dose Distribution

    Vorhees, Charles V.; Schaefer, Tori L.; Williams, Michael T.

    2007-01-01

    We previously demonstrated that postnatal day 11–20 ±3,4-methylenedioxymethamphetamine (MDMA) exposure reduces locomotor activity and impairs path integration and spatial learning independent of the effects on activity. The effects were seen when the drug was administered twice per day, but the optimal dosing regimen is unknown. We tested whether the same total daily dose of MDMA administered in different patterns would equally affect later behavior. A split-litter design (15 litters) was use...

  16. Chronic Unpredictable Stress Augments +3,4-Methylenedioxymethamphetamine (MDMA)-induced Monoamine Depletions: The Role of Corticosterone

    Johnson, Bethann N.; Yamamoto, Bryan K.

    2009-01-01

    Exposure to stress alters the behavioral and neurochemical effects of drugs of abuse. However, it is unknown if chronic stress can affect the serotonergic depletions induced by the psychostimulant drug 3,4-methylenedioxymethamphetamine (MDMA). Rats were exposed to 10 days of chronic unpredictable stress (CUS) which resulted in the predicted elevation of basal plasma corticosterone concentrations. On the 11th day, rats received 4 challenge doses of MDMA (5 mg/kg every 2 h, i.p.) or saline. Fiv...

  17. Reliability of poly 3,4-ethylenedioxythiophene strain gauge

    Mateiu, Ramona Valentina; Lillemose, Michael; Hansen, Thomas Steen;

    2007-01-01

    -polymer Microsystems. The measurements are made on microfabricated test chips with PEDT resistors patterned by conventional UV-lithography and reactive ion etching (RIE). We determine a gauge factor of 3.41 ± 0.42 for the strained PEDT and we see an increase in resistivity from 1.98 · 104 X m to 2.22 · 104 X m when......We report on the experimentally observed reliability of the piezoresistive effect in strained poly 3,4-ethylenedioxythiophene (PEDT). PEDT is an intrinsic conductive polymer which can be patterned by conventional Cleanroom processing, and thus presents a promising material for all...

  18. Developmental effects of 3,4-methylenedioxymethamphetamine: a review

    Skelton, Matthew R.; Williams, Michael T; Vorhees, Charles V.

    2008-01-01

    ± 3,4-Methylenedioxymethamphetamine (MDMA) is a chemical derivative of amphetamine that has become a popular drug of abuse and has been shown to deplete serotonin in the brains of users and animals exposed to it. To date, most studies have investigated the effects of MDMA on adult animals. With a majority of users of MDMA being young adults, the chances of the users becoming pregnant and exposing the fetuses to MDMA are also a concern. Evidence to date has shown that developmental exposure to...

  19. AGR 3/4 Irradiation Test Final As Run Report

    Collin, Blaise P. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-06-01

    Several fuel and material irradiation experiments have been planned for the Idaho National Laboratory Advanced Reactor Technologies Technology Development Office Advanced Gas Reactor Fuel Development and Qualification Program (referred to as the INL ART TDO/AGR fuel program hereafter), which supports the development and qualification of tristructural-isotropic (TRISO) coated particle fuel for use in HTGRs. The goals of these experiments are to provide irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, support development and validation of fuel performance and fission product transport models and codes, and provide irradiated fuel and materials for post irradiation examination and safety testing (INL 05/2015). AGR-3/4 combined the third and fourth in this series of planned experiments to test TRISO coated low enriched uranium (LEU) oxycarbide fuel. This combined experiment was intended to support the refinement of fission product transport models and to assess the effects of sweep gas impurities on fuel performance and fission product transport by irradiating designed-to-fail fuel particles and by measuring subsequent fission metal transport in fuel-compact matrix material and fuel-element graphite. The AGR 3/4 fuel test was successful in irradiating the fuel compacts to the burnup and fast fluence target ranges, considering the experiment was terminated short of its initial 400 EFPD target (Collin 2015). Out of the 48 AGR-3/4 compacts, 42 achieved the specified burnup of at least 6% fissions per initial heavy-metal atom (FIMA). Three capsules had a maximum fuel compact average burnup < 10% FIMA, one more than originally specified, and the maximum fuel compact average burnup was <19% FIMA for the remaining capsules, as specified. Fast neutron fluence fell in the expected range of 1.0 to 5.5×1025 n/m2 (E >0.18 MeV) for all compacts. In addition, the AGR-3/4 experiment was globally successful in keeping the

  20. 3,4-Diaminopyridinium 2-carboxy-4,6-dinitrophenolate

    Madhukar Hemamalini

    2010-11-01

    Full Text Available In the title salt, C5H8N3+·C7H3N2O7−, the pyridine N atom of the 3,4-diaminopyridine molecule is protonated. The 3,5-dinitrosalicylate anion shows whole-molecule disorder over two orientations with a refined occupancy ratio of 0.875 (4: 0.125 (4. In the crystal, the cations and anions are connected by intermolecular N—H...O and C—H...O hydrogen bonds, forming a three-dimensional network.

  1. Stereoselective Synthesis of 2,3,4,6-Tetrasubstituted Tetrahydropyrans

    GONG Jun-Fang; WU Yang-Jie; Véronique Micheletb; Jean-Pierre Genêt b

    2003-01-01

    @@ The construction of stereodefined, highly substituted tetrahydropyrans has attracted a lot of interest over the years since they constitute ubiquitous fragments of numerous biologically active natural products.[1] During the course of our synthetic studies toward ambruticin, a fascinating antibiotic[2] which came back in the front scene with three recent total synthesis, [3] we have been interested in the synthesis of 2,3,4,6-tetrasubstituted tetrahydropyrans 5 (Scheme 1). [4] Moreover, this kind of subunit is found to be embedded in several other natural products such as lasonolide A, polycavernoside A, ratjadone, or concanamycin A.

  2. Ultraporous poly(3,4-ethylenedioxythiophene) for nanometric electrochemical supercapacitor

    Ultrathin films of poly(3,4-ethylenedioxythiophene) (PEDOT) have been prepared by electropolymerization on steel and indium-tin oxide (ITO) substrates under identical experimental conditions. Scanning electron microscopy and atomic force microscopy indicate that the substrate affects dramatically both the morphology and topography of films when the polymerization times are very short. An ultraporous three-dimensional network involving ultrathin sticks with a fiber-like morphology was formed on ITO. Asymmetric and symmetric supercapacitors have been fabricated by assembling electrodes of PEDOT deposited on ITO and steel. The specific capacitance, electrochemical stability, supercapacitor behavior and Coulombic efficiency measured for devices with an ITO/steel configuration were similar to those reported for advanced PEDOT-inorganic hybrid composites. Furthermore, the performance of the ITO/steel assembly is higher than those determined for symmetric supercapacitors derived from two identical electrodes of PEDOT deposited on steel or on ITO. The unique properties of the asymmetric supercapacitors have been attributed to the ultraporous structure of the ultrathin films deposited on ITO, which is not significantly perturbed when the device is submitted to a very high number of consecutive oxidation–reduction processes, and the different electroactivities of the two electrodes. - Highlights: ► Ultrathin poly(3,4-ethylenedioxythiophene) (PEDOT) films show fiber-like morphology. ► The porosity of ultrathin PEDOT films induces a very high electrochemical stability. ► Asymmetric supercapacitors made of ultrathin PEDOT behave like hybrid nanocomposites.

  3. Uncertainty Quantification of Calculated Temperatures for the AGR 3/4 Experiment

    Pham, Binh Thi-Cam [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    A series of Advanced Gas Reactor (AGR) irradiation experiments are being conducted within the Advanced Reactor Technology (ART) Fuel Development and Qualification Program. The main objectives of the fuel experimental campaign are to provide the necessary data on fuel performance to support fuel process development, qualify a fuel design and fabrication process for normal operation and accident conditions, and support development and validation of fuel performance and fission product transport models and codes (PLN 3636, “Technical Program Plan for INL Advanced Reactor Technologies Technology Development Office/Advanced Gas Reactor Fuel Development and Qualification Program”). The AGR 3/4 test was inserted in the Northeast Flux Trap position in the Advanced Test Reactor (ATR) core at Idaho National Laboratory (INL) in December 2011 and successfully completed irradiation in mid-April 2014, resulting in irradiation of the tristructural isotropic (TRISO) fuel for 369.1 effective full-power days (EFPDs) during approximately 2.4 calendar years. The AGR 3/4 data, including the irradiation data and calculated results, were qualified and stored in the Nuclear Data Management and Analysis System (NDMAS). To support the U.S. TRISO fuel performance assessment and to provide data for validation of fuel performance and fission product transport models and codes, the daily as run thermal analysis has been performed separately on each of twelve AGR 3/4 capsules for the entire irradiation as discussed in ECAR-2807, “AGR 3/4 Daily As Run Thermal Analyses”. The ABAQUS code’s finite element-based thermal model predicts the daily average volume average (VA) fuel temperature (FT), peak FT, and graphite matrix, sleeve, and sink temperature in each capsule. The JMOCUP simulation codes were also created to perform depletion calculations for the AGR 3/4 experiment (ECAR-2753, “JMOCUP As-Run Daily Physics Depletion Calculation for the AGR 3/4 TRISO Particle Experiment in ATR

  4. Uncertainty Quantification of Calculated Temperatures for the AGR 3/4 Experiment

    A series of Advanced Gas Reactor (AGR) irradiation experiments are being conducted within the Advanced Reactor Technology (ART) Fuel Development and Qualification Program. The main objectives of the fuel experimental campaign are to provide the necessary data on fuel performance to support fuel process development, qualify a fuel design and fabrication process for normal operation and accident conditions, and support development and validation of fuel performance and fission product transport models and codes (PLN 3636, 'Technical Program Plan for INL Advanced Reactor Technologies Technology Development Office/Advanced Gas Reactor Fuel Development and Qualification Program'). The AGR 3/4 test was inserted in the Northeast Flux Trap position in the Advanced Test Reactor (ATR) core at Idaho National Laboratory (INL) in December 2011 and successfully completed irradiation in mid-April 2014, resulting in irradiation of the tristructural isotropic (TRISO) fuel for 369.1 effective full-power days (EFPDs) during approximately 2.4 calendar years. The AGR 3/4 data, including the irradiation data and calculated results, were qualified and stored in the Nuclear Data Management and Analysis System (NDMAS). To support the U.S. TRISO fuel performance assessment and to provide data for validation of fuel performance and fission product transport models and codes, the daily as run thermal analysis has been performed separately on each of twelve AGR 3/4 capsules for the entire irradiation as discussed in ECAR-2807, 'AGR 3/4 Daily As Run Thermal Analyses'. The ABAQUS code's finite element-based thermal model predicts the daily average volume average (VA) fuel temperature (FT), peak FT, and graphite matrix, sleeve, and sink temperature in each capsule. The JMOCUP simulation codes were also created to perform depletion calculations for the AGR 3/4 experiment (ECAR-2753, 'JMOCUP As-Run Daily Physics Depletion Calculation for the AGR 3/4 TRISO Particle

  5. A Day For Love

    2009-01-01

    Young couples drive Valentine’s Day booms in China It is not clear when Chinese couplesstarted celebrating Valentine’s Day,but it has now firmly established itself as an important day around the Spring Festival,

  6. A modified Kelvin impact model for pounding simulation of base-isolated building with adjacent structures

    Ye Kun; Li Li; Zhu Hongping

    2009-01-01

    Base isolation can effectively reduce the seismic forces on a superstructure, particularly in low- to medium-rise buildings. However, under strong near-fault ground motions, pounding may occur at the isolation level between the base-isolated building (BIB) and its surrounding retaining walls. To effectively investigate the behavior of the BIB pounding with adjacent structures, after assessing some commonly used impact models, a modified Kelvin impact model is proposed in this paper. Relevant parameters in the modified Kelvin model are theoretically derived and numerically verified through a simple pounding case. At the same time, inelasticity of the isolated superstructure is introduced in order to accurately evaluate the potential damage to the superstructure caused by the pounding of the BIB with adjacent structures. The reliability of the modified Kelvin impact model is validated through numerical comparisons with other impact models. However, the difference between the numerical results from the various impact analytical models is not significant. Many numerical simulations of BIBs are conducted to investigate the influence of various design parameters and conditions on the peak inter-story drills and floor accelerations during pounding. It is shown that pounding can substantially increase floor accelerations, especially at the ground floor where impacts occur. Higher modes of vibration are excited during poundings, increasing the inter-story drifts instead of keeping a nearly rigid-body motion of the superstructure. Furthermore, higher ductility demands can be imposed on lower floors of the superstructure. Moreover, impact stiffness seems to play a significant role in the acceleration response at the isolation level and the inter-story drifts of lower floors of the superstructure. Finally, the numerical results show that excessive flexibility of the isolation system used to minimize the floor accelerations may cause the BIB to be more susceptible to pounding

  7. Tetrakis(μ-3,4-dimethoxyphenylacetatobis[(3,4-dimethoxyphenylacetato(1,10-phenanthrolineholmium(III

    Jian-Feng Liu

    2010-10-01

    Full Text Available In the centrosymmetric title compound, [Ho2(C10H11O46(C12H8N22], the HoIII atom is nine-coordinated by seven O atoms from the 3,4-dimethoxyphenylacetate (L anions and two N atoms from a 1,10-phenanthroline (phen molecule. The L ligands are coordinated to the HoIII ions in three modes: chelating, bridging and bridging–tridentate. Intramolecular C—H...O interactions occur. The crystal packing is stabilized by intermolecular C—H...O interactions and weak aromatic π–π interactions between phen molecules and the aromatic rings of the L ligands [centroid–centroid distance = 3.821 (2 Å].

  8. COMPENSATION OF MEASUREMENT ERRORS WHEN REDUCING LINEAR DIMENSIONS OF THE KELVIN PROBE

    A. K. Tyavlovsky

    2013-01-01

    Full Text Available The study is based on results of modeling of measurement circuit containing vibrating-plate capacitor using a complex-harmonic analysis technique. Low value of normalized frequency of small-sized scanning Kelvin probe leads to high distortion factor of probe’s measurement signal that in turn leads to high measurement errors. The way to lower measurement errors is to register measurement signal on its second harmonic and to control the probe-to-sample gap by monitoring the ratio between the second and the first harmonics’ amplitudes.

  9. Analysis of Kelvin Probe operational models with application to SR-POEM

    We present a study of several models on which Kelvin Probe (KP) instruments with flat and spherical tips rely for operation and for the determination of the contact potential difference (CPD). The study is part of the development of a high-performance KP instrument that will be used in investigations of the patch effect for the sounding rocket principle of equivalence measurement experiment. Using covariance analysis for each model we investigate its performance as imposed by the Cramer-Rao bounds and the biases introduced in the estimation of the CPD, as well as its applicability to instrument control. (papers)

  10. Surface potential imaging of CNT-FET devices by scanning Kelvin probe microscopy

    We investigated the surface potential around nanotube channel during CNT-FET operation by scanning Kelvin probe microscopy (SKPM). The results demonstrate that the local surface potential distribution depends on the fabrication process of FET devices. We also measured the transfer characteristic of CNT-FET and compared with the surface potential image. In addition, we investigate the specific FET device with the closed CNT loops into which channel CNT penetrates. The surface potential distribution is completely different with that of a simple single CNT channel. We find that the closed loop of CNT has a capability of trapping the charge inside the loop

  11. Sample preparation for scanning Kelvin probe microscopy studies on cross sections of organic solar cells

    Michael Scherer

    2013-09-01

    Full Text Available We prepared cross sections of P3HT:PCBM bulk heterojunction (BHJ organic solar cells (OSCs for the characterization of their potential distribution with scanning Kelvin probe microscopy. We compared results of samples obtained by microtome cutting of OSCs on plastic substrates, cleaving of OSCs on glass substrates, and milling with a focused ion beam. Their potential distributions were in good agreement with each other. Under short circuit conditions, potential gradients were detected in vicinity of the electrode/organics interfaces, with negligible electric fields within the bulk. We contacted the OSCs in a defined manner and studied their potential distribution under operating conditions.

  12. Work function of few layer graphene covered nickel thin films measured with Kelvin probe force microscopy

    Few layer graphene and graphite are simultaneously grown on a ∼100 nm thick polycrystalline nickel film. The work function of few layer graphene/Ni is found to be 4.15 eV with a variation of 50 meV by local measurements with Kelvin probe force microscopy. This value is lower than the work function of free standing graphene due to peculiar electronic structure resulting from metal 3d-carbon 2p(π) hybridization

  13. The role of the cantilever in Kelvin probe force microscopy measurements

    George Elias

    2011-05-01

    Full Text Available The role of the cantilever in quantitative Kelvin probe force microscopy (KPFM is rigorously analyzed. We use the boundary element method to calculate the point spread function of the measuring probe: Tip and cantilever. The calculations show that the cantilever has a very strong effect on the absolute value of the measured contact potential difference even under ultra-high vacuum conditions, and we demonstrate a good agreement between our model and KPFM measurements in ultra-high vacuum of NaCl monolayers grown on Cu(111. The effect of the oscillating cantilever shape on the KPFM resolution and sensitivity has been calculated and found to be relatively small.

  14. Integrated scanning kelvin probe scanning electrochemical microscopy system : design, development and applications

    Maljusch, Artjom

    2012-01-01

    Ein integriertes System, das auf einer Kelvin-Sonde und einem elektrochemischen Rastermikroskop basiert, wurde entwickelt und aufgebaut. Der Vorteil dieses Systems besteht darin, dass es sequenzielle Experimente im SKP-Modus und unterschiedlichen SECM-Modi mit der gleichen Elektrode und über der gleichen Stelle auf der Probenoberfläche durchführen kann. Die speziell entwickelten "glasfreien" SKP-SECM-Elektroden ermöglichen eine hohe laterale Auflösung. Das System wurde für die Unt...

  15. COMPENSATION OF MEASUREMENT ERRORS WHEN REDUCING LINEAR DIMENSIONS OF THE KELVIN PROBE

    Tyavlovsky, A. K.; A. L. Zharin

    2015-01-01

    The study is based on results of modeling of measurement circuit containing vibrating-plate capacitor using a complex-harmonic analysis technique. Low value of normalized frequency of small-sized scanning Kelvin probe leads to high distortion factor of probe’s measurement signal that in turn leads to high measurement errors. The way to lower measurement errors is to register measurement signal on its second harmonic and to control the probe-to-sample gap by monitoring the ratio between the se...

  16. Note: Switching crosstalk on and off in Kelvin probe force microscopy

    In Kelvin Probe Force Microscopy (KPFM) electronic crosstalk can occur between the excitation signal and probe deflection signal. Here, we demonstrate how a small modification to our commercial instrument enables us to literally switch the crosstalk on and off. We study in detail the effect of crosstalk on open-loop KPFM and compare with closed-loop KPFM. We measure the pure crosstalk signal and verify that we can correct for it in the data-processing required for open-loop KPFM. We also demonstrate that open-loop KPFM results are independent of the frequency and amplitude of the excitation signal, provided that the influence of crosstalk has been eliminated

  17. Kelvin probe force microscopy study of ion implanted thermal oxide thin films on silicon

    Full text: Ion implantation through gate oxides may be used for future device fabrication. However, studies of the damage created have mostly been restricted to optical and magnetic studies with EPR, PL and IR absorption. We have studied the surface potential of keV energy P implanted 15 nm thermal oxides on silicon substrates with Kelvin probe Force Microscopy. Results have shown a surface potential change while there may not be any observed change in the topology. Analytical and numerical modeling has also been used to relate the change in potential to net charge. Copyright (2005) Australian Institute of Physics

  18. Investigation of the depletion layer by scanning capacitance force microscopy with Kelvin probe force microscopy

    Uruma, Takeshi; Satoh, Nobuo; Yamamoto, Hidekazu

    2016-08-01

    We have developed a scanning probe microscope (SPM) that combines atomic force microscopy (AFM) with both Kelvin probe force microscopy (KFM — to measure the surface potential) and scanning capacitance force microscopy (SCFM — to measure the differential capacitance). The surface physical characteristics of a commercial Si Schottky barrier diode (Si-SBD), with and without an applied reverse bias, were measured over the same area by our AFM/KFM/SCFM system. We thus investigated the discrete power device by calculating the depletion-layer width and drawing an energy-band diagram.

  19. Sub-milliKelvin spatial thermometry of a single Doppler cooled ion in a Paul trap

    Knünz, S.; Herrmann, M; Batteiger, V.; Saathoff, G.; Hänsch, T. W.; Udem, Th.

    2012-01-01

    We report on observations of thermal motion of a single, Doppler-cooled ion along the axis of a linear radio-frequency quadrupole trap. We show that for a harmonic potential the thermal occupation of energy levels leads to Gaussian distribution of the ion's axial position. The dependence of the spatial thermal spread on the trap potential is used for precise calibration of our imaging system's point spread function and sub-milliKelvin thermometry. We employ this technique to investigate the l...

  20. Sub-milliKelvin spatial thermometry of a single Doppler cooled ion in a Paul trap

    Knünz, S; Batteiger, V; Saathoff, G; Hänsch, T W; Udem, Th; 10.1103/PhysRevA.85.023427

    2012-01-01

    We report on observations of thermal motion of a single, Doppler-cooled ion along the axis of a linear radio-frequency quadrupole trap. We show that for a harmonic potential the thermal occupation of energy levels leads to Gaussian distribution of the ion's axial position. The dependence of the spatial thermal spread on the trap potential is used for precise calibration of our imaging system's point spread function and sub-milliKelvin thermometry. We employ this technique to investigate the laser detuning dependence of the Doppler temperature.

  1. Measuring Method of a Surface Property inside the Pore: Application of Kelvin's equation

    Amano, Ken-ichi

    2015-01-01

    Surface analyses inside the nanopore, micropore, and a very narrow pipe are important topics for development of the chemical engineering. Here, we propose a measuring method which evaluates the surface coverage of the chemically modified pore surface and the corrosion rate of the inner surface of the narrow pipe, etc. The method uses Kelvin's equation that expresses saturated vapor pressure of a liquid in the pore (pipe). The surface coverage and the corrosion rate are calculated by measuring saturated vapor pressure of the liquid in the pore and the pipe, respectively. In this letter, we explain the concept of the method briefly.

  2. Charge behavior on insulating monocrystallic surfaces by Kelvin probe force microscopy

    Full text: Detailed knowledge on the contact charging behavior of dielectric materials is of great interest for technological applications like tribocharging separation. The underlying mechanisms are still not well understood. The charging of quartz and calcite single crystal surfaces upon contact with an Atomic Force Microscope tip has been investigated using Kelvin Probe Force Microscopy. It turned out that the charging is strongly influenced by the sample history. Especially contact with different forms of water (bulk water or humid air) and sample heat treatment change the charging/discharging behavior significantly. (author)

  3. Work function of few layer graphene covered nickel thin films measured with Kelvin probe force microscopy

    Eren, B. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Material Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Gysin, U.; Marot, L., E-mail: Laurent.marot@unibas.ch; Glatzel, Th.; Steiner, R.; Meyer, E. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

    2016-01-25

    Few layer graphene and graphite are simultaneously grown on a ∼100 nm thick polycrystalline nickel film. The work function of few layer graphene/Ni is found to be 4.15 eV with a variation of 50 meV by local measurements with Kelvin probe force microscopy. This value is lower than the work function of free standing graphene due to peculiar electronic structure resulting from metal 3d-carbon 2p(π) hybridization.

  4. Mixed initial-boundary value problem for equations of motion of Kelvin-Voigt fluids

    Baranovskii, E. S.

    2016-07-01

    The initial-boundary value problem for equations of motion of Kelvin-Voigt fluids with mixed boundary conditions is studied. The no-slip condition is used on some portion of the boundary, while the impermeability condition and the tangential component of the surface force field are specified on the rest of the boundary. The global-in-time existence of a weak solution is proved. It is shown that the solution is unique and depends continuously on the field of external forces, the field of surface forces, and initial data.

  5. Stability for the Timoshenko Beam System with Local Kelvin-Voigt Damping

    Hong Liang ZHAO; Kang Sheng LIU; Chun Guo ZHANG

    2005-01-01

    In this paper, we consider a vibrating beam with one segment made of viscoelastic material of a Kelvin-Voigt (shorted as K-V) type and other parts made of elastic material by means of the Timoshenko model. We have deduced mathematical equations modelling its vibration and studied the stability of the semigroup associated with the equation system. We obtain the exponential stability under certain hypotheses of the smoothness and structural condition of the coefficients of the system,and obtain the strong asymptotic stability under weaker hypotheses of the coefficients.

  6. Two- and three-dimensional behavior of Rayleigh-Taylor and Kelvin-Helmholtz instabilities

    Two- and three-dimensional behavior of the Rayleigh-Taylor (R-T) and Kelvin-Helmholts (K-H) instabilities is examined with a newly developed hydrodynamic code CIP (Cubic Interpolated Pseudoparticle). The mushroom structure owing to the K-H instability is quite different in two and three dimensions. The simulation without gravity show a similar behavior and hence this difference between two and three dimensions does not originate from the R-T instability. This difference cannot be explained by a linear analysis on the K-H instability also. (author)

  7. Nonlinear evolution of the magnetized Kelvin-Helmholtz instability: From fluid to kinetic modeling

    Henri, P.; Cerri, S.S.; Califano, F.; Pegoraro, F.; Rossi, C.; Faganello, M.; Šebek, Ondřej; Trávníček, Pavel M.; Hellinger, Petr; Frederiksen, J. T.; Nordlund, A.; Markidis, S.; Keppens, R.; Lapenta, G.

    2013-01-01

    Roč. 20, č. 10 (2013), 102118/1-102118/13. ISSN 1070-664X Grant ostatní: EU(XE) SWIFF Project No. 263340; European Commission(XE) HPC-EUROPA2 - No. 228398; EU(XE) RI-283493; NASA (US) NNX11A1164G Institutional support: RVO:67985815 ; RVO:68378289 Keywords : Kelvin-Helmholtz instability * plasma kinetic theory * plasma magnetohydrodynamics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics; BL - Plasma and Gas Discharge Physics (UFA-U) Impact factor: 2.249, year: 2013

  8. Day to Day Life of Transnational Couples

    Ferreira, Tatiana

    2016-01-01

    In this chapter we focus on the ways that transnational spatial mobility affects the production and reproduction of daily life of couples when one of the partners migrates alone. The aim is to examine the impact of male migration on day to day life of couples in which the partners are geographically separated across nation-state borders. V/e will adopt a transnational approach in order to recognize the importance of the connections between migrants and their family members b...

  9. Mother’s Day

    张萍

    2009-01-01

    Mother’s Day is a day for each family to honor (尊敬,给……以光荣) its mother ,celebrated (庆祝)on various days in many places around the world.It complements (补足,补充) Father’s Day,the celebration

  10. [Monograph for 3-(4-methylbenzylidene)camphor (4-MBC)--HBM values for the sum of metabolites 3-(4-carboxybenzylidene)camphor (3-4CBC) and 3-(4-carboxybenzylidene)-6-hydroxycamphor (3-4 CBHC) in the urine of adults and children. Statement of the HBM Commission of the German Federal Environment Agency].

    2016-01-01

    The substance 3-(4-methylbenzylidene)camphor (4-MBC, CAS-No. 36861-47-9 as well as 38102-62-4) is used as UV-filter in cosmetics, mainly in sunscreen lotions. National as well as European evaluations are available for the substance, especially from the Scientific Committee on Consumer Products (SCCP). The SCCP did not derive a TDI-value, but used for a MoS assessment a NOAEL of 25 mg/(kg bw · d) based on effects on the thyroid gland of rats in a subchronic study with oral administration. Newer studies, however, indicate lower NOAEL values, leading to tolerable daily intakes of 0,01 mg/kg bw. The HBM Commission established for the metabolite 3-(4-carboxybenzylidene)camphor (3-4CBC) HBM-I values of 0,09 mg/l urine for adults and 0,06 mg/l urine for children. HBM-I values for the metabolite 3-(4-carboxybenzylidene)-6-hydroxycamphor (3-4CBHC) were set at 0,38 mg/l urine for adults and 0,25 mg/l urine for children. The rounded HBM-I value for the sum of metabolites 3-4CBC und 3-4CBHC is accordingly 0,5 mg/l urine for adults and 0,3 mg/l urine for children. PMID:26721474