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Sample records for surface resistance equation

  1. The Poisson equation on Klein surfaces

    Directory of Open Access Journals (Sweden)

    Monica Rosiu

    2016-04-01

    Full Text Available We obtain a formula for the solution of the Poisson equation with Dirichlet boundary condition on a region of a Klein surface. This formula reveals the symmetric character of the solution.

  2. Corrosion-resistant metal surfaces

    Science.gov (United States)

    Sugama, Toshifumi [Wading River, NY

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  3. Dirac equation on a curved surface

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, F.T., E-mail: fbrandt@usp.br; Sánchez-Monroy, J.A., E-mail: antosan@usp.br

    2016-09-07

    The dynamics of Dirac particles confined to a curved surface is examined employing the thin-layer method. We perform a perturbative expansion to first-order and split the Dirac field into normal and tangential components to the surface. In contrast to the known behavior of second order equations like Schrödinger, Maxwell and Klein–Gordon, we find that there is no geometric potential for the Dirac equation on a surface. This implies that the non-relativistic limit does not commute with the thin-layer method. Although this problem can be overcome when second-order terms are retained in the perturbative expansion, this would preclude the decoupling of the normal and tangential degrees of freedom. Therefore, we propose to introduce a first-order term which rescues the non-relativistic limit and also clarifies the effect of the intrinsic and extrinsic curvatures on the dynamics of the Dirac particles. - Highlights: • The thin-layer method is employed to derive the Dirac equation on a curved surface. • A geometric potential is absent at least to first-order in the perturbative expansion. • The effects of the extrinsic curvature are included to rescue the non-relativistic limit. • The resulting Dirac equation is consistent with the Heisenberg uncertainty principle.

  4. Aspheric surface testing by irradiance transport equation

    Science.gov (United States)

    Shomali, Ramin; Darudi, Ahmad; Nasiri, Sadollah; Asgharsharghi Bonab, Armir

    2010-10-01

    In this paper a method for aspheric surface testing is presented. The method is based on solving the Irradiance Transport Equation (ITE).The accuracy of ITE normally depends on the amount of the pick to valley of the phase distribution. This subject is investigated by a simulation procedure.

  5. Surface electrical resistivity of insulators

    International Nuclear Information System (INIS)

    Senn, B. C.; Liesegang, J.

    1996-01-01

    A method is presented here for measuring surface charge decay, and theory has been developed so as to produce determinations of resistivity in the surface region of insulator films or wafers. This method incorporates the use of a coaxial cylindrical capacitor arrangement and an electrometer interfaced to a PC. The charge transport theory given here is based on Mott-Gurney diffusion, and allows easy interpretation of the experimental data, especially for the initial phase of surface charge decay. Resistivity measurements are presented for glass, mica, perspex and polyethylene, covering a range of 10 9 to 10 18 Ωm, as an illustration of the useful range of the instrument for static and antistatic materials, particularly in film or sheet form. Values for the surface charge diffusion constants of the materials are also presented. The charge transport theory has also been extended to allow the experimental and computational theoretical comparison of surface charge decay not only over the initial phase of charge decay, but also over longer times. The theoretical predictions show excellent agreement with experiment using the values for the diffusion constants referred to above

  6. Wave Equation Inversion of Skeletonized SurfaceWaves

    KAUST Repository

    Zhang, Zhendong; Liu, Yike; Schuster, Gerard T.

    2015-01-01

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh dispersion curve for the fundamental-mode. We call this wave equation inversion of skeletonized surface waves because the dispersion curve

  7. Equations for the non linear evolution of the resistive tearing modes in toroidal plasmas

    International Nuclear Information System (INIS)

    Edery, D.; Pellat, R.; Soule, J.L.

    1979-09-01

    Following the tokamak ordering, we simplify the resistive MHD equations in toroidal geometry. We obtain a closed system of non linear equations for two scalar potentials of the magnetic and velocity fields and for plasma density and temperature. If we expand these equations in the inverse of aspect ratio they are exact to the two first orders. Our formalism should correctly describe the mode coupling by curvature effects /1/ and the toroidal displacement of magnetic surfaces /2/. It provides a natural extension of the well known cylindrical model /3/ and is now being solved on computer

  8. Surface impedance and optimum surface resistance of a superconductor with an imperfect surface

    Science.gov (United States)

    Gurevich, Alex; Kubo, Takayuki

    2017-11-01

    We calculate a low-frequency surface impedance of a dirty, s -wave superconductor with an imperfect surface incorporating either a thin layer with a reduced pairing constant or a thin, proximity-coupled normal layer. Such structures model realistic surfaces of superconducting materials which can contain oxide layers, absorbed impurities, or nonstoichiometric composition. We solved the Usadel equations self-consistently and obtained spatial distributions of the order parameter and the quasiparticle density of states which then were used to calculate a low-frequency surface resistance Rs(T ) and the magnetic penetration depth λ (T ) as functions of temperature in the limit of local London electrodynamics. It is shown that the imperfect surface in a single-band s -wave superconductor results in a nonexponential temperature dependence of Z (T ) at T ≪Tc which can mimic the behavior of multiband or d -wave superconductors. The imperfect surface and the broadening of the gap peaks in the quasiparticle density of states N (ɛ ) in the bulk give rise to a weakly temperature-dependent residual surface resistance. We show that the surface resistance can be optimized and even reduced below its value for an ideal surface by engineering N (ɛ ) at the surface using pair-breaking mechanisms, particularly by incorporating a small density of magnetic impurities or by tuning the thickness and conductivity of the normal layer and its contact resistance. The results of this work address the limit of Rs in superconductors at T ≪Tc , and the ways of engineering the optimal density of states by surface nanostructuring and impurities to reduce losses in superconducting microresonators, thin-film strip lines, and radio-frequency cavities for particle accelerators.

  9. The differential equation of an arbitrary reflecting surface

    Science.gov (United States)

    Melka, Richard F.; Berrettini, Vincent D.; Yousif, Hashim A.

    2018-05-01

    A differential equation describing the reflection of a light ray incident upon an arbitrary reflecting surface is obtained using the law of reflection. The derived equation is written in terms of a parameter and the value of this parameter determines the nature of the reflecting surface. Under various parametric constraints, the solution of the differential equation leads to the various conic surfaces but is not generally solvable. In addition, the dynamics of the light reflections from the conic surfaces are executed in the Mathematica software. Our derivation is the converse of the traditional approach and our analysis assumes a relation between the object distance and the image distance. This leads to the differential equation of the reflecting surface.

  10. Numerical solution of the resistive magnetohydrodynamic boundary-layer equations

    International Nuclear Information System (INIS)

    Glasser, A.H.; Jardin, S.C.; Tesauro, G.

    1983-10-01

    Three different techniques are presented for numerical solution of the equations governing the boundary layer of resistive magnetohydrodynamic tearing and interchange instabilities in toroidal geometry. Excellent agreement among these methods and with analytical results provides confidence in the correctness of the results. Solutions obtained in regimes where analytical medthods fail indicate a new scaling for the tearing mode as well as the existence of a new regime of stability

  11. Comment on 'Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies'

    International Nuclear Information System (INIS)

    Gutman, E M

    2010-01-01

    In a recent publication by Olives (2010 J. Phys.: Condens. Matter 22 085005) he studied 'the thermodynamics and mechanics of the surface of a deformable body, following and refining the general approach of Gibbs' and believed that 'a new definition of the surface stress is given'. However, using the usual way of deriving the equations of Gibbs-Duhem type the author, nevertheless, has fallen into a mathematical discrepancy because he has tried to unite in one equation different thermodynamic systems and 'a new definition of the surface stress' has appeared known in the usual theory of elasticity. (comment)

  12. The KZB equations on Riemann surfaces

    OpenAIRE

    Felder, Giovanni

    1996-01-01

    In this paper, based on the author's lectures at the 1995 les Houches Summer school, explicit expressions for the Friedan--Shenker connection on the vector bundle of WZW conformal blocks on the moduli space of curves with tangent vectors at $n$ marked points are given. The covariant derivatives are expressed in terms of ``dynamical $r$-matrices'', a notion borrowed from integrable systems. The case of marked points moving on a fixed Riemann surface is studied more closely. We prove a universa...

  13. Surface-Controlled Metal Oxide Resistive Memory

    KAUST Repository

    Ke, Jr-Jian

    2015-10-28

    To explore the surface effect on resistive random-access memory (ReRAM), the impact of surface roughness on the characteristics of ZnO ReRAM were studied. The thickness-independent resistance and the higher switching probability of ZnO ReRAM with rough surfaces indicate the importance of surface oxygen chemisorption on the switching process. Furthermore, the improvements in switching probability, switching voltage and resistance distribution observed for ReRAM with rough surfaces can be attributed to the stable oxygen adatoms under various ambience conditions. The findings validate the surface-controlled stability and uniformity of ReRAM and can serve as the guideline for developing practical device applications.

  14. Linearised collective Schroedinger equation for nuclear quadrupole surface vibrations

    International Nuclear Information System (INIS)

    Greiner, M.; Heumann, D.; Scheid, W.

    1990-11-01

    The linearisation of the Schroedinger equation for nuclear quadrupole surface vibrations yields a new spin degree of freedom, which is called collective spin and has a value of 3/2. With the introduction of collective spin dependent potentials, this linearised Schroedinger equation is then used for the description of low energy spectra and electromagnetic transition probabilities of some even-odd Xe, Ir and Au nuclei which have a spin 3/2 in their groundstate. (orig.)

  15. Truncatable bootstrap equations in algebraic form and critical surface exponents

    Energy Technology Data Exchange (ETDEWEB)

    Gliozzi, Ferdinando [Dipartimento di Fisica, Università di Torino andIstituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1, Torino, I-10125 (Italy)

    2016-10-10

    We describe examples of drastic truncations of conformal bootstrap equations encoding much more information than that obtained by a direct numerical approach. A three-term truncation of the four point function of a free scalar in any space dimensions provides algebraic identities among conformal block derivatives which generate the exact spectrum of the infinitely many primary operators contributing to it. In boundary conformal field theories, we point out that the appearance of free parameters in the solutions of bootstrap equations is not an artifact of truncations, rather it reflects a physical property of permeable conformal interfaces which are described by the same equations. Surface transitions correspond to isolated points in the parameter space. We are able to locate them in the case of 3d Ising model, thanks to a useful algebraic form of 3d boundary bootstrap equations. It turns out that the low-lying spectra of the surface operators in the ordinary and the special transitions of 3d Ising model form two different solutions of the same polynomial equation. Their interplay yields an estimate of the surface renormalization group exponents, y{sub h}=0.72558(18) for the ordinary universality class and y{sub h}=1.646(2) for the special universality class, which compare well with the most recent Monte Carlo calculations. Estimates of other surface exponents as well as OPE coefficients are also obtained.

  16. Wave Equation Inversion of Skeletonized SurfaceWaves

    KAUST Repository

    Zhang, Zhendong

    2015-08-19

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh dispersion curve for the fundamental-mode. We call this wave equation inversion of skeletonized surface waves because the dispersion curve for the fundamental-mode Rayleigh wave is inverted using finite-difference solutions to the wave equation. The best match between the predicted and observed dispersion curves provides the optimal S-wave velocity model. Results with synthetic and field data illustrate the benefits and limitations of this method.

  17. Surface resistivity measurement of plasma treated polymers

    International Nuclear Information System (INIS)

    Simon, D.; Pigram, P.J.; Liesegang, J.

    2000-01-01

    Full text: Resistivity of insulators is an important property of materials used within the integrated circuit and packaging industries. The measurement of electrical resistivity of insulator materials in the surface region in this work is interpreted through observations of surface charge decay. A self-field driven and diffusion charge transport theory is used to model the process and resistivity values obtained computationally. Data for the charge decay of surface charged samples are collected by suspending them inside a coaxial cylinder connected to an electrometer. Samples used have been low density polyethylene LDPE sheet, both pristine and surface treated. Some samples have been treated by air plasma at low vacuum pressures for different periods of time; others have been washed in ethyl acetate and then plasma treated before the resistivity measurement. The sets of resistivity measurements form the various treatments are compared below. X-ray photoelectron spectroscopy (XPS) has also been used to investigate and account for the observed variations in surface resistivity

  18. Skeletonized wave equation of surface wave dispersion inversion

    KAUST Repository

    Li, Jing

    2016-09-06

    We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel-time inversion, the complicated surface-wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the (kx,ω) domain. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2D or 3D velocity models. This procedure, denoted as wave equation dispersion inversion (WD), does not require the assumption of a layered model and is less prone to the cycle skipping problems of full waveform inversion (FWI). The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distribution in laterally heterogeneous media.

  19. 3-D resistive MHD calculations for tokamak plasmas: beyond the simple reduced set of equations

    International Nuclear Information System (INIS)

    Carreras, B.A.; Garcia, L.; Hender, T.C.; Hicks, H.R.; Holmes, J.A.; Lynch, V.E.; Masden, B.F.

    1983-01-01

    Numerical studies of the resistive stability of tokamak plasmas in cylindrical geometry have been performed using: (1) the full set of resistive Magnetohydrodynamic (MHD) equations and (2) an extended version of the reduced set of resistive MHD equations including diamagnetic and electron temperature effects. In particular, the nonlinear interaction of tearing modes of many helicities has been investigated. The numerical results confirm many of the features uncovered previously using the simple reduced equations. (author)

  20. Erosion resistance comparison of alternative surface treatments

    Science.gov (United States)

    Česánek, Z.; Schubert, J.; Houdková, Š.

    2017-05-01

    Erosion is a process characterized by the particle separation and the damage of component functional surfaces. Thermal spraying technology HP/HVOF (High Pressure / High Velocity Oxygen Fuel) is commonly used for protection of component surfaces against erosive wear. Alloy as well as cermet based coatings meet the requirements for high erosion resistance. Wear resistance is in many cases the determining property of required component functioning. The application suitability of coating materials is particularly influenced by different hardness. This paper therefore presents an erosion resistance comparison of alloy and cermet based coatings. The coatings were applied on steel substrates and were subjected to the erosive test using the device for evaluation of material erosion resistance working on the principle of centrifugal erodent flow. Abrasive sand Al2O3 with grain size 212-250 μm was selected as an erosive material. For this purpose, the specimens were prepared by thermal spraying technology HP/HVOF using commercially available powders Stellite 6, NiCrBSi, Cr3C2-25%NiCr, Cr3C2-25%CoNiCrAlY, Hastelloy C-276 and experimental coating TiMoCN-29% Ni. Erosion resistance of evaluated coatings was compared with erosive resistance of 1.4923 high alloyed steel without nitridation and in nitrided state and further with surface treatment using technology PVD. According to the evaluation, the resulting erosive resistance depends not only on the selected erodent and surface protection, but also on the erodent impact angle.

  1. Finite difference method for inner-layer equations in the resistive MagnetoHydroDynamic stability analysis

    International Nuclear Information System (INIS)

    Tokuda, Shinji; Watanabe, Tomoko.

    1996-08-01

    The matching problem in resistive MagnetoHydroDynamic stability analysis by the asymptotic matching method has been reformulated as an initial-boundary value problem for the inner-layer equations describing the plasma dynamics in the thin layer around a rational surface. The third boundary conditions at boundaries of a finite interval are imposed on the inner layer equations in the formulation instead of asymptotic conditions at infinities. The finite difference method for this problem has been applied to model equations whose solutions are known in a closed form. It has been shown that the initial value problem and the associated eigenvalue problem for the model equations can be solved by the finite difference method with numerical stability. The formulation presented here enables the asymptotic matching method to be a practical method for the resistive MHD stability analysis. (author)

  2. Wave-equation Qs Inversion of Skeletonized Surface Waves

    KAUST Repository

    Li, Jing

    2017-02-08

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is the one that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs inversion (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to full waveform inversion (FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsurface Qs distribution as long as the Vs model is known with sufficient accuracy.

  3. Skeletonized wave-equation Qs tomography using surface waves

    KAUST Repository

    Li, Jing

    2017-08-17

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is then found that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs tomography (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to Q full waveform inversion (Q-FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsur-face Qs distribution as long as the Vs model is known with sufficient accuracy.

  4. Wave-equation Qs Inversion of Skeletonized Surface Waves

    KAUST Repository

    Li, Jing; Dutta, Gaurav; Schuster, Gerard T.

    2017-01-01

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is the one that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs inversion (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to full waveform inversion (FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsurface Qs distribution as long as the Vs model is known with sufficient accuracy.

  5. Solving the incompressible surface Navier-Stokes equation by surface finite elements

    Science.gov (United States)

    Reuther, Sebastian; Voigt, Axel

    2018-01-01

    We consider a numerical approach for the incompressible surface Navier-Stokes equation on surfaces with arbitrary genus g (S ) . The approach is based on a reformulation of the equation in Cartesian coordinates of the embedding R3, penalization of the normal component, a Chorin projection method, and discretization in space by surface finite elements for each component. The approach thus requires only standard ingredients which most finite element implementations can offer. We compare computational results with discrete exterior calculus simulations on a torus and demonstrate the interplay of the flow field with the topology by showing realizations of the Poincaré-Hopf theorem on n-tori.

  6. Chemically resistant, biocompatible and microstructured surface protection

    International Nuclear Information System (INIS)

    Hoffmann, W.; Pham, M.T.; Hueller, J.

    1984-01-01

    Subject of the invention are chemicallly resistant, biocompatible, and microstructured surface protective coatings of electronic elements and sensors including chemical sensors. Such coatings consist of a radiation-modified organic substance made of a microlithographic material. Modification can be achieved by irradiation with ions, atoms or molecules having an energy between 1 KeV and 1 MeV and a flux between 10 13 and 10 18 particles per cm 2

  7. Ernst Equation and Riemann Surfaces: Analytical and Numerical Methods

    International Nuclear Information System (INIS)

    Ernst, Frederick J

    2007-01-01

    extending the techniques espoused by these authors to other physica lly interesting problems (e.g., when electromagnetic fields are involved) are discussed. In addition to these eight chapters, there are two appendices. The first concerns the theory of Riemann surfaces and the second describes the relationship between the Ernst equation and twistor theory. It should be mentioned that this book may be considered to be an homage to Olaf Richter, whose very promising research life ended prematurely in November 2003. Indeed, a substantial part of the book is based upon his habilitation thesis. It is the reviewer's opinion that the resulting book will be more useful as a resource for those who are already well versed in the subject of integrable systems than as an educational tool for novices who would like to enter this exciting branch of mathematical physics. (book review)

  8. Modelling the Influence of Ground Surface Relief on Electric Sounding Curves Using the Integral Equations Method

    Directory of Open Access Journals (Sweden)

    Balgaisha Mukanova

    2017-01-01

    Full Text Available The problem of electrical sounding of a medium with ground surface relief is modelled using the integral equations method. This numerical method is based on the triangulation of the computational domain, which is adapted to the shape of the relief and the measuring line. The numerical algorithm is tested by comparing the results with the known solution for horizontally layered media with two layers. Calculations are also performed to verify the fulfilment of the “reciprocity principle” for the 4-electrode installations in our numerical model. Simulations are then performed for a two-layered medium with a surface relief. The quantitative influences of the relief, the resistivity ratios of the contacting media, and the depth of the second layer on the apparent resistivity curves are established.

  9. Rate equation analysis of hydrogen uptake on Si (100) surfaces

    International Nuclear Information System (INIS)

    Inanaga, S.; Rahman, F.; Khanom, F.; Namiki, A.

    2005-01-01

    We have studied the uptake process of H on Si (100) surfaces by means of rate equation analysis. Flowers' quasiequilibrium model for adsorption and desorption of H [M. C. Flowers, N. B. H. Jonathan, A. Morris, and S. Wright, Surf. Sci. 396, 227 (1998)] is extended so that in addition to the H abstraction (ABS) and β 2 -channel thermal desorption (TD) the proposed rate equation further includes the adsorption-induced desorption (AID) and β 1 -TD. The validity of the model is tested by the experiments of ABS and AID rates in the reaction system H+D/Si (100). Consequently, we find it can well reproduce the experimental results, validating the proposed model. We find the AID rate curve as a function of surface temperature T s exhibits a clear anti-correlation with the bulk dangling bond density versus T s curve reported in the plasma-enhanced chemical vapor deposition (CVD) for amorphous Si films. The significance of the H chemistry in plasma-enhanced CVD is discussed

  10. Comment on 'Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies'

    Energy Technology Data Exchange (ETDEWEB)

    Gutman, E M, E-mail: gutman@bgu.ac.i [Department of Materials Engineering, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105 (Israel)

    2010-10-27

    In a recent publication by Olives (2010 J. Phys.: Condens. Matter 22 085005) he studied 'the thermodynamics and mechanics of the surface of a deformable body, following and refining the general approach of Gibbs' and believed that 'a new definition of the surface stress is given'. However, using the usual way of deriving the equations of Gibbs-Duhem type the author, nevertheless, has fallen into a mathematical discrepancy because he has tried to unite in one equation different thermodynamic systems and 'a new definition of the surface stress' has appeared known in the usual theory of elasticity. (comment)

  11. Skeletonized wave equation of surface wave dispersion inversion

    KAUST Repository

    Li, Jing; Schuster, Gerard T.

    2016-01-01

    We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel

  12. Calculations of stationary solutions for the non linear viscous resistive MHD equations in slab geometry

    International Nuclear Information System (INIS)

    Edery, D.

    1983-11-01

    The reduced system of the non linear resistive MHD equations is used in the 2-D one helicity approximation in the numerical computations of stationary tearing modes. The critical magnetic Raynolds number S (S=tausub(r)/tausub(H) where tausub(R) and tausub(H) are respectively the characteristic resistive and hydro magnetic times) and the corresponding linear solution are computed as a starting approximation for the full non linear equations. These equations are then treated numerically by an iterative procedure which is shown to be rapidly convergent. A numerical application is given in the last part of this paper

  13. Effect of non-uniform surface resistance on the quality factor of superconducting niobium cavity

    Science.gov (United States)

    Tan, Weiwei; Lu, Xiangyang; Yang, Ziqin; Zhao, Jifei; Yang, Deyu; Yang, Yujia

    2016-08-01

    The formula Rs = G /Q0 is commonly used in the calculation of the surface resistance of radio frequency niobium superconducting cavities. The applying of such equation is under the assumption that surface resistance is consistent over the cavity. However, the distribution of the magnetic field varies over the cavity. The magnetic field in the equator is much higher than that in the iris. According to Thermal Feedback Theory, it leads non-uniform distribution of the density of heat flux, which results in a different temperature distribution along the cavity inter surface. The BCS surface resistance, which depends largely on the temperature, is different in each local inner surface. In this paper, the effect of surface non-uniform resistance on the quality factor has been studied, through the calculation of Q0 in the original definition of it. The results show that it is necessary to consider the non-uniform distribution of magnetic field when the accelerating field is above 20 MV/m for TESLA cavities. Also, the effect of inhomogeneity of residual resistance on the quality factor is discussed. Its distribution barely affects the quality factor.

  14. A Relation Between the Eikonal Equation Associated to a Potential Energy Surface and a Hyperbolic Wave Equation.

    Science.gov (United States)

    Bofill, Josep Maria; Quapp, Wolfgang; Caballero, Marc

    2012-12-11

    The potential energy surface (PES) of a molecule can be decomposed into equipotential hypersurfaces. We show in this article that the hypersurfaces are the wave fronts of a certain hyperbolic partial differential equation, a wave equation. It is connected with the gradient lines, or the steepest descent, or the steepest ascent lines of the PES. The energy seen as a reaction coordinate plays the central role in this treatment.

  15. Surface resistance of superconductors - examples from Nb - O systems

    International Nuclear Information System (INIS)

    Palmer, F.

    1988-01-01

    The observed surface resistance of most superconductors can be written as the sum of two terms. R/sub obs/ = R/sub BCS/ + R/sub res/. This paper is divided into three sections. The first section describes the BCS theory of surface resistance in terms of a simplified two-fluid model. The second section describes several possible causes of residual resistance including normal conducting materials, tunneling across cracks in the surface, and direct generation of phonons by the RF electric field. The last section describes recent experiments having to do with the effects of oxide layers on surface resistance. Layers grown in pure oxygen at room temperature were found to have little or no effect, but if these layers are heated to temperatures near 300 0 C, they can alter both the BCS resistance and the residual resistance. Heated oxide layers also increased the dependence of the residual resistance on ambient magnetic field. 31 references, 13 figures, 3 tables

  16. Beltrami algebra and symmetry of Beltrami equation on Riemann surfaces

    International Nuclear Information System (INIS)

    Guo Hanying; Xu Kaiwen; Shen Jianmin; Wang Shikun

    1989-12-01

    It is shown that the Beltrami equation has an infinite dimensional symmetry, namely the Beltrami algebra, on its solution spaces. The Beltrami algebra with central extension and its supersymmetric version are explicitly found. (author). 12 refs

  17. Solution of the time-dependent, three-dimensional resistive magnetohydrodynamic equations

    International Nuclear Information System (INIS)

    Finan, C.H. III; Killeen, J.; California Univ., Davis

    1981-01-01

    Resistive magnetohydrodynamics (MHD) is described by a set of eight coupled, nonlinear, three-dimensional, time-dependent, partial differential equations. A computer code, IMP (Implicit MHD Program), has been developed to solve these equations numerically by the method of finite differences on an Eulerian mesh. In this model, the equations are expressed in orthogonal curvilinear coordinates, making the code applicable to a variety of coordinate systems. The Douglas-Gunn algorithm for Alternating-Direction Implicit (ADI) temporal advancement is used to avoid the limitations in timestep size imposed by explicit methods. The equations are expressed as conservation laws, the momentum and energy equations are nonconservative. This is to: (1) provide enhanced numerical stability by eliminating errors introduced by the nonvanishing of nabla x B on the finite difference mesh; and, (2) allow the simulation of low β plasmas. The resulting finite difference equations are a coupled system of nonlinear algebraic equations which are solved by the Newton-Raphson iteration technique. We apply our model to a number of problems of importance in magnetic fusion research. Ideal and resistive internal kink instabilities are simulated in a Cartesian geometry. Growth rates and nonlinear saturation amplitudes are found to be in agreement with previous analytic and numerical predictions. We also simulate these instabilities in a torus, which demonstrates the versatility of the orthogonal curvilinear coordinate representation. (orig.)

  18. Inductive Eigenmodes of a resistive toroidal surface in vacuum

    International Nuclear Information System (INIS)

    Lo Surdo, C.

    1999-01-01

    In this paper it has been studied the Electro-Magnetic (EM) Eigenmodes, sufficiently slow as to legitimate the pre-Maxwell approximation of Maxwell's system (or inductive Eigenmodes), of a given smooth, toroidal-unknotted, electrically resistive surface Τ with given smooth (surface) resistivity 0 d egree 3 . Within the above limitations (to be made more precise), the geometry of Τ is arbitrary. With the eigenvalue associated with the generic Eigenmode being defined as the opposite of its logarithmic time-derivative, one expects that the resulting spectrum be discrete and strictly positive. It shall be interested into the degenerate case where Τ be cut (i.e. electrically broken) along one or more of its irreducible cycles. This case will be analyzed autonomously, rather than as a limit (for ρ d egree → ∞ along the cuts) of the regular case. Without cuts, the Eigenproblem under consideration is nothing but the two-dimensional (2-dim) generalization of the classical case of a smooth, unknotted, electrically conductive, simple coil in infinite vacuum. Its analysis hinges on the classical potential theory, and turns out to be a special application of the linear, integrodifferential (elliptic) equation theory on a compact, multiply connected, 2-dim manifold. The attention and approach will be confined to strong (or classical) solutions, both in Τ and C Τ = R 3 / Τ. This study is divided in two parts: a General Part (Sects 1 divided 4) is devoted to the case of generic Τ and ρ d egree (within the convenient smoothness requirements), whereas a Special Part (Sects 5 divided 7) deals with the (more or less formal) discussion of a couple of particular cases (Τ ≡ a canonical torus), both of which with uniform ρ d egree. Some propaedeutical/supplementary information is provided in a number of Appendices [it

  19. [Corrosion resistant properties of different anodized microtopographies on titanium surfaces].

    Science.gov (United States)

    Fangjun, Huo; Li, Xie; Xingye, Tong; Yueting, Wang; Weihua, Guo; Weidong, Tian

    2015-12-01

    To investigate the corrosion resistant properties of titanium samples prepared by anodic oxidation with different surface morphologies. Pure titanium substrates were treated by anodic oxidation to obtain porous titanium films in micron, submicron, and micron-submicron scales. The surface morphologies, coating cross-sectional morphologies, crystalline structures, and surface roughness of these samples were characterized. Electrochemical technique was used to measure the corrosion potential (Ecorr), current density of corrosion (Icorr), and polarization resistance (Rp) of these samples in a simulated body fluid. Pure titanium could be modified to exhibit different surface morphologies by the anodic oxidation technique. The Tafel curve results showed that the technique can improve the corrosion resistance of pure titanium. Furthermore, the corrosion resistance varied with different surface morphologies. The submicron porous surface sample demonstrated the best corrosion resistance, with maximal Ecorr and Rp and minimal Icorr. Anodic oxidation technology can improve the corrosion resistance of pure titanium in a simulated body fluid. The submicron porous surface sample exhibited the best corrosion resistance because of its small surface area and thick barrier layer.

  20. Analytical approximate equations for the resistivity and its temperature coefficient in thin polycrystalline metallic films

    International Nuclear Information System (INIS)

    Tellier, C.R.; Tosser, A.J.

    1977-01-01

    In the usual thickness range of sputtered metallic films, analytical linearized approximate expressions of polycrystalline film resistivity and its t.c.r. are deduced from the Mayadas-Shatzkes theoretical equations. A good experimental fit is observed for Al rf sputtered metal films. (orig.) [de

  1. Effect of surfaces similarity on contact resistance of fractal rough surfaces under cyclic loading

    Science.gov (United States)

    Gao, Yuanwen; Liu, Limei; Ta, Wurui; Song, Jihua

    2018-03-01

    Although numerous studies have shown that contact resistance depends significantly on roughness and fractal dimension, it remains elusive how they affect contact resistance between rough surfaces. The interface similarity index is first proposed to describe the similarity of the contact surfaces, which gives a good indication of the actual contact area between surfaces. We reveal that the surfaces' similarity be an origin of contact resistance variation. The cyclic loading can increase the contact stiffness, and the contact stiffness increases with the increase of the interface similarity index. These findings explain the mechanism of surface roughness and fractal dimension on contact resistance, and also provide reference for the reliability design of the electrical connection.

  2. Solution of the Helmholtz-Poincare Wave Equation using the coupled boundary integral equations and optimal surface eigenfunctions

    International Nuclear Information System (INIS)

    Werby, M.F.; Broadhead, M.K.; Strayer, M.R.; Bottcher, C.

    1992-01-01

    The Helmholtz-Poincarf Wave Equation (H-PWE) arises in many areas of classical wave scattering theory. In particular it can be found for the cases of acoustical scattering from submerged bounded objects and electromagnetic scattering from objects. The extended boundary integral equations (EBIE) method is derived from considering both the exterior and interior solutions of the H-PWECs. This coupled set of expressions has the advantage of not only offering a prescription for obtaining a solution for the exterior scattering problem, but it also obviates the problem of irregular values corresponding to fictitious interior eigenvalues. Once the coupled equations are derived, they can be obtained in matrix form by expanding all relevant terms in partial wave expansions, including a bi-orthogonal expansion of the Green's function. However some freedom in the choice of the surface expansion is available since the unknown surface quantities may be expanded in a variety of ways so long as closure is obtained. Out of many possible choices, we develop an optimal method to obtain such expansions which is based on the optimum eigenfunctions related to the surface of the object. In effect, we convert part of the problem (that associated with the Fredholms integral equation of the first kind) an eigenvalue problem of a related Hermitian operator. The methodology will be explained in detail and examples will be presented

  3. A consistent hierarchy of generalized kinetic equation approximations to the master equation applied to surface catalysis.

    Science.gov (United States)

    Herschlag, Gregory J; Mitran, Sorin; Lin, Guang

    2015-06-21

    We develop a hierarchy of approximations to the master equation for systems that exhibit translational invariance and finite-range spatial correlation. Each approximation within the hierarchy is a set of ordinary differential equations that considers spatial correlations of varying lattice distance; the assumption is that the full system will have finite spatial correlations and thus the behavior of the models within the hierarchy will approach that of the full system. We provide evidence of this convergence in the context of one- and two-dimensional numerical examples. Lower levels within the hierarchy that consider shorter spatial correlations are shown to be up to three orders of magnitude faster than traditional kinetic Monte Carlo methods (KMC) for one-dimensional systems, while predicting similar system dynamics and steady states as KMC methods. We then test the hierarchy on a two-dimensional model for the oxidation of CO on RuO2(110), showing that low-order truncations of the hierarchy efficiently capture the essential system dynamics. By considering sequences of models in the hierarchy that account for longer spatial correlations, successive model predictions may be used to establish empirical approximation of error estimates. The hierarchy may be thought of as a class of generalized phenomenological kinetic models since each element of the hierarchy approximates the master equation and the lowest level in the hierarchy is identical to a simple existing phenomenological kinetic models.

  4. Investigation of Floor Surface Finishes for Optimal Slip Resistance Performance

    Directory of Open Access Journals (Sweden)

    In-Ju Kim

    2018-03-01

    Full Text Available Background: Increasing the slip resistance of floor surfaces would be desirable, but there is a lack of evidence on whether traction properties are linearly correlated with the topographic features of the floor surfaces or what scales of surface roughness are required to effectively control the slipperiness of floors. Objective: This study expands on earlier findings on the effects of floor surface finishes against slip resistance performance and determines the operative ranges of floor surface roughness for optimal slip resistance controls under different risk levels of walking environments. Methods: Dynamic friction tests were conducted among three shoes and nine floor specimens under wet and oily environments and compared with a soapy environment. Results: The test results showed the significant effects of floor surface roughness on slip resistance performance against all the lubricated environments. Compared with the floor-type effect, the shoe-type effect on slip resistance performance was insignificant against the highly polluted environments. The study outcomes also indicated that the oily environment required rougher surface finishes than the wet and soapy ones in their lower boundary ranges of floor surface roughness. Conclusion: The results of this study with previous findings confirm that floor surface finishes require different levels of surface coarseness for different types of environmental conditions to effectively manage slippery walking environments. Collected data on operative ranges of floor surface roughness seem to be a valuable tool to develop practical design information and standards for floor surface finishes to efficiently prevent pedestrian fall incidents. Keywords: floor surface finishes, operational levels of floor surface roughness, slip resistance, wet, soapy and oily environments

  5. Skeletonized wave-equation Qs tomography using surface waves

    KAUST Repository

    Li, Jing; Dutta, Gaurav; Schuster, Gerard T.

    2017-01-01

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data

  6. Iterative discrete ordinates solution of the equation for surface-reflected radiance

    Science.gov (United States)

    Radkevich, Alexander

    2017-11-01

    This paper presents a new method of numerical solution of the integral equation for the radiance reflected from an anisotropic surface. The equation relates the radiance at the surface level with BRDF and solutions of the standard radiative transfer problems for a slab with no reflection on its surfaces. It is also shown that the kernel of the equation satisfies the condition of the existence of a unique solution and the convergence of the successive approximations to that solution. The developed method features two basic steps: discretization on a 2D quadrature, and solving the resulting system of algebraic equations with successive over-relaxation method based on the Gauss-Seidel iterative process. Presented numerical examples show good coincidence between the surface-reflected radiance obtained with DISORT and the proposed method. Analysis of contributions of the direct and diffuse (but not yet reflected) parts of the downward radiance to the total solution is performed. Together, they represent a very good initial guess for the iterative process. This fact ensures fast convergence. The numerical evidence is given that the fastest convergence occurs with the relaxation parameter of 1 (no relaxation). An integral equation for BRDF is derived as inversion of the original equation. The potential of this new equation for BRDF retrievals is analyzed. The approach is found not viable as the BRDF equation appears to be an ill-posed problem, and it requires knowledge the surface-reflected radiance on the entire domain of both Sun and viewing zenith angles.

  7. Surface Resistance Measurements of LHC Dipole Beam Screen Samples

    CERN Document Server

    Caspers, Friedhelm; Ruggiero, F; Tan, J; Tsutsui, H

    2000-01-01

    An estimate of the resistive losses in the LHC dipole beam screen is given from cold surface resistance measurements using the shielded pair technique. Several beam screen samples have been evaluated, with different copper coating methods, including a sample with ribbed surface envisaged to reduce electron cloud losses thanks to its low reflectivity. Experimental data, derived by a proper analysis of the measured Q-factors and including error estimates are compared with theoretical predictions of the anomalous skin effect.

  8. Aging of residual surface resistance of superconducting lead cavities

    DEFF Research Database (Denmark)

    Danielsen, M.

    1972-01-01

    Measurements of the residual surface resistance of superconducting lead cavities as a function of time during a period of a month showed an oscillating variation. An explanation of the ageing curves is proposed. ©1972 The American Institute of Physics......Measurements of the residual surface resistance of superconducting lead cavities as a function of time during a period of a month showed an oscillating variation. An explanation of the ageing curves is proposed. ©1972 The American Institute of Physics...

  9. Surface-Controlled Metal Oxide Resistive Memory

    KAUST Repository

    Ke, Jr-Jian; Namura, Kyoko; Duran Retamal, Jose Ramon; Ho, Chin-Hsiang; Minamitake, Haruhiko; Wei, Tzu-Chiao; Tsai, Dung-Sheng; Lin, Chun-Ho; Suzuki, Motofumi; He, Jr-Hau

    2015-01-01

    be attributed to the stable oxygen adatoms under various ambience conditions. The findings validate the surface-controlled stability and uniformity of ReRAM and can serve as the guideline for developing practical device applications.

  10. Trapped surfaces in monopole-like Cauchy data of Einstein-Yang-Mills-Higgs equations

    International Nuclear Information System (INIS)

    Malec, E.; Koc, P.

    1989-08-01

    We choose the nonabelian monopole solution of Bogomolny, Prasad and Sommerfield as a part of Cauchy data for the evolution of Einstein-Yang-Mills-Higgs equations. Momentarily static spherically symmetric data for gravitational fields are obtained numerically via the Lichnerowicz equation. In the case of generic scaling of fields we have found initial data with trapped surfaces. (author). 13 refs

  11. The Use of Nonlinear Constitutive Equations to Evaluate Draw Resistance and Filter Ventilation

    Directory of Open Access Journals (Sweden)

    Eitzinger B

    2014-12-01

    Full Text Available This study investigates by nonlinear constitutive equations the influence of tipping paper, cigarette paper, filter, and tobacco rod on the degree of filter ventilation and draw resistance. Starting from the laws of conservation, the path to the theory of fluid dynamics in porous media and Darcy's law is reviewed and, as an extension to Darcy's law, two different nonlinear pressure drop-flow relations are proposed. It is proven that these relations are valid constitutive equations and the partial differential equations for the stationary flow in an unlit cigarette covering anisotropic, inhomogeneous and nonlinear behaviour are derived. From these equations a system of ordinary differential equations for the one-dimensional flow in the cigarette is derived by averaging pressure and velocity over the cross section of the cigarette. By further integration, the concept of an electrical analog is reached and discussed in the light of nonlinear pressure drop-flow relations. By numerical calculations based on the system of ordinary differential equations, it is shown that the influence of nonlinearities cannot be neglected because variations in the degree of filter ventilation can reach up to 20% of its nominal value.

  12. Estimating Daily Global Evapotranspiration Using Penman–Monteith Equation and Remotely Sensed Land Surface Temperature

    Directory of Open Access Journals (Sweden)

    Roozbeh Raoufi

    2017-11-01

    Full Text Available Daily evapotranspiration (ET is modeled globally for the period 2000–2013 based on the Penman–Monteith equation with radiation and vapor pressures derived using remotely sensed Land Surface Temperature (LST from the MODerate resolution Imaging Spectroradiometer (MODIS on the Aqua and Terra satellites. The ET for a given land area is based on four surface conditions: wet/dry and vegetated/non-vegetated. For each, the ET resistance terms are based on land cover, leaf area index (LAI and literature values. The vegetated/non-vegetated fractions of the land surface are estimated using land cover, LAI, a simplified version of the Beer–Lambert law for describing light transition through vegetation and newly derived light extension coefficients for each MODIS land cover type. The wet/dry fractions of the land surface are nonlinear functions of LST derived humidity calibrated using in-situ ET measurements. Results are compared to in-situ measurements (average of the root mean squared errors and mean absolute errors for 39 sites are 0.81 mm day−1 and 0.59 mm day−1, respectively and the MODIS ET product, MOD16, (mean bias during 2001–2013 is −0.2 mm day−1. Although the mean global difference between MOD16 and ET estimates is only 0.2 mm day−1, local temperature derived vapor pressures are the likely contributor to differences, especially in energy and water limited regions. The intended application for the presented model is simulating ET based on long-term climate forecasts (e.g., using only minimum, maximum and mean daily or monthly temperatures.

  13. Robust Imaging Methodology for Challenging Environments: Wave Equation Dispersion Inversion of Surface Waves

    KAUST Repository

    Li, Jing; Schuster, Gerard T.; Zeng, Zhaofa

    2017-01-01

    A robust imaging technology is reviewed that provide subsurface information in challenging environments: wave-equation dispersion inversion (WD) of surface waves for the shear velocity model. We demonstrate the benefits and liabilities of the method

  14. On the initial condition problem of the time domain PMCHWT surface integral equation

    KAUST Repository

    Uysal, Ismail Enes; Bagci, Hakan; Ergin, A. Arif; Ulku, H. Arda

    2017-01-01

    Non-physical, linearly increasing and constant current components are induced in marching on-in-time solution of time domain surface integral equations when initial conditions on time derivatives of (unknown) equivalent currents are not enforced

  15. Navier-Stokes Computations With One-Equation Turbulence Model for Flows Along Concave Wall Surfaces

    Science.gov (United States)

    Wang, Chi R.

    2005-01-01

    This report presents the use of a time-marching three-dimensional compressible Navier-Stokes equation numerical solver with a one-equation turbulence model to simulate the flow fields developed along concave wall surfaces without and with a downstream extension flat wall surface. The 3-D Navier- Stokes numerical solver came from the NASA Glenn-HT code. The one-equation turbulence model was derived from the Spalart and Allmaras model. The computational approach was first calibrated with the computations of the velocity and Reynolds shear stress profiles of a steady flat plate boundary layer flow. The computational approach was then used to simulate developing boundary layer flows along concave wall surfaces without and with a downstream extension wall. The author investigated the computational results of surface friction factors, near surface velocity components, near wall temperatures, and a turbulent shear stress component in terms of turbulence modeling, computational mesh configurations, inlet turbulence level, and time iteration step. The computational results were compared with existing measurements of skin friction factors, velocity components, and shear stresses of the developing boundary layer flows. With a fine computational mesh and a one-equation model, the computational approach could predict accurately the skin friction factors, near surface velocity and temperature, and shear stress within the flows. The computed velocity components and shear stresses also showed the vortices effect on the velocity variations over a concave wall. The computed eddy viscosities at the near wall locations were also compared with the results from a two equation turbulence modeling technique. The inlet turbulence length scale was found to have little effect on the eddy viscosities at locations near the concave wall surface. The eddy viscosities, from the one-equation and two-equation modeling, were comparable at most stream-wise stations. The present one-equation

  16. Self-dual Yang-Mills equation and deformation of surfaces

    International Nuclear Information System (INIS)

    Serikbaev, N.S.; Myrzakul, K.; Sajymbetova, S.K.; Koshkinbaev, A.D.; Myrzakulov, R.

    2003-01-01

    We show that many integrable systems and integrable spin systems in 2+1 dimensions can be obtained from the (2+1)- dimensional Gauss-Mainardi-Codazzi and Gauss-Weingarten equations, respectively. We also show that the (2+1)-dimensional Gauss-Mainardi-Codazzi equation which describes the deformation (motion) of surfaces is the exact reduction of the Yang-Mills-Higgs-Bogomolny and self-dual Yang-Mills equations. On the basis of this observation, we suggest that the (2+1)-dimensional Gauss-Mainardi-Codazzi equation is a candidate to be integrable, and the associated linear problem (Lax representation) with the spectral parameter is presented. (author)

  17. Soliton surfaces associated with generalized symmetries of integrable equations

    International Nuclear Information System (INIS)

    Grundland, A M; Post, S

    2011-01-01

    In this paper, based on the Fokas et al approach (Fokas and Gel'fand 1996 Commun. Math. Phys. 177 203-20; Fokas et al 2000 Sel. Math. 6 347-75), we provide a symmetry characterization of continuous deformations of soliton surfaces immersed in a Lie algebra using the formalism of generalized vector fields, their prolongation structure and links with the Frechet derivatives. We express the necessary and sufficient condition for the existence of such surfaces in terms of the invariance criterion for generalized symmetries and identify additional sufficient conditions which admit an explicit integration of the immersion functions of 2D surfaces in Lie algebras. We discuss in detail the su(N)-valued immersion functions generated by conformal symmetries of the CP N-1 sigma model defined on either the Minkowski or Euclidean space. We further show that the sufficient conditions for explicit integration of such immersion functions impose additional restrictions on the admissible conformal symmetries of the model defined on Minkowski space. On the other hand, the sufficient conditions are identically satisfied for arbitrary conformal symmetries of finite action solutions of the CP N-1 sigma model defined on Euclidean space.

  18. The Closest Point Method and Multigrid Solvers for Elliptic Equations on Surfaces

    KAUST Repository

    Chen, Yujia

    2015-01-01

    © 2015 Society for Industrial and Applied Mathematics. Elliptic partial differential equations are important from both application and analysis points of view. In this paper we apply the closest point method to solve elliptic equations on general curved surfaces. Based on the closest point representation of the underlying surface, we formulate an embedding equation for the surface elliptic problem, then discretize it using standard finite differences and interpolation schemes on banded but uniform Cartesian grids. We prove the convergence of the difference scheme for the Poisson\\'s equation on a smooth closed curve. In order to solve the resulting large sparse linear systems, we propose a specific geometric multigrid method in the setting of the closest point method. Convergence studies in both the accuracy of the difference scheme and the speed of the multigrid algorithm show that our approaches are effective.

  19. Surface Corrosion Resistance in Turning of Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Rui Zhang

    2015-01-01

    Full Text Available This work addresses the issues associated with implant surface modification. We propose a method to form the oxide film on implant surfaces by dry turning to generate heat and injecting oxygen-rich gas at the turning-tool flank. The morphology, roughness, composition, and thickness of the oxide films in an oxygen-rich atmosphere were characterized using scanning electron microscopy, optical profiling, and Auger electron spectroscopy. Electrochemical methods were used to study the corrosion resistance of the modified surfaces. The corrosion resistance trends, analyzed relative to the oxide film thickness, indicate that the oxide film thickness is the major factor affecting the corrosion resistance of titanium alloys in a simulated body fluid (SBF. Turning in an oxygen-rich atmosphere can form a thick oxide film on the implant surface. The thickness of surface oxide films processed at an oxygen concentration of 80% was improved to 4.6 times that of films processed at an oxygen concentration of 21%; the free corrosion potential shifted positively by 0.357 V, which significantly improved the corrosion resistance of titanium alloys in the SBF. Therefore, the proposed method may (partially replace the subsequent surface oxidation. This method is significant for biomedical development because it shortens the process flow, improves the efficiency, and lowers the cost.

  20. Explicit frequency equations of free vibration of a nonlocal Timoshenko beam with surface effects

    Science.gov (United States)

    Zhao, Hai-Sheng; Zhang, Yao; Lie, Seng-Tjhen

    2018-02-01

    Considerations of nonlocal elasticity and surface effects in micro- and nanoscale beams are both important for the accurate prediction of natural frequency. In this study, the governing equation of a nonlocal Timoshenko beam with surface effects is established by taking into account three types of boundary conditions: hinged-hinged, clamped-clamped and clamped-hinged ends. For a hinged-hinged beam, an exact and explicit natural frequency equation is obtained. However, for clamped-clamped and clamped-hinged beams, the solutions of corresponding frequency equations must be determined numerically due to their transcendental nature. Hence, the Fredholm integral equation approach coupled with a curve fitting method is employed to derive the approximate fundamental frequency equations, which can predict the frequency values with high accuracy. In short, explicit frequency equations of the Timoshenko beam for three types of boundary conditions are proposed to exhibit directly the dependence of the natural frequency on the nonlocal elasticity, surface elasticity, residual surface stress, shear deformation and rotatory inertia, avoiding the complicated numerical computation.

  1. In vivo measurement of vocal fold surface resistance.

    Science.gov (United States)

    Mizuta, Masanobu; Kurita, Takashi; Dillon, Neal P; Kimball, Emily E; Garrett, C Gaelyn; Sivasankar, M Preeti; Webster, Robert J; Rousseau, Bernard

    2017-10-01

    A custom-designed probe was developed to measure vocal fold surface resistance in vivo. The purpose of this study was to demonstrate proof of concept of using vocal fold surface resistance as a proxy of functional tissue integrity after acute phonotrauma using an animal model. Prospective animal study. New Zealand White breeder rabbits received 120 minutes of airflow without vocal fold approximation (control) or 120 minutes of raised intensity phonation (experimental). The probe was inserted via laryngoscope and placed on the left vocal fold under endoscopic visualization. Vocal fold surface resistance of the middle one-third of the vocal fold was measured after 0 (baseline), 60, and 120 minutes of phonation. After the phonation procedure, the larynx was harvested and prepared for transmission electron microscopy. In the control group, vocal fold surface resistance values remained stable across time points. In the experimental group, surface resistance (X% ± Y% relative to baseline) was significantly decreased after 120 minutes of raised intensity phonation. This was associated with structural changes using transmission electron microscopy, which revealed damage to the vocal fold epithelium after phonotrauma, including disruption of the epithelium and basement membrane, dilated paracellular spaces, and alterations to epithelial microprojections. In contrast, control vocal fold specimens showed well-preserved stratified squamous epithelia. These data demonstrate the feasibility of measuring vocal fold surface resistance in vivo as a means of evaluating functional vocal fold epithelial barrier integrity. Device prototypes are in development for additional testing, validation, and for clinical applications in laryngology. NA Laryngoscope, 127:E364-E370, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

  2. Fracture Resistance, Surface Defects and Structural Strength of Glass

    NARCIS (Netherlands)

    Rodichev, Y.M.; Veer, F.A.

    2010-01-01

    This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass

  3. New surface layers with low rolling resistance tested in Denmark

    DEFF Research Database (Denmark)

    Pettinari, Matteo; Schmidt, Bjarne; Jensen, Bjarne Bo

    2014-01-01

    Rolling Resistance coefficient that could improve energy efficiency of the roads. In particular, two new types of Split Mastic Asphalt (SMA) were developed and compared to a reference one; both mixtures have a relatively small maximum grain-size, 6 mm and 8 mm, respectively. Surface measurements...

  4. Inductive Eigenmodes of a resistive toroidal surface in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Lo Surdo, C. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dipt. Innovazione

    1999-07-01

    In this paper it has been studied the Electro-Magnetic (EM) Eigenmodes, sufficiently slow as to legitimate the pre-Maxwell approximation of Maxwell's system (or inductive Eigenmodes), of a given smooth, toroidal-un knotted, electrically resistive surface {tau} with given smooth (surface) resistivity 0 < {rho}{sub d}egree < {infinity}, and lying in the (empty) R{sup 3}. Within the above limitations (to be made more precise), the geometry of {tau} is arbitrary. With the eigenvalue associated with the generic Eigenmode being defined as the opposite of its logarithmic time-derivative, one expects that the resulting spectrum be discrete and strictly positive. It shall be interested into the degenerate case where {tau} be cut (i.e. electrically broken) along one or more of its irreducible cycles. This case will be analyzed autonomously, rather than as a limit (for {rho}{sub d}egree {yields} {infinity} along the cuts) of the regular case. Without cuts, the Eigenproblem under consideration is nothing but the two-dimensional (2-dim) generalization of the classical case of a smooth, unknotted, electrically conductive, simple coil in infinite vacuum. Its analysis hinges on the classical potential theory, and turns out to be a special application of the linear, integrodifferential (elliptic) equation theory on a compact, multiply connected, 2-dim manifold. The attention and approach will be confined to strong (or classical) solutions, both in {tau} and C {tau} = R{sup 3} / {tau}. This study is divided in two parts: a General Part (Sects 1 divided 4) is devoted to the case of generic {tau} and {rho}{sub d}egree (within the convenient smoothness requirements), whereas a Special Part (Sects 5 divided 7) deals with the (more or less formal) discussion of a couple of particular cases ({tau} {identical_to} a canonical torus), both of which with uniform {rho}{sub d}egree. Some propaedeutical/supplementary information is provided in a number of Appendices. [Italian] Il presente

  5. Photochemical surface modification of PP for abrasion resistance

    International Nuclear Information System (INIS)

    Bahners, Thomas; Haessler, Ruediger; Gao Shanglin; Maeder, Edith; Wego, Andreas; Schollmeyer, Eckhard

    2009-01-01

    The potential of a photo-chemical approach to increase the surface hardness of polypropylene (PP) has been studied. Using a 222 nm excimer lamp, fibers and film were irradiated in the presence of multi-functional substances diallylphthalate (DAP), tetraallyloxyethane (TAE), and pentaerithritoltriacylate (PETA) and characterized with regard to the resulting effect on abrasion resistance. AFM-based methods were employed to analyze thermo-mechanical surface properties. Nanoindentation and microthermal analyses of the outermost surface layers of UV treated fibers gave clear indications of an effective cross-linking of reactive substances present during irradiation. One may assume that the reactive media polymerize on top of the surface of the PP substrate and form a thin-layer. The abrasion resistance of the PP fibers was tested by applying stress through a rotating and axially oscillating roller of defined roughness and measuring the mass loss as a function of time. The abrasion resistance was found to be remarkably improved compared to the untreated fiber. Best effects were achieved using PETA as reactive substance. The experiments clearly showed the influence of processing conditions, namely with regard to homogeneous coverage of the substrate surface with the reactive medium.

  6. Laser Surface Alloying of Aluminum for Improving Acid Corrosion Resistance

    Science.gov (United States)

    Jiru, Woldetinsay Gutu; Sankar, Mamilla Ravi; Dixit, Uday Shanker

    2018-04-01

    In the present study, laser surface alloying of aluminum with magnesium, manganese, titanium and zinc, respectively, was carried out to improve acid corrosion resistance. Laser surface alloying was conducted using 1600 and 1800 W power source using CO2 laser. Acid corrosion resistance was tested by dipping the samples in a solution of 2.5% H2SO4 for 200 h. The weight loss due to acid corrosion was reduced by 55% for AlTi, 41% for AlMg alloy, 36% for AlZn and 22% for AlMn alloy. Laser surface alloyed samples offered greater corrosion resistance than the aluminum substrate. It was observed that localized pitting corrosion was the major factor to damage the surface when exposed for a long time. The hardness after laser surface alloying was increased by a factor of 8.7, 3.4, 2.7 and 2 by alloying with Mn, Mg, Ti and Zn, respectively. After corrosion test, hardness was reduced by 51% for AlTi sample, 40% for AlMg sample, 41.4% for AlMn sample and 33% for AlZn sample.

  7. Global solvability, non-resistive limit and magnetic boundary layer of the compressible heat-conductive MHD equations

    OpenAIRE

    Zhang, Jianwen; Zhao, Xiaokui

    2015-01-01

    In general, the resistivity is inversely proportional to the electrical conductivity, and is usually taken to be zero when the conducting fluid is of extremely high conductivity (e.g., ideal conductors). In this paper, we first establish the global well-posedness of strong solution to an initial-boundary value problem of the one-dimensional compressible, viscous, heat-conductive, non-resistive MHD equations with general heat-conductivity coefficient and large data. Then, the non-resistive lim...

  8. Alternating-direction implicit numerical solution of the time-dependent, three-dimensional, single fluid, resistive magnetohydrodynamic equations

    Energy Technology Data Exchange (ETDEWEB)

    Finan, C.H. III

    1980-12-01

    Resistive magnetohydrodynamics (MHD) is described by a set of eight coupled, nonlinear, three-dimensional, time-dependent, partial differential equations. A computer code, IMP (Implicit MHD Program), has been developed to solve these equations numerically by the method of finite differences on an Eulerian mesh. In this model, the equations are expressed in orthogonal curvilinear coordinates, making the code applicable to a variety of coordinate systems. The Douglas-Gunn algorithm for Alternating-Direction Implicit (ADI) temporal advancement is used to avoid the limitations in timestep size imposed by explicit methods. The equations are solved simultaneously to avoid syncronization errors.

  9. Estimation of monthly solar exposure on horizontal surface by Angstrom-type regression equation

    International Nuclear Information System (INIS)

    Ravanshid, S.H.

    1981-01-01

    To obtain solar flux intensity, solar radiation measuring instruments are the best. In the absence of instrumental data there are other meteorological measurements which are related to solar energy and also it is possible to use empirical relationships to estimate solar flux intensit. One of these empirical relationships to estimate monthly averages of total solar radiation on a horizontal surface is the modified angstrom-type regression equation which has been employed in this report in order to estimate the solar flux intensity on a horizontal surface for Tehran. By comparing the results of this equation with four years measured valued by Tehran's meteorological weather station the values of meteorological constants (a,b) in the equation were obtained for Tehran. (author)

  10. A surface-integral-equation approach to the propagation of waves in EBG-based devices

    NARCIS (Netherlands)

    Lancellotti, V.; Tijhuis, A.G.

    2012-01-01

    We combine surface integral equations with domain decomposition to formulate and (numerically) solve the problem of electromagnetic (EM) wave propagation inside finite-sized structures. The approach is of interest for (but not limited to) the analysis of devices based on the phenomenon of

  11. A Calderón multiplicative preconditioner for coupled surface-volume electric field integral equations

    KAUST Repository

    Bagci, Hakan; Andriulli, Francesco P.; Cools, Kristof; Olyslager, Femke; Michielssen, Eric

    2010-01-01

    A well-conditioned coupled set of surface (S) and volume (V) electric field integral equations (S-EFIE and V-EFIE) for analyzing wave interactions with densely discretized composite structures is presented. Whereas the V-EFIE operator is well

  12. Tokamak m = 1 magnetohydrodynamic calculations in toroidal geometry using a full set of nonlinear resistive magnetohydrodynamic equations

    International Nuclear Information System (INIS)

    Charlton, L.A.; Carreras, B.A.; Holmes, J.A.; Lynch, V.E.

    1988-01-01

    The linear stability and nonlinear evolution of the resistive m = 1 mode in tokamaks is studied using a full set of resistive magnetohydrodynamic (MHD) equations in toroidal geometry. The modification of the linear and nonlinear properties of the mode by a combination of strong toroidal effects and low resistivity is the focus of this work. Linearly there is a transition from resistive kink to resistive tearing behavior as the aspect ratio and resistivity are reduced, and there is a corresponding modification of the nonlinear behavior, including a slowing of the island growth and development of a Rutherford regime, as the tearing regime is approached. In order to study the sensitivity of the stability and evolution to assumptions concerning the equation of state, two sets of full nonlinear resistive MHD equations (a pressure convection set and an incompressible set) are used. Both sets give more stable nonlinear behavior as the aspect ratio is reduced. The pressure convection set shows a transition from a Kadomtsev reconnection at large aspect ratio to a saturation at small aspect ratio. The incompressible set yields Kadomtsev reconnection for all aspect ratios, but with a significant lengthening of the reconnection time and development of a Rutherford regime at an aspect ratio approaching the transition from a resistive kink mode to a tearing mode. The pressure convection set gives an incomplete reconnection similar to that sometimes seen experimentally. The pressure convection set is, however, strictly justified only at high beta

  13. A model expansion criterion for treating surface topography in ray path calculations using the eikonal equation

    International Nuclear Information System (INIS)

    Ma, Ting; Zhang, Zhongjie

    2014-01-01

    Irregular surface topography has revolutionized how seismic traveltime is calculated and the data are processed. There are two main schemes for dealing with an irregular surface in the seismic first-arrival traveltime calculation: (1) expanding the model and (2) flattening the surface irregularities. In the first scheme, a notional infill medium is added above the surface to expand the physical space into a regular space, as required by the eikonal equation solver. Here, we evaluate the chosen propagation velocity in the infill medium through ray path tracking with the eikonal equation-solved traveltime field, and observe that the ray paths will be physically unrealistic for some values of this propagation velocity. The choice of a suitable propagation velocity in the infill medium is crucial for seismic processing of irregular topography. Our model expansion criterion for dealing with surface topography in the calculation of traveltime and ray paths using the eikonal equation highlights the importance of both the propagation velocity of the infill physical medium and the topography gradient. (paper)

  14. Soliton surfaces via a zero-curvature representation of differential equations

    International Nuclear Information System (INIS)

    Grundland, A M; Post, S

    2012-01-01

    The main aim of this paper is to introduce a new version of the Fokas–Gel’fand formula for immersion of soliton surfaces in Lie algebras. The paper contains a detailed exposition of the technique for obtaining exact forms of 2D surfaces associated with any solution of a given nonlinear ordinary differential equation which can be written in the zero-curvature form. That is, for any generalized symmetry of the zero-curvature condition of the associated integrable model, it is possible to construct soliton surfaces whose Gauss–Mainardi–Codazzi equations are equivalent to infinitesimal deformations of the zero-curvature representation of the considered model. Conversely, it is shown (proposition 1) that for a given immersion function of a 2D soliton surface in a Lie algebra, it is possible to derive the associated generalized vector field in the evolutionary form which characterizes all symmetries of the zero-curvature condition. The theoretical considerations are illustrated via surfaces associated with the Painlevé equations P1, P2 and P3, including transcendental functions, the special cases of the rational and Airy solutions of P2 and the classical solutions of P3. (paper)

  15. On the initial condition problem of the time domain PMCHWT surface integral equation

    KAUST Repository

    Uysal, Ismail Enes

    2017-05-13

    Non-physical, linearly increasing and constant current components are induced in marching on-in-time solution of time domain surface integral equations when initial conditions on time derivatives of (unknown) equivalent currents are not enforced properly. This problem can be remedied by solving the time integral of the surface integral for auxiliary currents that are defined to be the time derivatives of the equivalent currents. Then the equivalent currents are obtained by numerically differentiating the auxiliary ones. In this work, this approach is applied to the marching on-in-time solution of the time domain Poggio-Miller-Chan-Harrington-Wu-Tsai surface integral equation enforced on dispersive/plasmonic scatterers. Accuracy of the proposed method is demonstrated by a numerical example.

  16. Laser surface modification of stainless steels for cavitation erosion resistance

    Science.gov (United States)

    Kwok, Chi Tat

    1999-12-01

    Austenitic stainless steel UNS S31603 (Fe -17.6Cr -11.2Ni -2.5Mo -1.4Mn -0.4Si -0.03C) has higher pitting corrosion resistance but lower cavitation erosion resistance than that of UNS S30400. This is because of its lower tendency for strain induced martensitic transformation and higher stacking fault energy as compared with those of UNS S30400. In order to improve its cavitation erosion resistance, surface modification of S31603 was performed by laser surface melting and laser surface alloying using a 2-kW CW Nd-YAG laser and a 3-kW CW CO2 laser. For laser surface melting, austenitic stainless steel UNS S30400, super duplex stainless steel UNS S32760 and martensitic stainless steel UNS S42000 were also investigated for comparison purpose. For laser surface alloying, alloying materials including various elements (Co, Cr, Ni, Mo, Mn, Si & C), alloys (AlSiFe & NiCrSiB), ceramics (Si3N 4, SiC, Cr3C2, TiC, CrB & Cr2O 3) and alloys-ceramics (Co-WC, Ni-WC, Ni-Al2O3, Ni-Cr2C3) were used to modify the surface of S31603. The alloyed surface was achieved first by flame spraying or pre-placing of the alloy powder on the S31603 surface and then followed by laser surface remelting. The cavitation erosion characteristics of laser surface modified specimens in 3.5% NaCl solution at 23°C were studied by means of a 20-kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 mum. In addition, their pitting corrosion behaviour was evaluated by electrochemical techniques. The microstructures, compositions, phase changes and damage mechanisms under cavitation erosion were investigated by optical microscopy, SEM, EDAX and X-ray diffractometry. Mechanical properties such as microhardness profile were also examined. The cavitation erosion resistance Re (reciprocal of the mean depth of penetration rate) of laser surface melted S31603 was found to be improved by 22% and was attributed to the existence of tensile residual stress. Improvement on the Re of S42000 was found to be 8.5 times

  17. Fracture Resistance, Surface Defects and Structural Strength of Glass

    OpenAIRE

    Rodichev, Y.M.; Veer, F.A.

    2010-01-01

    This paper poses the theory that the fracture resistance of basic float glass is dependent on it physicochemical properties and the surface defects fonned under the float glass production, glass processing and handling at the service conditions compose the aggregate basis for structural glass strength assessment. The effect of loading conditions, constructional and technological factors on the engineering strength of glass can be evaluated in certain cases using fracture mechanics with inform...

  18. Investigations of the surface resistance of superconducting materials

    International Nuclear Information System (INIS)

    Junginger, Tobias

    2012-01-01

    In particle accelerators superconducting RF cavities are widely used to achieve high accelerating gradients and low losses. Power consumption is proportional to the surface resistance R S which depends on a number of external parameters, including frequency, temperature, magnetic and electric field. Presently, there is no widely accepted model describing the increase of R S with applied field. In the frame of this project the 400 MHz Quadrupole Resonator has been extended to 800 and 1200 MHz to study surface resistance and intrinsic critical RF magnetic field of superconducting samples over a wide parameter range, establishing it as a world-wide unique test facility for superconducting materials. Different samples were studied and it was shown that R S is mainly caused by the RF electric field in the case of strongly oxidized surfaces. This can be explained by interface tunnel exchange of electrons between the superconductor and localized states in adjacent oxides. For well prepared surfaces, however, the majority of the dissipation is caused by the magnetic field and R S factorizes into field and temperature dependent parts. These different loss mechanisms were correlated to surface topography of the samples and distribution of oxides by using ultrasonic force microscopy and X-ray photon spectroscopy.

  19. Non-rigid registration of breast surfaces using the laplace and diffusion equations

    Directory of Open Access Journals (Sweden)

    Ou Jao J

    2010-02-01

    Full Text Available Abstract A semi-automated, non-rigid breast surface registration method is presented that involves solving the Laplace or diffusion equations over undeformed and deformed breast surfaces. The resulting potential energy fields and isocontours are used to establish surface correspondence. This novel surface-based method, which does not require intensity images, anatomical landmarks, or fiducials, is compared to a gold standard of thin-plate spline (TPS interpolation. Realistic finite element simulations of breast compression and further testing against a tissue-mimicking phantom demonstrate that this method is capable of registering surfaces experiencing 6 - 36 mm compression to within a mean error of 0.5 - 5.7 mm.

  20. A new surface resistance measurement method with ultrahigh sensitivity

    International Nuclear Information System (INIS)

    Liang, Changnian.

    1993-01-01

    A superconducting niobium triaxial cavity has been designed and fabricated to study residual surface resistance of planar superconducting materials. The edge of a 25.4 mm or larger diameter sample in the triaxial cavity is located outside the strong field region. Therefore, the edge effects and possible losses between the thin film and the substrate have been minimized, ensuring that induced RF losses are intrinsic to the test material. The fundamental resonant frequency of the cavity is the same as the working frequency of CEBAF cavities. The cavity has a compact size compared to its TE 011 counterpart, which makes it more sensitive to the sample's loss. For even higher sensitivity, a calorimetry method has been used to measure the RF losses on the superconducting sample. At 2 K, a 2 μK temperature change can be resolved by using carbon resistor sensors. The temperature distribution caused by RF heating is measured by 16 carbon composition resistor sensors. A 0.05 μW heating power can be detected as such a resolution, which translates to a surface resistance of 0.02 nΩ at a surface magnetic field of 52 Oe. This is the most sensitive device for surface resistance measurements to date. In addition, losses due to the indium seal, coupling probes, field emission sites other than the sample, and all of the high field resonator surface, are excluded in the measurement. Surface resistance of both niobium and high-Tc superconducting thin films has been measured. A low R s of 35.2 μΩ was measured for a 25.4 mm diameter YBa 2 Cu 3 O 7 thin film at 1.5 GHz and at 2 K. The measurement result is the first result for a large area epitaxially grown thin film sample at such a low RF frequency. The abrupt disappearance of multipacting between two parallel plates has been observed and monitored with the 16 temperature mapping sensors. Field emission or some field dependent anomalous RF losses on the niobium plate have also been observed

  1. A wavelet-based PWTD algorithm-accelerated time domain surface integral equation solver

    KAUST Repository

    Liu, Yang

    2015-10-26

    © 2015 IEEE. The multilevel plane-wave time-domain (PWTD) algorithm allows for fast and accurate analysis of transient scattering from, and radiation by, electrically large and complex structures. When used in tandem with marching-on-in-time (MOT)-based surface integral equation (SIE) solvers, it reduces the computational and memory costs of transient analysis from equation and equation to equation and equation, respectively, where Nt and Ns denote the number of temporal and spatial unknowns (Ergin et al., IEEE Trans. Antennas Mag., 41, 39-52, 1999). In the past, PWTD-accelerated MOT-SIE solvers have been applied to transient problems involving half million spatial unknowns (Shanker et al., IEEE Trans. Antennas Propag., 51, 628-641, 2003). Recently, a scalable parallel PWTD-accelerated MOT-SIE solver that leverages a hiearchical parallelization strategy has been developed and successfully applied to the transient problems involving ten million spatial unknowns (Liu et. al., in URSI Digest, 2013). We further enhanced the capabilities of this solver by implementing a compression scheme based on local cosine wavelet bases (LCBs) that exploits the sparsity in the temporal dimension (Liu et. al., in URSI Digest, 2014). Specifically, the LCB compression scheme was used to reduce the memory requirement of the PWTD ray data and computational cost of operations in the PWTD translation stage.

  2. Instanton calculus without equations of motion: semiclassics from monodromies of a Riemann surface

    Science.gov (United States)

    Gulden, Tobias; Janas, Michael; Kamenev, Alex

    2015-02-01

    Instanton calculations in semiclassical quantum mechanics rely on integration along trajectories which solve classical equations of motion. However in systems with higher dimensionality or complexified phase space these are rarely attainable. A prime example are spin-coherent states which are used e.g. to describe single molecule magnets (SMM). We use this example to develop instanton calculus which does not rely on explicit solutions of the classical equations of motion. Energy conservation restricts the complex phase space to a Riemann surface of complex dimension one, allowing to deform integration paths according to Cauchy’s integral theorem. As a result, the semiclassical actions can be evaluated without knowing actual classical paths. Furthermore we show that in many cases such actions may be solely derived from monodromy properties of the corresponding Riemann surface and residue values at its singular points. As an example, we consider quenching of tunneling processes in SMM by an applied magnetic field.

  3. Downscaling Coarse Actual ET Data Using Land Surface Resistance

    Science.gov (United States)

    Shen, T.

    2017-12-01

    This study proposed a new approach of downscaling ETWATCH 1km actual evapotranspiration (ET) product to a spatial resolution of 30m using land surface resistance that simulated mainly from monthly Landsat8 data and Jarvis method, which combined the benefits of both high temporal resolution of ETWATCH product and fine spatial resolution of Landsat8. The driving factor, surface resistance (Rs), was chosen for the reason that could reflect the transfer ability of vapor flow over canopy. Combined resistance Rs both upon canopy conditions, atmospheric factors and available water content of soil, which remains stable inside one ETWATCH pixel (1km). In this research, we used ETWATCH 1km ten-day actual ET product from April to October in a total of twenty-one images and monthly 30 meters cloud-free NDVI of 2013 (two images from HJ as a substitute due to cloud contamination) combined meteorological indicators for downscaling. A good agreement and correlation were obtained between the downscaled data and three flux sites observation in the middle reach of Heihe basin. The downscaling results show good consistency with the original ETWATCH 1km data both temporal and spatial scale over different land cover types with R2 ranged from 0.8 to 0.98. Besides, downscaled result captured the progression of vegetation transpiration well. This study proved the practicability of new downscaling method in the water resource management.

  4. Fermions on a Riemann surface and the Kadomtsev-Petviashvili equation

    International Nuclear Information System (INIS)

    Zabrodin, A.V.

    1989-01-01

    It is shown that the S matrix of free massless fermions on a Riemann surface of finite genus generates quasiperiodic solutions of the Kadomtsev-Petviashvili equation. An operator that changes the genus of a solution is constructed, and the law of composition of such operators is discussed. The construction is a generalization of the well-known operator approach in the case of soliton solutions to the general case of quasiperiodic τ functions

  5. Solution of volume-surface integral equations using higher-order hierarchical Legendre basis functions

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Meincke, Peter; Breinbjerg, Olav

    2007-01-01

    The problem of electromagnetic scattering by composite metallic and dielectric objects is solved using the coupled volume-surface integral equation (VSIE). The method of moments (MoM) based on higher-order hierarchical Legendre basis functions and higher-order curvilinear geometrical elements...... with the analytical Mie series solution. Scattering by more complex metal-dielectric objects are also considered to compare the presented technique with other numerical methods....

  6. A posteriori error estimates for finite volume approximations of elliptic equations on general surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Lili; Tian, Li; Wang, Desheng

    2008-10-31

    In this paper, we present a residual-based a posteriori error estimate for the finite volume discretization of steady convection– diffusion–reaction equations defined on surfaces in R3, which are often implicitly represented as level sets of smooth functions. Reliability and efficiency of the proposed a posteriori error estimator are rigorously proved. Numerical experiments are also conducted to verify the theoretical results and demonstrate the robustness of the error estimator.

  7. Layer Dependence of Graphene for Oxidation Resistance of Cu Surface

    Institute of Scientific and Technical Information of China (English)

    Yu-qing Song; Xiao-ping Wang

    2017-01-01

    We studied the oxidation resistance of graphene-coated Cu surface and its layer dependence by directly growing monolayer graphene with different multilayer structures coexisted,diminishing the influence induced by residue and transfer technology.It is found that the Cu surface coated with the monolayer graphene demonstrate tremendous difference in oxidation pattern and oxidation rate,compared to that coated with the bilayer graphene,which is considered to be originated from the strain-induced linear oxidation channel in monolayer graphene and the intersection of easily-oxidized directions in each layer of bilayer graphene,respectively.We reveal that the defects on the graphene basal plane but not the boundaries are the main oxidation channel for Cu surface under graphene protection.Our finding indicates that compared to putting forth efforts to improve the quality of monolayer graphene by reducing defects,depositing multilayer graphene directly on metal is a simple and effective way to enhance the oxidation resistance of graphene-coated metals.

  8. A liquid aluminum corrosion resistance surface on steel substrate

    International Nuclear Information System (INIS)

    Wang Deqing; Shi Ziyuan; Zou Longjiang

    2003-01-01

    The process of hot dipping pure aluminum on a steel substrate followed by oxidation was studied to form a surface layer of aluminum oxide resistant to the corrosion of aluminum melt. The thickness of the pure aluminum layer on the steel substrate is reduced with the increase in temperature and time in initial aluminizing, and the thickness of the aluminum layer does not increase with time at given temperature when identical temperature and complete wetting occur between liquid aluminum and the substrate surface. The thickness of the Fe-Al intermetallic layer on the steel base is increased with increasing bath temperature and time. Based on the experimental data and the mathematics model developed by the study, a maximum exists in the thickness of the Fe-Al intermetallic at certain dipping temperature. X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis reveals that the top portion of the steel substrate is composed of a thin layer of α-Al 2 O 3 , followed by a thinner layer of FeAl 3 , and then a much thicker one of Fe 2 Al 5 on the steel base side. In addition, there is a carbon enrichment zone in diffusion front. The aluminum oxide surface formed on the steel substrate is in perfect condition after corrosion test in liquid aluminum at 750 deg. C for 240 h, showing extremely good resistance to aluminum melt corrosion

  9. Exploring surface cleaning strategies in hospital to prevent contact transmission of methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Lei, Hao; Jones, Rachael M; Li, Yuguo

    2017-01-18

    Cleaning of environmental surfaces in hospitals is important for the control of methicillin-resistant Staphylococcus aureus (MRSA) and other hospital-acquired infections transmitted by the contact route. Guidance regarding the best approaches for cleaning, however, is limited. In this study, a mathematical model based on ordinary differential equations was constructed to study MRSA concentration dynamics on high-touch and low-touch surfaces, and on the hands and noses of two patients (in two hospitals rooms) and a health care worker in a hypothetical hospital environment. Two cleaning interventions - whole room cleaning and wipe cleaning of touched surfaces - were considered. The performance of the cleaning interventions was indicated by a reduction in MRSA on the nose of a susceptible patient, relative to no intervention. Whole room cleaning just before first patient care activities of the day was more effective than whole room cleaning at other times, but even with 100% efficiency, whole room cleaning only reduced the number of MRSA transmitted to the susceptible patient by 54%. Frequent wipe cleaning of touched surfaces was shown to be more effective that whole room cleaning because surfaces are rapidly re-contaminated with MRSA after cleaning. Wipe cleaning high-touch surfaces was more effective than wipe cleaning low-touch surfaces for the same frequency of cleaning. For low wipe cleaning frequency (≤3 times per hour), high-touch surfaces should be targeted, but for high wipe cleaning frequency (>3 times per hour), cleaning should target high- and low-touch surfaces in proportion to the surface touch frequency. This study reproduces the observations from a field study of room cleaning, which provides support for the validity of our findings. Daily whole room cleaning, even with 100% cleaning efficiency, provides limited reduction in the number of MRSA transmitted to susceptible patients via the contact route; and should be supplemented with frequent targeted

  10. Recent developments on the Kardar-Parisi-Zhang surface-growth equation.

    Science.gov (United States)

    Wio, Horacio S; Escudero, Carlos; Revelli, Jorge A; Deza, Roberto R; de la Lama, Marta S

    2011-01-28

    The stochastic nonlinear partial differential equation known as the Kardar-Parisi-Zhang (KPZ) equation is a highly successful phenomenological mesoscopic model of surface and interface growth processes. Its suitability for analytical work, its explicit symmetries and its prediction of an exact dynamic scaling relation for a one-dimensional substratum led people to adopt it as a 'standard' model in the field during the last quarter of a century. At the same time, several conjectures deserving closer scrutiny were established as dogmas throughout the community. Among these, we find the beliefs that 'genuine' non-equilibrium processes are non-variational in essence, and that the exactness of the dynamic scaling relation owes its existence to a Galilean symmetry. Additionally, the equivalence among planar and radial interface profiles has been generally assumed in the literature throughout the years. Here--among other topics--we introduce a variational formulation of the KPZ equation, remark on the importance of consistency in discretization and challenge the mainstream view on the necessity for scaling of both Galilean symmetry and the one-dimensional fluctuation-dissipation theorem. We also derive the KPZ equation on a growing domain as a first approximation to radial growth, and outline the differences with respect to the classical case that arises in this new situation.

  11. High-order fractional partial differential equation transform for molecular surface construction.

    Science.gov (United States)

    Hu, Langhua; Chen, Duan; Wei, Guo-Wei

    2013-01-01

    Fractional derivative or fractional calculus plays a significant role in theoretical modeling of scientific and engineering problems. However, only relatively low order fractional derivatives are used at present. In general, it is not obvious what role a high fractional derivative can play and how to make use of arbitrarily high-order fractional derivatives. This work introduces arbitrarily high-order fractional partial differential equations (PDEs) to describe fractional hyperdiffusions. The fractional PDEs are constructed via fractional variational principle. A fast fractional Fourier transform (FFFT) is proposed to numerically integrate the high-order fractional PDEs so as to avoid stringent stability constraints in solving high-order evolution PDEs. The proposed high-order fractional PDEs are applied to the surface generation of proteins. We first validate the proposed method with a variety of test examples in two and three-dimensional settings. The impact of high-order fractional derivatives to surface analysis is examined. We also construct fractional PDE transform based on arbitrarily high-order fractional PDEs. We demonstrate that the use of arbitrarily high-order derivatives gives rise to time-frequency localization, the control of the spectral distribution, and the regulation of the spatial resolution in the fractional PDE transform. Consequently, the fractional PDE transform enables the mode decomposition of images, signals, and surfaces. The effect of the propagation time on the quality of resulting molecular surfaces is also studied. Computational efficiency of the present surface generation method is compared with the MSMS approach in Cartesian representation. We further validate the present method by examining some benchmark indicators of macromolecular surfaces, i.e., surface area, surface enclosed volume, surface electrostatic potential and solvation free energy. Extensive numerical experiments and comparison with an established surface model

  12. Transient analysis of electromagnetic wave interactions on plasmonic nanostructures using a surface integral equation solver

    KAUST Repository

    Uysal, Ismail Enes

    2016-08-09

    Transient electromagnetic interactions on plasmonic nanostructures are analyzed by solving the Poggio-Miller-Chan-Harrington-Wu-Tsai (PMCHWT) surface integral equation (SIE). Equivalent (unknown) electric and magnetic current densities, which are introduced on the surfaces of the nanostructures, are expanded using Rao-Wilton-Glisson and polynomial basis functions in space and time, respectively. Inserting this expansion into the PMCHWT-SIE and Galerkin testing the resulting equation at discrete times yield a system of equations that is solved for the current expansion coefficients by a marching on-in-time (MOT) scheme. The resulting MOT-PMCHWT-SIE solver calls for computation of additional convolutions between the temporal basis function and the plasmonic medium\\'s permittivity and Green function. This computation is carried out with almost no additional cost and without changing the computational complexity of the solver. Time-domain samples of the permittivity and the Green function required by these convolutions are obtained from their frequency-domain samples using a fast relaxed vector fitting algorithm. Numerical results demonstrate the accuracy and applicability of the proposed MOT-PMCHWT solver. © 2016 Optical Society of America.

  13. The one-parameter-model - a constitutive equation applied to a heat resistant alloy

    International Nuclear Information System (INIS)

    Schwarze, E.; Schuster, H.; Nickel, H.

    1992-01-01

    In the present work a constitutive model earlier developed and used to predict experimental results of hot tests and fatigue tests from creep experiments of metallic materials were modified to comply with the properties of a high temperature resistant material. The improved model accounts for the properties of a material developing a density and a structure of dislocation lines which are capable of interactions with particles (carbides) from a second phase. The time and temperature dependent evolution of the carbide structure has been described by an equation which explains the formation of seeds as well as their growths (Ostwald ripening). The extended model was applied to Incoloy 800H which is known to develop a carbide structure. Therefore hot tensile and fatigue tests, creep and relaxation experiments using the heats ADU and BAK (KFA specifications) at temperature between 800deg C and 900deg C were performed including both solution treated specimens and specimens heat treated for 10, 100 and 1000 hours. As compared with the results from tensile tests where the carbide structures play a subordinated role, alternately, these structures have a decisive influence on the creep properties of specimens during the primary creep phase, i.e. low stresses and high temperatures. (orig.) [de

  14. Field dependent surface resistance of niobium on copper cavities

    Directory of Open Access Journals (Sweden)

    T. Junginger

    2015-07-01

    Full Text Available The surface resistance R_{S} of superconducting cavities prepared by sputter coating a niobium film on a copper substrate increases significantly stronger with the applied rf field compared to cavities of bulk material. A possible cause is that the thermal boundary resistance between the copper substrate and the niobium film induces heating of the inner cavity wall, resulting in a higher R_{S}. Introducing helium gas in the cavity, and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by less than 120 mK when R_{S} increases with E_{acc} by 100  nΩ. This is more than one order of magnitude less than what one would expect from global heating. Additionally, the effects of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for the current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered R_{S}.

  15. Effects of rational surface density on resistive g turbulence

    International Nuclear Information System (INIS)

    Beklemishev, A.D.; Sugama, H.; Horton, W.

    1993-01-01

    The Beklemishev-Horton theory states that the anomalous transport coefficient is proportional to the density of rational surfaces provided that the interaction between the modes localized around different rational surfaces is weak compared with modes of the same helicity. The authors examine the effects of the density of states ρ using resistive g turbulence in 2D (single-helicity) and 3D (multi-helicity) simulations. They find that the modes with different helicities do not equipartition the available energy, but rather the coalescence or inverse cascade effect is strong so that a few low order mode rational surfaces receive most of the energy. The quasilinear flattening at the surfaces is a strong effect and they use bifurcation theory to derive that the effective diffusivity increases as χ eff = χ 0 ρ/(1 - Cρ) where C is a constant determined by interaction integrals. For a sufficiently high density of states Cρ ≤ 1, the higher order nonlinear interaction must be taken into account

  16. Discrete exterior calculus discretization of incompressible Navier–Stokes equations over surface simplicial meshes

    KAUST Repository

    Mohamed, Mamdouh S.

    2016-02-11

    A conservative discretization of incompressible Navier–Stokes equations is developed based on discrete exterior calculus (DEC). A distinguishing feature of our method is the use of an algebraic discretization of the interior product operator and a combinatorial discretization of the wedge product. The governing equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. The discretization is then carried out by substituting with the corresponding discrete operators based on the DEC framework. Numerical experiments for flows over surfaces reveal a second order accuracy for the developed scheme when using structured-triangular meshes, and first order accuracy for otherwise unstructured meshes. By construction, the method is conservative in that both mass and vorticity are conserved up to machine precision. The relative error in kinetic energy for inviscid flow test cases converges in a second order fashion with both the mesh size and the time step.

  17. Nonlinear differential equations for the wavefront surface at arbitrary Hartmann-plane distances.

    Science.gov (United States)

    Téllez-Quiñones, Alejandro; Malacara-Doblado, Daniel; Flores-Hernández, Ricardo; Gutiérrez-Hernández, David A; León-Rodríguez, Miguel

    2016-03-20

    In the Hartmann test, a wave aberration function W is estimated from the information of the spot diagram drawn in an observation plane. The distance from a reference plane to the observation plane, the Hartmann-plane distance, is typically chosen as z=f, where f is the radius of a reference sphere. The function W and the transversal aberrations {X,Y} calculated at the plane z=f are related by two well-known linear differential equations. Here, we propose two nonlinear differential equations to denote a more general relation between W and the transversal aberrations {U,V} calculated at any arbitrary Hartmann-plane distance z=r. We also show how to directly estimate the wavefront surface w from the information of {U,V}. The use of arbitrary r values could improve the reliability of the measurements of W, or w, when finding difficulties in adequate ray identification at z=f.

  18. Discrete exterior calculus discretization of incompressible Navier-Stokes equations over surface simplicial meshes

    Science.gov (United States)

    Mohamed, Mamdouh S.; Hirani, Anil N.; Samtaney, Ravi

    2016-05-01

    A conservative discretization of incompressible Navier-Stokes equations is developed based on discrete exterior calculus (DEC). A distinguishing feature of our method is the use of an algebraic discretization of the interior product operator and a combinatorial discretization of the wedge product. The governing equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. The discretization is then carried out by substituting with the corresponding discrete operators based on the DEC framework. Numerical experiments for flows over surfaces reveal a second order accuracy for the developed scheme when using structured-triangular meshes, and first order accuracy for otherwise unstructured meshes. By construction, the method is conservative in that both mass and vorticity are conserved up to machine precision. The relative error in kinetic energy for inviscid flow test cases converges in a second order fashion with both the mesh size and the time step.

  19. A Modular Approach to Model Oscillating Control Surfaces Using Navier Stokes Equations

    Science.gov (United States)

    Guruswamy, Guru P.; Lee, Henry

    2014-01-01

    The use of active controls for rotorcraft is becoming more important for modern aerospace configurations. Efforts to reduce the vibrations of helicopter blades with use of active-controls are in progress. Modeling oscillating control surfaces using the linear aerodynamics theory is well established. However, higher-fidelity methods are needed to account for nonlinear effects, such as those that occur in transonic flow. The aeroelastic responses of a wing with an oscillating control surface, computed using the transonic small perturbation (TSP) theory, have been shown to cause important transonic flow effects such as a reversal of control surface effectiveness that occurs as the shock wave crosses the hinge line. In order to account for flow complexities such as blade-vortex interactions of rotor blades higher-fidelity methods based on the Navier-Stokes equations are used. Reference 6 presents a procedure that uses the Navier-Stokes equations with moving-sheared grids and demonstrates up to 8 degrees of control-surface amplitude, using a single grid. Later, this procedure was extended to accommodate larger amplitudes, based on sliding grid zones. The sheared grid method implemented in EulerlNavier-Stokes-based aeroelastic code ENS AERO was successfully applied to active control design by industry. Recently there are several papers that present results for oscillating control surface using Reynolds Averaged Navier-Stokes (RANS) equations. References 9 and 10 report 2-D cases by filling gaps with overset grids. Reference 9 compares integrated forces with the experiment at low oscillating frequencies whereas Ref. 10 reports parametric studies but with no validation. Reference II reports results for a 3D case by modeling the gap region with a deformed grid and compares force results with the experiment only at the mid-span of flap. In Ref. II grid is deformed to match the control surface deflections at the section where the measurements are made. However, there is no

  20. Time Domain Surface Integral Equation Solvers for Quantum Corrected Electromagnetic Analysis of Plasmonic Nanostructures

    KAUST Repository

    Uysal, Ismail Enes

    2016-10-01

    Plasmonic structures are utilized in many applications ranging from bio-medicine to solar energy generation and transfer. Numerical schemes capable of solving equations of classical electrodynamics have been the method of choice for characterizing scattering properties of such structures. However, as dimensions of these plasmonic structures reduce to nanometer scale, quantum mechanical effects start to appear. These effects cannot be accurately modeled by available classical numerical methods. One of these quantum effects is the tunneling, which is observed when two structures are located within a sub-nanometer distance of each other. At these small distances electrons “jump" from one structure to another and introduce a path for electric current to flow. Classical equations of electrodynamics and the schemes used for solving them do not account for this additional current path. This limitation can be lifted by introducing an auxiliary tunnel with material properties obtained using quantum models and applying a classical solver to the structures connected by this auxiliary tunnel. Early work on this topic focused on quantum models that are generated using a simple one-dimensional wave function to find the tunneling probability and assume a simple Drude model for the permittivity of the tunnel. These tunnel models are then used together with a classical frequency domain solver. In this thesis, a time domain surface integral equation solver for quantum corrected analysis of transient plasmonic interactions is proposed. This solver has several advantages: (i) As opposed to frequency domain solvers, it provides results at a broad band of frequencies with a single simulation. (ii) As opposed to differential equation solvers, it only discretizes surfaces (reducing number of unknowns), enforces the radiation condition implicitly (increasing the accuracy), and allows for time step selection independent of spatial discretization (increasing efficiency). The quantum model

  1. Temporal step fluctuations on a conductor surface: electromigration force, surface resistivity and low-frequency noise

    International Nuclear Information System (INIS)

    Williams, E D; Bondarchuk, O; Tao, C G; Yan, W; Cullen, W G; Rous, P J; Bole, T

    2007-01-01

    Scattering of charge carriers from surface structures will become an increasing factor in the resistivity as the structure decreases in size to the nanoscale. The effects of scattering at the most basic surface defect, a kink in a step edge, are here analyzed using the continuum step model. Using a Langevin analysis, it has been shown that the electromigration force on the atoms at the step edge causes changes in the temporal evolution of the step-edge. For an electromigration force acting perpendicular to the average step edge and mass-transport dominated by step-edge diffusion, significant deviations from the usual t 1/4 scaling of the displacement correlation function occur dependent on a critical time τ and the direction of the force relative to the step edge (i.e. uphill or downhill). Experimental observations of step fluctuations on Ag(111) show the predicted changes among step fluctuations without current, and with current in the up- and down-hill directions for a current density of order 10 5 A cm -2 . The results yield the magnitude of the electromigration force acting on kinked sites at the step-edge. This in turn yields the contribution of the fluctuating steps to the surface resistivity, which exceeds 1% of the bulk resistivity as wire diameters decrease below 10s of nanometres. The temporal fluctuations of kink density can thus also be related to resistivity noise. Relating the known fluctuation spectrum of the step displacements to fluctuations in their lengths, the corresponding resistivity noise is predicted to show spectral signatures of ∼f -1/2 for step fluctuations governed by random attachment/detachment, and ∼f -3/4 for step fluctuations governed by step-edge diffusion

  2. The Path to High Q-Factors in Superconducting Accelerating Cavities: Flux Expulsion and Surface Resistance Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Martinello, Martina [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-12-01

    Accelerating cavities are devices resonating in the radio-frequency (RF) range used to accelerate charged particles in accelerators. Superconducting accelerating cavities are made out of niobium and operate at the liquid helium temperature. Even if superconducting, these resonating structures have some RF driven surface resistance that causes power dissipation. In order to decrease as much as possible the power losses, the cavity quality factor must be increased by decreasing the surface resistance. In this dissertation, the RF surface resistance is analyzed for a large variety of cavities made with different state-of-the-art surface treatments, with the goal of finding the surface treatment capable to return the highest Q-factor values in a cryomodule-like environment. This study analyzes not only the superconducting properties described by the BCS surface resistance, which is the contribution that takes into account dissipation due to quasi-particle excitations, but also the increasing of the surface resistance due to trapped flux. When cavities are cooled down below their critical temperature inside a cryomodule, there is always some remnant magnetic field that may be trapped increasing the global RF surface resistance. This thesis also analyzes how the fraction of external magnetic field, which is actually trapped in the cavity during the cooldown, can be minimized. This study is performed on an elliptical single-cell horizontally cooled cavity, resembling the geometry of cavities cooled in accelerator cryomodules. The horizontal cooldown study reveals that, as in case of the vertical cooldown, when the cooling is performed fast, large thermal gradients are created along the cavity helping magnetic flux expulsion. However, for this geometry the complete magnetic flux expulsion from the cavity equator is more difficult to achieve. This becomes even more challenging in presence of orthogonal magnetic field, that is easily trapped on top of the cavity equator

  3. The path to high Q-factors in superconducting accelerating cavities: Flux expulsion and surface resistance optimization

    Science.gov (United States)

    Martinello, Martina

    Accelerating cavities are devices resonating in the radio-frequency (RF) range used to accelerate charged particles in accelerators. Superconducting accelerating cavities are made out of niobium and operate at the liquid helium temperature. Even if superconducting, these resonating structures have some RF driven surface resistance that causes power dissipation. In order to decrease as much as possible the power losses, the cavity quality factor must be increased by decreasing the surface resistance. In this dissertation, the RF surface resistance is analyzed for a large variety of cavities made with different state-of-the-art surface treatments, with the goal of finding the surface treatment capable to return the highest Q-factor values in a cryomodule-like environment. This study analyzes not only the superconducting properties described by the BCS surface resistance, which is the contribution that takes into account dissipation due to quasi-particle excitations, but also the increasing of the surface resistance due to trapped flux. When cavities are cooled down below their critical temperature inside a cryomodule, there is always some remnant magnetic field that may be trapped increasing the global RF surface resistance. This thesis also analyzes how the fraction of external magnetic field, which is actually trapped in the cavity during the cooldown, can be minimized. This study is performed on an elliptical single-cell horizontally cooled cavity, resembling the geometry of cavities cooled in accelerator cryomodules. The horizontal cooldown study reveals that, as in case of the vertical cooldown, when the cooling is performed fast, large thermal gradients are created along the cavity helping magnetic flux expulsion. However, for this geometry the complete magnetic flux expulsion from the cavity equator is more difficult to achieve. This becomes even more challenging in presence of orthogonal magnetic field, that is easily trapped on top of the cavity equator

  4. Wave-equation dispersion inversion of surface waves recorded on irregular topography

    KAUST Repository

    Li, Jing

    2017-08-17

    Significant topographic variations will strongly influence the amplitudes and phases of propagating surface waves. Such effects should be taken into account, otherwise the S-velocity model inverted from the Rayleigh dispersion curves will contain significant inaccuracies. We now show that the recently developed wave-equation dispersion inversion (WD) method naturally takes into account the effects of topography to give accurate S-velocity tomograms. Application of topographic WD to demonstrates that WD can accurately invert dispersion curves from seismic data recorded over variable topography. We also apply this method to field data recorded on the crest of mountainous terrain and find with higher resolution than the standard WD tomogram.

  5. Wave-equation dispersion inversion of surface waves recorded on irregular topography

    KAUST Repository

    Li, Jing; Schuster, Gerard T.; Lin, Fan-Chi; Alam, Amir

    2017-01-01

    Significant topographic variations will strongly influence the amplitudes and phases of propagating surface waves. Such effects should be taken into account, otherwise the S-velocity model inverted from the Rayleigh dispersion curves will contain significant inaccuracies. We now show that the recently developed wave-equation dispersion inversion (WD) method naturally takes into account the effects of topography to give accurate S-velocity tomograms. Application of topographic WD to demonstrates that WD can accurately invert dispersion curves from seismic data recorded over variable topography. We also apply this method to field data recorded on the crest of mountainous terrain and find with higher resolution than the standard WD tomogram.

  6. Surface perturbations of a shallow viscous fluid heated from below and the (2+1)-dimensional Burgers equation

    International Nuclear Information System (INIS)

    Kraenkel, R.A.; Pereira, J.G.; Manna, M.A.

    1991-01-01

    The (2+1)-dimensional Burgers equation is obtained as the equation of motion governing the surface perturbations of a shallow viscous fluid heated from below, provided the Rayleigh number of the system satisfy the condition R ≠ 30. A solution to this equation is explicity exhibited and it is argued that it describes the nonlinear evolution of a nearly one-dimensional kink. (author)

  7. Continuous surface force based lattice Boltzmann equation method for simulating thermocapillary flow

    International Nuclear Information System (INIS)

    Zheng, Lin; Zheng, Song; Zhai, Qinglan

    2016-01-01

    In this paper, we extend a lattice Boltzmann equation (LBE) with continuous surface force (CSF) to simulate thermocapillary flows. The model is designed on our previous CSF LBE for athermal two phase flow, in which the interfacial tension forces and the Marangoni stresses as the results of the interface interactions between different phases are described by a conception of CSF. In this model, the sharp interfaces between different phases are separated by a narrow transition layers, and the kinetics and morphology evolution of phase separation would be characterized by an order parameter via Cahn–Hilliard equation which is solved in the frame work of LBE. The scalar convection–diffusion equation for temperature field is resolved by thermal LBE. The models are validated by thermal two layered Poiseuille flow, and two superimposed planar fluids at negligibly small Reynolds and Marangoni numbers for the thermocapillary driven convection, which have analytical solutions for the velocity and temperature. Then thermocapillary migration of two/three dimensional deformable droplet are simulated. Numerical results show that the predictions of present LBE agreed with the analytical solution/other numerical results. - Highlights: • A CSF LBE to thermocapillary flows. • Thermal layered Poiseuille flows. • Thermocapillary migration.

  8. Continuous surface force based lattice Boltzmann equation method for simulating thermocapillary flow

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Lin, E-mail: lz@njust.edu.cn [School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Zheng, Song [School of Mathematics and Statistics, Zhejiang University of Finance and Economics, Hangzhou 310018 (China); Zhai, Qinglan [School of Economics Management and Law, Chaohu University, Chaohu 238000 (China)

    2016-02-05

    In this paper, we extend a lattice Boltzmann equation (LBE) with continuous surface force (CSF) to simulate thermocapillary flows. The model is designed on our previous CSF LBE for athermal two phase flow, in which the interfacial tension forces and the Marangoni stresses as the results of the interface interactions between different phases are described by a conception of CSF. In this model, the sharp interfaces between different phases are separated by a narrow transition layers, and the kinetics and morphology evolution of phase separation would be characterized by an order parameter via Cahn–Hilliard equation which is solved in the frame work of LBE. The scalar convection–diffusion equation for temperature field is resolved by thermal LBE. The models are validated by thermal two layered Poiseuille flow, and two superimposed planar fluids at negligibly small Reynolds and Marangoni numbers for the thermocapillary driven convection, which have analytical solutions for the velocity and temperature. Then thermocapillary migration of two/three dimensional deformable droplet are simulated. Numerical results show that the predictions of present LBE agreed with the analytical solution/other numerical results. - Highlights: • A CSF LBE to thermocapillary flows. • Thermal layered Poiseuille flows. • Thermocapillary migration.

  9. Nuclear reactor vessel surface inspecting technique applying electric resistance probe

    International Nuclear Information System (INIS)

    Yamaguchi, T.; Enami, K.; Yoshioka, M.

    1975-01-01

    A new technique for inspecting the inner surface of the PWR type nuclear reactor vessel by use of an electric resistance probe is introduced, centering on a data processing system. This system is composed of a mini-computer, a system typewriter, an interface unit, a D-A converter and controller, and X-Y recorder and others. Its functions are judging flaws and making flaw detection maps. In order to judge flaws by flaw detection signals, three kinds of flaw judging methods have been developed. In case there is a flaw, its position and depth are calculated and listed on the system typewriter. The flaw detection maps are expressed in four kinds of modes and they are displayed on the X-Y recorder. (auth.)

  10. Estimation of subsurface hydrological parameters around Akwuke, Enugu, Nigeria using surface resistivity measurements

    International Nuclear Information System (INIS)

    Utom, Ahamefula U; Odoh, Benard I; Egboka, Boniface C E; Egboka, Nkechi E; Okeke, Harold C

    2013-01-01

    As few boreholes may be available and carrying out pumping tests can be expensive and time consuming, relationships between aquifer characteristics and the electrical parameters of different geoelectric layers exist. Data from 19 vertical electrical soundings (VESs; 13 of these selected for evaluation) was recorded with a Schlumberger electrode configuration in the area around Akwuke, Enugu, Nigeria. The data was interpreted by computer iterative modelling with curve matching for calibration purposes. Geoelectric cross-sections along a number of lines were prepared to ascertain the overall distribution of the resistivity responses of the subsurface lithology. Identified probable shallow aquifer resistivity, thickness and depth values are in the range of 28–527 Ωm, 2.1–22.5 m and 3.1–28.3 m respectively. As our aquifer system consists of fine-grained, clay–silty sand materials, a modification of the Archie equations (Waxman–Smits model) was adopted to determine the true formation factor using the relationship between the apparent formation factor and the pore water resistivity. This representation of the effects of a separate conducting path due to the presence of clay particles in the aquifer materials was used in making reliable estimations of aquifer properties. The average hydraulic conductivity of 8.96 × 10 −4 m s −1 transmissivity ranging between 1.88 × 10 −3 and 2.02 × 10 −3 m 2 s −1 estimated from surface resistivity measurements correlated well with the available field data. Results of the study also showed a direct relationship between aquifer transmissivity and modified transverse resistance (R 2 = 0.85). (paper)

  11. Beyond Cassie equation: Local structure of heterogeneous surfaces determines the contact angles of microdroplets

    Science.gov (United States)

    Zhang, Bo; Wang, Jianjun; Liu, Zhiping; Zhang, Xianren

    2014-01-01

    The application of Cassie equation to microscopic droplets is recently under intense debate because the microdroplet dimension is often of the same order of magnitude as the characteristic size of substrate heterogeneities, and the mechanism to describe the contact angle of microdroplets is not clear. By representing real surfaces statistically as an ensemble of patterned surfaces with randomly or regularly distributed heterogeneities (patches), lattice Boltzmann simulations here show that the contact angle of microdroplets has a wide distribution, either continuous or discrete, depending on the patch size. The origin of multiple contact angles observed is ascribed to the contact line pinning effect induced by substrate heterogeneities. We demonstrate that the local feature of substrate structure near the contact line determines the range of contact angles that can be stabilized, while the certain contact angle observed is closely related to the contact line width. PMID:25059292

  12. A Calderón multiplicative preconditioner for coupled surface-volume electric field integral equations

    KAUST Repository

    Bagci, Hakan

    2010-08-01

    A well-conditioned coupled set of surface (S) and volume (V) electric field integral equations (S-EFIE and V-EFIE) for analyzing wave interactions with densely discretized composite structures is presented. Whereas the V-EFIE operator is well-posed even when applied to densely discretized volumes, a classically formulated S-EFIE operator is ill-posed when applied to densely discretized surfaces. This renders the discretized coupled S-EFIE and V-EFIE system ill-conditioned, and its iterative solution inefficient or even impossible. The proposed scheme regularizes the coupled set of S-EFIE and V-EFIE using a Calderón multiplicative preconditioner (CMP)-based technique. The resulting scheme enables the efficient analysis of electromagnetic interactions with composite structures containing fine/subwavelength geometric features. Numerical examples demonstrate the efficiency of the proposed scheme. © 2006 IEEE.

  13. Effect of Surface Modification on Corrosion Resistance of Uncoated and DLC Coated Stainless Steel Surface

    Science.gov (United States)

    Scendo, Mieczyslaw; Staszewska-Samson, Katarzyna

    2017-08-01

    Corrosion resistance of 4H13 stainless steel (EN-X46Cr13) surface uncoated and coated with an amorphous hydrogenated carbon (a-C:H) film [diamond-like carbon (DLC)] in acidic chloride solution was investigated. The DLC films were deposited on steel surface by a plasma deposition, direct current discharge (PDCD) method. The Fourier transform infrared (FTIR) was used to determine the chemical groups existing on DLC films. The surface of the specimens was observed by a scanning electron microscope (SEM). The tribological properties of the both materials were examined using a ball-on disk tribometer. The microhardness (HV) of diamond-like carbon film increased over five times in relation to the 4H13 stainless steel without of DLC coating. Oxidation kinetic parameters were determined by gravimetric and electrochemical methods. The high value of polarization resistance indicates that the DLC film on substrate was characterized by low electrical conductivity. The corrosion rate of 4H13 stainless steel with of DLC film decreased about eight times in relation to uncoated surface of 4H13 stainless steel.

  14. Derivation of the Wenzel and Cassie Equations from a Phase Field Model for Two Phase Flow on Rough Surface

    KAUST Repository

    Xu, Xianmin; Wang, Xiaoping

    2010-01-01

    In this paper, the equilibrium behavior of an immiscible two phase fluid on a rough surface is studied from a phase field equation derived from minimizing the total free energy of the system. When the size of the roughness becomes small, we derive the effective boundary condition for the equation by the multiple scale expansion homogenization technique. The Wenzel and Cassie equations for the apparent contact angles on the rough surfaces are then derived from the effective boundary condition. The homogenization results are proved rigorously by the F-convergence theory. © 2010 Society for Industrial and Applied Mathematics.

  15. Microwave surface resistance of bulk YBa2Cu3O6+x material

    Science.gov (United States)

    Fathy, A.; Kalokitis, D.; Belohoubek, E.; Sundar, H. G. K.; Safari, A.

    1988-10-01

    Superconducting Y-Ba-Cu-O samples were prepared by conventional solid-state reaction. The microwave surface resistance of 1:2:3 compound superconductor material was measured in a special disk resonator structure at 10 GHz. At liquid-nitrogen temperatures the microwave surface resistance is comparable to that of Au. At lower temperature (~10 K) the surface resistance is an order of magnitude lower than that of Au at the same temperature.

  16. Theoretical study of the surface resistivity of (111) surfaces of NixPt1-x(111) alloys

    International Nuclear Information System (INIS)

    Rous, P. J.

    2001-01-01

    A layer-Korringa - Kohn - Rostoker calculation is used to study the compositional dependence of the surface resistivity of the (111) surface of Ni x Pt 1-x (111) alloys. The compositional disorder in the bulk and at the surface is described by the coherent potential approximation. If it is assumed that the atomic planes near the (111) surface Ni x Pt 1-x have the same composition as the bulk layers, then a weak Nordheim effect is observed in the compositional dependence of the surface resistivity. However, we show that surface segregation in Ni x Pt 1-x (111) causes an inverse Nordheim dependence in the actual surface resistivity as the bulk composition is varied. [copyright] 2001 American Institute of Physics

  17. Magnetic field integral equation analysis of surface plasmon scattering by rectangular dielectric channel discontinuities.

    Science.gov (United States)

    Chremmos, Ioannis

    2010-01-01

    The scattering of a surface plasmon polariton (SPP) by a rectangular dielectric channel discontinuity is analyzed through a rigorous magnetic field integral equation method. The scattering phenomenon is formulated by means of the magnetic-type scalar integral equation, which is subsequently treated through an entire-domain Galerkin method of moments (MoM), based on a Fourier-series plane wave expansion of the magnetic field inside the discontinuity. The use of Green's function Fourier transform allows all integrations over the area and along the boundary of the discontinuity to be performed analytically, resulting in a MoM matrix with entries that are expressed as spectral integrals of closed-form expressions. Complex analysis techniques, such as Cauchy's residue theorem and the saddle-point method, are applied to obtain the amplitudes of the transmitted and reflected SPP modes and the radiated field pattern. Through numerical results, we examine the wavelength selectivity of transmission and reflection against the channel dimensions as well as the sensitivity to changes in the refractive index of the discontinuity, which is useful for sensing applications.

  18. Analysis of Leaky Modes in Photonic Crystal Fibers Using the Surface Integral Equation Method

    Directory of Open Access Journals (Sweden)

    Jung-Sheng Chiang

    2018-04-01

    Full Text Available A fully vectorial algorithm based on the surface integral equation method for the modelling of leaky modes in photonic crystal fibers (PCFs by solely solving the complex propagation constants of characteristic equations is presented. It can be used for calculations of the complex effective index and confinement losses of photonic crystal fibers. As complex root examination is the key technique in the solution, the new algorithm which possesses this technique can be used to solve the leaky modes of photonic crystal fibers. The leaky modes of solid-core PCFs with a hexagonal lattice of circular air-holes are reported and discussed. The simulation results indicate how the confinement loss by the imaginary part of the effective index changes with air-hole size, the number of rings of air-holes, and wavelength. Confinement loss reductions can be realized by increasing the air-hole size and the number of air-holes. The results show that the confinement loss rises with wavelength, implying that the light leaks more easily for longer wavelengths; meanwhile, the losses are decreased significantly as the air-hole size d/Λ is increased.

  19. Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering.

    Science.gov (United States)

    McAnally, Michael O; McMahon, Jeffrey M; Van Duyne, Richard P; Schatz, George C

    2016-09-07

    We present a coupled wave semiclassical theory to describe plasmonic enhancement effects in surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS). A key result is that the plasmon enhanced fields which drive the vibrational equation of motion for each normal mode results in dispersive lineshapes in the SE-FSRS spectrum. This result, which reproduces experimental lineshapes, demonstrates that plasmon-enhanced stimulated Raman methods provide unique sensitivity to a plasmonic response. Our derived SE-FSRS theory shows a plasmonic enhancement of |gpu|(2)ImχR(ω)gst (2)/ImχR(ω), where |gpu|(2) is the absolute square of the plasmonic enhancement from the Raman pump, χR(ω) is the Raman susceptibility, and gst is the plasmonic enhancement of the Stokes field in SE-FSRS. We conclude with a discussion on potential future experimental and theoretical directions for the field of plasmonically enhanced coherent Raman scattering.

  20. Measurement uncertainty evaluation of cellular spheroids surface tension in compressing tests using Young-Laplace equation

    Science.gov (United States)

    Beatrici, Anderson; Santos Baptista, Leandra; Mauro Granjeiro, José

    2018-03-01

    Regenerative Medicine comprises the Biotechnology, Tissue Engineering and Biometrology for stem cell therapy. Starting from stem cells extracted from the patient, autologous implant, these cells are cultured and differentiated into other tissues, for example, articular cartilage. These cells are reorganized into microspheres (cell spheroids). Such tissue units are recombined into functional tissues constructs that can be implanted in the injured region for regeneration. It is necessary the biomechanical characterization of these constructed to determine if their properties are similar to native tissue. In this study was carried out the modeling of the calculation of uncertainty of the surface tension of cellular spheroids with the use of the Young-Laplace equation. We obtained relative uncertainties about 10%.

  1. The orthogonal gradients method: A radial basis functions method for solving partial differential equations on arbitrary surfaces

    KAUST Repository

    Piret, Cé cile

    2012-01-01

    Much work has been done on reconstructing arbitrary surfaces using the radial basis function (RBF) method, but one can hardly find any work done on the use of RBFs to solve partial differential equations (PDEs) on arbitrary surfaces. In this paper

  2. Surface resistance of RE123 films with artificial pinning centers

    International Nuclear Information System (INIS)

    Mukaida, M.; Saito, A.; Kita, R.; Matsumoto, K.; Ichinose, A.; Yoshida, Y.; Horii, S.; Yamada, K.; Mori, N.

    2006-01-01

    Effects of artificial pinning centers (APCs) into ErBa 2 Cu 3 O 7-δ films are discussed. The APCs used in this paper is BaZrO 3 and Zn which are mixed into ErBa 2 Cu 3 O 7-δ ceramic targets. The targets with various contents of APCs are ablated and films are grown on substrates with the APCs. X-ray diffraction patterns show there are no other phases than ErBa 2 Cu 3 O 7-δ and APCs. Transmission electron microscopy (TEM) shows the BaZrO 3 APSs grow along the c-axis of the films. The introduction of APCs decreases surface resistance (R S ) of ErBa 2 Cu 3 O 7-δ films and increases critical current density (J C ) of the films. R S measurements revealed that the ErBa 2 Cu 3 O 7-δ films with APCs showed a lower R S than that of the ErBa 2 Cu 3 O 7-δ films without APCs

  3. Tailoring surface properties of ArF resists thin films with functionally graded materials (FGM)

    Science.gov (United States)

    Takemoto, Ichiki; Ando, Nobuo; Edamatsu, Kunishige; Fuji, Yusuke; Kuwana, Koji; Hashimoto, Kazuhiko; Funase, Junji; Yokoyama, Hiroyuki

    2007-03-01

    Our recent research effort has been focused on new top coating-free 193nm immersion resists with regard to leaching of the resist components and lithographic performance. We have examined methacrylate-based resins that control the surface properties of ArF resists thin films by surface segregation behavior. For a better understanding of the surface properties of thin films, we prepared the six resins (Resin 1-6) that have three types fluorine containing monomers, a new monomer (Monomer A), Monomer B and Monomer C, respectively. We blended the base polymer (Resin 0) with Resin (1-6), respectively. We evaluated contact angles, surface properties and lithographic performances of the polymer blend resists. The static and receding contact angles of the resist that contains Resin (1-6) are greater than that of the base polymer (Resin 0) resist. The chemical composition of the surface of blend polymers was investigated with X-ray photoelectron spectroscopy (XPS). It was shown that there was significant segregation of the fluorine containing resins to the surface of the blend films. We analyzed Quantitative Structure-Property Relationships (QSPR) between the surface properties and the chemical composition of the surface of polymer blend resists. The addition of 10 wt% of the polymer (Resin 1-6) to the base polymer (Resin 0) did not influence the lithographic performance. Consequently, the surface properties of resist thin films can be tailored by the appropriate choice of fluorine containing polymer blends.

  4. The Closest Point Method and Multigrid Solvers for Elliptic Equations on Surfaces

    KAUST Repository

    Chen, Yujia; Macdonald, Colin B.

    2015-01-01

    © 2015 Society for Industrial and Applied Mathematics. Elliptic partial differential equations are important from both application and analysis points of view. In this paper we apply the closest point method to solve elliptic equations on general

  5. On a Linear Equation Arising in Isometric Embedding of Torus-like Surface

    Institute of Scientific and Technical Information of China (English)

    Chunhe LI

    2009-01-01

    The solvability of a linear equation and the regularity of the solution are discussed.The equation is arising in a geometric problem which is concerned with the realization of Alexandroff's positive annul in R3.

  6. Bacterial resistance of self-assembled surfaces using PPOm-b-PSBMAn zwitterionic copolymer - concomitant effects of surface topography and surface chemistry on attachment of live bacteria.

    Science.gov (United States)

    Hsiao, Sheng-Wen; Venault, Antoine; Yang, Hui-Shan; Chang, Yung

    2014-06-01

    Three well-defined diblock copolymers made of poly(sulfobetaine methacrylate) (poly(SBMA)) and poly(propylene oxide) (PPO) groups were synthesized by atom transfer radical polymerization (ATRP) method. They were physically adsorbed onto three types of surfaces having different topography, including smooth flat surface, convex surface, and indented surface. Chemical state of surfaces was characterized by XPS while the various topographies were examined by SEM and AFM. Hydrophilicity of surfaces was dependent on both the surface chemistry and the surface topography, suggesting that orientation of copolymer brushes can be tuned in the design of surfaces aimed at resisting bacterial attachment. Escherichia coli, Staphylococcus epidermidis, Streptococcus mutans and Escherichia coli with green fluorescent protein (E. coli GFP) were used in bacterial tests to assess the resistance to bacterial attachment of poly(SBMA)-covered surfaces. Results highlighted a drastic improvement of resistance to bacterial adhesion with the increasing of poly(SBMA) to PPO ratio, as well as an important effect of surface topography. The chemical effect was directly related to the length of the hydrophilic moieties. When longer, more water could be entrapped, leading to improved anti-bacterial properties. The physical effect impacted on the orientation of the copolymer brushes, as well as on the surface contact area available. Convex surfaces as well as indented surfaces wafer presented the best resistance to bacterial adhesion. Indeed, bacterial attachment was more importantly reduced on these surfaces compared with smooth surfaces. It was explained by the non-orthogonal orientation of copolymer brushes, resulting in a more efficient surface coverage of zwitterionic molecules. This work suggests that not only the control of surface chemistry is essential in the preparation of surfaces resisting bacterial attachment, but also the control of surface topography and orientation of antifouling

  7. Mapping the Qademah Fault with Traveltime, Surface-wave, and Resistivity Tomograms

    KAUST Repository

    Hanafy, Sherif M.

    2015-08-19

    Traveltime, surface-wave, and resistivity tomograms are used to track the buried Qademah fault located near King Abdullah Economic City (KAEC), Saudi Arabia. The fault location is confirmed by the 1) resistivity tomogram obtained from an electrical resistivity experiment, 2) the refraction traveltime tomogram, 3) the reflection image computed from 2D seismic data set recorded at the northern part of the fault, and 4) the surface-wave tomogram.

  8. Mapping the Qademah Fault with Traveltime, Surface-wave, and Resistivity Tomograms

    KAUST Repository

    Hanafy, Sherif M.

    2015-01-01

    Traveltime, surface-wave, and resistivity tomograms are used to track the buried Qademah fault located near King Abdullah Economic City (KAEC), Saudi Arabia. The fault location is confirmed by the 1) resistivity tomogram obtained from an electrical resistivity experiment, 2) the refraction traveltime tomogram, 3) the reflection image computed from 2D seismic data set recorded at the northern part of the fault, and 4) the surface-wave tomogram.

  9. Effect of Surface Contaminants Remained on the Blasted Surface on Epoxy Coating Performance and Corrosion Resistance

    International Nuclear Information System (INIS)

    Baek, Kwang Ki; Park, Chung Seo; Kim, Ki Hong; Chung, Mong Kyu; Park, Jin Hwan

    2006-01-01

    One of the critical issues in the coating specification is the allowable limit of surface contaminant(s) - such as soluble salt(s), grit dust, and rust - after grit blasting. Yet, there is no universally accepted data supporting the relationship between the long-term coating performance and the amount of various surface contaminants allowed after grit blasting. In this study, it was attempted to prepare epoxy coatings applied on grit-blasted steel substrate dosed with controlled amount of surface contaminants - such as soluble salt(s), grit dust, and rust. Then, coating samples were subjected to 4,200 hours of cyclic test(NORSOK M-501), which were then evaluated in terms of resistance to rust creepage, blistering, chalking, rusting, cracking and adhesion strength. Additional investigations on the possible damage at the paint/steel interface were carried out using an Electrochemical Impedance Spectroscopy(EIS) and observations of under-film-corrosion. Test results suggested that the current industrial specifications were well matched with the allowable degree of rust, whereas the allowable amount of soluble salt and grit dust after grit blasting showed a certain deviation from the specifications currently employed for fabrication of marine vessels and offshore facilities

  10. Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men.

    Science.gov (United States)

    Schoenfeld, Brad J; Ratamess, Nicholas A; Peterson, Mark D; Contreras, Bret; Sonmez, G T; Alvar, Brent A

    2014-10-01

    Regimented resistance training has been shown to promote marked increases in skeletal muscle mass. Although muscle hypertrophy can be attained through a wide range of resistance training programs, the principle of specificity, which states that adaptations are specific to the nature of the applied stimulus, dictates that some programs will promote greater hypertrophy than others. Research is lacking, however, as to the best combination of variables required to maximize hypertophic gains. The purpose of this study was to investigate muscular adaptations to a volume-equated bodybuilding-type training program vs. a powerlifting-type routine in well-trained subjects. Seventeen young men were randomly assigned to either a hypertrophy-type resistance training group that performed 3 sets of 10 repetition maximum (RM) with 90 seconds rest or a strength-type resistance training (ST) group that performed 7 sets of 3RM with a 3-minute rest interval. After 8 weeks, no significant differences were noted in muscle thickness of the biceps brachii. Significant strength differences were found in favor of ST for the 1RM bench press, and a trend was found for greater increases in the 1RM squat. In conclusion, this study showed that both bodybuilding- and powerlifting-type training promote similar increases in muscular size, but powerlifting-type training is superior for enhancing maximal strength.

  11. Surface Resistance Measurements and Estimate of the Beam-Induced Resistive Wall Heating of the LHC Dipole Beam Screen

    CERN Document Server

    Caspers, Friedhelm; Ruggiero, F; Tan, J

    1999-01-01

    An estimate of the resistive losses in the LHC beam screen is given from cold surface resistance measurements using the shielded pair technique, with particular emphasis on the effect of a high magnetic field. Two different copper coating methods, namely electro-deposition and co-lamination, have been evaluated. Experimental data are compared with theories including the anomalous skin effect and the magneto-resistance effect. It is shown whether the theory underestimates or not the losses depends strongly on the RRR value, on the magnetic field and on the surface characteristics. In the pessimistic case and for nominal machine parameters, the estimated beam-induced resistive wall heating can be as large as 260 mW/m for two circulating beams.

  12. Formulations by surface integral equations for numerical simulation of non-destructive testing by eddy currents

    International Nuclear Information System (INIS)

    Vigneron, Audrey

    2015-01-01

    The thesis addresses the numerical simulation of non-destructive testing (NDT) using eddy currents, and more precisely the computation of induced electromagnetic fields by a transmitter sensor in a healthy part. This calculation is the first step of the modeling of a complete control process in the CIVA software platform developed at CEA LIST. Currently, models integrated in CIVA are restricted to canonical (modal computation) or axially-symmetric geometries. The need for more diverse and complex configurations requires the introduction of new numerical modeling tools. In practice the sensor may be composed of elements with different shapes and physical properties. The inspected parts are conductive and may contain dielectric or magnetic elements. Due to the cohabitation of different materials in one configuration, different regimes (static, quasi-static or dynamic) may coexist. Under the assumption of linear, isotropic and piecewise homogeneous material properties, the surface integral equation (SIE) approach allows to reduce a volume-based problem to an equivalent surface-based problem. However, the usual SIE formulations for the Maxwell's problem generally suffer from numerical noise in asymptotic situations, and especially at low frequencies. The objective of this study is to determine a version that is stable for a range of physical parameters typical of eddy-current NDT applications. In this context, a block-iterative scheme based on a physical decomposition is proposed for the computation of primary fields. This scheme is accurate and well-conditioned. An asymptotic study of the integral Maxwell's problem at low frequencies is also performed, allowing to establish the eddy-current integral problem as an asymptotic case of the corresponding Maxwell problem. (author) [fr

  13. Surface morphology modelling for the resistivity analysis of low temperature sputtered indium tin oxide thin films on polymer substrates

    International Nuclear Information System (INIS)

    Yin Xuesong; Tang Wu; Weng Xiaolong; Deng Longjiang

    2009-01-01

    Amorphous or weakly crystalline indium tin oxide (ITO) thin film samples have been prepared on polymethylmethacrylate and polyethylene terephthalate substrates by RF-magnetron sputtering at a low substrate temperature. The surface morphological and electrical properties of the ITO layers were measured by atomic force microscopy (AFM) and a standard four-point probe measurement. The effect of surface morphology on the resistivity of ITO thin films was studied, which presented some different variations from crystalline films. Then, a simplified film system model, including the substrate, continuous ITO layer and ITO surface grain, was proposed to deal with these correlations. Based on this thin film model and the AFM images, a quadratic potential was introduced to simulate the characteristics of the ITO surface morphology, and the classical Kronig-Penney model, the semiconductor electrical theory and the modified Neugebauer-Webb model were used to expound the detailed experimental results. The modelling equation was highly in accord with the experimental variations of the resistivity on the characteristics of the surface morphology.

  14. Solving very large scattering problems using a parallel PWTD-enhanced surface integral equation solver

    KAUST Repository

    Liu, Yang

    2013-07-01

    The computational complexity and memory requirements of multilevel plane wave time domain (PWTD)-accelerated marching-on-in-time (MOT)-based surface integral equation (SIE) solvers scale as O(NtNs(log 2)Ns) and O(Ns 1.5); here N t and Ns denote numbers of temporal and spatial basis functions discretizing the current [Shanker et al., IEEE Trans. Antennas Propag., 51, 628-641, 2003]. In the past, serial versions of these solvers have been successfully applied to the analysis of scattering from perfect electrically conducting as well as homogeneous penetrable targets involving up to Ns ≈ 0.5 × 106 and Nt ≈ 10 3. To solve larger problems, parallel PWTD-enhanced MOT solvers are called for. Even though a simple parallelization strategy was demonstrated in the context of electromagnetic compatibility analysis [M. Lu et al., in Proc. IEEE Int. Symp. AP-S, 4, 4212-4215, 2004], by and large, progress in this area has been slow. The lack of progress can be attributed wholesale to difficulties associated with the construction of a scalable PWTD kernel. © 2013 IEEE.

  15. Robust Imaging Methodology for Challenging Environments: Wave Equation Dispersion Inversion of Surface Waves

    KAUST Repository

    Li, Jing

    2017-12-22

    A robust imaging technology is reviewed that provide subsurface information in challenging environments: wave-equation dispersion inversion (WD) of surface waves for the shear velocity model. We demonstrate the benefits and liabilities of the method with synthetic seismograms and field data. The benefits of WD are that 1) there is no layered medium assumption, as there is in conventional inversion of dispersion curves, so that the 2D or 3D S-velocity model can be reliably obtained with seismic surveys over rugged topography, and 2) WD mostly avoids getting stuck in local minima. The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic media and the inversion of dispersion curves associated with Love wave. The liability is that is almost as expensive as FWI and only recovers the Vs distribution to a depth no deeper than about 1/2~1/3 wavelength.

  16. Travelling wave solutions for a surface wave equation in fluid mechanics

    Directory of Open Access Journals (Sweden)

    Tian Yi

    2016-01-01

    Full Text Available This paper considers a non-linear wave equation arising in fluid mechanics. The exact traveling wave solutions of this equation are given by using G'/G-expansion method. This process can be reduced to solve a system of determining equations, which is large and difficult. To reduce this process, we used Wu elimination method. Example shows that this method is effective.

  17. AUTOJOM, Quadratic Equation Coefficient for Conic Volume, Parallelepipeds, Wedges, Pyramids. JOMREAD, Check of 3-D Geometry Structure from Quadratic Surfaces

    International Nuclear Information System (INIS)

    2005-01-01

    Nature of physical problem solved: AUTOJOM is a computer program that will generate the coefficients of any quadratic equation used to define conic volumes and also the coefficients of the planes needed to define parallelepipeds, wedges, and pyramids. JOMREAD is a computer code to check any 3D geometry composed of and constructed with quadratic surfaces

  18. Interpretation of hole-to-surface resistivity measurements at Yucca Mountain, Nevada Test Site

    International Nuclear Information System (INIS)

    Daniels, J.J.; Scott, J.H.

    1981-01-01

    Hole-to-surface resistivity measurements at Yucca Mountain indicate the presence of many near-surface geologic inhomogeneities, with no definite indication of deep structural features. A resistive anomaly near drill hole UE25a-6 is interpreted as a thin, vertical, resistive body that nearly intersects the surface, and may be caused by a silicified, or calcified, fracture zone. A resistive anomaly near hole UE25a-7 is probably caused by a near surface, horizontal, lens-shaped body that may represent a devitrified zone in the Tiva Canyon Member. Many conductive anomalies were detected to the southwest of hole UE25a-4. However, these anomalies are interpreted to be caused by variations in the thickness of the surface alluvium

  19. A new capacitive/resistive probe method for studying magnetic surfaces

    International Nuclear Information System (INIS)

    Kitajima, Sumio; Takayama, Masakazu; Zama, Tatsuya; Takaya, Kazuhiro; Takeuchi, Nobunao; Watanabe, Hiroshige

    1991-01-01

    A new capacitive/resistive probe method for mapping the magnetic surfaces from resistance or capacitance between a magnetic surface and a vacuum vessel was developed and tested. Those resistances and capacitances can be regarded as components of a simple electrical bridge circuit. This method exploits electrical transient response of the bridge circuit for a square pulse. From equiresistance or equicapacitance points, the magnetic surface structure can be deduced. Measurements on the Tohoku University Heliac, which is a small-size standard heliac, show good agreement with numerical calculations. This method is particularly useful for pulse-operated machines. (author)

  20. Method For Creating Corrosion Resistant Surface On An Aluminum Copper Alloy

    Science.gov (United States)

    Mansfeld, Florian B.; Wang, You; Lin, Simon H.

    1997-06-03

    A method for treating the surface of aluminum alloys hang a relatively high copper content is provided which includes the steps of removing substantially all of the copper from the surface, contacting the surface with a first solution containing cerium, electrically charging the surface while contacting the surface in an aqueous molybdate solution, and contacting the surface with a second solution containing cerium. The copper is substantially removed from the surface in the first step either by (i) contacting the surface with an acidic chromate solution or by (ii) contacting the surface with an acidic nitrate solution while subjecting the surface to an electric potential. The corrosion-resistant surface resulting from the invention is excellent, consistent and uniform throughout the surface. Surfaces treated by the invention may often be certified for use in salt-water services.

  1. Controlling friction in a manganite surface by resistive switching

    OpenAIRE

    Schmidt, Hendrik; Krisponeit, Jon-Olaf; Samwer, Konrad; Volkert, Cynthia A.

    2016-01-01

    We report a significant change in friction of a $\\rm La_{0.55}Ca_{0.45}MnO_3$ thin film measured as a function of the materials resistive state under ultrahigh vacuum conditions at room temperature by friction force microscopy. While friction is high in the insulating state, it clearly changes to lower values if the probed local region is switched to the conducting state via nanoscale resistance switching. Thus we demonstrate active control of friction without having to change the temperature...

  2. Comparison of surface fractal dimensions of chromizing coating and P110 steel for corrosion resistance estimation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Naiming, E-mail: lnmlz33@163.com [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Guo, Junwen [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Xie, Faqin [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Zou, Jiaojuan; Tian, Wei [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Yao, Xiaofei [School of Materials and Chemical Engineering, Xi’an Technological University, Xi’an 710032 (China); Zhang, Hongyan; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2014-08-30

    Highlights: • Continuous chromizing coating was synthesized on P110 steel by pack cementation. • The chromizing coating showed better corrosion resistance. • Comparison of surface fractal dimensions can estimate corrosion resistance. - Abstract: In the field of corrosion research, mass gain/loss, electrochemical tests and comparing the surface elemental distributions, phase constitutions as well as surface morphologies before and after corrosion are extensively applied to investigate the corrosion behavior or estimate the corrosion resistance of materials that operated in various environments. Most of the above methods are problem oriented, complex and longer-period time-consuming. However from an object oriented point of view, the corroded surfaces of materials often have self-similar characterization: fractal property which can be employed to efficiently achieve damaged surface analysis. The present work describes a strategy of comparison of the surface fractal dimensions for corrosion resistance estimation: chromizing coating was synthesized on P110 steel surface to improve its performance via pack cementation. Scanning electron microscope (SEM) was used to investigate the surface morphologies of the original and corroded samples. Surface fractal dimensions of the detected samples were calculated by binary images related to SEM images of surface morphologies with box counting algorithm method. The results showed that both surface morphologies and surface fractal dimensions of P110 steel varied greatly before and after corrosion test, but the chromizing coating changed slightly. The chromizing coating indicated better corrosion resistance than P110 steel. Comparison of surface fractal dimensions of original and corroded samples can rapidly and exactly realize the estimation of corrosion resistance.

  3. Comparison of surface fractal dimensions of chromizing coating and P110 steel for corrosion resistance estimation

    International Nuclear Information System (INIS)

    Lin, Naiming; Guo, Junwen; Xie, Faqin; Zou, Jiaojuan; Tian, Wei; Yao, Xiaofei; Zhang, Hongyan; Tang, Bin

    2014-01-01

    Highlights: • Continuous chromizing coating was synthesized on P110 steel by pack cementation. • The chromizing coating showed better corrosion resistance. • Comparison of surface fractal dimensions can estimate corrosion resistance. - Abstract: In the field of corrosion research, mass gain/loss, electrochemical tests and comparing the surface elemental distributions, phase constitutions as well as surface morphologies before and after corrosion are extensively applied to investigate the corrosion behavior or estimate the corrosion resistance of materials that operated in various environments. Most of the above methods are problem oriented, complex and longer-period time-consuming. However from an object oriented point of view, the corroded surfaces of materials often have self-similar characterization: fractal property which can be employed to efficiently achieve damaged surface analysis. The present work describes a strategy of comparison of the surface fractal dimensions for corrosion resistance estimation: chromizing coating was synthesized on P110 steel surface to improve its performance via pack cementation. Scanning electron microscope (SEM) was used to investigate the surface morphologies of the original and corroded samples. Surface fractal dimensions of the detected samples were calculated by binary images related to SEM images of surface morphologies with box counting algorithm method. The results showed that both surface morphologies and surface fractal dimensions of P110 steel varied greatly before and after corrosion test, but the chromizing coating changed slightly. The chromizing coating indicated better corrosion resistance than P110 steel. Comparison of surface fractal dimensions of original and corroded samples can rapidly and exactly realize the estimation of corrosion resistance

  4. A rapid numerical method for solving Serre-Green-Naghdi equations describing long free surface gravity waves

    Science.gov (United States)

    Favrie, N.; Gavrilyuk, S.

    2017-07-01

    A new numerical method for solving the Serre-Green-Naghdi (SGN) equations describing dispersive waves on shallow water is proposed. From the mathematical point of view, the SGN equations are the Euler-Lagrange equations for a ‘master’ lagrangian submitted to a differential constraint which is the mass conservation law. One major numerical challenge in solving the SGN equations is the resolution of an elliptic problem at each time instant. This is the most time-consuming part of the numerical method. The idea is to replace the ‘master’ lagrangian by a one-parameter family of ‘augmented’ lagrangians, depending on a greater number of variables, for which the corresponding Euler-Lagrange equations are hyperbolic. In such an approach, the ‘master’ lagrangian is recovered by the augmented lagrangian in some limit (for example, when the corresponding parameter is large). The choice of such a family of augmented lagrangians is proposed and discussed. The corresponding hyperbolic system is numerically solved by a Godunov type method. Numerical solutions are compared with exact solutions to the SGN equations. It appears that the computational time in solving the hyperbolic system is much lower than in the case where the elliptic operator is inverted. The new method is applied, in particular, to the study of ‘Favre waves’ representing non-stationary undular bores produced after reflection of the fluid flow with a free surface at an immobile wall.

  5. Study of the Electromagnetic Waves Propagation over the Improved Fractal Sea Surface Based on Parabolic Equation Method

    Directory of Open Access Journals (Sweden)

    Wenwan Ding

    2016-01-01

    Full Text Available An improved fractal sea surface model, which can describe the capillary waves very well, is introduced to simulate the one-dimension rough sea surface. In this model, the propagation of electromagnetic waves (EWs is computed by the parabolic equation (PE method using the finite-difference (FD algorithm. The numerical simulation results of the introduced model are compared with those of the Miller-Brown model and the Elfouhaily spectrum inversion model. It has been shown that the effects of the fine structure of the sea surface on the EWs propagation in the introduced model are more apparent than those in the other two models.

  6. Resistance of surface-dried virus to common disinfection procedures

    NARCIS (Netherlands)

    Terpstra, F. G.; van den Blink, A. E.; Bos, L. M.; Boots, A. G. C.; Brinkhuis, F. H. M.; Gijsen, E.; van Remmerden, Y.; Schuitemaker, H.; van 't Wout, A. B.

    2007-01-01

    It is believed that surface-dried viruses can remain infectious and may therefore pose a threat to public health. To help address this issue, we studied 0.1 N NaOH and 0.1% hypochlorite for their capacity to inactivate surface-dried lipid-enveloped (LE) [human immunodeficiency virus (HIV), bovine

  7. Effects of photovoltaic module soiling on glass surface resistance and potential-induced degradation

    DEFF Research Database (Denmark)

    Hacke, Peter; Burton, Patrick; Hendrickson, Alexander

    2015-01-01

    The sheet resistance of three soil types (Arizona road dust, soot, and sea salt) on glass were measured by the transmission line method as a function of relative humidity (RH) between 39% and 95% at 60°C. Sea salt yielded a 3.5 orders of magnitude decrease in resistance on the glass surface when ...

  8. An open circuit voltage equation enabling separation of cathode and anode polarization resistances of ceria electrolyte based solid oxide fuel cells

    Science.gov (United States)

    Zhang, Yanxiang; Chen, Yu; Yan, Mufu

    2017-07-01

    The open circuit voltage (OCV) of solid oxide fuel cells is generally overestimated by the Nernst equation and the Wagner equation, due to the polarization losses at electrodes. Considering both the electronic conduction of electrolyte and the electrode polarization losses, we express the OCV as an implicit function of the characteristic oxygen pressure of electrolyte (p* [atm], at which the electronic and ionic conductivities are the same), and the relative polarization resistance of electrodes (rc = Rc/Ri and ra = Ra/Ri, where Ri/c/a [Ωcm2] denotes the ionic resistance of electrolyte, and the polarization resistances of cathode and anode, respectively). This equation approaches to the Wagner equation when the electrodes are highly active (rc and ra → 0), and approaches to the Nernst equation when the electrolyte is a purely ionic conductor (p* → 0). For the fuel cells whose OCV is well below the prediction of the Wagner equation, for example with thin doped ceria electrolyte, it is demonstrated that the combination of OCV and impedance spectroscopy measurements allows the determination of p*, Rc and Ra. This equation can serve as a simple yet powerful tool to study the internal losses in the cell under open circuit condition.

  9. Development of a High Slip-resistant Footwear Outsole Using a Hybrid Rubber Surface Pattern

    OpenAIRE

    YAMAGUCHI, Takeshi; HOKKIRIGAWA, Kazuo

    2014-01-01

    Abstract: The present study examined whether a new footwear outsole with tread blocks and a hybrid rubber surface pattern, composed of rough and smooth surfaces, could increase slip resistance and reduce the risk of fall while walking on a wet floor surface. A drag test was performed to measure static and dynamic coefficient of friction (SCOF and DCOF, respectively) values for the footwear with the hybrid rubber surface pattern outsole and two types of commercially available boots that are co...

  10. Discrete exterior calculus discretization of incompressible Navier–Stokes equations over surface simplicial meshes

    KAUST Repository

    Mohamed, Mamdouh S.; Hirani, Anil N.; Samtaney, Ravi

    2016-01-01

    A conservative discretization of incompressible Navier–Stokes equations is developed based on discrete exterior calculus (DEC). A distinguishing feature of our method is the use of an algebraic discretization of the interior product operator and a

  11. Impact of Volcanic Ash on Road and Airfield Surface Skid Resistance

    Directory of Open Access Journals (Sweden)

    Daniel M. Blake

    2017-08-01

    Full Text Available Volcanic ash deposited on paved surfaces during volcanic eruptions often compromises skid resistance, which is a major component of safety. We adopt the British pendulum test method in laboratory conditions to investigate the skid resistance of road asphalt and airfield concrete surfaces covered by volcanic ash sourced from various locations in New Zealand. Controlled variations in ash characteristics include type, depth, wetness, particle size and soluble components. We use Stone Mastic Asphalt (SMA for most road surface experiments but also test porous asphalt, line-painted road surfaces, and a roller screed concrete mix used for airfields. Due to their importance for skid resistance, SMA surface macrotexture and microtexture are analysed with semi-quantitative image analysis, microscopy and a standardised sand patch volumetric test, which enables determination of the relative effectiveness of different cleaning techniques. We find that SMA surfaces covered by thin deposits (~1 mm of ash result in skid resistance values slightly lower than those observed on wet uncontaminated surfaces. At these depths, a higher relative soluble content for low-crystalline ash and a coarser particle size results in lower skid resistance. Skid resistance results for relatively thicker deposits (3–5 mm of non-vesiculated basaltic ash are similar to those for thin deposits. There are similarities between road asphalt and airfield concrete, although there is little difference in skid resistance between bare airfield surfaces and airfield surfaces covered by 1 mm of ash. Based on our findings, we provide recommendations for maintaining road safety and effective cleaning techniques in volcanic ash environments.

  12. Ginzburg-Landau equations for a d-wave superconductor with applications to vortex structure and surface problems

    International Nuclear Information System (INIS)

    Xu, J.; Ren, Y.; Ting, C.S.

    1995-01-01

    The properties of a d x 2 -y 2 -wave superconductor in an external magnetic field are investigated on the basis of Gorkov's theory of weakly coupled superconductors. The Ginzburg-Landau (GL) equations, which govern the spatial variations of the order parameter and the supercurrent, are microscopically derived. The single vortex structure and surface problems in such a superconductor are studied using these equations. It is shown that the d-wave vortex structure is very different from the conventional s-wave vortex: the s-wave and d-wave components, with the opposite winding numbers, are found to coexist in the region near the vortex core. The supercurrent and local magnetic field around the vortex are calculated. Far away from the vortex core, both of them exhibit a fourfold symmetry, in contrast to an s-wave superconductor. The surface problem in a d-wave superconductor is also studied by solving the GL equations. The total order parameter near the surface is always a real combination of s- and d-wave components, which means that the proximity effect cannot induce a time-reversal symmetry-breaking state at the surface

  13. Unsteady free surface flow in porous media: One-dimensional model equations including vertical effects and seepage face

    Science.gov (United States)

    Di Nucci, Carmine

    2018-05-01

    This note examines the two-dimensional unsteady isothermal free surface flow of an incompressible fluid in a non-deformable, homogeneous, isotropic, and saturated porous medium (with zero recharge and neglecting capillary effects). Coupling a Boussinesq-type model for nonlinear water waves with Darcy's law, the two-dimensional flow problem is solved using one-dimensional model equations including vertical effects and seepage face. In order to take into account the seepage face development, the system equations (given by the continuity and momentum equations) are completed by an integral relation (deduced from the Cauchy theorem). After testing the model against data sets available in the literature, some numerical simulations, concerning the unsteady flow through a rectangular dam (with an impermeable horizontal bottom), are presented and discussed.

  14. Effect of the surface film electric resistance on eddy current detectability of surface cracks in Alloy 600 tubes

    International Nuclear Information System (INIS)

    Saario, T.; Paine, J.P.N.

    1995-01-01

    The most widely used technique for NDE of steam generator tubing is eddy current. This technique can reliably detect cracks grown in sodium hydroxide environment only at depths greater than 50% through wall. However, cracking caused by thiosulphate solutions have been detected and sized at shallower depths. The disparity has been proposed to be caused by the different electric resistance of the crack wall surface films and corrosion products in the cracks formed in different environments. This work was undertaken to clarify the role of surface film electric resistance on the disparity found in eddy current detectability of surface cracks in alloy 600 tubes. The proposed model explaining the above mentioned disparity is the following. The detectability of tightly closed cracks by the eddy current technique depends on the electric resistance of the surface films of the crack walls. The nature and resistance of the films which form on the crack walls during operation depends on the composition of the solution inside the crack and close to the crack location. During cooling down of the steam generator, because of contraction and loss of internal pressurization, the cracks are rather tightly closed so that exchange of electrolyte and thus changes in the film properties become difficult. As a result, the surface condition prevailing at high temperature is preserved. If the environment is such that the films formed on the crack walls under operating conditions have low electric resistance, eddy current technique will fail to indicate these cracks or will underestimate the size of these cracks. However, if the electric resistance of the films is high, a tightly closed crack will resemble an open crack and will be easily indicated and correctly sized by eddy current technique

  15. Measurements of the anomalous RF surface resistance of niobium using a dielectric resonator

    International Nuclear Information System (INIS)

    Moffat, D.; Bolore, M.; Bonin, B.; Jacques, E.; Safa, H.

    1996-01-01

    The surface resistance of high and low residual resistance ratio (RRR) niobium plates at 4.2 K and 1.8 K has been measured as a function of many processing and testing parameters. A dielectric resonator was used instead of a resonant cavity. This resonator offered the ability to make many, sensitive measurements with an efficient use of time and helium. It was found that the surface resistance, R s , of RRR = 190 niobium increased noticeably from the theoretical value if the cooling rate was slower than ∼ 10 K/min. (author)

  16. Dependence of the microwave surface resistance of superconducting niobium on the magnitude of the rf field

    Energy Technology Data Exchange (ETDEWEB)

    Romanenko, A.; Grassellino, A. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)

    2013-06-24

    Utilizing difference in temperature dependencies we decoupled Bardeen-Cooper-Schrieffer (BCS) and residual components of the microwave surface resistance of superconducting niobium at all rf fields up to B{sub rf}{approx}115 mT. We reveal that the residual resistance decreases with field at B{sub rf} Less-Than-Or-Equivalent-To 40 mT and strongly increases in chemically treated niobium at B{sub rf}>80 mT. We find that BCS surface resistance is weakly dependent on field in the clean limit, whereas a strong and peculiar field dependence emerges after 120 Degree-Sign C vacuum baking.

  17. LEAST SQUARE APPROACH FOR ESTIMATING OF LAND SURFACE TEMPERATURE FROM LANDSAT-8 SATELLITE DATA USING RADIATIVE TRANSFER EQUATION

    Directory of Open Access Journals (Sweden)

    Y. Jouybari-Moghaddam

    2017-09-01

    Full Text Available Land Surface Temperature (LST is one of the significant variables measured by remotely sensed data, and it is applied in many environmental and Geoscience studies. The main aim of this study is to develop an algorithm to retrieve the LST from Landsat-8 satellite data using Radiative Transfer Equation (RTE. However, LST can be retrieved from RTE, but, since the RTE has two unknown parameters including LST and surface emissivity, estimating LST from RTE is an under the determined problem. In this study, in order to solve this problem, an approach is proposed an equation set includes two RTE based on Landsat-8 thermal bands (i.e.: band 10 and 11 and two additional equations based on the relation between the Normalized Difference Vegetation Index (NDVI and emissivity of Landsat-8 thermal bands by using simulated data for Landsat-8 bands. The iterative least square approach was used for solving the equation set. The LST derived from proposed algorithm is evaluated by the simulated dataset, built up by MODTRAN. The result shows the Root Mean Squared Error (RMSE is less than 1.18°K. Therefore; the proposed algorithm can be a suitable and robust method to retrieve the LST from Landsat-8 satellite data.

  18. Least Square Approach for Estimating of Land Surface Temperature from LANDSAT-8 Satellite Data Using Radiative Transfer Equation

    Science.gov (United States)

    Jouybari-Moghaddam, Y.; Saradjian, M. R.; Forati, A. M.

    2017-09-01

    Land Surface Temperature (LST) is one of the significant variables measured by remotely sensed data, and it is applied in many environmental and Geoscience studies. The main aim of this study is to develop an algorithm to retrieve the LST from Landsat-8 satellite data using Radiative Transfer Equation (RTE). However, LST can be retrieved from RTE, but, since the RTE has two unknown parameters including LST and surface emissivity, estimating LST from RTE is an under the determined problem. In this study, in order to solve this problem, an approach is proposed an equation set includes two RTE based on Landsat-8 thermal bands (i.e.: band 10 and 11) and two additional equations based on the relation between the Normalized Difference Vegetation Index (NDVI) and emissivity of Landsat-8 thermal bands by using simulated data for Landsat-8 bands. The iterative least square approach was used for solving the equation set. The LST derived from proposed algorithm is evaluated by the simulated dataset, built up by MODTRAN. The result shows the Root Mean Squared Error (RMSE) is less than 1.18°K. Therefore; the proposed algorithm can be a suitable and robust method to retrieve the LST from Landsat-8 satellite data.

  19. Analysis of atmospheric flow over a surface protrusion using the turbulence kinetic energy equation with reference to aeronautical operating systems

    Science.gov (United States)

    Frost, W.; Harper, W. L.

    1975-01-01

    Flow over surface obstructions can produce significantly large wind shears such that adverse flying conditions can occur for aeronautical systems (helicopters, STOL vehicles, etc.). Atmospheric flow fields resulting from a semi-elliptical surface obstruction in an otherwise horizontally homogeneous statistically stationary flow are modelled with the boundary-layer/Boussinesq-approximation of the governing equation of fluid mechanics. The turbulence kinetic energy equation is used to determine the dissipative effects of turbulent shear on the mean flow. Iso-lines of turbulence kinetic energy and turbulence intensity are plotted in the plane of the flow and highlight regions of high turbulence intensity in the stagnation zone and sharp gradients in intensity along the transition from adverse to favourable pressure gradient. Discussion of the effects of the disturbed wind field in CTOL and STOL aircraft flight path and obstruction clearance standards is given. The results indicate that closer inspection of these presently recommended standards as influenced by wind over irregular terrains is required.

  20. Protein resistance of surfaces modified with oligo(ethylene glycol) aryl diazonium derivatives.

    Science.gov (United States)

    Fairman, Callie; Ginges, Joshua Z; Lowe, Stuart B; Gooding, J Justin

    2013-07-22

    Anti-fouling surfaces are of great importance for reducing background interference in biosensor signals. Oligo(ethylene glycol) (OEG) moieties are commonly used to confer protein resistance on gold, silicon and carbon surfaces. Herein, we report the modification of surfaces using electrochemical deposition of OEG aryl diazonium salts. Using electrochemical and contact angle measurements, the ligand packing density is found to be loose, which supports the findings of the fluorescent protein labelling that aryl diazonium OEGs confer resistance to nonspecific adsorption of proteins albeit lower than alkane thiol-terminated OEGs. In addition to protein resistance, aryl diazonium attachment chemistry results in stable modification. In common with OEG species on gold electrodes, OEGs with distal hydroxyl moieties do confer superior protein resistance to those with a distal methoxy group. This is especially the case for longer derivatives where superior coiling of the OEG chains is possible. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Asymptotic behavior of monodromy singularly perturbed differential equations on a Riemann surface

    CERN Document Server

    Simpson, Carlos

    1991-01-01

    This book concerns the question of how the solution of a system of ODE's varies when the differential equation varies. The goal is to give nonzero asymptotic expansions for the solution in terms of a parameter expressing how some coefficients go to infinity. A particular classof families of equations is considered, where the answer exhibits a new kind of behavior not seen in most work known until now. The techniques include Laplace transform and the method of stationary phase, and a combinatorial technique for estimating the contributions of terms in an infinite series expansion for the solution. Addressed primarily to researchers inalgebraic geometry, ordinary differential equations and complex analysis, the book will also be of interest to applied mathematicians working on asymptotics of singular perturbations and numerical solution of ODE's.

  2. Heat-resisting alloys for hard surfacing and sealing pad welding

    Directory of Open Access Journals (Sweden)

    R.O. Wielgosz

    2010-07-01

    Full Text Available The paper deals with heat-resisting alloys used to harden surfaces of elements operating in increased temperatures. It also deals with alloysused to seal cooperating surfaces of elements operating in the conditions of increased temperatures and aggressive utilities. Application methods and properties of thus obtained layers have been presented and adhesion of layers with matrix material has been assessed.

  3. The orthogonal gradients method: A radial basis functions method for solving partial differential equations on arbitrary surfaces

    KAUST Repository

    Piret, Cécile

    2012-05-01

    Much work has been done on reconstructing arbitrary surfaces using the radial basis function (RBF) method, but one can hardly find any work done on the use of RBFs to solve partial differential equations (PDEs) on arbitrary surfaces. In this paper, we investigate methods to solve PDEs on arbitrary stationary surfaces embedded in . R3 using the RBF method. We present three RBF-based methods that easily discretize surface differential operators. We take advantage of the meshfree character of RBFs, which give us a high accuracy and the flexibility to represent the most complex geometries in any dimension. Two out of the three methods, which we call the orthogonal gradients (OGr) methods are the result of our work and are hereby presented for the first time. © 2012 Elsevier Inc.

  4. Corrosion resistance of the welded AISI 316L after various surface treatments

    Directory of Open Access Journals (Sweden)

    Tatiana Liptáková

    2014-01-01

    Full Text Available The main aim of this work is to monitor the surface treatment impact on the corrosion resistance of the welded stainless steel AISI 316L to local corrosion forms. The excellent corrosion resistance of austenitic stainless steel is caused by the existence of stable, thin and well adhering passive layer which quality is strongly influenced by welding. Therefore surface treatment of stainless steel is very important with regard to its local corrosion susceptibility Surfaces of welded stainless steel were treated by various mechanical methods (grinding, garnet blasting. Surface properties were studied by SEM, corrosion resistance was evaluated after exposition tests in chlorides environment using weight and metalographic analysis. The experimental outcomes confirmed that the mechanical finishing has a significant effect on the corrosion behavior of welded stainless steel AISI 316L.

  5. Analysis of the incompressible Navier-Stokes equations with a quasi free-surface condition

    NARCIS (Netherlands)

    E.H. van Brummelen (Harald)

    1999-01-01

    textabstractNumerical solution of free-surface flows with a free-surface that can be represented by a height-function, is of great practical importance. Dedicated methods have been developed for the efficient solution of steady free-surface potential flow. These methods solve a sequence of

  6. A modified SOR method for the Poisson equation in unsteady free-surface flow calculations.

    NARCIS (Netherlands)

    Botta, E.F.F.; Ellenbroek, Marcellinus Hermannus Maria

    1985-01-01

    Convergence difficulties that sometimes occur if the successive overrelaxation (SOR) method is applied to the Poisson equation on a region with irregular free boundaries are analyzed. It is shown that these difficulties are related to the treatment of the free boundaries and caused by the appearance

  7. Study on the surface oxidation resistance of uranium metal in the atmosphere of carbon monoxide

    International Nuclear Information System (INIS)

    Wang Xiaolin; Fu Yibei; Xie Renshou

    1999-01-01

    The surface reactions of different layers on uranium metal with carbon monoxide at 25, 80 and 200 degree C are studied by X-ray photoelectron spectroscopy (XPS). The experimental results show that the carbon monoxide is adsorbed on the surface oxide layer of uranium and interacted each other. The content of oxygen in the surface oxide and O/U ratio are decreased with increasing the exposure of carbon monoxide to the surface layer. The effect of reduction on the metal surface is more obviously with a higher temperature and increasing of layer thickness. The investigation indicates the uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide

  8. Automation for measuring the surface resistivity of RPC by Arduino motor shield

    International Nuclear Information System (INIS)

    Pandey, A.; Kumar, A.; Singh, M.K.; Marimuthu, N.; Singh, V.

    2016-01-01

    India Based Neutrino Observatory (INO) is planning to use ∼ 30,000 Resistive Plate Chamber (RPC) detectors of size 2m x 2m. Each resistive plate chamber is made up of glass or Bakelite whose resistance is of the order 10 12 Ω/cm 2 , and two pick-up panels. Both glass electrodes of the detector have one side (outer) painted with thin and uniform coating of graphite paint. This provides the resistivity of range 100 - 300 kΩ per square. This range of resistivity provides distribution of voltage over the surface of glass electrodes. Uniform coating will provide uniform electric field inside the glass plate chamber and high resistivity value will help in confining the induced charge on the surface. It is one of the necessary criteria for good RPC detector that the coating of graphite paint should be uniform. Therefore it is required to measure the resistivity for the verification of uniformity. Last few years we have been focusing our efforts in this direction. In this connection, we made sequential improvement from the previous work. The present system is cost effective, automatically recording measurement in the computer, fast and accurate. Earlier MOTOR BEE ver. 5.0 microcontroller was used which was an imported and costly material. After massive search in the local market Arduino microcontroller was discovered, which controls the movement of all motors and it also saves the value of resistivity in the computer automatically

  9. Improved surface corrosion resistance of WE43 magnesium alloy by dual titanium and oxygen ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Ying [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Guosong; Lu, Qiuyuan [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Jun [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Xu, Ruizhen [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Yeung, Kelvin W.K., E-mail: wkkyeung@hku.hk [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2013-02-01

    Magnesium alloys are potential biodegradable materials and have attracted much attention due to their outstanding biological performance and mechanical properties. However, their rapid degradation inside the human body cannot meet clinical needs. In order to improve the corrosion resistance, dual titanium and oxygen ion implantation is performed to modify the surface of the WE43 magnesium alloy. X-ray photoelectron spectroscopy is used to characterize the microstructures in the near surface layer and electrochemical impedance spectroscopy, potentiodynamic polarization, and immersion tests are employed to investigate the corrosion resistance of the implanted alloys in simulated body fluids. The results indicate that dual titanium and oxygen ion implantation produces a TiO{sub 2}-containing surface film which significantly enhances the corrosion resistance of WE43 magnesium alloy. Our data suggest a simple and practical means to improve the corrosion resistance of degradable magnesium alloys. - Highlights: ► Surface modification of WE43 magnesium alloy using dual ion implantation ► Dual Ti and O ion implantation produces a homogeneous TiO{sub 2}-containing surface film ► Significant improvement of the alloy corrosion resistance after the dual ion implantation.

  10. A boundary integral equation method using auxiliary interior surface approach for acoustic radiation and scattering in two dimensions.

    Science.gov (United States)

    Yang, S A

    2002-10-01

    This paper presents an effective solution method for predicting acoustic radiation and scattering fields in two dimensions. The difficulty of the fictitious characteristic frequency is overcome by incorporating an auxiliary interior surface that satisfies certain boundary condition into the body surface. This process gives rise to a set of uniquely solvable boundary integral equations. Distributing monopoles with unknown strengths over the body and interior surfaces yields the simple source formulation. The modified boundary integral equations are further transformed to ordinary ones that contain nonsingular kernels only. This implementation allows direct application of standard quadrature formulas over the entire integration domain; that is, the collocation points are exactly the positions at which the integration points are located. Selecting the interior surface is an easy task. Moreover, only a few corresponding interior nodal points are sufficient for the computation. Numerical calculations consist of the acoustic radiation and scattering by acoustically hard elliptic and rectangular cylinders. Comparisons with analytical solutions are made. Numerical results demonstrate the efficiency and accuracy of the current solution method.

  11. Effects of PV Module Soiling on Glass Surface Resistance and Potential-Induced Degradation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter; Burton, Patrick; Hendrickson, Alex; Spartaru, Sergiu; Glick, Stephen; Terwilliger, Kent

    2015-12-03

    The sheet resistance of three soil types (Arizona road dust, soot, and sea salt) on glass were measured by the transmission line method as a function of relative humidity (RH) between 39% and 95% at 60 degrees C. Sea salt yielded a 3.5 order of magnitude decrease in resistance on the glass surface when the RH was increased over this RH range. Arizona road dust showed reduced sheet resistance at lower RH, but with less humidity sensitivity over the range tested. The soot sample did not show significant resistivity change compared to the unsoiled control. Photovoltaic modules with sea salt on their faces were step-stressed between 25% and 95% RH at 60 degrees C applying -1000 V bias to the active cell circuit. Leakage current from the cell circuit to ground ranged between two and ten times higher than that of the unsoiled controls. Degradation rate of modules with salt on the surface increased with increasing RH and time.

  12. Airflow resistivity instrument for in situ measurement on the earth's ground surface

    Science.gov (United States)

    Zuckerwar, A. J.

    1983-01-01

    An airflow resistivity instrument features a novel specimen holder, especially designed for in situ measurement on the earth's ground surface. This capability eliminates the disadvantages of prior intrusive instruments, which necessitate the removal of a test specimen from the ground. A prototype instrument can measure airflow resistivities in the range 10-5000 cgs rayl/cm, at specimen depths up to 15.24 cm (6 in.), and at differential pressures up to 2490.8 dyn sq cm (1 in. H2O) across the specimen. Because of the close relationship between flow resistivity and acoustic impedance, this instrument should prove useful in acoustical studies of the earth's ground surface. Results of airflow resistivity measurements on an uncultivated grass field for varying values of moisture content are presented.

  13. Study of the surface resistance of niobium sputter-coated copper cavities

    CERN Document Server

    Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Peck, M A; Russo, R; Valente, A M

    1999-01-01

    A systematic study of the superconducting properties of niobium films deposited on the inner wall of copper radiofrequency cavities is presented. Films are grown by sputtering with different discharge gases (Xe, Kr, Ar and Ar/Ne mixtures) on substrates prepared under different conditions. The measured quantities include the surface resistance at 1.5 GHz, the critical temperature and the penetration depth. The surface resistance is analyzed in terms of its dependence on temperature, RF field and the density of trapped fluxons. Once allowance for electron scattering is made by means of a single mean free path parameter, good agreement with BCS theory is observed. The residual resistance is observed to be essentially noncorrelated with the superconducting properties, although influenced by specific coating conditions. On occasions, very low residual resistances, in the nano-ohm range, have been maintained over a broad range of RF field, indicating the absence of fundamental limitations specific to the film techn...

  14. Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates

    International Nuclear Information System (INIS)

    Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu; Gong, Lijun; He, Wei

    2017-01-01

    Highlights: • Air atmosphere plasmacould generatehydrophilic groups of photo-resistive film. • Better wettability of photo-resistive filmled tohigher plating uniformity of copper pillars. • New flow isreduced cost, simplified process and elevated productivity. - Abstract: The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O_2−CF_4 low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of C−O, O−C=O, C=O and −NO_2 by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

  15. Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Gong, Lijun [Research and Development Department, Guangzhou Fastprint Circuit Tech Co., Ltd., Guangzhou 510663 (China); He, Wei, E-mail: heweiz@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research and Development Department, Guangdong Guanghua Sci-Tech Co., Ltd., Shantou 515000 (China)

    2017-07-31

    Highlights: • Air atmosphere plasmacould generatehydrophilic groups of photo-resistive film. • Better wettability of photo-resistive filmled tohigher plating uniformity of copper pillars. • New flow isreduced cost, simplified process and elevated productivity. - Abstract: The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O{sub 2}−CF{sub 4} low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of C−O, O−C=O, C=O and −NO{sub 2} by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

  16. Influence of surface roughness of stainless steel on microbial adhesion and corrosion resistance

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Bagge-Ravn, Dorthe; Kold, John

    2003-01-01

    Abstract The aim of this study was to evaluate if hygienic characteristics of stainless steel used in the food industry could be improved by smoothing surface roughness from an Ra of 0.9 to 0.01 ƒÝm. The adherence of Pseudomonas sp., Listeria monocytogenes and Candida lipolytica to stainless steel...... was not affected by surface roughness (Ra) ranging from grit 4000 polished stainless steel (Ra steel (Ra 0.9). Neither adhesion of Ps. aeruginosa nor its removal by an alkaline commercial cleaner in a flow system was affected by surface roughness. Pitting corrosion resistance...... was evaluated in a commercial disinfectant and in 1 M NaCl. Electropolished and grit 4000 polished steel proved more corrosion resistant as opposed to grit 80 and 120 polished surfaces. In conclusion, the surface finish did not influence bacterial attachment, colonisation, or removal, but is an important...

  17. Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

    Science.gov (United States)

    Martinello, M.; Grassellino, A.; Checchin, M.; Romanenko, A.; Melnychuk, O.; Sergatskov, D. A.; Posen, S.; Zasadzinski, J. F.

    2016-08-01

    Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. This effect is attributed to the lowering of the Mattis-Bardeen surface resistance with increasing accelerating field; however, the microscopic origin of this phenomenon is poorly understood. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper, we conduct a systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surface treatments for niobium resonators. Adding these results together, we are able to show which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. These results also provide insights on the physics behind the change in the field dependence of the Mattis-Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.

  18. Development of stress corrosion cracking resistant welds of 321 stainless steel by simple surface engineering

    Science.gov (United States)

    Mankari, Kamal; Acharyya, Swati Ghosh

    2017-12-01

    We hereby report a simple surface engineering technique to make AISI grade 321 stainless steel (SS) welds resistant to stress corrosion cracking (SCC) in chloride environment. Heat exchanger tubes of AISI 321 SS, welded either by (a) laser beam welding (LBW) or by (b) metal inert gas welding (MIG) were used for the study. The welds had high magnitude of tensile residual stresses and had undergone SCC in chloride environment while in service. The welds were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Subsequently, the welded surfaces were subjected to buffing operation followed by determination of residual stress distribution and surface roughness by XRD and surface profilometer measurements respectively. The susceptibility of the welds to SCC was tested in buffed and un-buffed condition as per ASTM G-36 in boiling MgCl2 for 5 h and 10 h, followed by microstructural characterization by using optical microscope and FESEM. The results showed that the buffed surfaces (both welds and base material) were resistant to SCC even after 10 h of exposure to boiling MgCl2 whereas the un-buffed surfaces underwent severe SCC for the same exposure time. Buffing imparted high magnitude of compressive stresses on the surface of stainless steel together with reduction in its surface roughness and reduction in plastic strain on the surface which made the welded surface, resistant to chloride assisted SCC. Buffing being a very simple, portable and economic technique can be easily adapted by the designers as the last step of component fabrication to make 321 stainless steel welds resistant to chloride assisted SCC.

  19. Investigation of surface resistance of copper in classical and anomalous skin-effect region

    International Nuclear Information System (INIS)

    Kutovoj, V.A.; Egorov, A.M.

    2008-01-01

    The surface resistance of copper in classical and anomalous skin-effect region has been investigated, and the surface resistance improvement factor equal to the ratio of the surface resistance of copper at room temperature to that of helium temperature, depending on the electromagnetic field frequency, has been determined. The improvement factor has been shown to have inverse power law dependence on frequency. The frequencies at which the improvement factor of copper equals 10 have been determined. It has been found that the quality factor of a resonance high-frequency system made of copper, operating at temperature T ≥ 4.2 K can be increased 10 times or more as against a quality factor of a resonance high-frequency system operating at room temperature

  20. Microwave surface resistance of YBa2Cu3O/sub 6.9/ superconducting films

    International Nuclear Information System (INIS)

    Martens, J.S.; Beyer, J.B.; Ginley, D.S.

    1988-01-01

    The microwave surface resistance of an YBa 2 Cu 3 O/sub 6.9/ superconducting thick film was measured over the range 7.0--16.7 GHz at 77 K. This was done by placing a sample in a TE 01 /sub n/ wavemeter cavity and observing the change in selectivity of the cavity. The material's surface resistance is of the same order of magnitude as that of silver at 77 K from 8 to 12 GHz and improves about another order at 4.2 K. The power-law behavior of surface resistance with frequency is probably close to quadratic. This is similar to the behavior of low critical temperature superconductors

  1. Fluxon induced surface resistance and field emission in niobium films at 1.5 GHz

    CERN Document Server

    Benvenuti, Cristoforo; Darriulat, Pierre; Peck, M A; Valente, A M; Van't Hof, C A

    2001-01-01

    The surface resistance of superconducting niobium films induced by the presence of trapped magnetic flux, presumably in the form of a pinned fluxon lattice, is shown to be modified by the presence of a field emitting impurity or defect. The modification takes the form of an additional surface resistance proportional to the density of the fluxon lattice and increasing linearly with the amplitude of the microwave above a threshold significantly lower than the field emission threshold. Such an effect, a precursor of electron emission, is observed for the first time in a study using radiofrequency cavities operating at their fundamental 1.5 GHz frequency. The measured properties of the additional surface resistance severely constrain possible explanations of the observed effect. (23 refs).

  2. Staphylococcus cohnii--resident of hospital environment: cell-surface features and resistance to antibiotics.

    Science.gov (United States)

    Szewczyk, E M; Rózalska, M

    2000-01-01

    Staphylococcus cohnii strains dominated in the environment of investigated hospitals. We isolated 420 strains of the species mainly from hospitals environments, but also from infants--Intensive Care Units patients, its medical staff and non-hospital environments. S. cohnii subspecies cohnii was seen to dominate (361 strains). Seventy seven percent of these strains expressed cell-surface hydrofobicity, most of them were slime producers (61%) and this feature was correlated with their methicillin resistance. Among S. cohnii ssp. cohnii strains isolated from ICU environment 90% were resistant to methicillin, 43% expressed high-level resistance to mupirocin and high percentages were resistant to many other antibiotics. These strains may constitute a dangerous reservoir of resistance genes in a hospital.

  3. Rapid identification of bacterial resistance to Ciprofloxacin using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Kastanos, Evdokia; Hadjigeorgiou, Katerina; Pitris, Costas

    2014-02-01

    Due to its effectiveness and broad coverage, Ciprofloxacin is the fifth most prescribed antibiotic in the US. As current methods of infection diagnosis and antibiotic sensitivity testing (i.e. an antibiogram) are very time consuming, physicians prescribe ciprofloxacin before obtaining antibiogram results. In order to avoid increasing resistance to the antibiotic, a method was developed to provide both a rapid diagnosis and the sensitivity to the antibiotic. Using Surface Enhanced Raman Spectroscopy, an antibiogram was obtained after exposing the bacteria to Ciprofloxacin for just two hours. Spectral analysis revealed clear separation between sensitive and resistant bacteria and could also offer some inside into the mechanisms of resistance.

  4. Drag resistance measurements for newly applied antifouling coatings and welding seams on ship hull surface

    DEFF Research Database (Denmark)

    Wang, Xueting; Olsen, S. M.; Andres, E.

    Drag resistances of newly applied antifouling coatings and welding seams on ship hull surface have been investigated using a pilot-scale rotary setup. Both conventional biocide-based antifouling (AF) coatings and silicone-based fouling release (FR) coatings have been studied and compared in their......Drag resistances of newly applied antifouling coatings and welding seams on ship hull surface have been investigated using a pilot-scale rotary setup. Both conventional biocide-based antifouling (AF) coatings and silicone-based fouling release (FR) coatings have been studied and compared...

  5. Liouville master equation for multielectron dynamics: Neutralization of highly charged ions near a LiF surface

    International Nuclear Information System (INIS)

    Wirtz, Ludger; Reinhold, Carlos O.; Lemell, Christoph; Burgdoerfer, Joachim

    2003-01-01

    We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte Carlo solution of the Liouville master equation for the joint probability density of the ionic motion and the electronic population of the projectile and the target surface. It includes single as well as double particle-hole (de)excitation processes and incorporates electron correlation effects through the conditional dynamics of population strings. The input in terms of elementary one- and two-electron transfer rates is determined from classical trajectory Monte Carlo calculations as well as quantum-mechanical Auger calculations. For slow projectiles and normal incidence, the ionic motion depends sensitively on the interplay between image acceleration towards the surface and repulsion by an ensemble of positive hole charges in the surface ('trampoline effect'). For Ne 10+ we find that image acceleration is dominant and no collective backscattering high above the surface takes place. For grazing incidence, our simulation delineates the pathways to complete neutralization. In accordance with recent experimental observations, most ions are reflected as neutral or even as singly charged negative particles, irrespective of the charge state of the incoming ions

  6. A general analytical equation for phase diagrams of an N-layer ferroelectric thin film with two surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z X; Teng, B H; Rong, Y H; Lu, X H; Yang, X [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: phytbh@163.com

    2010-03-15

    Within the framework of effective-field theory with correlations, the phase diagrams of an N-layer ferroelectric thin film with two surface layers are studied by the differential operator technique based on the spin-1/2 transverse Ising model. A general analytical equation for the phase diagram of a ferroelectric thin film with arbitrary layer number as well as exchange interactions and transverse fields is derived, and then the effects of exchange interactions and transverse fields on phase diagrams are discussed for an arbitrary layer number N. Meanwhile, the crossover features, from the ferroelectric-dominant phase diagram (FPD) to the paraelectric-dominant phase diagram (PPD), for various parameters of an N-layer ferroelectric thin film with two surface layers are investigated. As a result, an N-independent common intersection point equation is obtained, and the three-dimensional curved surfaces for the crossover values are constructed. In comparison with the usual mean-field approximation, the differential operator technique with correlations reduces to some extent the ferroelectric features of a ferroelectric thin film.

  7. XPS and surface resistivity measurements of plasma - treated FEP co-polymer

    International Nuclear Information System (INIS)

    Pitrus, R.K.; Brack, N.; Liesegang, J.; Pigram, P.J.

    2002-01-01

    Full text: Fluorinated polymers such as fluorinated ethylene propylene (FEP) and poly(tetrafluoroethylene) (PTFE) play an important role in many applications due to their many desirable properties such as chemical resistivity, inertness, electrical stability and low dielectric constant; however, one disadvantage of fluorinated polymers is their extreme surface hydrophobicity. Previous studies show that plasma treatment will modify the surface by increasing the surface free energy and also offer a rapid and convenient method for pre-treating the polymers for many purposes. This paper, through resistivity and XPS (x-ray photoelectron spectroscopy) measurements, attempts to discover basic effects of such plasma treatment. Fluorinated ethylene propylene (FEP) co-polymer film of (0.05) mm thickness (obtained commercially) and with the following structure (CF 2 -CF 2 )-(CF(CF 3 )CF 2 )- was used. A suitable cleaning procedure was used to remove adventitious carbon from the surface. XPS has been used to study FEP film properties. The spectra of XPS were analyzed with the main focus on carbon and fluorine as they compose the elemental component of FEP film. A value of 2.05 was obtained for the F/C ratio, which is slightly higher than the theoretical F/C value estimated from the chemical structure of FEP (F/C 2). The clean film was then air plasma treated (pressure 10 -1 torr and power 30W) for various treatment times to produce a higher energy fluoropolymer surface. XPS studies investigated changes to the polymer surface and determined that oxidation occurs on the FEP surface. The oxidation reactions on the FEP surface form oxygen functional groups such as C-O and C=O groups. The results also show that the percentage of CF 2 and CF 3 in the co-polymer surface decreased with exposure time and the percentage of CF, C-C, C-O and C=O increased. There is a sharp decrease in F/C ratio and increase in O/C ratio. In addition to XPS, the resistivity of FEP-film was measured by a

  8. Influence of surface condition on the corrosion resistance of copper alloy condenser tubes in sea water

    Energy Technology Data Exchange (ETDEWEB)

    Sato, S; Nagata, K; Yamauchi, S

    1979-07-01

    Investigation was made on the influence of various surface conditions of aluminum brass tube. The corrosion behavior of aluminum brass tube, with nine kinds of surface conditions, was studied in stagnant 0.1N NaHCo/sub 3/ solution and flowing sea water (natural, Fe/sup + +/ containing and S/sup - -/ containing water). Surface treatments investigated contained bright annealing, special annealing to form carbon film, hot oxidizing and pickling. Anodic polarization measurements in 0.1N NaHCO/sub 3/ solution showed that the oxidized surface was superior and that the pickled surface was inferior. However, relation between these characteristics and corrosion resistance in sea water has not been established. Electrochemical characteristics in flowing sea water were dependent on the surface conditions in the very beginning of immersion time; nobler corrosion potential for the surface with carbon film, higher polarization resistance for the bright annealed and the oxidized surface, and faster decrease of polarization resistance in S/sup - -/ containing sea water for the pickled surface. However, these differences disappeared in the immersion time of only 2 to 7 days. It was revealed, by the statistical analysis on the corrosion depth in corrosion test in flowing sea water and in jet impingement test, that the corrosion behavior was not influenced by surface conditions, but was significantly influenced by quality of sea water and sponge ball cleaning. Sulfide ion of 0.05 ppm caused severe pitting corrosion, and sponge ball cleaning of 5 chances a week caused erosion corrosion. From above results, it was concluded that surface conditions of aluminum brass were not important to sea water corrosion, and that quality of sea water and operating condition such as sponge ball cleaning were more significant.

  9. Simulations of incompressible Navier Stokes equations on curved surfaces using discrete exterior calculus

    Science.gov (United States)

    Samtaney, Ravi; Mohamed, Mamdouh; Hirani, Anil

    2015-11-01

    We present examples of numerical solutions of incompressible flow on 2D curved domains. The Navier-Stokes equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. A conservative discretization of Navier-Stokes equations on simplicial meshes is developed based on discrete exterior calculus (DEC). The discretization is then carried out by substituting the corresponding discrete operators based on the DEC framework. By construction, the method is conservative in that both the discrete divergence and circulation are conserved up to machine precision. The relative error in kinetic energy for inviscid flow test cases converges in a second order fashion with both the mesh size and the time step. Numerical examples include Taylor vortices on a sphere, Stuart vortices on a sphere, and flow past a cylinder on domains with varying curvature. Supported by the KAUST Office of Competitive Research Funds under Award No. URF/1/1401-01.

  10. Effects of surface topography and vibrations on wetting: Superhydrophobicity, icephobicity and corrosion resistance

    Science.gov (United States)

    Ramachandran, Rahul

    Concrete and metallic materials are widely used in construction and water industry. The interaction of both these materials with water and ice (or snow) produces undesirable results and is therefore of interest. Water that gets absorbed into the pores of dry concrete expands on freezing and can lead to crack formation. Also, the ice accretion on concrete surfaces such as roadways can have disastrous consequence. Metallic components used in the water industry undergo corrosion due to contact with aqueous corrosive solutions. Therefore, it is desirable to make concrete water/ice-repellent, and to make metallic surfaces corrosion-resistant. Recent advances in micro/nanotechnology have made it possible to design functional micro/nanostructured surfaces with micro/nanotopography providing low adhesion. Some examples of such surfaces are superhydrophobic surfaces, which are extremely water repellent, and icephobic surfaces, which have low ice adhesion, repel incoming water droplets before freezing, or delay ice nucleation. This dissertation investigates the effects of surface micro/nanotopography and small amplitude fast vibrations on the wetting and adhesion of concrete with the goal of producing hydrophobic and icephobic concrete, and on the wetting of metallic surfaces to prevent corrosion. The relationship between surface micro/nanotopography and small fast vibrations is established using the method of separation of motions. Both these small scale effects can be substituted by an effective force or energy. The structure-property relationships in materials and surfaces are established. Both vibrations as well as surface micro/nanopatterns can affect wetting properties such as contact angle and surface free energy. Hydrophobic engineered cementitious composite samples are produced by controlling their surface topography and surface free energy. The surface topography is controlled by varying the concrete mixture composition. The surface free energy of concrete is

  11. Modeling and analysis of surface potential of single gate fully depleted SOI MOSFET using 2D-Poisson's equation

    Science.gov (United States)

    Mani, Prashant; Tyagi, Chandra Shekhar; Srivastav, Nishant

    2016-03-01

    In this paper the analytical solution of the 2D Poisson's equation for single gate Fully Depleted SOI (FDSOI) MOSFET's is derived by using a Green's function solution technique. The surface potential is calculated and the threshold voltage of the device is minimized for the low power consumption. Due to minimization of threshold voltage the short channel effect of device is suppressed and after observation we obtain the device is kink free. The structure and characteristics of SingleGate FDSOI MOSFET were matched by using MathCAD and silvaco respectively.

  12. Resistance of Pseudomonas aeruginosa to liquid disinfectants on contaminated surfaces before formation of biofilms.

    Science.gov (United States)

    Sagripanti, J L; Bonifacino, A

    2000-01-01

    A comparison was made of the effectiveness of popular disinfectants (Cavicide, Cidexplus, Clorox, Exspor, Lysol, Renalin, and Wavicide) under conditions prescribed for disinfection in the respective product labels on Pseudomonas aeruginosa either in suspension or deposited onto surfaces of metallic or polymeric plastic devices. The testing also included 7 nonformulated germicidal agents (glutaraldehyde, formaldehyde, peracetic acid, hydrogen peroxide, sodium hypochlorite, phenol, and cupric ascorbate) commonly used in disinfection and decontamination. Results showed that P. aeruginosa is on average 300-fold more resistant when present on contaminated surfaces than in suspension. This increase in resistance agrees with results reported in studies of biofilms, but unexpectedly, it precedes biofilm formation. The surface to which bacteria are attached can influence the effectiveness of disinfectants. Viable bacteria attached to devices may require dislodging through more than a one-step method for detection. The data, obtained with a sensitive and quantitative test, suggest that disinfectants are less effective on contaminated surfaces than generally acknowledged.

  13. Superhydrophobic copper surfaces fabricated by fatty acid soaps in aqueous solution for excellent corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin, E-mail: songaixin@sdu.edu.cn; Hao, Jingcheng

    2017-03-31

    Highlights: • The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol. • The fabrication process of superhydrophobic metal surfaces greatly increases the safety in industrial manufacture in commercial scale. • The superhydrophobic copper surfaces show excellent corrosion resistance. - Abstract: A simple and safe one-step immersion method was developed to obtain the stable superhydrophobic copper surfaces with excellent corrosion resistance ability using fatty acids in water-medium instead of ethanol. An organic alkali, N,N-dimethylcyclohexylamine (DMCHA), was chosen to solve the poor solubility of fatty acids in water and the high Krafft point of carboxylate salts with inorganic counterions. The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol (more than 2 d), which is universally feasible for the fabrication of superhydrophobic metal surfaces in industry scale, thereby greatly increasing the safety in industrial manufacture.

  14. Why Did the Bear Cross the Road? Comparing the Performance of Multiple Resistance Surfaces and Connectivity Modeling Methods

    Directory of Open Access Journals (Sweden)

    Samuel A. Cushman

    2014-12-01

    Full Text Available There have been few assessments of the performance of alternative resistance surfaces, and little is known about how connectivity modeling approaches differ in their ability to predict organism movements. In this paper, we evaluate the performance of four connectivity modeling approaches applied to two resistance surfaces in predicting the locations of highway crossings by American black bears in the northern Rocky Mountains, USA. We found that a resistance surface derived directly from movement data greatly outperformed a resistance surface produced from analysis of genetic differentiation, despite their heuristic similarities. Our analysis also suggested differences in the performance of different connectivity modeling approaches. Factorial least cost paths appeared to slightly outperform other methods on the movement-derived resistance surface, but had very poor performance on the resistance surface obtained from multi-model landscape genetic analysis. Cumulative resistant kernels appeared to offer the best combination of high predictive performance and sensitivity to differences in resistance surface parameterization. Our analysis highlights that even when two resistance surfaces include the same variables and have a high spatial correlation of resistance values, they may perform very differently in predicting animal movement and population connectivity.

  15. The characteristics of surface oxidation and corrosion resistance of nitrogen implanted zircaloy-4

    International Nuclear Information System (INIS)

    Tang, G.; Choi, B.H.; Kim, W.; Jung, K.S.; Kwon, H.S.; Lee, S.J.; Lee, J.H.; Song, T.Y.; Shon, D.H.; Han, J.G.

    1997-01-01

    This work is concerned with the development and application of ion implantation techniques for improving the corrosion resistance of zircaloy-4. The corrosion resistance in nitrogen implanted zircaloy-4 under a 120 keV nitrogen ion beam at an ion dose of 3 x 10 17 cm -2 depends on the implantation temperature. The characteristics of surface oxidation and corrosion resistance were analyzed with the change of implantation temperature. It is shown that as implantation temperature rises from 100 to 724 C, the colour of specimen surface changes from its original colour to light yellow at 100 C, golden at 175 C, pink at 300 C, blue at 440 C and dark blue at 550 C. As the implantation temperature goes above 640 C, the colour of surface changes to light black, and the surface becomes a little rough. The corrosion resistance of zircaloy-4 implanted with nitrogen is sensitive to the implantation temperature. The pitting potential of specimens increases from 176 to 900 mV (SCE) as the implantation temperature increases from 100 to 300 C, and decreases from 900 to 90 mV(SCE) as the implantation temperature increases from 300 to 640 C. The microstructure, the distribution of oxygen, nitrogen and carbon elements, the oxide grain size and the feature of the precipitation in the implanted surface were investigated by optical microscope, TEM, EDS, XRD and AES. The experimental results reveal that the ZrO 2 is distributed mainly on the outer surface. The ZrN is distributed under the ZrO 2 layer. The characteristics of the distribution of ZrO 2 and ZrN in the nitrogen-implanted zircaloy-4 is influenced by the implantation temperature of the sample, and in turn the corrosion resistance is influenced. (orig.)

  16. Assimilation of Sea Surface Temperature in a doubly, two-way nested primitive equation model of the Ligurian Sea

    Science.gov (United States)

    Barth, A.; Alvera-Azcarate, A.; Rixen, M.; Beckers, J.-M.; Testut, C.-E.; Brankart, J.-M.; Brasseur, P.

    2003-04-01

    The GHER 3D primitive equation model is implemented with three different resolutions: a low resolution model (1/4^o) covering the whole Mediterranean Sea, an intermediate resolution model (1/20^o) of the Liguro-Provençal basin and a high resolution model (1/60^o) simulating the fine mesoscale structures in the Ligurian Sea. Boundary conditions and the averaged fields (feedback) are exchanged between two successive nesting levels. The model of the Ligurian Sea is also coupled with the assimilation package SESAM. It allows to assimilate satellite data and in situ observations using the local adaptative SEEK (Singular Evolutive Extended Kalman) filter. Instead of evolving the error space by the numerically expensive Lyapunov equation, a simplified algebraic equation depending on the misfit between observation and model forecast is used. Starting from the 1st January 1998 the low and intermediate resolution models are spun up for 18 months. The initial conditions for the Ligurian Sea are interpolated from the intermediate resolution model. The three models are then integrated until August 1999. During this period AVHRR Sea Surface Temperature of the Ligurian Sea is assimilated. The results are validated by using CTD and XBT profiles of the SIRENA cruise from the SACLANT Center. The overall objective of this study is pre-operational. It should help to identify limitations and weaknesses of forecasting methods and to suggest improvements of existing operational models.

  17. Data fusion analysis of a surface direct-current resistivity and well pick data set

    International Nuclear Information System (INIS)

    Clayton, E.A.; Lewis, R.E.

    1995-09-01

    Pacific Northwest Laboratory (PNL) has been tasked with testing, debugging, and refining the Hanford Site data fusion workstation (DFW), with the assistance of Coleman Research Corporation (CRC), before delivering the DFW to the environmental restoration client at the Hanford Site. Data fusion is the mathematical combination (or fusion) of disparate data sets into a single interpretation. The data fusion software used in this study was developed by CRC. This report discusses the results of evaluating a surface direct-current (dc) resistivity and well-pick data set using two methods: data fusion technology and commercially available software (i.e., RESIX Plus from Interpex Ltd., Golden, Colorado), the conventional method of analysis. The report compares the two technologies; describes the survey, procedures, and results; and includes conclusions and recommendations. The surface dc resistivity and well-pick data set had been acquired by PNL from a study performed in May 1993 at Eielson Air Force Base near Fairbanks, Alaska. The resistivity survey data were acquired to map the top of permafrost in support of a hydrogeologic study. This data set provided an excellent opportunity to test and refine the dc resistivity capabilities of the DFW; previously, the data fusion software was untested on dc resistivity data. The DFW was used to evaluate the dc resistivity survey data and to produce a 3-dimensional earth model of the study area

  18. Smooth Surfaces: A review of current and planned smooth surface technologies for fouling resistance in boiler

    Energy Technology Data Exchange (ETDEWEB)

    Corkery, Robert; Baefver, Linda; Davidsson, Kent; Feiler, Adam

    2012-02-15

    Here we have described the basics of boilers, fuels, combustion, flue gas composition and mechanisms of deposition. We have reviewed coating technologies for boiler tubes, including their materials compositions, nano structures and performances. The surface forces in boilers, in particular those relevant to formation of unwanted deposits in boilers have also been reviewed, and some comparative calculations have been included to indicate the procedures needed for further study. Finally practical recommendations on the important considerations in minimizing deposition on boiler surfaces are made

  19. Near-surface characterization for seismic exploration based on gravity and resistivity data

    Czech Academy of Sciences Publication Activity Database

    Mrlina, Jan

    (2016), č. článku 41892. [Middle East Geoscience Conference and Exhibition /12./. Manama, 07.03.2016-10.03.2016] Institutional support: RVO:67985530 Keywords : gravity and resistivity surveys * near-surface formations * seismic velocity Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  20. Ultrasensitive probing of the protein resistance of PEG surfaces by secondary ion mass spectrometry

    DEFF Research Database (Denmark)

    Kingshott, P.; McArthur, S.; Thissen, H.

    2002-01-01

    The highly sensitive surface analytical techniques X-ray photoelectron spectroscopy (XPS) and time-of-flight static secondary ion mass spectrometry (ToF-SIMS) were used to test the resistance of poly(ethylene glycol) (PEG) coatings towards adsorption of lysozyme (LYS) and fibronectin (FN). PEG co...

  1. Crack resistance of pvd coatings : Influence of surface treatment prior to deposition

    NARCIS (Netherlands)

    Zoestbergen, E; de Hosson, J.T.M.

    The crack resistance of three different PVD coatings, TiN, Ti(C,N), and a multilayer system of alternating TiN and TiAlN, have been investigated. The three coating systems were deposited onto substrates with a different surface roughness to study the influence of this pretreatment on the crack

  2. Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-07-01

    In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

  3. Improving the contact resistance at low force using gold coated carbon nanotube surfaces

    Science.gov (United States)

    McBride, J. W.; Yunus, E. M.; Spearing, S. M.

    2010-04-01

    Investigations to determine the electrical contact performance under repeated cycles at low force conditions for carbon-nanotube (CNT) coated surfaces were performed. The surfaces under investigation consisted of multi-walled CNT synthesized on a silicon substrate and coated with a gold film. These planar surfaces were mounted on the tip of a PZT actuator and contacted with a plated Au hemispherical probe. The dynamic applied force used was 1 mN. The contact resistance (Rc) of these surfaces was investigated with the applied force and with repeated loading cycles performed for stability testing. The surfaces were compared with a reference Au-Au contact under the same experimental conditions. This initial study shows the potential for the application of gold coated CNT surfaces as an interface in low force electrical contact applications.

  4. Combined slurry and cavitation erosion resistance of surface modified SS410 stainless steel

    Science.gov (United States)

    Amarendra, H. J.; Pratap, M. S.; Karthik, S.; Punitha Kumara, M. S.; Rajath, H. C.; Ranjith, H.; Shubhatunga, S. V.

    2018-03-01

    Slurry erosion and combined slurry and cavitation erosion resistance of thermal spray coatings are studied and compared with the as-received martensitic stainless steel material. 70Ni-Cr coatings are deposited on SS 410 material through plasma thermal spray process. The synergy effect of the combined slurry and cavitation erosion resistance of plasma thermal spray coatings were investigated in a slurry pot tester in the presence of bluff bodies known as Cavitation Inducers. Results showed the combined slurry and cavitation erosion resistance of martensitic stainless steel - 410 can be improved by plasma thermal spray coating. It is observed that the plasma spray coated specimens are better erosion resistant than the as- received material, subjected to erosion test under similar conditions. As-received and the surface modified steels are mechanically characterized for its hardness, bending. Morphological studies are conducted through scanning electron microscope.

  5. Influence of impurities and ion surface alloying on the corrosion resistance of E110 alloy

    International Nuclear Information System (INIS)

    Kalin, B. A.; Volkov, N. V.; Valikov, R. A.; Novikov, V. V.; Markelov, V. A.; Pimenov, Yu. V.

    2013-01-01

    The corrosion resistance of zirconium alloys depends on their structural-phase state, the type of core coolant and operating factors. The formation of a protective oxide film on the zirconium alloys is sensitive to the content of impurity atoms present in the charge base of alloys and accumulating in them in the manufacture of products. The impurity composition of the initial zirconium is determined by the method of its manufacture and generally remains unchanged in the products, deter-mining their properties, including their corrosion resistance. An increased content of impurities (C, N, Al, Mo, Fe) both individually and in their combination negatively affects the corrosion resistance of zirconium and its alloys. One of the potentially effective methods to increase the protective properties of oxide films on zirconium alloys is a surface alloying using the regime of mixing the atoms of a film, preliminarily coated on the surface, and the atoms of a target. This method makes it possible to form a given structural-phase state in the thin surface layer with unique physicochemical properties and thus to in-crease the corrosion resistance and wear resistance of fuel claddings. In this context, the object of investigation was samples of cladding tubes from alloy E110 with various content of impurity elements (nitrogen, aluminum, and carbon) with the aim to reduce the negative influence of impurities on the corrosion resistance by changing the structural-phase state of the surface layer of fuel claddings and fuel assembly components with alloying in the regime of ion mixing of atoms

  6. Gaussian-windowed frame based method of moments formulation of surface-integral-equation for extended apertures

    Energy Technology Data Exchange (ETDEWEB)

    Shlivinski, A., E-mail: amirshli@ee.bgu.ac.il [Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Lomakin, V., E-mail: vlomakin@eng.ucsd.edu [Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0407 (United States)

    2016-03-01

    Scattering or coupling of electromagnetic beam-field at a surface discontinuity separating two homogeneous or inhomogeneous media with different propagation characteristics is formulated using surface integral equation, which are solved by the Method of Moments with the aid of the Gabor-based Gaussian window frame set of basis and testing functions. The application of the Gaussian window frame provides (i) a mathematically exact and robust tool for spatial-spectral phase-space formulation and analysis of the problem; (ii) a system of linear equations in a transmission-line like form relating mode-like wave objects of one medium with mode-like wave objects of the second medium; (iii) furthermore, an appropriate setting of the frame parameters yields mode-like wave objects that blend plane wave properties (as if solving in the spectral domain) with Green's function properties (as if solving in the spatial domain); and (iv) a representation of the scattered field with Gaussian-beam propagators that may be used in many large (in terms of wavelengths) systems.

  7. Intermodulation distortion and surface resistance in impurity-doped YBCO and MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Agassi, Y.D. [Naval Surface Warfare Center, Carderock Division, Bethesda, MD 20817 (United States); Oates, D.E., E-mail: oates@ll.mit.edu [MIT-Lincoln Laboratory, Lexington, MA 02420 (United States)

    2014-11-15

    Highlights: • Calculations of impurity-doping effects on surface resistance and intermodulation distortion. • The calculations are compared with previously published measurements in YBCO and MgB{sub 2}. • Excellent agreement between calculations and experiments are shown. • The effects of the symmetry of the energy gap are presented and discussed. - Abstract: Calculations of the microwave intermodulation distortion (IMD) and surface resistance of impurity-doped YBCO, MgB{sub 2} and Nb are presented. These are qualitatively distinct superconductors due to their energy-gap symmetries, d-wave (ℓ = 2), i-wave (ℓ = 6) and s-wave (ℓ = 0), respectively. The calculations are compared with previously published IMD and surface-resistance measurements of impurity-doped YBCO and Nb. The agreement between the data and fitted calculations is excellent in all cases. In the absence of IMD and surface-resistance measurements for doped MgB{sub 2}, we present representative predictions. The calculations are based on a Green’s-function approach that yields analytical expressions for the penetration depth and the nonlinear kernel in the constitutive relation. This penetration-depth expression reproduces the measured T{sup 2} low-temperature variation for doped superconductors and the surface-resistance reduction over that of the pure material. Regarding the IMD in superconductors with a nodal energy gap, the effect of doping is to enhance its magnitude and suppress its low-temperature 1/T{sup 2} divergence predicted by the nonlinear Meissner effect.

  8. Fracture resistance of dental nickel–titanium rotary instruments with novel surface treatment: Thin film metallic glass coating

    Directory of Open Access Journals (Sweden)

    Chih-Wen Chi

    2017-05-01

    Conclusion: The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure.

  9. OPTIMIZATION OF SURFACE RESISTIVITY AND RELATIVE PERMITTIVITY OF SILICONE RUBBER FOR HIGH VOLTAGE APPLICATION USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    N.N. Ali

    2017-06-01

    Full Text Available Silicone Rubber (SiR is considered as one of the most established insulator in High Voltage (HV industry. SiR possess a great function ability such as its lighter weight, great heat resistance and substantial electrical insulation properties. Dynamic research were performed all around the world in order to explore the unique insulating behavior of SiR but very little are done on the optimization of SiR in term of their processing parameters and formulation. In this work, four materials and processing factors were introduced; A: Alumina Trihydrate (ATH, B: Dicumyl-Peroxide (DCP, C: mixing speed and D: mixing time in order to analyze its contribution towards improving the surface resistivity and relative permittivity of SIR rubber. The factors range were set based on prior screening and are defined as; ATH (10 – 50 pphr, Dicumyl Peroxide (0.50 -1.50 pphr, speed of mixer (40 – 70 rpm and mixing period (5 – 10 mins which were then varied accordingly to produce an overall 19 samples of SiR blends. The testing results were analyzed using statistical Design of Experiment (DOE by applying two level full factorial from Design Expert Software (v10 to discover the inter-correlation between the factors studied and benefaction of each factor in improving both surface resistivity and relative permittivity responses of produced SiR blends. The model analysis on surface resistivity shows the coefficient of determination R2 value of 88.72% while the one for relative permittivity shows R2 value of 82.34 %. Combination of both dependent variables had yielded an optimization suggestion for SiR formulation and processing strategy of ATH: 50 pphr, DCP: 0.50 pphr, mixing speed: 70 rpm and mixing period: 10 mins with the desirability level of 0.835. The optimized formulation had resulted in the production of SiR blend with the characteristic of surface resistivity of 1.02039x10^14 Ω/sq and relative permittivity of 4.0231, respectively. In conclusion, it can be

  10. Syndecans as cell surface receptors: Unique structure equates with functional diversity

    DEFF Research Database (Denmark)

    Choi, Youngsil; Chung, Heesung; Jung, Heyjung

    2011-01-01

    An increasing number of functions for syndecan cell surface heparan sulfate proteoglycans have been proposed over the last decade. Moreover, aberrant syndecan regulation has been found to play a critical role in multiple pathologies, including cancers, as well as wound healing and inflammation....... As receptors, they have much in common with other molecules on the cell surface. Syndecans are type I transmembrane molecules with cytoplasmic domains that link to the actin cytoskeleton and can interact with a number of regulators. However, they are also highly complex by virtue of their external...... glycosaminoglycan chains, especially heparan sulfate. This heterodisperse polysaccharide has the potential to interact with many ligands from diverse protein families. Here, we relate the structural features of syndecans to some of their known functions....

  11. Research surface resistance of copper normal and abnormal skin-effects depending on the frequency of electromagnetic field

    International Nuclear Information System (INIS)

    Kutovyi, V.A.; Komir, A.I.

    2013-01-01

    The results of the frequency dependence of surface resistance of copper in diffuse and specular reflection of electrons from the conductive surface of the high-frequency resonance of the system depending on the frequency of the electromagnetic field in the normal and anomalous skin effect. Found, the surface resistance of copper is reduced by more than 10 times at the temperature of liquid helium, as compared with a surface resistivity at room temperature, at frequencies f ≤ 173 MHz, for diffuse reflection of conduction electrons from the surface of the conductive layer, and the specular reflection - at frequencies f ≤ 346 MHz

  12. Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

    International Nuclear Information System (INIS)

    Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

    1990-04-01

    Measurements are reported of the millimeter-wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid-phase process. The measurements were performed by replacing the endplate of a TE(011) cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. For the parallel configuration, the surface resistance at 77 K and 80 GHz is given. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K and the surface resistance is derived at 88 K. The effect of microstructure on surface resistance is discussed. 19 refs

  13. Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

    Science.gov (United States)

    Wosik, J.; Kranenburg, R. A.; Wolfe, J. C.; Selvamanickam, V.; Salama, K.

    1991-01-01

    Measurements of the millimeter wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid phase process are reported. The measurements were performed by replacing the endplate of a TE011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. It is shown that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 milliohms. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K, and the surface resistance is less than 50 milliohms at 88 K. The effect of microstructure on surface resistance is discussed.

  14. Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3Ox bulk material

    International Nuclear Information System (INIS)

    Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

    1991-01-01

    We report measurements of the millimeter wave surface resistance of grain-aligned YBa 2 Cu 3 O x bulk material grown by a liquid phase process. The measurements were performed by replacing the endplate of a TE 011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. We show that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 mΩ. For a very well-aligned sample with a very low density of Y 2 BaCuO y precipitates, measured in the perpendicular configuration, the transition width (10%--90%) is about 2 K and the surface resistance is less than 50 mΩ at 88 K. The effect of microstructure on surface resistance is discussed

  15. Generating reference evapotranspiration surfaces from the Hargreaves equation at watershed scale

    Directory of Open Access Journals (Sweden)

    C. Aguilar

    2011-08-01

    Full Text Available In this study, Hargreaves' formulation is considered to be appropriate for the water and energy balance at a daily scale due to its simplicity of application once the distributed values of temperature are available at cell scale. However, the coefficient of the Hargreaves equation must be previously calibrated. The interplay of different factors at different temporal scales became evident in the calibration process at the local scale of weather stations. The best fits against daily estimates by ASCE-PM were achieved when differentiating between the wet and the dry season. For the spatial distribution of Hargreaves coefficient at watershed scale, a regionalization in the area around each weather station was proposed in terms of areas of influence. The best results at watershed scale were obtained after a spatial correction for alpine areas, when the average of the difference cell by cell between ASCE-PM and Hargreaves's distributed daily estimates were 0.02 and 0.15 mm day−1 for the wet and the dry seasons, respectively. In all the cases, the best interpolation results were obtained using C-I (calculate and interpolate procedures.

  16. Laser Tailoring the Surface Chemistry and Morphology for Wear, Scale and Corrosion Resistant Superhydrophobic Coatings.

    Science.gov (United States)

    Boinovich, Ludmila B; Emelyanenko, Kirill A; Domantovsky, Alexander G; Emelyanenko, Alexandre M

    2018-06-04

    A strategy, combining laser chemical modification with laser texturing, followed by chemisorption of the fluorinated hydrophobic agent was used to fabricate the series of superhydrophobic coatings on an aluminum alloy with varied chemical compositions and parameters of texture. It was shown that high content of aluminum oxynitride and aluminum oxide formed in the surface layer upon laser treatment allows solving the problem of enhancement of superhydrophobic coating resistance to abrasive loads. Besides, the multimodal structure of highly porous surface layer leads to self-healing ability of fabricated coatings. Long-term behavior of designed coatings in "hard" hot water with an essential content of calcium carbonate demonstrated high antiscaling resistance with self-cleaning potential against solid deposits onto the superhydrophobic surfaces. Study of corrosion protection properties and the behavior of coatings at long-term contact with 0.5 M NaCl solution indicated extremely high chemical stability and remarkable anticorrosion properties.

  17. Improving the corrosion resistance of proton exchange membrane fuel cell carbon supports by pentafluorophenyl surface functionalization

    Science.gov (United States)

    Forouzandeh, Farisa; Li, Xiaoan; Banham, Dustin W.; Feng, Fangxia; Joseph Kakanat, Abraham; Ye, Siyu; Birss, Viola

    2018-02-01

    In this study, the effect of surface functionalization on the electrochemical corrosion resistance of a high surface area, mesoporous colloid imprinted carbon powder (CIC), as well as microporous Vulcan carbon (VC, serving as the benchmark), was demonstrated, primarily for PEM fuel cell applications. CIC-22, which is highly hydrophilic and was synthesized with 22 nm silica colloid templates, and as-received, mildly hydrophobic, VC powders, were functionalized with 2,3,4,5,6-pentafluorophenyl (-PhF5) surface groups using a straightforward diazonium reduction reaction. These carbons were then subjected to corrosion testing, involving a potential cycling-step sequence in room temperature 0.5 M H2SO4. Using cyclic voltammetry and charge/time analysis, the double layer and pseudo-capacitive gravimetric charges of the carbons, prior to and after the application of these potential steps, were tracked in order to obtain information about surface area changes and the extent of carbon oxidation, respectively. It is shown that the corrosion resistance was improved by ca. 50-80% by surface functionalization, likely due to a combination of surface passivation (loss of carbon active sites) and increased surface hydrophobicity.

  18. Resistivity scaling due to electron surface scattering in thin metal layers

    Science.gov (United States)

    Zhou, Tianji; Gall, Daniel

    2018-04-01

    The effect of electron surface scattering on the thickness-dependent electrical resistivity ρ of thin metal layers is investigated using nonequilibrium Green's function density functional transport simulations. Cu(001) thin films with thickness d =1 -2 nm are used as a model system, employing a random one-monolayer-high surface roughness and frozen phonons to cause surface and bulk scattering, respectively. The zero-temperature resistivity increases from 9.7 ±1.0 μ Ω cm at d =1.99 nm to 18.7 ±2.6 μ Ω cm at d =0.9 0 nm, contradicting the asymptotic T =0 prediction from the classical Fuchs-Sondheimer model. At T =9 00 K, ρ =5.8 ±0.1 μ Ω cm for bulk Cu and ρ =13.4 ±1.1 and 22.5 ±2.4 μ Ω cm for layers with d =1.99 and 0.90 nm, respectively, indicating an approximately additive phonon contribution which, however, is smaller than for bulk Cu or atomically smooth layers. The overall data indicate that the resistivity contribution from surface scattering is temperature-independent and proportional to 1 /d , suggesting that it can be described using a surface-scattering mean-free path λs for 2D transport which is channel-independent and proportional to d . Data fitting indicates λs=4 ×d for the particular simulated Cu(001) surfaces with a one-monolayer-high surface roughness. The 1 /d dependence deviates considerably from previous 1 /d2 predictions from quantum models, indicating that the small-roughness approximation in these models is not applicable to very thin (<2 nm) layers, where the surface roughness is a considerable fraction of d .

  19. Corrosion resistance and biocompatibility of titanium surface coated with amorphous tantalum pentoxide

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ying-Sui [Department of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China); Chang, Jean-Heng [Dental Department, Cheng Hsin General Hospital, Taipei, Taiwan (China); Huang, Her-Hsiung, E-mail: hhhuang@ym.edu.tw [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan (China)

    2013-01-01

    Tantalum pentoxide (Ta{sub 2}O{sub 5}) possesses good corrosion resistance and biocompatibility. This study aimed to improve the corrosion resistance and biocompatibility of titanium (Ti) by coating it with an amorphous Ta{sub 2}O{sub 5} surface layer. An amorphous Ta{sub 2}O{sub 5} layer was prepared on the Ti surface using a simple hydrolysis–condensation process at room temperature. The surface characteristics of the test specimens were analyzed using X-ray photoelectron spectroscopy, glancing angle X-ray diffraction, field emission scanning electron microscopy, and contact angle measurements. The corrosion resistance of the test specimens was evaluated from the potentiodynamic polarization curves and ion release measurements in simulated blood plasma (SBP). The biocompatibility of the test specimens was evaluated in terms of the protein (albumin) adsorption, cell adhesion, and cell growth of human bone marrow mesenchymal stem cells (hBMSCs). The amorphous Ta{sub 2}O{sub 5} layer with a porous micro-/nano-scale topography, which was deposited on the Ti surface using a simple hydrolysis–condensation process, increased the corrosion resistance (i.e., increased the corrosion potential and decreased the anodic current and ion release) of the Ti in the SBP and improved the surface wettability, albumin adsorption, and cell adhesion. We conclude that the presence of an amorphous Ta{sub 2}O{sub 5} layer on the Ti surface increased the corrosion resistance and biocompatibility of Ti. - Highlights: ► Amorphous Ta{sub 2}O{sub 5} layer was coated on Ti using simple hydrolysis–condensation process. ► Ta{sub 2}O{sub 5} surface layer showed a micro-/nano-scale porous topography. ► Ta{sub 2}O{sub 5} layer enhanced wettability and corrosion resistance of Ti. ► Ta{sub 2}O{sub 5} layer enhanced protein adsorption, cell adhesion, and cell proliferation of Ti.

  20. Fluoride influences nickel-titanium orthodontic wires′ surface texture and friction resistance

    Directory of Open Access Journals (Sweden)

    Mona Aly Abbassy

    2016-01-01

    Full Text Available Objectives: The aim of this study was to investigate the effects exerted by the acidulated fluoride gel on stainless steel and nickel-titanium (Ni-Ti orthodontic wires. Materials and Methods: Sixty stainless steel and Ni-Ti orthodontic archwires were distributed into forty archwires used for in vitro study and twenty for in situ study. Fluoride was applied for 1 h in the in vitro experiment while it was applied for 5 min in the in situ experiment. The friction resistance of all wires with ceramic brackets before/after topical fluoride application was measured using a universal testing machine at 1 min intervals of moving wire. Moreover, surface properties of the tested wires before/after fluoride application and before/after friction test were examined by a scanning electron microscope (SEM. Dunnett′s t-test was used to compare frictional resistance of as-received stainless steel wires and Ni-Ti wires to the wires treated by fluoride in vitro and in situ (P < 0.05. Two-way ANOVA was used to compare the effect of fluoride application and type of wire on friction resistance in vitro and in situ (P < 0.05. Results: Ni-Ti wires recorded significantly high friction resistance after fluoride application when compared to stainless steel wires in vitro, P < 0.05. Fluoride application did not significantly affect the friction resistance of the tested wires in situ, P < 0.05. SEM observation revealed deterioration of the surface texture of the Ni-Ti wires after fluoride application in vitro and in situ. Conclusions: The in vitro fluoride application caused an increase in friction resistance of Ni-Ti wires when compared to stainless steel wires. In vitro and in situ fluoride application caused deterioration in surface properties of Ni-Ti wires.

  1. A novel method to prepare superhydrophobic, UV resistance and anti-corrosion steel surface

    KAUST Repository

    Isimjan, Tayirjan T.

    2012-11-01

    Both TiO 2 and SiO 2 coated steel surfaces containing micro- and nanoscale binary structures with different surface roughness were successfully fabricated by means of a facile layer by layer deposition process followed by heat treatment. The resulting surfaces were modified by the low free energy chemical PTES (1H,1H,2H,2H-Perfluorodecyltriethoxysilane). The experimental results of wettability exhibit that such modified surfaces have a strong repulsive force to water droplets, their static contact angles exceed 165°, receding angle>160°, advanced angles>170° and slide angle<1°. The resulting surfaces not only exhibit superhydrophobic properties but also show strong UV resistance (after coating SiO 2 on top of TiO 2) and strong stability to various solvents including 0.01% HCl solution. © 2012 Elsevier B.V.

  2. Maxwell's equations in axisymmetrical geometry: coupling H(curl) finite element in volume and H(div) finite element in surface. The numerical code FuMel

    International Nuclear Information System (INIS)

    Cambon, S.; Lacoste, P.

    2011-01-01

    We propose a finite element method to solve the axisymmetric scattering problem posed on a regular bounded domain. Here we shall show how to reduce the initial 3D problem into a truncated sum of 2D independent problems posed into a meridian plane of the object. Each of these problem results in the coupling of a partial differential equation into the interior domain and an integral equation on the surface simulating the free space. Then variational volume and boundary integral formulations of Maxwell's equation on regular surfaces are derived. We introduce some general finite element adapted to cylindrical coordinates and constructed from nodal and mixed finite element both for the interior (volume) and for the integral equation (surface). (authors)

  3. Neoclassical MHD equations for tokamaks

    International Nuclear Information System (INIS)

    Callen, J.D.; Shaing, K.C.

    1986-03-01

    The moment equation approach to neoclassical-type processes is used to derive the flows, currents and resistive MHD-like equations for studying equilibria and instabilities in axisymmetric tokamak plasmas operating in the banana-plateau collisionality regime (ν* approx. 1). The resultant ''neoclassical MHD'' equations differ from the usual reduced equations of resistive MHD primarily by the addition of the important viscous relaxation effects within a magnetic flux surface. The primary effects of the parallel (poloidal) viscous relaxation are: (1) Rapid (approx. ν/sub i/) damping of the poloidal ion flow so the residual flow is only toroidal; (2) addition of the bootstrap current contribution to Ohm's laws; and (3) an enhanced (by B 2 /B/sub theta/ 2 ) polarization drift type term and consequent enhancement of the perpendicular dielectric constant due to parallel flow inertia, which causes the equations to depend only on the poloidal magnetic field B/sub theta/. Gyroviscosity (or diamagnetic vfiscosity) effects are included to properly treat the diamagnetic flow effects. The nonlinear form of the neoclassical MHD equations is derived and shown to satisfy an energy conservation equation with dissipation arising from Joule and poloidal viscous heating, and transport due to classical and neoclassical diffusion

  4. Why did the bear cross the road? Comparing the performance of multiple resistance surfaces and connectivity modeling methods

    Science.gov (United States)

    Samuel A. Cushman; Jesse S. Lewis; Erin L. Landguth

    2014-01-01

    There have been few assessments of the performance of alternative resistance surfaces, and little is known about how connectivity modeling approaches differ in their ability to predict organism movements. In this paper, we evaluate the performance of four connectivity modeling approaches applied to two resistance surfaces in predicting the locations of highway...

  5. Advancement in the Understanding of the Field and Frequency Dependent Microwave Surface Resistance of Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Martinello, M. [Fermilab; Aderhold, S. [Fermilab; Chandrasekaran, S. K. [Fermilab; Checchin, M. [Fermilab; Grassellino, A. [Fermilab; Melnychuk, O. [Fermilab; Posen, S. [Fermilab; Romanenko, A. [Fermilab; Sergatskov, D. A. [Fermilab

    2017-07-24

    The radio-frequency surface resistance of niobium resonators is incredibly reduced when nitrogen impurities are dissolved as interstitial in the material, conferring ultra-high Q-factors at medium values of accelerating field. This effect has been observed in both high and low temperature nitrogen treatments. As a matter of fact, the peculiar anti Q-slope observed in nitrogen doped cavities, i.e. the decreasing of the Q-factor with the increasing of the radio-frequency field, come from the decreasing of the BCS surface resistance component as a function of the field. Such peculiar behavior has been considered consequence of the interstitial nitrogen present in the niobium lattice after the doping treatment. The study here presented show the field dependence of the BCS surface resistance of cavities with different resonant frequencies, such as: 650 MHz, 1.3 GHz, 2.6 GHz and 3.9 GHz, and processed with different state-of-the-art surface treatments. These findings show for the first time that the anti Q-slope might be seen at high frequency even for clean Niobium cavities, revealing useful suggestion on the physics underneath the anti Q-slope effect.

  6. Experiments on the rf surface resistance of the perovskite superconductors at 3 GHz

    International Nuclear Information System (INIS)

    Hein, M.; Klein, N.; Mueller, G.; Piel, H.; Roeth, R.W.

    1988-01-01

    Since the discovery of the perovskite superconductors many experiments to explore their physical properties have been performed and various potential applications have been considered. The high critical temperature of more than 90 K obtained with Y 1 Ba 2 Cu 3 O/sub 7-δ/ (Y may be substituted by other rare earth elements) makes these superconductors interesting for applications in microwave technology. This has focused the authors interest on the investigation of their rf properties. Due to the sensitivity of the rf surface resistance to surface impurities and remaining non superconducting phases rf measurements are a good means to provide useful information about the quality of sample preparation and about physical properties of the superconductor itself. This contribution reports on the experimental determination of the rf surface resistance of Y 1 Ba 2 Cu 3 O/sub 7-δ/ and Eu 1 Ba 2 Cu 3 O/sub 7-δ/ in the normal and superconducting state at 3 GHz. In the first chapter the preparation of the ceramic samples and initial dc experiments are described. The main part of the paper describes the rf measurements which are performed in a superconducting niobium host cavity. The obtained results for both the surface resistance and the high field performance are discussed with respect to the preparation of the samples and regarding possible applications. 7 references, 7 figures, 2 tables

  7. Surface electric resistance of YBa2Cu3O7-δ ceramics and its dependence on magnetic field

    International Nuclear Information System (INIS)

    Gorochev, O.A.; Graboj, I.Eh.; Kaul', A.R.; Mitrofanov, V.P.

    1989-01-01

    Method of dielectric resonator in the 4.2-300 K temperature range is used to measure surface electric resistance of YBa 2 Cu 3 O 7-δ ceramics samples produced by different technologies. The temperature dependence of surface resistance near transition temperature is calculated. At 77.3 K dependence of electric resistance on external magnetic field at H≤200Oe is determined. Calculated dependence is verified in experiment

  8. Hierarchically ordered self-lubricating superhydrophobic anodized aluminum surfaces with enhanced corrosion resistance.

    Science.gov (United States)

    Vengatesh, Panneerselvam; Kulandainathan, Manickam Anbu

    2015-01-28

    Herein, we report a facile method for the fabrication of self-lubricating superhydrophobic hierarchical anodic aluminum oxide (AAO) surfaces with improved corrosion protection, which is greatly anticipated to have a high impact in catalysis, aerospace, and the shipping industries. This method involves chemical grafting of as-formed AAO using low surface free energy molecules like long chain saturated fatty acids, perfluorinated fatty acid (perfluorooctadecanoic acid, PFODA), and perfluorosulfonicacid-polytetrafluoroethylene copolymer. The pre and post treatment processes in the anodization of aluminum (Al) play a vital role in the grafting of fatty acids. Wettability and surface free energy were analyzed using a contact angle meter and achieved 161.5° for PFODA grafted anodized aluminum (PFODA-Al). This study was also aimed at evaluating the surface for corrosion resistance by Tafel polarization and self-lubricating properties by tribological studies using a pin-on-disc tribometer. The collective results showed that chemically grafted AAO nanostructures exhibit high corrosion resistance toward seawater and low frictional coefficient due to low surface energy and self-lubricating property of fatty acids covalently linked to anodized Al surfaces.

  9. Numerical Simulations of Scattering of Light from Two-Dimensional Rough Surfaces Using the Reduced Rayleigh Equation

    Directory of Open Access Journals (Sweden)

    Tor eNordam

    2013-09-01

    Full Text Available A formalism is introduced for the non-perturbative, purely numerical, solution of the reduced Rayleigh equation for the scattering of light from two-dimensional penetrable rough surfaces. Implementation and performance issues of the method, and various consistency checks of it, are presented and discussed. The proposed method is found, within the validity of the Rayleigh hypothesis, to give reliable results. For a non-absorbing metal surface the conservation of energy was explicitly checked, and found to be satisfied to within 0.03%, or better, for the parameters assumed. This testifies to the accuracy of the approach and a satisfactory discretization. As an illustration, we calculate the full angular distribution of the mean differential reflection coefficient for the scattering of p- or s-polarized light incident on two-dimensional dielectric or metallic randomly rough surfaces defined by (isotropic or anisotropic Gaussian and cylindrical power spectra. Simulation results obtained by the proposed method agree well with experimentally measured scattering data taken from similar well-characterized, rough metal samples, or to results obtained by other numerical methods.

  10. Fabricating superhydrophobic polymer surfaces with excellent abrasion resistance by a simple lamination templating method.

    Science.gov (United States)

    Xu, Qian Feng; Mondal, Bikash; Lyons, Alan M

    2011-09-01

    Fabricating robust superhydrophobic surfaces for commercial applications is challenging as the fine-scale surface features, necessary to achieve superhydrophobicity, are susceptible to mechanical damage. Herein, we report a simple and inexpensive lamination templating method to create superhydrophobic polymer surfaces with excellent abrasion resistance and water pressure stability. To fabricate the surfaces, polyethylene films were laminated against woven wire mesh templates. After cooling, the mesh was peeled from the polymer creating a 3D array of ordered polymer microposts on the polymer surface. The resulting texture is monolithic with the polymer film and requires no chemical modification to exhibit superhydrophobicity. By controlling lamination parameters and mesh dimensions, polyethylene surfaces were fabricated that exhibit static contact angles of 160° and slip angles of 5°. Chemical and mechanical stability was evaluated using an array of manual tests as well as a standard reciprocating abraser test. Surfaces remained superhydrophobic after more than 5500 abrasion cycles at a pressure of 32.0 kPa. In addition, the surface remains dry after immersing into water for 5 h at 55 kPa. This method is environmental friendly, as it employs no solvents or harsh chemicals and may provide an economically viable path to manufacture large areas of mechanically robust superhydrophobic surfaces from inexpensive polymers and reusable templates.

  11. Biofilm Formation of Staphylococcus aureus on Various Surfaces and Their Resistance to Chlorine Sanitizer.

    Science.gov (United States)

    Lee, Jung-Su; Bae, Young-Min; Lee, Sook-Young; Lee, Sun-Young

    2015-10-01

    This study investigated the effect of material types (polystyrene, polypropylene, glass, and stainless steel) and glucose addition on Staphylococcus aureus biofilm formation, and the relationship between biofilm formation measured by crystal violet (CV) staining and the number of biofilm cells determined by cell counts was studied. We also evaluated the efficacy of chlorine sanitizer on inhibiting various different types of S. aureus biofilms on the surface of stainless steel. Levels of biofilm formation of S. aureus were higher on hydrophilic surfaces (glass and stainless steel) than on hydrophobic surfaces (polypropylene and polystyrene). With the exception of biofilm formed on glass, the addition of glucose in broth significantly increased the biofilm formation of S. aureus on all surfaces and for all tested strains (P ≤ 0.05). The number of biofilm cells was not correlated with the biomass of the biofilms determined using the CV staining method. The efficacy of chlorine sanitizer against biofilm of S. aureus was not significantly different depending on types of biofilm (P > 0.05). Therefore, further studies are needed in order to determine an accurate method quantifying levels of bacterial biofilm and to evaluate the resistance of bacterial biofilm on the material surface. Biofilm formation of Staphylococcus aureus on the surface was different depending on the surface characteristics and S. aureus strains. There was low correlation between crystal violet staining method and viable counts technique for measuring levels of biofilm formation of S. aureus on the surfaces. These results could provide helpful information for finding and understanding the quantification method and resistance of bacterial biofilm on the surface. © 2015 Institute of Food Technologists®

  12. Effect of implantoplasty on fracture resistance and surface roughness of standard diameter dental implants.

    Science.gov (United States)

    Costa-Berenguer, Xavier; García-García, Marta; Sánchez-Torres, Alba; Sanz-Alonso, Mariano; Figueiredo, Rui; Valmaseda-Castellón, Eduard

    2018-01-01

    To assess the effect of implantoplasty on the fracture resistance, surface roughness, and macroscopic morphology of standard diameter (4.1 mm) external connection dental implants. An in vitro study was conducted in 20 screw-shaped titanium dental implants with an external connection. In 10 implants, the threads and surface were removed and polished with high-speed burs (implantoplasty), while the remaining 10 implants were used as controls. The final implant dimensions were recorded. The newly polished surface quality was assessed by scanning electron microscopy (SEM) and by 3D surface roughness analysis using a confocal laser microscope. Finally, all the implants were subjected to a mechanical pressure resistance test. A descriptive analysis of the data was made. Also, Student's t tests were employed to detect differences regarding the compression tests. Implantoplasty was carried out for a mean time of 10 min and 48 s (standard deviation (SD) of 1 min 22 s). Macroscopically, the resulting surface had a smooth appearance, although small titanium shavings and silicon debris were present. The final surface roughness (S a values 0.1 ± 0.02 μm) was significantly lower than that of the original (0.75 ± 0.08 μm S a ) (p = .005). There was minimal reduction in the implant's inner body diameter (0.19 ± 0.03 mm), and no statistically significant differences were found between the test and control implants regarding the maximum resistance force (896 vs 880 N, respectively). Implantoplasty, although technically demanding and time-consuming, does not seem to significantly alter fracture resistance of standard diameter external connection implants. A smooth surface with S a values below 0.1 μm can be obtained through the use of silicon polishers. A larger sample is required to confirm that implantoplasty does not significantly affect the maximum resistance force of standard diameter external connection implants. © 2017 John Wiley & Sons A/S. Published

  13. Experimental calibration and validation of sewer/surface flow exchange equations in steady and unsteady flow conditions

    Science.gov (United States)

    Rubinato, Matteo; Martins, Ricardo; Kesserwani, Georges; Leandro, Jorge; Djordjević, Slobodan; Shucksmith, James

    2017-09-01

    The linkage between sewer pipe flow and floodplain flow is recognised to induce an important source of uncertainty within two-dimensional (2D) urban flood models. This uncertainty is often attributed to the use of empirical hydraulic formulae (the one-dimensional (1D) weir and orifice steady flow equations) to achieve data-connectivity at the linking interface, which require the determination of discharge coefficients. Because of the paucity of high resolution localised data for this type of flows, the current understanding and quantification of a suitable range for those discharge coefficients is somewhat lacking. To fulfil this gap, this work presents the results acquired from an instrumented physical model designed to study the interaction between a pipe network flow and a floodplain flow. The full range of sewer-to-surface and surface-to-sewer flow conditions at the exchange zone are experimentally analysed in both steady and unsteady flow regimes. Steady state measured discharges are first analysed considering the relationship between the energy heads from the sewer flow and the floodplain flow; these results show that existing weir and orifice formulae are valid for describing the flow exchange for the present physical model, and yield new calibrated discharge coefficients for each of the flow conditions. The measured exchange discharges are also integrated (as a source term) within a 2D numerical flood model (a finite volume solver to the 2D Shallow Water Equations (SWE)), which is shown to reproduce the observed coefficients. This calibrated numerical model is then used to simulate a series of unsteady flow tests reproduced within the experimental facility. Results show that the numerical model overestimated the values of mean surcharge flow rate. This suggests the occurrence of additional head losses in unsteady conditions which are not currently accounted for within flood models calibrated in steady flow conditions.

  14. Method of moving frames to solve time-dependent Maxwell's equations on anisotropic curved surfaces: Applications to invisible cloak and ELF propagation

    Science.gov (United States)

    Chun, Sehun

    2017-07-01

    Applying the method of moving frames to Maxwell's equations yields two important advancements for scientific computing. The first is the use of upwind flux for anisotropic materials in Maxwell's equations, especially in the context of discontinuous Galerkin (DG) methods. Upwind flux has been available only to isotropic material, because of the difficulty of satisfying the Rankine-Hugoniot conditions in anisotropic media. The second is to solve numerically Maxwell's equations on curved surfaces without the metric tensor and composite meshes. For numerical validation, spectral convergences are displayed for both two-dimensional anisotropic media and isotropic spheres. In the first application, invisible two-dimensional metamaterial cloaks are simulated with a relatively coarse mesh by both the lossless Drude model and the piecewisely-parametered layered model. In the second application, extremely low frequency propagation on various surfaces such as spheres, irregular surfaces, and non-convex surfaces is demonstrated.

  15. Investigation of series resistance and surface states in Au/n - GaP structures

    International Nuclear Information System (INIS)

    Kiymaz, A.; Onal, B.; Ozer, M.; Acar, S.

    2009-01-01

    The variation in series resistance and surface state density of Au/n - GaP Schottky diodes have been systematically investigated at room temperature by using capacitance-voltage C-V and conductance-voltage G/w-V measurements techniques. The C-V and G/w-V characteristics of these devices were investigated by considering series resistance effects in a wide frequency range. It is shown that the capacitance of the Au/n - GaP Schottky diode decreases with increasing frequency. It is assumed that the surface states were responsible for this behaviour. The distribution profile of Rs-V gives a peak in the depletion region at low frequencies and disappears with increasing frequencies

  16. Corrosion resistance and cytocompatibility of tantalum-surface-functionalized biomedical ZK60 Mg alloy

    International Nuclear Information System (INIS)

    Jin, Weihong; Wang, Guomin; Lin, Zhengjie; Feng, Hongqing; Li, Wan; Peng, Xiang; Qasim, Abdul Mateen; Chu, Paul K.

    2017-01-01

    Highlights: • Films comprising Ta_2O_5, Ta suboxide, and Ta are sputter-deposited on ZK60 Mg alloy. • The Ta-containing film significantly mitigates degradation of ZK60. • The modified ZK60 exhibits notably enhanced cell adhesion and proliferation. - Abstract: Tantalum (Ta) is introduced to the surface of the ZK60 Mg alloy by reactive magnetron sputtering to enhance the corrosion resistance and cytocompatibility. The film thickness and composition, corrosion behavior, and cytocompatibility are studied by various techniques systematically. The surface layer composed of Ta_2O_5, Ta suboxide, and Ta increases the corrosion resistance of ZK60 while simultaneously improving cell attachment, spreading, and proliferation in vitro. The enhancement mechanism is proposed and discussed.

  17. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  18. Biofilm-Forming Staphylococcus epidermidis Expressing Vancomycin Resistance Early after Adhesion to a Metal Surface

    Directory of Open Access Journals (Sweden)

    Toshiyuki Sakimura

    2015-01-01

    Full Text Available We investigated biofilm formation and time of vancomycin (VCM resistance expression after adhesion to a metal surface in Staphylococcus epidermidis. Biofilm-forming Staphylococcus epidermidis with a VCM MIC of 1 μg/mL was used. The bacteria were made to adhere to a stainless steel washer and treated with VCM at different times and concentrations. VCM was administered 0, 2, 4, and 8 hours after adhesion. The amount of biofilm formed was evaluated based on the biofilm coverage rates (BCRs before and after VCM administration, bacterial viability in biofilm was visually observed using the fluorescence staining method, and the viable bacterial count in biofilm was measured. The VCM concentration required to decrease BCR significantly compared with that of VCM-untreated bacteria was 4 μg/mL, even in the 0 hr group. In the 4 and 8 hr groups, VCM could not inhibit biofilm growth even at 1,024 μg/mL. In the 8 hr group, viable bacteria remained in biofilm at a count of 104 CFU even at a high VCM concentration (1,024 μg/mL. It was suggested that biofilm-forming Staphylococcus epidermidis expresses resistance to VCM early after adhesion to a metal surface. Resistance increased over time after adhesion as the biofilm formed, and strong resistance was expressed 4–8 hours after adhesion.

  19. Rough surface electrical contact resistance considering scale dependent properties and quantum effects

    International Nuclear Information System (INIS)

    Jackson, Robert L.; Crandall, Erika R.; Bozack, Michael J.

    2015-01-01

    The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness

  20. Improving wettability of photo-resistive film surface with plasma surface modification for coplanar copper pillar plating of IC substrates

    Science.gov (United States)

    Xiang, Jing; Wang, Chong; Chen, Yuanming; Wang, Shouxu; Hong, Yan; Zhang, Huaiwu; Gong, Lijun; He, Wei

    2017-07-01

    The wettability of the photo-resistive film (PF) surfaces undergoing different pretreatments including the O2sbnd CF4 low-pressure plasma (OCLP) and air plasma (AP), is investigated by water contact angle measurement instrument (WCAMI) before the bottom-up copper pillar plating. Chemical groups analysis performed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) shows that after the OCLP and wash treatment, the wettability of PF surface is attenuated, because embedded fluorine and decreased oxygen content both enhance hydrophobicity. Compared with OCLP treatment, the PF surface treatment by non-toxic air plasma displays features of Csbnd O, Osbnd Cdbnd O, Cdbnd O and sbnd NO2 by AIR-FTIR and XPS, and a promoted wettability by WCAM. Under the identical electroplating condition, the surface with a better wettability allows electrolyte to spontaneously soak all the places of vias, resulting in improved copper pillar uniformity. Statistical analysis of metallographic data shows that more coplanar and flat copper pillars are achieved with the PF treatment of air plasma. Such modified copper-pillar-plating technology meets the requirement of accurate impedance, the high density interconnection for IC substrates.

  1. Effect of swift heavy ion irradiation on surface resistance of DyBa 2

    Indian Academy of Sciences (India)

    We report the observation of a pronounced peak in surface resistance at microwave frequencies of 4.88 GHz and 9.55 GHz and its disappearance after irradiation with swift ions in laser ablated DyBa2Cu3O7- (DBCO) thin films. The measurements were carried out in zero field as well as in the presence of magnetic fields ...

  2. The Effect of Surface Patterning on Corrosion Resistance of Biomedical Devices

    Science.gov (United States)

    Guo, Mengnan; Toloei, Alisina; Rotermund, Harm H.

    2016-10-01

    In this study, two styles of surface topographies have been created on stainless steel wires to test their corrosion resistance as simulated implanted biomedical devices. Grade 316 LVM stainless steel wire was initially polished to G1500 surface finish before treatment to produce the two different topographies: 1. Unidirectional roughness was created using SiC papers and 2. Various patterns were created with specific hole diameter and inter-hole spacing using focused ion beam (FIB). In order to simulate the environment of implanted biomedical devices, a three-electrode electrochemical cell with 0.9% (by mass) NaCl solution has been used to test the corrosion resistance of the samples by potentiodynamic polarization test method. SEM and EDS analyzed the appearance and chemical composition of different elements including oxygen on the surface. The potential of stable pitting, time related to the initiation of the stable pitting, and the highest corrosion current associated with stable pitting have been compared for samples with the two styles of topography. It was found that surfaces with patterns have a relatively higher pitting potential and it takes longer time to initiate stable pitting than the surface without any patterns.

  3. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan

    2016-12-29

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a method includes preparing a pretreated target area on a CFRP composite surface using laser pulsed irradiation and bonding an electrode to exposed fibers in the pretreated target area. The surface preparation can allow the electrode to have a low contact resistance with the CFRP composite.

  4. Study of the effect of nano surface morphology on the stain-resistant property of ceramic tiles

    International Nuclear Information System (INIS)

    Pan, S P; Hung, J K; Liu, Y T

    2014-01-01

    In this study, six types of commercially available ceramic tiles, including nano-structured ceramic tiles and regular ceramic tiles, were selected to investigate the effect of surface morphology on their stain-resistant property. The stain-resistant efficiencies of various ceramic tiles with nano-size surface were measured in order to determine the appropriate method for testing ceramic tiles with nano-structure surface

  5. Superhydrophobic surface fabricated on iron substrate by black chromium electrodeposition and its corrosion resistance property

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Feng, Haitao [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Lin, Feng [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Yabin [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Wang, Liping [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Dong, Yaping [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Li, Wu, E-mail: liwu2016@126.com [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China)

    2016-08-15

    Highlights: • Superhydrophobic surface was fabricated by black chromium electrodeposition and stearic acid modification. • The reaction process is simple, and of low cost, and no special instrument or environment is needed. • The obtained superhydrophobic surface presents good water repellency, and performs well at corrosion resistance. - Abstract: The fabrication of superhydrophobic surface on iron substrate is carried out through 20 min black chromium electrodeposition, followed by immersing in 0.05 M ethanolic stearic acid solution for 12 h. The resultant superhydrophobic complex film is characterized by scanning electron microscope (SEM), disperse Spectrometer (EDS), atomic force microscope (AFM), water contact angle (CA), sliding angle (SA) and X-ray photoelectron spectroscope (XPS), and its corrosion resistance property is measured with cyclic voltammetry (CV), linear polarization and electrochemical impedance spectroscopy (EIS). The results show that the fabricated superhydrophobic film has excellent water repellency (CA, 158.8°; SA, 2.1°) and significantly high corrosion resistance (1.31 × 10{sup 6} Ω cm{sup −2}) and excellent corrosion protection efficiency (99.94%).

  6. A simple approach to measure the surface resistivity of insulating materials

    DEFF Research Database (Denmark)

    Yang, Zhenyu; Wang, Qian

    2011-01-01

    A simple approach for measuring high surface resistivity of insulating materials using standard laboratory equipments is proposed. The developed system consists of a DC power transformer, a concentric ring probe assembly and a digital multi-meter. The DC power transformer can provide either 500V ...... for different materials, source voltages, and serially connected resistors. The testing results showed that the developed system and methods can provide a reasonably accurate measurement of surface resistivity of insulating materials in a robust and economic manner.......A simple approach for measuring high surface resistivity of insulating materials using standard laboratory equipments is proposed. The developed system consists of a DC power transformer, a concentric ring probe assembly and a digital multi-meter. The DC power transformer can provide either 500V...... or 250V DC signal. The probe assembly is constructed according to Danish Standard (DS/EN 1149-1:2006). The multi-meter (Agilent 3440 1A 6½) is used to measure the micro voltage over a known resistor which is serially connected with electrodes in the probe assembly. In order to obtain reliable...

  7. Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing

    Directory of Open Access Journals (Sweden)

    Yue Xiao

    2018-05-01

    Full Text Available Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system, and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18–2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

  8. Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing.

    Science.gov (United States)

    Xiao, Yue; Wang, Feng; Cui, Peide; Lei, Lei; Lin, Juntao; Yi, Mingwei

    2018-05-29

    Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system), and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18⁻2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

  9. Extreme Wetting-Resistant Multiscale Nano-/Microstructured Surfaces for Viscoelastic Liquid Repellence

    Directory of Open Access Journals (Sweden)

    Aoythip Chunglok

    2016-01-01

    Full Text Available We demonstrate exceptional wetting-resistant surfaces capable of repelling low surface tension, non-Newtonian, and highly viscoelastic liquids. Theoretical analysis and experimental result confirm that a higher level of multiscale roughness topography composed of at least three structural length scales, ranging from nanometer to supermicron sizes, is crucial for the reduction of liquid-solid adhesion hysteresis. With Cassie-Baxter nonwetting state satisfied at all roughness length scales, the surface has been proven to effectively repel even highly adhesive liquid. Practically, this high-level hierarchical structure can be achieved through fractal-like structures of silica aggregates induced by siloxane oligomer interparticle bridges. The induced aggregation and surface functionalization of the silica particles can be performed simultaneously within a single reaction step, by utilizing trifunctional fluoroalkylsilane precursors that largely form a disordered fluoroalkylsiloxane grafting layer under the presence of sufficient native moisture preadsorbed at the silica surface. Spray-coating deposition of a particle surface layer on a precoated primer layer ensures facile processability and scalability of the fabrication method. The resulting low-surface-energy multiscale roughness exhibits outstanding liquid repellent properties, generating equivalent lotus effect for highly viscous and adhesive natural latex concentrate, with apparent contact angles greater than 160°, and very small roll-off angles of less than 3°.

  10. Rapid fabrication of large-area, corrosion-resistant superhydrophobic Mg alloy surfaces.

    Science.gov (United States)

    Xu, Wenji; Song, Jinlong; Sun, Jing; Lu, Yao; Yu, Ziyuan

    2011-11-01

    A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined.

  11. Hyper-resistivity and electron thermal conductivity due to destroyed magnetic surfaces in axisymmetric plasma equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Weening, R. H. [Department of Radiologic Sciences, Thomas Jefferson University, 901 Walnut Street, Philadelphia, Pennsylvania 19107-5233 (United States)

    2012-06-15

    In order to model the effects of small-scale current-driven magnetic fluctuations in a mean-field theoretical description of a large-scale plasma magnetic field B(x,t), a space and time dependent hyper-resistivity {Lambda}(x,t) can be incorporated into the Ohm's law for the parallel electric field E Dot-Operator B. Using Boozer coordinates, a theoretical method is presented that allows for a determination of the hyper-resistivity {Lambda}({psi}) functional dependence on the toroidal magnetic flux {psi} for arbitrary experimental steady-state Grad-Shafranov axisymmetric plasma equilibria, if values are given for the parallel plasma resistivity {eta}({psi}) and the local distribution of any auxiliary plasma current. Heat transport in regions of plasma magnetic surfaces destroyed by resistive tearing modes can then be modeled by an electron thermal conductivity k{sub e}({psi})=({epsilon}{sub 0}{sup 2}m{sub e}/e{sup 2}){Lambda}({psi}), where e and m{sub e} are the electron charge and mass, respectively, while {epsilon}{sub 0} is the permittivity of free space. An important result obtained for axisymmetric plasma equilibria is that the {psi}{psi}-component of the metric tensor of Boozer coordinates is given by the relation g{sup {psi}{psi}}({psi}){identical_to}{nabla}{psi} Dot-Operator {nabla}{psi}=[{mu}{sub 0}G({psi})][{mu}{sub 0}I({psi})]/{iota}({psi}), with {mu}{sub 0} the permeability of free space, G({psi}) the poloidal current outside a magnetic surface, I({psi}) the toroidal current inside a magnetic surface, and {iota}({psi}) the rotational transform.

  12. Surface microstructures and corrosion resistance of Ni-Ti-Nb shape memory thin films

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kun [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Huang, Xu [Memry Corporation, Bethel, CT 06801 (United States); Gibson, Des [Institute of Thin Films, Sensors & Imaging, Scottish Universities Physics Alliance, University of the West of Scotland, Paisley PA1 2BE (United Kingdom); Zheng, Yang; Liu, Jiao; Sun, Lu [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Fu, Yong Qing, E-mail: richard.fu@northumbria.ac.uk [Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom)

    2017-08-31

    Highlights: • The corrosion resistance of Ni-Ti-Nb shape memory thin films is investigated. • Modified surface oxide layers improve the corrosion resistance of Ni-Ti-Nb films. • Further Nb additions reduce the potential corrosion tendency of the films. - Abstract: Ni-Ti-Nb and Ni-Ti shape memory thin films were sputter-deposited onto silicon substrates and annealed at 600 °C for crystallization. X-ray diffraction (XRD) measurements indicated that all of the annealed Ni-Ti-Nb films were composed of crystalline Ni-Ti (Nb) and Nb-rich grains. X-ray photoelectron spectroscopy (XPS) tests showed that the surfaces of Ni-Ti-Nb films were covered with Ti oxides, NiO and Nb{sub 2}O{sub 5}. The corrosion resistance of the Ni-Ti-Nb films in 3.5 wt.% NaCl solution was investigated using electrochemical tests such as open-circuit potential (OCP) and potentio-dynamic polarization tests. Ni-Ti-Nb films showed higher OCPs, higher corrosion potentials (E{sub corr}) and lower corrosion current densities (i{sub corr}) than the binary Ni-Ti film, which indicated a better corrosion resistance. The reason may be that Nb additions modified the passive layer on the film surface. The OCPs of Ni-Ti-Nb films increased with further Nb additions, whereas no apparent difference of E{sub corr} and i{sub corr} was found among the Ni-Ti-Nb films.

  13. Surface resistance of YBa2Cu3O7 films deposited on LaGaO3 substrates

    International Nuclear Information System (INIS)

    Cooke, D.W.; Gray, E.R.; Houlton, R.J.; Javadi, H.H.S.; Maez, M.A.; Bennett, B.L.; Rusnak, B.; Meyer, E.A.; Arendt, P.N.; Beery, J.G.; Brown, D.R.; Garzon, F.H.; Raistriek, I.D.; Bolmaro, B.; Elliott, N.E.; Rollett, A.D.; Klein, N.; Muller, G.; Orbach, S.; Piel, H.; Josefowicz, J.Y.; Rensch, O.B.; Drabeck, L.; Gruner, G.

    1989-01-01

    Superconducting films of YBa 2 Cu 3 O 7 deposited onto LaGaO 3 substrates were prepared by e-beam and magnetron sputtering techniques. Surface resistance measurements made at 22 GHz, 86 GHz, and 148 GHz show that these films are superior to those deposited by similar techniques onto SrTiO 3 . Typical surface resistance values measured at 22 GHz and 12 K are ∼2 m(cgom) with the lowest value being 0.2 m(cgom), which is only 2 to 4 times higher than Nb. The surface resistance is proportional to the square of the measuring frequency

  14. Erosion resistance of pipe bends with bio-inspired internal surfaces

    Science.gov (United States)

    Zhang, Chengchun; Matar, Omar

    2013-11-01

    Guided by the structure of a shell surface, a bio-inspired surface is proposed to enhance the erosion resistance of pipe bends carrying crude-oil and sand in the turbulent flow regime. A comparison of the erosion rate between a smooth bend and the bio-inspired one is carried out using numerical simulations: large eddy simulations are used to simulate turbulence, and these are coupled to a discrete element method for the solid particles. The results indicate that the bio-inspired surface can control effectively the liquid-solid flow near the wall, and decrease the particle-wall force. This, then, leads to a reduction in the erosion rate brought about by the sand transported by the crude-oil in the pipe bend. The China Scholarship Council is gratefully acknowledged.

  15. Heat-resistant organic molecular layer as a joint interface for metal reduction on plastics surfaces

    International Nuclear Information System (INIS)

    Sang, Jing; Aisawa, Sumio; Hirahara, Hidetoshi; Kudo, Takahiro; Mori, Kunio

    2016-01-01

    Graphical abstract: - Highlights: • In situ adsorption behaviors of TES on PA6 surface were clarified by QCM. • Highest adsorption of TES on PA6 was obtained in pH 3 and 0.1 M solution. • Molecular layers of TES with uniform structures were prepared on PA6 surface. • TES layer improved PA6 local heat resistance from 150 °C to 230 °C. • TES molecular layer successfully reduced Ag ion to Ag"0. - Abstract: Heat-resistant organic molecular layers have been fabricated by triazine-based silane coupling agent for metal reduction on plastic surfaces using adsorption method. These molecular layers were used as an interfacial layer between polyamide (PA6) and metal solution to reduce Ag"+ ion to Ag"0. The interfacial behaviors of triazine molecular layer at the interfaces between PA6 and Ag solution were investigated using quartz crystal microbalance (QCM). The kinetics of molecular adsorption on PA6 was investigated by using triazine-based silane coupling agent solutions at different pH and concentration. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and local nano thermal analysis were employed to characterize the surfaces and interfaces. The nano thermal analysis results show that molecular layers of triazine-based silane coupling agent greatly improved heat resistance of PA6 resin from 170 °C up to 230 °C. This research developed an in-depth insight for molecular behaviors of triazine-based silane coupling agent at the PA6 and Ag solution interfaces and should be of significant value for interfacial research between plastics and metal solution in plating industry.

  16. Heat-resistant organic molecular layer as a joint interface for metal reduction on plastics surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Jing [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Aisawa, Sumio, E-mail: aisawa@iwate-u.ac.jp [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Hirahara, Hidetoshi [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Kudo, Takahiro [Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan); Mori, Kunio [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan)

    2016-04-15

    Graphical abstract: - Highlights: • In situ adsorption behaviors of TES on PA6 surface were clarified by QCM. • Highest adsorption of TES on PA6 was obtained in pH 3 and 0.1 M solution. • Molecular layers of TES with uniform structures were prepared on PA6 surface. • TES layer improved PA6 local heat resistance from 150 °C to 230 °C. • TES molecular layer successfully reduced Ag ion to Ag{sup 0}. - Abstract: Heat-resistant organic molecular layers have been fabricated by triazine-based silane coupling agent for metal reduction on plastic surfaces using adsorption method. These molecular layers were used as an interfacial layer between polyamide (PA6) and metal solution to reduce Ag{sup +} ion to Ag{sup 0}. The interfacial behaviors of triazine molecular layer at the interfaces between PA6 and Ag solution were investigated using quartz crystal microbalance (QCM). The kinetics of molecular adsorption on PA6 was investigated by using triazine-based silane coupling agent solutions at different pH and concentration. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and local nano thermal analysis were employed to characterize the surfaces and interfaces. The nano thermal analysis results show that molecular layers of triazine-based silane coupling agent greatly improved heat resistance of PA6 resin from 170 °C up to 230 °C. This research developed an in-depth insight for molecular behaviors of triazine-based silane coupling agent at the PA6 and Ag solution interfaces and should be of significant value for interfacial research between plastics and metal solution in plating industry.

  17. Hole-to-surface resistivity measurements at Gibson Dome (drill hole GD-1) Paradox basin, Utah

    Science.gov (United States)

    Daniels, J.J.

    1984-01-01

    Hole-to-surface resistivity measurements were made in a deep drill hole (GD-1), in San Juan County, Utah, which penetrated a sequence of sandstone, shale, and evaporite. These measurements were made as part of a larger investigation to study the suitability of an area centered around the Gibson Dome structure for nuclear waste disposal. The magnitude and direction of the total electric field resulting from a current source placed in a drill hole is calculated from potential difference measurements for a grid of closely-spaced stations. A contour map of these data provides a detailed map of the distribution of the electric field away from the drill hole. Computation of the apparent resistivity from the total electric field helps to interpret the data with respect to the ideal situation of a layered earth. Repeating the surface measurements for different source depths gives an indication of variations in the geoelectric section with depth. The quantitative interpretation of the field data at Gibson Dome was hindered by the pressure of a conductive borehole fluid. However, a qualitative interpretation of the field data indicates the geoelectric section around drill hole GD-1 is not perfectly layered. The geoelectric section appears to dip to the northwest, and contains anomalies in the resistivity distribution that may be representative of localized thickening or folding of the salt layers.

  18. Development of a High Slip-resistant Footwear Outsole Using a Hybrid Rubber Surface Pattern

    Science.gov (United States)

    YAMAGUCHI, Takeshi; HOKKIRIGAWA, Kazuo

    2014-01-01

    Abstract: The present study examined whether a new footwear outsole with tread blocks and a hybrid rubber surface pattern, composed of rough and smooth surfaces, could increase slip resistance and reduce the risk of fall while walking on a wet floor surface. A drag test was performed to measure static and dynamic coefficient of friction (SCOF and DCOF, respectively) values for the footwear with the hybrid rubber surface pattern outsole and two types of commercially available boots that are conventionally used in food factories and restaurant kitchens with respect to a stainless steel floor covered with glycerol solution. Gait trials were conducted with 14 participants who wore the footwear on the wet stainless steel floor. The drag test results indicated that the hybrid rubber surface pattern sole exhibited higher SCOF (≥0.44) and DCOF (≥0.39) values than the soles of the comparative footwear (pfootwear with the hybrid rubber surface pattern outsole were significantly lower than those for the comparative footwear, which resulted in no falls during trials. PMID:25055846

  19. Polyamide desalination membrane characterization and surface modification to enhance fouling resistance.

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mukul M. (Univeristy of Texas at Austin, Austin, TX); Freeman, Benny D. (Univeristy of Texas at Austin, Austin, TX); Van Wagner, Elizabeth M. (Univeristy of Texas at Austin, Austin, TX); Hickner, Michael A. (Pennsylvania State University, University Park, PA); Altman, Susan Jeanne

    2010-08-01

    The market for polyamide desalination membranes is expected to continue to grow during the coming decades. Purification of alternative water sources will also be necessary to meet growing water demands. Purification of produced water, a byproduct of oil and gas production, is of interest due to its dual potential to provide water for beneficial use as well as to reduce wastewater disposal costs. However, current polyamide membranes are prone to fouling, which decreases water flux and shortens membrane lifetime. This research explored surface modification using poly(ethylene glycol) diglycidyl ether (PEGDE) to improve the fouling resistance of commercial polyamide membranes. Characterization of commercial polyamide membrane performance was a necessary first step before undertaking surface modification studies. Membrane performance was found to be sensitive to crossflow testing conditions. Concentration polarization and feed pH strongly influenced NaCl rejection, and the use of continuous feed filtration led to higher water flux and lower NaCl rejection than was observed for similar tests performed using unfiltered feed. Two commercial polyamide membranes, including one reverse osmosis and one nanofiltration membrane, were modified by grafting PEGDE to their surfaces. Two different PEG molecular weights (200 and 1000) and treatment concentrations (1% (w/w) and 15% (w/w)) were studied. Water flux decreased and NaCl rejection increased with PEGDE graft density ({micro}g/cm{sup 2}), although the largest changes were observed for low PEGDE graft densities. Surface properties including hydrophilicity, roughness and charge were minimally affected by surface modification. The fouling resistance of modified and unmodified membranes was compared in crossflow filtration studies using model foulant solutions consisting of either a charged surfactant or an oil in water emulsion containing n-decane and a charged surfactant. Several PEGDE-modified membranes demonstrated improved

  20. Surface effects of electrode-dependent switching behavior of resistive random-access memory

    KAUST Repository

    Ke, Jr Jian

    2016-09-26

    The surface effects of ZnO-based resistive random-access memory (ReRAM) were investigated using various electrodes. Pt electrodes were found to have better performance in terms of the device\\'s switching functionality. A thermodynamic model of the oxygen chemisorption process was proposed to explain this electrode-dependent switching behavior. The temperature-dependent switching voltage demonstrates that the ReRAM devices fabricated with Pt electrodes have a lower activation energy for the chemisorption process, resulting in a better resistive switching performance. These findings provide an in-depth understanding of electrode-dependent switching behaviors and can serve as design guidelines for future ReRAM devices.

  1. Multidrug-Resistant Bacteria Isolated from Surface Water in Bassaseachic Falls National Park, Mexico.

    Science.gov (United States)

    Delgado-Gardea, Ma Carmen E; Tamez-Guerra, Patricia; Gomez-Flores, Ricardo; Zavala-Díaz de la Serna, Francisco Javier; Eroza-de la Vega, Gilberto; Nevárez-Moorillón, Guadalupe Virginia; Pérez-Recoder, María Concepción; Sánchez-Ramírez, Blanca; González-Horta, María Del Carmen; Infante-Ramírez, Rocío

    2016-06-16

    Bacterial pathogens are a leading cause of waterborne disease, and may result in gastrointestinal outbreaks worldwide. Inhabitants of the Bassaseachic Falls National Park in Chihuahua, Mexico show seasonal gastroenteritis problems. This aim of this study was to detect enteropathogenic microorganisms responsible for diarrheal outbreaks in this area. In 2013, 49 surface water samples from 13 selected sampling sites along the Basaseachi waterfall and its main rivers, were collected during the spring, summer, autumn, and winter seasons. Fecal and total coliform counts were determined using standard methods; the AutoScan-4 system was used for identification of isolates and the antibiotic resistance profile by challenging each organism using 21 antibiotics. Significant differences among seasons were detected, where autumn samples resulted in the highest total (p water-borne microorganisms exhibited resistance to cefazoline, cefuroxime, ampicillin, and ampicillin-sulbactam. The presence of these microorganisms near rural settlements suggests that wastewater is the contamination source, providing one possible transmission mechanism for diarrheal outbreaks.

  2. Effect of fluoride on ion exchange, remineralization and acid resistance of surface enamel

    Energy Technology Data Exchange (ETDEWEB)

    Aponte-Merced, L A; Feagin, F F [Alabama Univ., Birmingham (USA)

    1979-01-01

    In a system of constant ion activities the rates of F/sup -/ exchange in enamel, under conditions of exchange alone and remineralization, depended on the concentration of F/sup -/ in solutions. Acid resistance of surface minerals resulted from exchange of F/sup -/ for OH/sup -/ in the enamel at pH 7.0 and 4.5. The level of 0.5 mM NaF, compared to 0.05 and 5.0 mM, caused maximum rates of isotopic exchange of /sup 45/Ca and maximum acid resistance of enamel. Similarly low levels of F/sup -/ may be feasible for use in caries prevention in the absence and presence of remineralization.

  3. Averaged RMHD equations

    International Nuclear Information System (INIS)

    Ichiguchi, Katsuji

    1998-01-01

    A new reduced set of resistive MHD equations is derived by averaging the full MHD equations on specified flux coordinates, which is consistent with 3D equilibria. It is confirmed that the total energy is conserved and the linearized equations for ideal modes are self-adjoint. (author)

  4. SUS 321 HTB boiler tubing with fire grained internal surface resistant to steam-induced oxidation

    International Nuclear Information System (INIS)

    Kanero, Takahiro; Minami, Yuusuke; Kodera, Toshihide

    1981-01-01

    Considerable amount of scale is produced by high temperature steam on the austenitic stainless steel tubes used for the superheaters and reheaters of large boilers for power generation. The scale of outer layer separates off due to the thermal stress at the time of starting-up and stopping, and causes the blocking of pipes and the erosion of turbine blades. Following the increase of nuclear power generation, large boilers are used for medium load, accordingly it is expected that the troubles like these increase. In this paper, the manufacturing method and the properties of SUS 321 HTB with fine grain internal surface are reported, which was developed to reduce the rate of growth of scale and to prevent the separation of scale. In order to prevent the separation of scale from austenitic stainless steel tubes, the reduction of scale thickness, surface treatment such as chrome plating, the use of alloys with excellent oxidation resistance, the formation of chrome-rich film rapidly, the heat treatment of cold-worked tubes and so on were carried out. The nitrification of SUS 321 H steel brought about two-phase structure of the fine grain internal surface with excellent oxidation resistance and the rest of coarse grains with high creep strength. (Kako, I.)

  5. Giant magnetoresistance, three-dimensional Fermi surface and origin of resistivity plateau in YSb semimetal.

    Science.gov (United States)

    Pavlosiuk, Orest; Swatek, Przemysław; Wiśniewski, Piotr

    2016-12-09

    Very strong magnetoresistance and a resistivity plateau impeding low temperature divergence due to insulating bulk are hallmarks of topological insulators and are also present in topological semimetals where the plateau is induced by magnetic field, when time-reversal symmetry (protecting surface states in topological insulators) is broken. Similar features were observed in a simple rock-salt-structure LaSb, leading to a suggestion of the possible non-trivial topology of 2D states in this compound. We show that its sister compound YSb is also characterized by giant magnetoresistance exceeding one thousand percent and low-temperature plateau of resistivity. We thus performed in-depth analysis of YSb Fermi surface by band calculations, magnetoresistance, and Shubnikov-de Haas effect measurements, which reveals only three-dimensional Fermi sheets. Kohler scaling applied to magnetoresistance data accounts very well for its low-temperature upturn behavior. The field-angle-dependent magnetoresistance demonstrates a 3D-scaling yielding effective mass anisotropy perfectly agreeing with electronic structure and quantum oscillations analysis, thus providing further support for 3D-Fermi surface scenario of magnetotransport, without necessity of invoking topologically non-trivial 2D states. We discuss data implying that analogous field-induced properties of LaSb can also be well understood in the framework of 3D multiband model.

  6. Effect of distribution of striated laser hardening tracks on dry sliding wear resistance of biomimetic surface

    Science.gov (United States)

    Su, Wei; Zhou, Ti; Zhang, Peng; Zhou, Hong; Li, Hui

    2018-01-01

    Some biological surfaces were proved to have excellent anti-wear performance. Being inspired, Nd:YAG pulsed laser was used to create striated biomimetic laser hardening tracks on medium carbon steel samples. Dry sliding wear tests biomimetic samples were performed to investigate specific influence of distribution of laser hardening tracks on sliding wear resistance of biomimetic samples. After comparing wear weight loss of biomimetic samples, quenched sample and untreated sample, it can be suggested that the sample covered with dense laser tracks (3.5 mm spacing) has lower wear weight loss than the one covered with sparse laser tracks (4.5 mm spacing); samples distributed with only dense laser tracks or sparse laser tracks (even distribution) were proved to have better wear resistance than samples distributed with both dense and sparse tracks (uneven distribution). Wear mechanisms indicate that laser track and exposed substrate of biomimetic sample can be regarded as hard zone and soft zone respectively. Inconsecutive striated hard regions, on the one hand, can disperse load into small branches, on the other hand, will hinder sliding abrasives during wear. Soft regions with small range are beneficial in consuming mechanical energy and storing lubricative oxides, however, soft zone with large width (>0.5 mm) will be harmful to abrasion resistance of biomimetic sample because damages and material loss are more obvious on surface of soft phase. As for the reason why samples with even distributed bionic laser tracks have better wear resistance, it can be explained by the fact that even distributed laser hardening tracks can inhibit severe worn of local regions, thus sliding process can be more stable and wear extent can be alleviated as well.

  7. Mass and heat transfer between evaporation and condensation surfaces: Atomistic simulation and solution of Boltzmann kinetic equation.

    Science.gov (United States)

    Zhakhovsky, Vasily V; Kryukov, Alexei P; Levashov, Vladimir Yu; Shishkova, Irina N; Anisimov, Sergey I

    2018-04-16

    Boundary conditions required for numerical solution of the Boltzmann kinetic equation (BKE) for mass/heat transfer between evaporation and condensation surfaces are analyzed by comparison of BKE results with molecular dynamics (MD) simulations. Lennard-Jones potential with parameters corresponding to solid argon is used to simulate evaporation from the hot side, nonequilibrium vapor flow with a Knudsen number of about 0.02, and condensation on the cold side of the condensed phase. The equilibrium density of vapor obtained in MD simulation of phase coexistence is used in BKE calculations for consistency of BKE results with MD data. The collision cross-section is also adjusted to provide a thermal flux in vapor identical to that in MD. Our MD simulations of evaporation toward a nonreflective absorbing boundary show that the velocity distribution function (VDF) of evaporated atoms has the nearly semi-Maxwellian shape because the binding energy of atoms evaporated from the interphase layer between bulk phase and vapor is much smaller than the cohesive energy in the condensed phase. Indeed, the calculated temperature and density profiles within the interphase layer indicate that the averaged kinetic energy of atoms remains near-constant with decreasing density almost until the interphase edge. Using consistent BKE and MD methods, the profiles of gas density, mass velocity, and temperatures together with VDFs in a gap of many mean free paths between the evaporation and condensation surfaces are obtained and compared. We demonstrate that the best fit of BKE results with MD simulations can be achieved with the evaporation and condensation coefficients both close to unity.

  8. Preparation of electrodes on cfrp composites with low contact resistance comprising laser-based surface pre-treatment

    KAUST Repository

    Almuhammadi, Khaled Hamdan; Lubineau, Gilles; Alfano, Marco Francesco; Buttner, Ulrich

    2016-01-01

    Various examples are provided related to the preparation of electrodes on carbon fiber reinforced polymer (CFRP) composites with low contact resistance. Laser-based surface preparation can be used for bonding to CFRP composites. In one example, a

  9. Mechanical properties and corrosion resistance of supermartensitic stainless steel surfaces nitrided by plasma immersion ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Schibicheski, Bruna Corina Emanuely; Souza, Gelson Biscaia de; Oliveira, Willian Rafael de; Serbena, Francisco Carlos, E-mail: bruna_schibicheski@hotmail.com [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil); Marino, Cláudia E.B. [Universidade Federal do Paraná (UFPR), Curitiba, PR (Brazil)

    2016-07-01

    Full text: The supermartensitic stainless steel UNS S41426 is employed in marine oil and gas extraction ducts, where it is subjected to severe conditions of temperature, pressure and exposure to corrosive agents (as the H{sub 2}S). In such environments, pitting corrosion is a major cause of degradation of metallic alloys [1]. This work investigated the effectiveness of the nitrogen inlet, attained here by the plasma immersion ion implantation (PIII) technique, in improving the mechanical properties and corrosion resistance of the material surface. Samples were initially austenitized at 1100°C with a subsequent room temperature oil quenching in order to obtain a fully martensitic structure. The nitriding was carried out under 10 kV implantation energy and 30 ms pulse width. The temperatures ranged from 300 °C to 400°C, achieved by controlling the pulse repetition rates. Samples were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, instrumented indentation, scanning electron microscopy, potentiodynamic anodic polarization tests (in NaCl solution), and cathodic hydrogenation tests (in H{sub 2}SO{sub 4} solution). The PIII nitriding produced stratified layers up to 30 mm thick containing nitrogen expanded martensite and iron nitride phases (γ’-Fe{sub 4}N, ε- Fe{sub 2+x}N), depending on the treatment temperature. Consequently, the surface hardness increased from ∼3GPa (reference) up to ∼13GPa (400°C). Regarding the corrosion resistance, the nitrided surfaces presented a significant improvement as compared with the pristine surface, evidenced by the increase of the corrosion potential, which was also correlated to the hydrogen embrittlement reduction and the subsequent suppression of morphological changes. References: [1] M.G. Fontana, Corrosion Engineering, Singapore: McGraw-Hill, 1987. [2] B.C.E.S. Kurelo et al., Applied Surface Science 349 (2015) 403-414. (author)

  10. The influence of the carbon surface chemical composition on Dubinin-Astakhov equation parameters calculated from SF{sub 6} adsorption data-grand canonical Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Furmaniak, Sylwester; Terzyk, Artur P; Gauden, Piotr A [Department of Chemistry, Physicochemistry of Carbon Materials Research Group, N Copernicus University, Gagarin Street 7, 87-100 Torun (Poland); Kowalczyk, Piotr [Nanochemistry Research Institute, Curtin University, PO Box U1987, Perth, WA 6845 (Australia); Harris, Peter J F, E-mail: aterzyk@chem.uni.torun.pl [Centre for Advanced Microscopy, University of Reading, Whiteknights, Reading RG6 6AF (United Kingdom)

    2011-10-05

    Using grand canonical Monte Carlo simulation we show, for the first time, the influence of the carbon porosity and surface oxidation on the parameters of the Dubinin-Astakhov (DA) adsorption isotherm equation. We conclude that upon carbon surface oxidation, the adsorption decreases for all carbons studied. Moreover, the parameters of the DA model depend on the number of surface oxygen groups. That is why in the case of carbons containing surface polar groups, SF{sub 6} adsorption isotherm data cannot be used for characterization of the porosity. (paper)

  11. Antibiotic resistance patterns of Escherichia coli strains isolated from surface water and groundwater samples in a pig production area

    Directory of Open Access Journals (Sweden)

    Roger Neto Schneider

    2009-09-01

    Full Text Available The use of antibiotics, so excessive and indiscriminate in intensive animal production, has triggered an increase in the number of resistant microorganisms which can be transported to aquatic environments. The aim of this study was to determine the profile of the antimicrobial resistance of samples of Escherichia coli isolated from groundwater and surface water in a region of pig breeding. Through the test of antimicrobial susceptibility, we analyzed 205 strains of E. coli. A high rate of resistance to cefaclor was observed, both in surface water (51.9% and groundwater (62.9%, while all samples were sensitive to amikacin. The percentages of multi-resistant samples were 25.96% and 26.73% in surface water and groundwater, respectively, while 19.23% and 13.86% were sensitive to all antibiotics tested. It was determined that the rate of multiple antibiotic resistance (MAR was 0.164 for surface water and 0.184 for groundwater. No significant differences were found in the profile of the antimicrobial resistance in strains of E. coli isolated in surface water and groundwater, but the index MAR calculated in certain points of groundwater may offer a potential risk of transmission of resistant genes.

  12. Comparison of multi-drug resistant environmental methicillin-resistant Staphylococcus aureus [MRSA] isolated from recreational beaches and high touch surfaces in built environments

    Directory of Open Access Journals (Sweden)

    Marilyn C Roberts

    2013-04-01

    Full Text Available Over the last decade community-acquired methicillin-resistant Staphylococcus aureus [MRSA] has emerged as a major cause of disease in the general population with no health care exposure or known classical risk factors for MRSA infections. The potential community reservoirs have not been well defined though certain strains such as ST398 and USA300 have been well studied in some settings. MRSA has been isolated from recreational beaches, high-touch surfaces in homes, universities and other community environmental surfaces. However, in most cases the strains were not characterized to determine if they are related to community-acquired or hospital-acquired clinical strains. We compared 55 environmental MRSA from 805 samples including sand, fresh and marine water samples from local marine and fresh water recreational beaches (n=296, high touch surfaces on the University of Washington campus (n=294, surfaces in UW undergraduate housing (n=85, and the local community (n=130. Eleven USA300, representing 20% of the isolates, were found on the UW campus surfaces, student housing surfaces and on the community surfaces but not in the recreational beach samples from the Northwest USA. Similarly, the predominant animal ST133 was found in the recreational beach samples but not in the high touch surface samples. All USA300 isolates were multi-drug resistant carrying 2-6 different antibiotic resistance genes coding for kanamycin, macrolides and/or macrolides-lincosamides-streptogramin B and tetracycline, with the majority [72%] carrying 4-6 different antibiotic resistance genes. A surprising 98% of the 55 MRSA isolates were resistant to other classes of antibiotics and most likely represent reservoirs for these genes in the environment.

  13. Enhancement of the oxidation resistance of carbon fibres in C/C composites via surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Labruquere, S.; Pailler, R.; Naslain, R. [Bordeaux Univ., Pessac (France). Lab. des Composites Thermostructuraux; Desbat, B. [Lab. de Spectroscopie Moleculaire et Cristalline, Univ. of Bordeaux, Talence (France)

    1997-12-31

    Carbon-carbon (C/C) composites are commonly used in rockets and braking systems. However, the carbon reacts with oxygen, burning away rapidly at temperatures as low as 450 C. This work deals with the protection of carbon fibres from oxidation between 600 and 1000 C. Two kinds of methods were investigated to protect carbon fibres: (i) surface treatment with aqueous solutions (e.g. of H3PO4) and (ii) chemical vapour deposition (CVD) of SiC coatings. Oxidation resistance of the as treated preforms was studied under dry air atmosphere. (orig.) 2 refs.

  14. Effect of the linseed oil surface treatment on the performance of resistive plate chambers

    International Nuclear Information System (INIS)

    Abbrescia, M.; Colaleo, A.; Iaselli, G.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Ranieri, A.; Romano, F.; Arena, V.; Bonomi, G.; Braj, A.; Gianini, G.; Liguori, G.; Ratti, S.P.; Riccardi, C.; Viola, L.; Vitulo, P.

    1997-01-01

    Results on the behaviour of several bakelite resistive plate chambers (RPCs) without the linseed oil treatment of the internal electrodes will be presented. Efficiency, collected charge and cluster size distributions will be compared to the ones of a standard oiled RPC. Currents and single rate are the quantities most affected by the surface treatment of the electrodes beyond the optical/mechanical properties. A factor 4 less in currents and at least a factor 10 less in single rate is achieved using standard oiled RPCs operated in streamer mode. (orig.)

  15. Dependence of the surface resistance of niobium coated copper cavities on the coating temperature

    International Nuclear Information System (INIS)

    Darriulat, P.; Durand, C.; Janot, P.; Rensing, N.; Weingarten, W.; Bosland, P.; Gobin, J.; Martignac, J.

    1996-01-01

    Six hydro-formed copper 1.5 GHz cavities have been baked and coated with niobium at different temperatures between 100 deg C and 200 deg C, while keeping the other discharge parameters unchanged. Their surface resistance has been measured as a function RF field and trapped magnetic field. Its dependence on deposition temperature confirms earlier indications obtained using 350 MHz LEP cavities that 150 deg C leads to optimal performances. The critical temperatures of Nb/Cu and bulk niobium cavities have also been measured. (author)

  16. Enhancing the formation and shear resistance of nitrifying biofilms on membranes by surface modification

    DEFF Research Database (Denmark)

    Lackner, Susanne; Holmberg, Maria; Terada, Akihiko

    2009-01-01

    Polypropylene (PP) membranes and polyethylene (PE) surfaces were modified to enhance formation and shear resistance of nitrifying biofilms for wastewater treatment applications. A combination of plasma polymerization and wet chemistry was employed to ultimately introduce poly(ethyleneglycol) (PEG......) chains with two different functional groups (-PEG-NH2 and -PEG-CH3). Biofilm growth experiments using a mixed nitrifying bacterial culture revealed that the specific combination of PEG chains with amino groups resulted in most biofilm formation on both PP and PE samples. Detachment experiments showed...... structure might be possible explanations of the superiority of the -PEG-NH2 modification. The success of the-PEG-NH2 modification was independent of the original surface and might, therefore, be used in wastewater treatment bioreactors to improve reactor performance by making biofilm formation more stable...

  17. Benney's long wave equations

    International Nuclear Information System (INIS)

    Lebedev, D.R.

    1979-01-01

    Benney's equations of motion of incompressible nonviscous fluid with free surface in the approximation of long waves are analyzed. The connection between the Lie algebra of Hamilton plane vector fields and the Benney's momentum equations is shown

  18. Oxidation resistant peroxide cross-linked UHMWPE produced by blending and surface diffusion

    International Nuclear Information System (INIS)

    Gul, Rizwan M; Oral, Ebru; Muratoglu, Orhun K

    2014-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) has been widely used as acetabular cup in total hip replacement (THR) and tibial component in total knee replacement (TKR). Crosslinking of UHMWPE has been successful used to improve its wear performance leading to longer life of orthopedic implants. Crosslinking can be performed by radiation or organic peroxides. Peroxide crosslinking is a convenient process as it does not require specialized equipment and the level of crosslinking can be manipulated by changing the amount of peroxide added. However, there is concern about the long-term stability of these materials due to possible presence of by-products. Vitamin E has been successfully used to promote long-term oxidative stability of UHMWPE. In this study, UHMWPE has been crosslinked using organic peroxide in the presence of Vitamin E to produce an oxidation resistant peroxide crosslinked material. Crosslinking was performed both in bulk by mixing peroxide and resin, and only on the surface using diffusion of peroxides.The results show that UHMWPE can be crosslinked using organic peroxides in the presence of vitamin E by both methods. However, the level of crosslinking decreases with the increase in vitamin E content. The wear resistance increases with the increase in crosslink density, and oxidation resistance significantly increases due to the presence of vitamin E

  19. Oxidation resistant peroxide cross-linked UHMWPE produced by blending and surface diffusion

    International Nuclear Information System (INIS)

    Gul, R. M.; Oral, E.; Muratoglu, O. K.

    2013-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) has been widely used as acetabular cup in total hip replacement (THR) and tibial component in total knee replacement (TKR). Crosslinking of UHMWPE has been successful used to improve its wear performance leading to longer life of orthopedic implants. Crosslinking can be performed by radiation or organic peroxides. Peroxide crosslinking is a convenient process as it does not require specialized equipment and the level of crosslinking can be manipulated by changing the amount of peroxide added. However, there is concern about the long-term stability of these materials due to possible presence of by-products. Vitamin E has been successfully used to promote long-term oxidative stability of UHMWPE. In this study, UHMWPE has been crosslinked using organic peroxide in the presence of Vitamin E to produce an oxidation resistant peroxide crosslinked material. Crosslinking was performed both in bulk by mixing peroxide and resin, and only on the surface using diffusion of peroxides.The results show that UHMWPE can be crosslinked using organic peroxides in the presence of vitamin E by both methods. However, the level of crosslinking decreases with the increase in vitamin E content. The wear resistance increases with the increase in crosslink density, and oxidation resistance significantly increases due to the presence of vitamin E. (author)

  20. Modeling electrochemical resistance with coal surface properties in a direct carbon fuel cell based on molten carbonate

    Science.gov (United States)

    Eom, Seongyong; Ahn, Seongyool; Kang, Kijoong; Choi, Gyungmin

    2017-12-01

    In this study, a numerical model of activation and ohmic polarization is modified, taking into account the correlation function between surface properties and inner resistance. To investigate the correlation function, the surface properties of coal are changed by acid treatment, and the correlations between the inner resistance measured by half-cell tests and the surface characteristics are analyzed. A comparison between the model and experimental results demonstrates that the absolute average deviations for each fuel are less than 10%. The numerical results show that the sensitivities of the coal surface properties affecting polarization losses change depending on the operating temperature. The surface oxygen concentrations affect the activation polarization and the sensitivity decreased with increasing temperature. The surface ash of coal is an additional index to be considered along with ohmic polarization and it has the greatest effect on the surface properties at 973 K.

  1. Study of surface properties of ATLAS12 strip sensors and their radiation resistance

    Energy Technology Data Exchange (ETDEWEB)

    Mikestikova, M., E-mail: mikestik@fzu.cz [Academy of Sciences of the Czech Republic, Institute of Physics, Na Slovance 2, 18221 Prague 8 (Czech Republic); Allport, P.P.; Baca, M.; Broughton, J.; Chisholm, A.; Nikolopoulos, K.; Pyatt, S.; Thomas, J.P.; Wilson, J.A. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Kierstead, J.; Kuczewski, P.; Lynn, D. [Brookhaven National Laboratory, Physics Department and Instrumentation Division, Upton, NY 11973-5000 (United States); Hommels, L.B.A. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Ullan, M. [Centro Nacional de Microelectronica (IMB-CNM, CSIC), Campus UAB-Bellaterra, 08193 Barcelona (Spain); Bloch, I.; Gregor, I.M.; Tackmann, K. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Hauser, M.; Jakobs, K.; Kuehn, S. [Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); and others

    2016-09-21

    A radiation hard n{sup +}-in-p micro-strip sensor for the use in the Upgrade of the strip tracker of the ATLAS experiment at the High Luminosity Large Hadron Collider (HL-LHC) has been developed by the “ATLAS ITk Strip Sensor collaboration” and produced by Hamamatsu Photonics. Surface properties of different types of end-cap and barrel miniature sensors of the latest sensor design ATLAS12 have been studied before and after irradiation. The tested barrel sensors vary in “punch-through protection” (PTP) structure, and the end-cap sensors, whose stereo-strips differ in fan geometry, in strip pitch and in edge strip ganging options. Sensors have been irradiated with proton fluences of up to 1×10{sup 16} n{sub eq}/cm{sup 2}, by reactor neutron fluence of 1×10{sup 15} n{sub eq}/cm{sup 2} and by gamma rays from {sup 60}Co up to dose of 1 MGy. The main goal of the present study is to characterize the leakage current for micro-discharge breakdown voltage estimation, the inter-strip resistance and capacitance, the bias resistance and the effectiveness of PTP structures as a function of bias voltage and fluence. It has been verified that the ATLAS12 sensors have high breakdown voltage well above the operational voltage which implies that different geometries of sensors do not influence their stability. The inter-strip isolation is a strong function of irradiation fluence, however the sensor performance is acceptable in the expected range for HL-LHC. New gated PTP structure exhibits low PTP onset voltage and sharp cut-off of effective resistance even at the highest tested radiation fluence. The inter-strip capacitance complies with the technical specification required before irradiation and no radiation-induced degradation was observed. A summary of ATLAS12 sensors tests is presented including a comparison of results from different irradiation sites. The measured characteristics are compared with the previous prototype of the sensor design, ATLAS07. - Highlights:

  2. Bacteria-Mineral Interactions on the Surfaces of Metal-Resistant Bacteria

    International Nuclear Information System (INIS)

    Malkin, A.J.

    2010-01-01

    The extraordinary ability of indigenous microorganisms, like metal-resistant bacteria, for biotransformation of toxic compounds is of considerable interest for the emerging area of environmental bioremediation. However, the underlying mechanisms by which metal-resistant bacteria transform toxic compounds are currently unknown and await elucidation. The project's objective was to study stress-induced responses of metal-resistant bacteria to environmental changes and chemical stimulants. This project involved a multi-institutional collaboration of our LLNL group with the group of Dr. H.-Y. Holman (Lawrence Berkeley National Laboratory). In this project, we have utilized metal-resistant bacteria Arthrobacter oxydans as a model bacterial system. We have utilized atomic force microscopy (AFM) to visualize for the first time at the nanometer scale formation of stress-induced structures on bacterial surfaces in response to Cr (VI) exposure. We have demonstrated that structure, assembly, and composition of these stress-induced structures are dependent on Cr (VI) concentrations. Our AFM observations of the appearance and development of stress-induced layers on the surfaces of Arthrobacter oxydans bacteria exposed to Cr (VI) were confirmed by Dr. Holman's biochemical, electron microscopy, and synchrotron infrared spectromicroscopy studies. In general, in vitro imaging of live microbial and cellular systems represents one of the most challenging issues in application of AFM. Various approaches for immobilization of bacteria on the substrate for in vitro imaging were tested in this project. Imaging of live bacteria was achieved, however further optimization of experimental methods are needed for high-resolution visualization of the cellular environmental structural dynamics by AFM. This project enhanced the current insight into molecular architecture, structural and environmental variability of bacterial systems. The project partially funded research for two book chapters (1

  3. Measurements of the anomalous RF surface resistance of niobium using a dielectric resonator

    International Nuclear Information System (INIS)

    Moffat, D.; Bolore, M.; Bonin, B.; Jacques, E.; Safa, H.

    1996-01-01

    The surface resistance of high and low RRR niobium plates at 4.2 K and 1.8 K has been measured as a function of many processing and testing parameters. A dielectric resonator was used instead of a resonant cavity. This resonator offered the ability to make many, sensitive measurements with an efficient use of time and helium. It was found that the surface resistance, R s , of RRR=190 niobium increased noticeably from the theoretical value if the cooling rate was slower than∼10 K/min. Fast-cooled plates subsequently warmed to 130 K, and the recooled, showed a larger increase in R s than plates warmed to either 100 K or 160 K. Both chemically polished, and electropolished RRR=190 plates showed the effects of the 'Q-virus'. A heat treatment of 200 deg C made the RRR=190 plates less susceptible to the 'Q-virus'. RRR=30 niobium plates did not show any increase in R s , regardless of treatment. (author)

  4. Bilinear magnetoelectric resistance as a probe of three-dimensional spin texture in topological surface states

    Science.gov (United States)

    He, Pan; Zhang, Steven S.-L.; Zhu, Dapeng; Liu, Yang; Wang, Yi; Yu, Jiawei; Vignale, Giovanni; Yang, Hyunsoo

    2018-05-01

    Surface states of three-dimensional topological insulators exhibit the phenomenon of spin-momentum locking, whereby the orientation of an electron spin is determined by its momentum. Probing the spin texture of these states is of critical importance for the realization of topological insulator devices, but the main technique currently available is spin- and angle-resolved photoemission spectroscopy. Here we reveal a close link between the spin texture and a new kind of magnetoresistance, which depends on the relative orientation of the current with respect to the magnetic field as well as the crystallographic axes, and scales linearly with both the applied electric and magnetic fields. This bilinear magnetoelectric resistance can be used to map the spin texture of topological surface states by simple transport measurements. For a prototypical Bi2Se3 single layer, we can map both the in-plane and out-of-plane components of the spin texture (the latter arising from hexagonal warping). Theoretical calculations suggest that the bilinear magnetoelectric resistance originates from conversion of a non-equilibrium spin current into a charge current under application of the external magnetic field.

  5. On the field dependent surface resistance of niobium on copper cavities

    CERN Document Server

    Junginger, Tobias

    2015-01-01

    The surface resistance Rs of superconducting cavities prepared by sputter coating a thin niobium film on a copper substrate increases significantly stronger with the applied RF field compared to cavities of bulk material. A possible cause is that due to the thermal boundary resistance between the copper substrate and the niobium film Rs is enhanced due to global heating of the inner cavity wall. Introducing helium gas in the cavity and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by only 60+/-60 mK when Rs increases with Eacc by 100 nOhm. This is more than one order of magnitude less than what one would expect from global heating. Additionally the effect of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered Rs.

  6. Surface microstructures and corrosion resistance of Ni-Ti-Nb shape memory thin films

    Science.gov (United States)

    Li, Kun; Li, Yan; Huang, Xu; Gibson, Des; Zheng, Yang; Liu, Jiao; Sun, Lu; Fu, Yong Qing

    2017-08-01

    Ni-Ti-Nb and Ni-Ti shape memory thin films were sputter-deposited onto silicon substrates and annealed at 600 °C for crystallization. X-ray diffraction (XRD) measurements indicated that all of the annealed Ni-Ti-Nb films were composed of crystalline Ni-Ti (Nb) and Nb-rich grains. X-ray photoelectron spectroscopy (XPS) tests showed that the surfaces of Ni-Ti-Nb films were covered with Ti oxides, NiO and Nb2O5. The corrosion resistance of the Ni-Ti-Nb films in 3.5 wt.% NaCl solution was investigated using electrochemical tests such as open-circuit potential (OCP) and potentio-dynamic polarization tests. Ni-Ti-Nb films showed higher OCPs, higher corrosion potentials (Ecorr) and lower corrosion current densities (icorr) than the binary Ni-Ti film, which indicated a better corrosion resistance. The reason may be that Nb additions modified the passive layer on the film surface. The OCPs of Ni-Ti-Nb films increased with further Nb additions, whereas no apparent difference of Ecorr and icorr was found among the Ni-Ti-Nb films.

  7. Investigation of the magnetic neutral line region with the frame of two-fluid equations: A possibility of anomalous resistivity inferred from MMS observations

    Science.gov (United States)

    Kobayashi, Y.; Kitamura, N.; Ieda, A.; Yoshizumi, M.; Imada, S.; Tsugawa, Y.; Burch, J. L.; Russell, C. T.; Moore, T. E.; Giles, B. L.; Paterson, W.; Torbert, R. B.; Ergun, R.; Saito, Y.; Yokota, S.; Machida, S.

    2017-12-01

    Magnetic reconnection is a basic physical process by which energy of magnetic field is converted into the kinetic energy of plasmas. In recent years, MMS missionconsisting of four spacecraft has been conducted aiming at elucidating the physical mechanism of merging themagnetic fields in the vicinity of the magnetic neutral linethat exists in the central part of the structure. In this paper, we examine the magnetic field frozen-in relation near the magnetic neutral line as well as the causal relationship between electron and ion dynamics in the frame of two fluid equations.Theoretically, it is shown that electrons are frozen-in to the magnetic fields while ion's frozen-in relation is broken in the ion dissipation region. However, when we examined the observational data around 1307 UT on October 16, 2015 when MMS spacecraft passed through the vicinity of the magnetic neutral line [Burch et al., Science 2016] , it was confirmed that the frozen-ion relation was not established for electrons in the ion dissipation region. In addition, we found that intense wave electric fields in this region. From the spectral analysis of the waves, it turned out that their characteristic frequencies are the lower-hybrid and electron cyclotron frequencies.In the framework of the two-fluid equation, we can evaluate the values of each term of the equations of motion for both ions and electrons except for the collision term from MMS spacecraft data. Therefore, it is possible to obtain collision terms for both species. Since magnetospheric plasma is basically collisionless, it is considered that the collision term is due to anomalous resistivity associated with the excited waves . On the other hand, in the two-fluid equation system, the two vectors corresponding to the collision terms of ions and electrons have the same absolute value. Because the force exerted between the two is the internal force, they should face in the opposite direction. However, the vectors corresponding to the

  8. Analysis of the Effect of Surface Modification on Polyimide Composites Coated with Erosion Resistant Materials

    Science.gov (United States)

    Ndalama, Tchinga; Hirschfeld, Deidre; Sutter, James K. (Technical Monitor)

    2003-01-01

    The aim of this research is to enhance performance of composite coatings through modification of graphite-reinforced polyimide composite surfaces prior to metal bond coat/ hard topcoat application for use in the erosive and/or oxidative environments of advanced engines. Graphite reinforced polyimide composites, PMR-15 and PMR-II-50, formed by sheet molding and pre-pregging will be surface treated, overlaid with a bond coat and then coated with WC-Co. The surface treatment will include cleaning, RF plasma or ultraviolet light- ozone etching, and deposition of SiO(x) groups. These surface treatments will be studied in order to investigate and improve adhesion and oxidation resistance. The following panels were provided by NASA-Glenn Research Center(NASA-GRC): Eight compression molded PMR-II-50; 6 x 6 x 0.125 in. Two vacuum-bagged PMR-II-50; 12 x 12 x 0.125 in. Eight compression molded PMR-15; 6 x 6 x 0.125 in. One vacuum-bagged PMR-15; 12 x 12 x 0.125 in. All panels were made using a 12 x 12 in. T650-35 8HS (3K-tow) graphite fabric. A diamond-wafering blade, with deionized water as a cutting fluid, was used to cut PMR-II-50 and PMR-15 panels into 1 x 1 in. pieces for surface tests. The panel edges exhibiting delamination were used for the preliminary surface preparation tests as these would be unsuitable for strength and erosion testing. PMR-15 neat resin samples were also provided by NASA GRC. Surface profiles of the as-received samples were determined using a Dektak III Surface profile measuring system. Two samples of compression molded PMR-II-50 and PMR-15, vacuum-bagged PMR-II-50 and PMR-15 were randomly chosen for surface profile measurement according to ANSI/ASME B46.1. Prior to each measurement, the samples were blasted with compressed air to remove any artifacts. Five 10 mm-long scans were made on each sample. The short and long wavelength cutoff filter values were set at 100 and 1000 m, diamond stylus radius was 12.5 microns. Table 1 is a summary of the

  9. An ultrathin wide-band planar metamaterial absorber based on a fractal frequency selective surface and resistive film

    International Nuclear Information System (INIS)

    Fan Yue-Nong; Cheng Yong-Zhi; Nie Yan; Wang Xian; Gong Rong-Zhou

    2013-01-01

    We propose an ultrathin wide-band metamaterial absorber (MA) based on a Minkowski (MIK) fractal frequency selective surface and resistive film. This absorber consists of a periodic arrangement of dielectric substrates sandwiched with an MIK fractal loop structure electric resonator and a resistive film. The finite element method is used to simulate and analyze the absorption of the MA. Compared with the MA-backed copper film, the designed MA-backed resistive film exhibits an absorption of 90% at a frequency region of 2 GHz–20 GHz. The power loss density distribution of the MA is further illustrated to explain the mechanism of the proposed MA. Simulated absorptions at different incidence cases indicate that this absorber is polarization-insensitive and wide-angled. Finally, further simulated results indicate that the surface resistance of the resistive film and the dielectric constant of the substrate can affect the absorbing property of the MA. This absorber may be used in many military fields

  10. Effects of striated laser tracks on thermal fatigue resistance of cast iron samples with biomimetic non-smooth surface

    International Nuclear Information System (INIS)

    Tong, Xin; Zhou, Hong; Liu, Min; Dai, Ming-jiang

    2011-01-01

    In order to enhance the thermal fatigue resistance of cast iron materials, the samples with biomimetic non-smooth surface were processed by Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser. With self-controlled thermal fatigue test method, the thermal fatigue resistance of smooth and non-smooth samples was investigated. The effects of striated laser tracks on thermal fatigue resistance were also studied. The results indicated that biomimetic non-smooth surface was benefit for improving thermal fatigue resistance of cast iron sample. The striated non-smooth units formed by laser tracks which were vertical with thermal cracks had the best propagation resistance. The mechanisms behind these influences were discussed, and some schematic drawings were introduced to describe them.

  11. Microvillar cell surface as a natural defense system against xenobiotics: a new interpretation of multidrug resistance.

    Science.gov (United States)

    Lange, K; Gartzke, J

    2001-08-01

    The phenomenon of multidrug resistance (MDR) is reinterpreted on the basis of the recently proposed concept of microvillar signaling. According to this notion, substrate and ion fluxes across the surface of differentiated cells occur via transporters and ion channels that reside in membrane domains at the tips of microvilli (MV). The flux rates are regulated by the actin-based cytoskeletal core structure of MV, acting as a diffusion barrier between the microvillar tip compartment and the cytoplasm. The expression of this diffusion barrier system is a novel aspect of cell differentiation and represents a functional component of the natural defense system of epithelial cells against environmental hazardous ions and lipophilic compounds. Because of the specific organization of epithelial Ca(2+) signaling and the secretion, lipophilic compounds associated with the plasma membrane are transferred from the basal to the apical cell surface by a lipid flow mechanism. Drug release from the apical pole occurs by either direct secretion from the cell surface or metabolization by the microvillar cytochrome P-450 system and efflux of the metabolites and conjugation products through the large multifunctional anion channels localized in apical MV. The natural microvillar defense system also provides a mechanistic basis of acquired MDR in tumor cells. The microvillar surface organization is lost in rapidly growing cells such as tumor or embryonic cells but is restored during exposure of tumor cells to cytotoxins by induction of a prolonged G(0)/G(1) resting phase.

  12. Cerium Addition Improved the Dry Sliding Wear Resistance of Surface Welding AZ91 Alloy

    Directory of Open Access Journals (Sweden)

    Qingqiang Chen

    2018-02-01

    Full Text Available In this study, the effects of cerium (Ce addition on the friction and wear properties of surface welding AZ91 magnesium alloys were evaluated by pin-on-disk dry sliding friction and wear tests at normal temperature. The results show that both the friction coefficient and wear rate of surfacing magnesium alloys decreased with the decrease in load and increase in sliding speed. The surfacing AZ91 alloy with 1.5% Ce had the lowest friction coefficient and wear rate. The alloy without Ce had the worst wear resistance, mainly because it contained a lot of irregularly shaped and coarse β-Mg17Al12 phases. During friction, the β phase readily caused stress concentration and thus formed cracks at the interface between β phase and α-Mg matrix. The addition of Ce reduced the size and amount of Mg17Al12, while generating Al4Ce phase with a higher thermal stability. The Al-Ce phase could hinder the grain-boundary sliding and migration and reduced the degree of plastic deformation of subsurface metal. Scanning electron microscopy observation showed that the surfacing AZ91 alloy with 1.5% Ce had a total of four types of wear mechanism: abrasion, oxidation, and severe plastic deformation were the primary mechanisms; delamination was the secondary mechanism.

  13. Effect of surface modification on the corrosion resistivity in supercritical water

    International Nuclear Information System (INIS)

    Penttila, S.; Horvath, A.; Toivonen, A.; Zolnai, Z.

    2011-01-01

    This paper summarizes the results of high temperature corrosion studies of the candidate austenitic alloys at relevant operating conditions for SCWR. The high temperature and pressure above the thermodynamic critical point of water result in higher oxidation rate which might be critical for thin-wall components like fuel cladding. The goal of this work was to study the effect of surface preparation on the oxidation rate on Ti-stabilized austenitic alloy 1.4970. Surfaces were prepared with ion implantation using He"+- and N"+-ions. Samples were immersed in supercritical water at 650"oC/25 MPa, for up to 2000 hours. Added to this, conventional surface treatments were conducted for austenitic alloy 316L tube samples in order to study the effect of cold work in sample surface on corrosion resistance. The corrosion rate was evaluated by measuring the weight change of the samples. The compositions of the oxide layers were analyzed using scanning electron microscope (SEM) in conjunction with Energy Dispersive Spectroscopy (EDS). (author)

  14. Radio-frequency surface resistance of tunmgsten in weak magnetic fields

    International Nuclear Information System (INIS)

    Bojko, V.V.; Toniya, V.A.

    1988-01-01

    The surface impedance of single crystal tungsten specimens under anomalous skin effect in a magnetic field H is investigated experimentally. It is found that in magnetic fields ranging from 0 to 1 kOe the surface resistance R of tungsten varies in a nonmonotonous manner and experiences several extrema. The position of the latter with respect to magnetic field strength depends on the conduction electron mean free path l, on the roughness of the specimen surface and frequency of the irradiating electromagnetic wave. It is found that such behavior of R(H) is due to variation of the nature of the conduction electron scattering at the metal-external medium interface with increasing H. The geometrical dimensions of the surface roughnesses are determined at which diffuse scattering of the current occurs. The results are compared with the theoretical calculations, and a number of contradictions between the theory and experiments are noted. The effect of the magnetic field of the electromagnetic wave H ∼ on the conductivity of tungsten in the absence of H is studied

  15. Multidrug-Resistant Bacteria Isolated from Surface Water in Bassaseachic Falls National Park, Mexico

    Directory of Open Access Journals (Sweden)

    Ma. Carmen E. Delgado-Gardea

    2016-06-01

    Full Text Available Bacterial pathogens are a leading cause of waterborne disease, and may result in gastrointestinal outbreaks worldwide. Inhabitants of the Bassaseachic Falls National Park in Chihuahua, Mexico show seasonal gastroenteritis problems. This aim of this study was to detect enteropathogenic microorganisms responsible for diarrheal outbreaks in this area. In 2013, 49 surface water samples from 13 selected sampling sites along the Basaseachi waterfall and its main rivers, were collected during the spring, summer, autumn, and winter seasons. Fecal and total coliform counts were determined using standard methods; the AutoScan-4 system was used for identification of isolates and the antibiotic resistance profile by challenging each organism using 21 antibiotics. Significant differences among seasons were detected, where autumn samples resulted in the highest total (p < 0.05 and fecal (p < 0.001 coliform counts, whereas the lowest total coliform counts were recorded in spring. Significant differences between sampling sites were observed, where samples from sites 6, 8, and 11 had the highest total coliform counts (p < 0.009, whereas samples from site 9 exhibited the lowest one. From the microbiological analysis, 33 bacterial isolates from 13 different sites and four sampling seasons were selected; 53% of isolates were resistant to at least one antibiotic, and 15% exhibited a multidrug resistance (MDB phenotype. MDB were identified as Klebsiella oxytoca (two out of four identified isolates, Escherichia coli (2/7, and Enterobacter cloacae (1/3. In addition, some water-borne microorganisms exhibited resistance to cefazoline, cefuroxime, ampicillin, and ampicillin-sulbactam. The presence of these microorganisms near rural settlements suggests that wastewater is the contamination source, providing one possible transmission mechanism for diarrheal outbreaks.

  16. Failure of the Nernst-Einstein equation to correlate electrical resistances and rates of ionic self-exchange across certain fixed charge membranes.

    Science.gov (United States)

    Gottlieb, M H; Sollner, K

    1968-05-01

    The electrical resistances and rates of self-exchange of univalent critical ions across several types of collodion matrix membranes of high ionic selectivity were studied over a wide range of conditions. The relationship which was observed between these quantities with membranes of a certain type, namely those activated with poly-2-vinyl-N-methyl pyridinium bromide, cannot be explained on the basis of current concepts of the movement of ions across ion exchange membranes. Rates of self-exchange across these membranes were several times greater than those calculated from the electrical resistances of the membranes on the basis of an expression derived by the use of the Nernst-Einstein equation. The magnitude of the discrepancy was greatest at low concentrations of the ambient electrolyte solution and was independent of the species of both critical and noncritical ions. The data obtained with other types of collodion matrix membranes were, at least approximately, in agreement with the predictions based on the Nernst-Einstein equation. Self-exchange rates across the anion permeable protamine collodion membranes, and across the cation permeable polystyrene sulfonic acid collodion membranes, were about 20% less than those calculated from the electrical resistances. The direction and magnitude of these differences, also observed by other investigators, are qualitatively understood as an electroosmotic effect. With cation permeable membranes prepared by the oxidation of preformed collodion membranes, almost exact agreement was obtained between measured and calculated self-exchange rates; the cause of the apparent absence of an electroosmotic effect with these membranes is unknown.

  17. A new contact electric resistance technique for in-situ measurement of the electric resistance of surface films on metals in electrolytes at high temperatures and pressures

    International Nuclear Information System (INIS)

    Saario, T.; Marichev, V.A.

    1993-01-01

    Surface films play a major role in corrosion assisted cracking. A new Contact Electric Resistance (CER) method has been recently developed for in situ measurement of the electric resistance of surface films. The method has been upgraded for high temperature high pressure application. The technique can be used for any electrically conductive material in any environment including liquid, gas or vacuum. The technique has been used to determine in situ the electric resistance of films on metals during adsorption of water and anions, formation and destruction of oxides and hydrides, electroplating of metals and to study the electric resistance of films on semiconductors. The resolution of the CER technique is 10 -9 Ω, which corresponds to about 0.03 monolayers of deposited copper during electrochemical deposition Cu/Cu 2+ . Electric resistance data can be measured with a frequency of the order of one hertz, which enables one to follow in situ the kinetics of surface film related processes. The kinetics of these processes and their dependence on the environment, temperature, pH and electrochemical potential can be investigated

  18. Method of determination of temperature and heat resistance of the points on the integrated circuit crystal surface

    Directory of Open Access Journals (Sweden)

    Popov V. M.

    2011-12-01

    Full Text Available Method for visualization of integrated circuit (IC surface temperature by means of the liquid crystal film deposited from solution on its surface is proposed. The boundaries of local regions represent isotherms with corresponding phase transitions. On the base of isotherms positions and consumed by IC power thermal resistances between crystal and environment are determined.

  19. Cell surface alteration in Epstein-Barr virus-transformed cells from patients with extreme insulin resistance

    International Nuclear Information System (INIS)

    Gorden, D.L.; Robert, A.; Moncada, V.Y.; Taylor, S.I.; Muehlhauser, J.C.; Carpentier, J.L.

    1990-01-01

    An abnormality was detected in the morphology of the cell surface of Epstein-Barr virus-transformed lymphocytes of patients with genetic forms of insulin resistance. In cells from two patients with leprechaunism and two patients with type A extreme insulin resistance, scanning electron microscopy demonstrated a decrease in the percentage of the cell surface occupied by microvilli in cells from the patients with leprechaunism and type A insulin resistance compared with control cells. When cells from a healthy control subject and one of the patients with leprechaunism (Lep/Ark-1) were incubated with 125 I-labeled insulin, there was a decrease in the percentage of 125 I-insulin associated with microvilli on the cell surface. Thus, the decreased localization of insulin receptors with the microvillous region of the cell surface was in proportion to the decrease in microvilli

  20. Effects of Ultrasonic Nanocrystal Surface Modification on the Residual Stress, Microstructure, and Corrosion Resistance of 304 Stainless Steel Welds

    Science.gov (United States)

    Ye, Chang; Telang, Abhishek; Gill, Amrinder; Wen, Xingshuo; Mannava, Seetha R.; Qian, Dong; Vasudevan, Vijay K.

    2018-03-01

    In this study, ultrasonic nanocrystal surface modification (UNSM) of 304 stainless steel welds was carried out. UNSM effectively eliminates the tensile stress generated during welding and imparts beneficial compressive residual stresses. In addition, UNSM can effectively refine the grains and increase hardness in the near-surface region. Corrosion tests in boiling MgCl2 solution demonstrate that UNSM can significantly improve the corrosion resistance due to the compressive residual stresses and changes in the near-surface microstructure.

  1. A model for investigating the influence of road surface texture and tyre tread pattern on rolling resistance

    Science.gov (United States)

    Hoever, Carsten; Kropp, Wolfgang

    2015-09-01

    The reduction of rolling resistance is essential for a more environmentally friendly road transportation sector. Both tyre and road design can be utilised to reduce rolling resistance. In both cases a reliable simulation tool is needed which is able to quantify the influence of design parameters on the rolling resistance of a tyre rolling on a specific road surface. In this work a previously developed tyre/road interaction model is extended to account for different tread patterns and for losses due to small-scale tread deformation. Calculated contact forces and tyre vibrations for tyre/road interaction under steady-state rolling are used to predict rolling losses in the tyre. Rolling resistance is calculated for a series of different tyre/road combinations. Results are compared with rolling resistance measurements. The agreement between simulations and measurements is generally very good. It is found that both the tyre structure and small-scale tread deformations contribute to the rolling losses. The small-scale contribution depends mainly on the road roughness profile. The mean profile depth of the road surface is identified to correlate very well with the rolling resistance. Additional calculations are performed for non-traditional rubberised road surfaces, however, with mixed results. This possibly indicates the existence of additional loss mechanisms for these surfaces.

  2. Fabrication of hydrophobic surface with hierarchical structure on Mg alloy and its corrosion resistance

    International Nuclear Information System (INIS)

    Wang Jun; Li Dandan; Liu Qi; Yin Xi; Zhang Ying; Jing Xiaoyan; Zhang Milin

    2010-01-01

    A hydrotalcite/hydromagnesite conversion coating with hierarchical structure has been fabricated on a Mg alloy substrate by in situ hydrothermal crystallization method. A MgO layer existing between the hydrotalcite/hydromagnesite film and the substrate was formed prior to the hydrotalcite/hydromagnesite film during the crystallization process. After surface treatment with silane coupling agent, the surface of conversion coating changes from hydrophilic to hydrophobic. Scanning electron microscopy (SEM) revealed that the silylated conversion coating with hierarchical structure maintains the original rough surface of which was composed of numerous micro-scale flakes and beautiful flower-like protrusions. Polarization measurements have shown that the hydrophobic conversion coating exhibited a low corrosion current density value of 0.432 μA/cm 2 , which means that the hydrophobic conversion coating can effectively protect Mg alloy from corrosion. Electrochemical impedance spectroscopy (EIS) showed that the impedance of the hydrophobic conversion coating was 9000 Ω. It means that the coating served as a passive layer with high charge transfer resistance.

  3. Resistance of bacterial biofilms formed on stainless steel surface to disinfecting agent.

    Science.gov (United States)

    Królasik, Joanna; Zakowska, Zofia; Krepska, Milena; Klimek, Leszek

    2010-01-01

    The natural ability of microorganisms for adhesion and biofilm formation on various surfaces is one of the factors causing the inefficiency of a disinfection agent, despite its proven activity in vitro. The aim of the study was to determine the effectiveness of disinfecting substances on bacterial biofilms formed on stainless steel surface. A universally applied disinfecting agent was used in the tests. Bacterial strains: Listeria innocua, Pseudomonas putida, Micrococcus luteus, Staphylococcus hominis strains, were isolated from food contact surfaces, after a cleaning and disinfection process. The disinfecting agent was a commercially available acid specimen based on hydrogen peroxide and peroxyacetic acid, the substance that was designed for food industry usage. Model tests were carried out on biofilm formed on stainless steel (type 304, no 4 finish). Biofilms were recorded by electron scanning microscope. The disinfecting agent in usable concentration, 0.5% and during 10 minutes was ineffective for biofilms. The reduction of cells in biofilms was only 1-2 logarithmic cycles. The use of the agent in higher concentration--1% for 30 minutes caused reduction of cell number by around 5 logarithmic cycles only in the case of one microorganism, M. luteus. For other types: L. innocua, P. putida, S. hominis, the requirements placed on disinfecting agents were not fulfilled. The results of experiments proved that bacterial biofilms are resistant to the disinfectant applied in its operational parameters. Disinfecting effectiveness was achieved after twofold increase of the agent's concentration.

  4. Methicillin-resistant Staphylococcus aureus isolates from surfaces and personnel at a hospital laundry facility.

    Science.gov (United States)

    Michael, K E; No, D; Roberts, M C

    2016-09-01

    Examine a clinical laundry facility for the presence of methicillin-resistant Staphylococcus aureus (MRSA) on environmental surfaces and among personnel. Nasal and face samples along with surface samples were collected four times in 2015. MRSA isolates were confirmed using standardized biochemical assays and molecular characterization. MRSA was identified in 33/120 (28%) samples from the dirty and 3/120 (3%) samples from the clean environmental areas. MRSA isolates included: (dirty) ST5 SCCmec type II, ST8 SCCmec type IV, ST231 SCCmec type II, ST239 SCCmec type III, ST239 SCCmec type IV, ST256 SCCmec type IV and (clean) ST5 SCCmec type II and ST8 SCCmec type IV. Five different employees were MRSA positive, 4/8 (50%) from the dirty: and 1/15 (6·7%) from the clean, but there was a 10-fold higher MRSA carriage 6/22 (27%) dirty vs 1/38 (2·6%) clean when all 50 human samples were combined. MRSA prevalence was significantly higher (28 vs 3%) in dirty vs clean areas within the laundry facility suggesting a greater risk for personnel on the dirty side. This is the first report of isolation and characterization of MRSA from surfaces and personnel from a clinical laundry facility. © 2016 The Society for Applied Microbiology.

  5. Facile and scalable preparation of highly wear-resistance superhydrophobic surface on wood substrates using silica nanoparticles modified by VTES

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Shanshan; Liu, Ming [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Wu, Yiqiang, E-mail: wuyq0506@126.com [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Hunan Provincial Collaborative Innovation Center for High-efficiency Utilization of Wood and Bamboo Resources, Central South University of Forestry and Technology, Changsha 410004 (China); Luo, Sha [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Qing, Yan, E-mail: qingyan0429@163.com [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Hunan Provincial Collaborative Innovation Center for High-efficiency Utilization of Wood and Bamboo Resources, Central South University of Forestry and Technology, Changsha 410004 (China); Chen, Haibo [College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China)

    2016-11-15

    Graphical abstract: Highly wear-resistance superhydrophobic surface on wood substrates was fabricated using silica nanoparticles modified by VTES. Display Omitted - Highlights: • Superhydrophobic surface on wood substrates was efficiently fabricated using nanoparticles modified by VTES. • The superhydrophobic surface exhibited a CA of 154° and a SAclose to 0°. • The superhydrophobic surface showed a durable and robust wear-resistance performance. - Abstract: In this study, an efficient, facile method has been developed for fabricating superhydrophobic surfaces on wood substrates using silica nanoparticles modified by VTES. The as-prepared superhydrophobic wood surface had a water contact angle of 154° and water slide angle close to 0°. Simultaneously, this superhydrophobic wood showed highly durable and robust wear resistance when having undergone a long period of sandpaper abrasion or being scratched by a knife. Even under extreme conditions of boiling water, the superhydrophobicity of the as-prepared wood composite was preserved. Characterizations by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy showed that a typical and tough hierarchical micro/nanostructure was created on the wood substrate and vinyltriethoxysilane contributed to preventing the agglomeration of silica nanoparticles and serving as low-surface-free-energy substances. This superhydrophobic wood was easy to fabricate, mechanically resistant and exhibited long-term stability. Therefore, it is considered to be of significant importance in the industrial production of functional wood, especially for outdoor applications.

  6. Families of null surfaces in the Minkowski tri dimensional space-time and its associated differential equations

    International Nuclear Information System (INIS)

    Silva O, G.; Garcia G, P.

    2004-01-01

    In this work we describe the procedure to obtain all the family of third order ordinary differential equations connected by a contact transformation such that in their spaces of solutions is defined a conformal three dimensional Minkowski metric. (Author)

  7. Implications of next generation attenuation ground motion prediction equations for site coefficients used in earthquake resistant design

    Science.gov (United States)

    Borcherdt, Roger D.

    2014-01-01

    Proposals are developed to update Tables 11.4-1 and 11.4-2 of Minimum Design Loads for Buildings and Other Structures published as American Society of Civil Engineers Structural Engineering Institute standard 7-10 (ASCE/SEI 7–10). The updates are mean next generation attenuation (NGA) site coefficients inferred directly from the four NGA ground motion prediction equations used to derive the maximum considered earthquake response maps adopted in ASCE/SEI 7–10. Proposals include the recommendation to use straight-line interpolation to infer site coefficients at intermediate values of (average shear velocity to 30-m depth). The NGA coefficients are shown to agree well with adopted site coefficients at low levels of input motion (0.1 g) and those observed from the Loma Prieta earthquake. For higher levels of input motion, the majority of the adopted values are within the 95% epistemic-uncertainty limits implied by the NGA estimates with the exceptions being the mid-period site coefficient, Fv, for site class D and the short-period coefficient, Fa, for site class C, both of which are slightly less than the corresponding 95% limit. The NGA data base shows that the median value  of 913 m/s for site class B is more typical than 760 m/s as a value to characterize firm to hard rock sites as the uniform ground condition for future maximum considered earthquake response ground motion estimates. Future updates of NGA ground motion prediction equations can be incorporated easily into future adjustments of adopted site coefficients using procedures presented herein. 

  8. Identification of a time-varying point source in a system of two coupled linear diffusion-advection- reaction equations: application to surface water pollution

    International Nuclear Information System (INIS)

    Hamdi, Adel

    2009-01-01

    This paper deals with the identification of a point source (localization of its position and recovering the history of its time-varying intensity function) that constitutes the right-hand side of the first equation in a system of two coupled 1D linear transport equations. Assuming that the source intensity function vanishes before reaching the final control time, we prove the identifiability of the sought point source from recording the state relative to the second coupled transport equation at two observation points framing the source region. Note that at least one of the two observation points should be strategic. We establish an identification method that uses these records to identify the source position as the root of a continuous and strictly monotonic function. Whereas the source intensity function is recovered using a recursive formula without any need of an iterative process. Some numerical experiments on a variant of the surface water pollution BOD–OD coupled model are presented

  9. Diversity and antimicrobial resistance of Salmonella enterica isolates from surface water in Southeastern United States.

    Science.gov (United States)

    Li, Baoguang; Vellidis, George; Liu, Huanli; Jay-Russell, Michele; Zhao, Shaohua; Hu, Zonglin; Wright, Anita; Elkins, Christopher A

    2014-10-01

    A study of prevalence, diversity, and antimicrobial resistance of Salmonella enterica in surface water in the southeastern United States was conducted. A new scheme was developed for recovery of Salmonella from irrigation pond water and compared with the FDA's Bacteriological Analytical Manual (8th ed., 2014) (BAM) method. Fifty-one isolates were recovered from 10 irrigation ponds in produce farms over a 2-year period; nine Salmonella serovars were identified by pulsed-field gel electrophoresis analysis, and the major serovar was Salmonella enterica serovar Newport (S. Newport, n = 29), followed by S. enterica serovar Enteritidis (n = 6), S. enterica serovar Muenchen (n = 4), S. enterica serovar Javiana (n = 3), S. enterica serovar Thompson (n = 2), and other serovars. It is noteworthy that the PulseNet patterns of some of the isolates were identical to those of the strains that were associated with the S. Thompson outbreaks in 2010, 2012, and 2013, S. Enteritidis outbreaks in 2011 and 2013, and an S. Javiana outbreak in 2012. Antimicrobial susceptibility testing confirmed 16 S. Newport isolates of the multidrug resistant-AmpC (MDR-AmpC) phenotype, which exhibited resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline (ACSSuT), and to the 1st, 2nd, and 3rd generations of cephalosporins (cephalothin, amoxicillin-clavulanic acid, and ceftriaxone). Moreover, the S. Newport MDR-AmpC isolates had a PFGE pattern indistinguishable from the patterns of the isolates from clinical settings. These findings suggest that the irrigation water may be a potential source of contamination of Salmonella in fresh produce. The new Salmonella isolation scheme significantly increased recovery efficiency from 21.2 (36/170) to 29.4% (50/170) (P = 0.0002) and streamlined the turnaround time from 5 to 9 days with the BAM method to 4 days and thus may facilitate microbiological analysis of environmental water. Copyright © 2014, American Society for

  10. Study of surface properties of ATLAS12 strip sensors and their radiation resistance

    Science.gov (United States)

    Mikestikova, M.; Allport, P. P.; Baca, M.; Broughton, J.; Chisholm, A.; Nikolopoulos, K.; Pyatt, S.; Thomas, J. P.; Wilson, J. A.; Kierstead, J.; Kuczewski, P.; Lynn, D.; Hommels, L. B. A.; Ullan, M.; Bloch, I.; Gregor, I. M.; Tackmann, K.; Hauser, M.; Jakobs, K.; Kuehn, S.; Mahboubi, K.; Mori, R.; Parzefall, U.; Clark, A.; Ferrere, D.; Sevilla, S. Gonzalez; Ashby, J.; Blue, A.; Bates, R.; Buttar, C.; Doherty, F.; McMullen, T.; McEwan, F.; O'Shea, V.; Kamada, S.; Yamamura, K.; Ikegami, Y.; Nakamura, K.; Takubo, Y.; Unno, Y.; Takashima, R.; Chilingarov, A.; Fox, H.; Affolder, A. A.; Casse, G.; Dervan, P.; Forshaw, D.; Greenall, A.; Wonsak, S.; Wormald, M.; Cindro, V.; Kramberger, G.; Mandić, I.; Mikuž, M.; Gorelov, I.; Hoeferkamp, M.; Palni, P.; Seidel, S.; Taylor, A.; Toms, K.; Wang, R.; Hessey, N. P.; Valencic, N.; Hanagaki, K.; Dolezal, Z.; Kodys, P.; Bohm, J.; Stastny, J.; Bevan, A.; Beck, G.; Milke, C.; Domingo, M.; Fadeyev, V.; Galloway, Z.; Hibbard-Lubow, D.; Liang, Z.; Sadrozinski, H. F.-W.; Seiden, A.; To, K.; French, R.; Hodgson, P.; Marin-Reyes, H.; Parker, K.; Jinnouchi, O.; Hara, K.; Sato, K.; Hagihara, M.; Iwabuchi, S.; Bernabeu, J.; Civera, J. V.; Garcia, C.; Lacasta, C.; Marti i Garcia, S.; Rodriguez, D.; Santoyo, D.; Solaz, C.; Soldevila, U.

    2016-09-01

    A radiation hard n+-in-p micro-strip sensor for the use in the Upgrade of the strip tracker of the ATLAS experiment at the High Luminosity Large Hadron Collider (HL-LHC) has been developed by the "ATLAS ITk Strip Sensor collaboration" and produced by Hamamatsu Photonics. Surface properties of different types of end-cap and barrel miniature sensors of the latest sensor design ATLAS12 have been studied before and after irradiation. The tested barrel sensors vary in "punch-through protection" (PTP) structure, and the end-cap sensors, whose stereo-strips differ in fan geometry, in strip pitch and in edge strip ganging options. Sensors have been irradiated with proton fluences of up to 1×1016 neq/cm2, by reactor neutron fluence of 1×1015 neq/cm2 and by gamma rays from 60Co up to dose of 1 MGy. The main goal of the present study is to characterize the leakage current for micro-discharge breakdown voltage estimation, the inter-strip resistance and capacitance, the bias resistance and the effectiveness of PTP structures as a function of bias voltage and fluence. It has been verified that the ATLAS12 sensors have high breakdown voltage well above the operational voltage which implies that different geometries of sensors do not influence their stability. The inter-strip isolation is a strong function of irradiation fluence, however the sensor performance is acceptable in the expected range for HL-LHC. New gated PTP structure exhibits low PTP onset voltage and sharp cut-off of effective resistance even at the highest tested radiation fluence. The inter-strip capacitance complies with the technical specification required before irradiation and no radiation-induced degradation was observed. A summary of ATLAS12 sensors tests is presented including a comparison of results from different irradiation sites. The measured characteristics are compared with the previous prototype of the sensor design, ATLAS07.

  11. Observation of Stable Low Surface Resistance in Large-Grain Niobium SRF Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Rongli [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Huang, Shichun [Institute of Modern Physics (IMP)/Chinese Academy of Sciences (CAS), Lanzhou (China)

    2016-05-01

    Low surface resistance, or high unloaded quality factor (Q0), superconducting radio frequency (SRF) cavities are being pursued actively nowadays as their application in large-scale CW SRF accelerators can save capital and operational cost in cryogenics. There are different options in realization of such cavities. One of them is the large-grain (LG) niobium cavity. In this contribution, we present new experimental results in evaluation of LG niobium cavities cooled down in the presence of an external magnetic field. High Q0 values are achieved even with an ambient magnetic field of up to 100 mG. More over, it is observed that these high Q0 values are super-robust against repeated quench, literally not affected at all after the cavity being deliberately quenched for hundreds of times in the presence of an ambient magnetic field of up to 200 mG.

  12. Wear Resistance of Steel 20MnCr5 After Surfacing with Micro-jet Cooling

    Directory of Open Access Journals (Sweden)

    Tarasiuk W.

    2016-09-01

    Full Text Available This paper presents results of experimental research concerning the impact of an innovative method of micro-jet cooling on the padding weld performed with MIG welding. Micro-jet cooling is a novel method patented in 2011. It enables to steer the parameters of weld cooling in a precise manner. In addition, various elements which may e.g. enhance hardness or alter tribological properties can be entered into its top surface, depending on the applied cooling gas. The material under study was steel 20MnCr5, which was subject to the welding process with micro-jet cooling and without cooling. Nitrogen was used as a cooling gas. The main parameter of weld assessment was wear intensity. The tests were conducted in a tribological pin-on-disc type position. The following results exhibit growth at approximately 5% in wear resistance of padding welds with micro-jet cooling.

  13. Analysis Of Post-Wet-Chemistry Heat Treatment Effects On Nb SRF Surface Resistance

    International Nuclear Information System (INIS)

    Dhakal, Pashupati; Ciovati, Gianluigi; Kneisel, Peter K.; Myneni, Ganapati Rao

    2014-01-01

    Most of the current research in superconducting radio frequency (SRF) cavities is focused on ways to reduce the construction and operating cost of SRF-based accelerators as well as on the development of new or improved cavity processing techniques. The increase in quality factors is the result of the reduction of the surface resistance of the materials. A recent test on a 1.5 GHz single cell cavity made from ingot niobium of medium purity and heat treated at 1400 °C in a ultra-high vacuum induction furnace resulted in a residual resistance of ∼ 1nΩ and a quality factor at 2.0 K increasing with field up to ∼ 5A-10 10 at a peak magnetic field of 90 mT. In this contribution, we present some results on the investigation of the origin of the extended Q 0 -increase, obtained by multiple HF rinses, oxypolishing and heat treatment of A ''all NbA'' cavities

  14. Analysis of the surface resistance of the superconducting accelerating cavities of the S-DALINAC

    Energy Technology Data Exchange (ETDEWEB)

    Brunken, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, Darmstadt D-64289 (Germany); Gopych, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, Darmstadt D-64289 (Germany); Graef, H.-D. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, Darmstadt D-64289 (Germany); Laier, U. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, Darmstadt D-64289 (Germany)]. E-mail: U.Laier@gsi.de; Mueller, W. [Institut fuer Theorie Elektromagnetischer Felder, Technische Universitaet Darmstadt, Schlossgartenstrasse 8, Darmstadt D-64289 (Germany); Platz, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, Darmstadt D-64289 (Germany); Richter, A. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, Darmstadt D-64289 (Germany); Watzlawik, S. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, Darmstadt D-64289 (Germany); Weiland, T. [Institut fuer Theorie Elektromagnetischer Felder, Technische Universitaet Darmstadt, Schlossgartenstrasse 8, Darmstadt D-64289 (Germany)

    2006-08-01

    The quality factors of the 20 cell, 3GHz niobium cavities of the S-DALINAC are smaller by almost a factor of three compared to their design value. Combined with the limited cryogenic power of the helium refrigerator in use, this restricts the maximum electron energy of the S-DALINAC in continuous wave operation. Extensive studies to elaborate the origin of this degradation are presented. A 120{sup -}bar C baking combined with appropriate diagnostic tools for an attempt to improve the Q values has been applied to nine of the 11 cavities. The impact of this treatment on the BCS and residual resistance was evaluated and both were improved. Additionally, quality factor measurements of all modes of the TM{sub 010} passband allowed to derive a spatial distribution of the mean surface resistance. The RF losses in the end cells are systematically higher compared to the inner cells. The studies presented in this article allowed to develop a model describing the Q degradation of the resonators and thereby identifying possible prospects to cure this limitation.

  15. Improving degradation resistance of sisal fiber in concrete through fiber surface treatment

    Science.gov (United States)

    Wei, Jianqiang; Meyer, Christian

    2014-01-01

    As part of an ongoing effort to improve the sustainability of reinforced concrete, recycled concrete aggregate is being considered together with natural fibers such as sisal fiber as replacement of synthetic reinforcement. Since natural fibers are known to undergo potential deterioration in the alkaline cement matrix especially in outdoor erosive environment, they need to be treated to improve their durability. This paper describes two such methods (thermal and Na2CO3 treatment) and evaluates their effects on the degradation resistance of sisal fiber and durability of sisal fiber-reinforced concrete with recycled concrete aggregate. Concrete specimens were subjected to cycles of wetting and drying to accelerate aging. The microstructure, tensile strength and Young's modulus of sisal fiber as well as the weight loss of the composite were evaluated. Of primary interest were the effects on compressive and splitting tensile strength of sisal fiber-reinforced concrete. Thermal treatment and Na2CO3 surface treatment were shown to improve the durability of the composite as measured by splitting tensile strength by 36.5% and 46.2% and the compressive strength by 31.1% and 45.4%, respectively. The mechanisms of these two treatment methods were also analyzed. The thermal treatment achieved improvement of cellulose's crystallization, which ensured the initial strength and improved durability of sisal fiber. A layer consisting of calcium carbonate sediments, which protects the internals of a fiber from the strong alkali solution formed in the cement hydration process, was formed and filled in pits and cavities on the Na2CO3 treated sisal fiber's surface to improve their corrosion resistance and durability and reduced the detrimental effects of Na+ ions on concrete.

  16. EFFECT OF SURFACE SEALING ON STAIN RESISTANCE OF A NANO-HYBRID RESIN COMPOSITE*

    Directory of Open Access Journals (Sweden)

    Günçe SAYGI

    2015-04-01

    Full Text Available Purpose: This study investigated the influence of sealant application on stain resistance of a nanohybrid resin composite compared to the efficacy of a bonding agent used as a surface sealant on prolonging color stability of the resin composite. Materials and Methods: 28 disc-shaped materials were prepared from a nano-hybrid resin composite Filtek Z550 and assigned to four groups: G1K: nonsealed; G2:Adper Single Bond; G3: Fortify ; G4: Biscover LV. After 24 h storage in distilled water at 37˚C, all specimens were subjected to thermocycling and immersed into coffee solution. Color measurements were performed using spectrophotometer (VITA Easyshade; Vident according to CIEL*a*b* system. Results: Color change values were significantly different among the groups in each evaluation period except for after thermocycling (p<0.05. For 7 days evaluation period, the difference between G3 and G4 group was statistically significant while G4 exhibited statistically significant differences (p<0.05 and p<0.0001 respectively compared to control (G1 in 14 day whereas no significant difference was found between GI and GII in 28-day evaluation period. However, ΔE values of sealed specimens (GIII, GIV differed significantly from non-sealed (GI specimens after 28 days of immersion in coffee solution (p<0.05 and p<0.0001 respectively. Conclusion: It may be concluded that using a bonding agent as a surface sealant does not increase stain resistance of resin composites of the sealants evaluated. Biscover LV showed the highest efficacy to prolong color stability of the resin composite.

  17. Evaluation of different methods to recover methicillin-resistant Staphylococcus aureus from hospital environmental surfaces.

    LENUS (Irish Health Repository)

    Dolan, A

    2011-11-01

    The environment is implicated as a source of healthcare-associated infections (HAIs) and there is a need for evidence-based approaches to environmental sampling to assess cleanliness and improve infection prevention and control. We assessed, in vitro, different approaches to sampling the environment for meticillin-resistant Staphylococcus aureus (MRSA). In a laboratory-based investigation, the recovery of MRSA from two common hospital environments using six different sampling methods was evaluated, with a wild-type strain of MRSA. A 100 cm(2) section of mattress and a laboratory bench surface were contaminated with known inocula of MRSA. Bacteria were recovered by sampling at 30 min after inoculation, using either saline-moistened cotton swabs, neutralising buffer swabs, eSwabs or macrofoam swabs, which were all enriched in tryptone soya broth, or by sampling with direct contact plates or chromogenic \\'sweep\\' plates. The sensitivity (i.e. the minimum number of bacteria inoculated on to a surface which subsequently produced a positive result) of each method was determined for each surface. The most sensitive methods were eSwabs and macrofoam swabs, requiring 6.1 × 10(-1) and 3.9 × 10(-1) MRSA\\/cm(2), respectively, to produce a positive result from the bench surface. The least sensitive swabbing method was saline-moistened cotton swabs, requiring 1.1 × 10(3) MRSA\\/cm(2) of mattress. The recovery of bacteria from environmental samples varies with the swabs and methodology used and negative culture results do not exclude a pathogen-free environment. Greater standardisation is required to facilitate the assessment of cleanliness of healthcare environments.

  18. Air and surface contamination patterns of meticillin-resistant Staphylococcus aureus on eight acute hospital wards.

    Science.gov (United States)

    Creamer, E; Shore, A C; Deasy, E C; Galvin, S; Dolan, A; Walley, N; McHugh, S; Fitzgerald-Hughes, D; Sullivan, D J; Cunney, R; Coleman, D C; Humphreys, H

    2014-03-01

    Meticillin-resistant Staphylococcus aureus (MRSA) can be recovered from hospital air and from environmental surfaces. This poses a potential risk of transmission to patients. To investigate associations between MRSA isolates recovered from air and environmental surfaces with those from patients when undertaking extensive patient and environmental sampling. This was a prospective observational study of patients and their environment in eight wards of a 700-bed tertiary care hospital during 2010 and 2011. Sampling of patients, air and surfaces was carried out on all ward bays, with more extended environmental sampling in ward high-dependency bays and at particular times of the day. The genetic relatedness of isolates was determined by DNA microarray profiling and spa typing. MRSA was recovered from 30/706 (4.3%) patients and from 19/132 (14.4%) air samples. On 9/132 (6.8%) occasions both patient and air samples yielded MRSA. In 32 high-dependency bays, MRSA was recovered from 12/161 (7.4%) patients, 8/32 (25%) air samples, and 21/644 (3.3%) environmental surface samples. On 10/132 (7.6%) occasions, MRSA was isolated from air in the absence of MRSA-positive patients. Patient demographic data combined with spa typing and DNA microarray profiling revealed four likely transmission clusters, where patient and environmental isolates were deemed to be very closely related. Air sampling yielded MRSA on frequent occasions, especially in high-dependency bays. Environmental and air sampling combined with patient demographic data, spa typing and DNA microarray profiling indicated the presence of clusters that were not otherwise apparent. Copyright © 2014 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  19. Efficient three-dimensional resist profile-driven source mask optimization optical proximity correction based on Abbe-principal component analysis and Sylvester equation

    Science.gov (United States)

    Lin, Pei-Chun; Yu, Chun-Chang; Chen, Charlie Chung-Ping

    2015-01-01

    As one of the critical stages of a very large scale integration fabrication process, postexposure bake (PEB) plays a crucial role in determining the final three-dimensional (3-D) profiles and lessening the standing wave effects. However, the full 3-D chemically amplified resist simulation is not widely adopted during the postlayout optimization due to the long run-time and huge memory usage. An efficient simulation method is proposed to simulate the PEB while considering standing wave effects and resolution enhancement techniques, such as source mask optimization and subresolution assist features based on the Sylvester equation and Abbe-principal component analysis method. Simulation results show that our algorithm is 20× faster than the conventional Gaussian convolution method.

  20. Antibiotic resistance patterns of Escherichia coli strains isolated from surface water and groundwater samples in a pig production area

    OpenAIRE

    Roger Neto Schneider; André Nadvorny; Verônica Schmidt

    2009-01-01

    The use of antibiotics, so excessive and indiscriminate in intensive animal production, has triggered an increase in the number of resistant microorganisms which can be transported to aquatic environments. The aim of this study was to determine the profile of the antimicrobial resistance of samples of Escherichia coli isolated from groundwater and surface water in a region of pig breeding. Through the test of antimicrobial susceptibility, we analyzed 205 strains of E. coli. A high rate of res...

  1. Resistivity of thin gold films on mica induced by electron-surface scattering: Application of quantitative scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Robles, Marcelo E.; Gonzalez-Fuentes, Claudio A.; Henriquez, Ricardo; Kremer, German; Moraga, Luis; Oyarzun, Simón; Suarez, Marco Antonio; Flores, Marcos; Munoz, Raul C.

    2012-01-01

    We report a comparison between the resistivity measured on thin gold films deposited on mica, with predictions based upon classical theories of size effects (Drude's, Sondheimer's and Calecki's), as well as predictions based upon quantum theories of electron-surface scattering (the modified theory of Sheng, Xing and Wang, the theory of Tesanovic, Jaric and Maekawa, and that of Trivedi and Aschroft). From topographic images of the surface recorded with a Scanning Tunneling Microscope, we determined the rms roughness amplitude, δ and the lateral correlation length, ξ corresponding to a Gaussian representation of the average height-height autocorrelation function, describing the roughness of each sample in the scale of length set by the Fermi wave length. Using (δ, ξ) as input data, we present a rigorous comparison between resistivity data and predictions based upon the theory of Calecki as well as quantum theoretical predictions without adjustable parameters. The resistivity was measured on gold films of different thickness evaporated onto mica substrates, between 4 K and 300 K. The resistivity data covers the range 0.1 < x(T) < 6.8, for 4 K < T < 300 K, where x(T) is the ratio between film thickness and electron mean free path in the bulk at temperature T. We experimentally identify electron-surface and electron-phonon scattering as the microscopic electron scattering mechanisms giving rise to the macroscopic resistivity. The different theories are all capable of estimating the thin film resistivity to an accuracy better than 10%; however the mean free path and the resistivity characterizing the bulk turn out to depend on film thickness. Surprisingly, only the Sondheimer theory and its quantum version, the modified theory of Sheng, Xing and Wang, predict and increase in resistivity induced by size effects that seems consistent with published galvanomagnetic phenomena also arising from electron-surface scattering measured at low temperatures.

  2. Cavitation erosion resistance of AISI 316L stainless steel laser surface-modified with NiTi

    International Nuclear Information System (INIS)

    Chiu, K.Y.; Cheng, F.T.; Man, H.C.

    2005-01-01

    The present study is part of a project on the surface modification of AISI 316 stainless steel using various forms of NiTi for enhancing cavitation erosion resistance. In this study, NiTi powder was preplaced on the AISI 316L substrate and melted with a high-power CW Nd:YAG laser. With appropriate laser processing parameters, an alloyed layer of a few hundred micrometers thick was formed and fusion bonded to the substrate without the formation of a brittle interface. EDS analysis showed that the layer contained Fe as the major constituent element while the XRD patterns of the surface showed an austenitic structure, similar to that of 316 stainless steel. The cavitation erosion resistance of the modified layer (316-NiTi-Laser) could reach about 29 times that of AISI 316L stainless steel. The improvement could be attributed to a much higher surface hardness and elasticity as revealed by instrumented nanoindentation tests. Among various types of samples, the cavitation erosion resistance was ranked in descending order as: NiTi plate > 316-NiTi-Laser > 316-NiTi-TIG > AISI 316L, where 316-NiTi-TIG stands for samples surfaced with the tungsten inert gas (TIG) process using NiTi wire. Though the laser-surfaced samples and the TIG-surfaced samples had similar indentation properties, the former exhibited a higher erosion resistance mainly because of a more homogeneous alloyed layer with much less defects. In both the laser-surfaced and TIG-surfaced samples, the superelastic behavior typical of austenitic NiTi was only partially retained and the superior cavitation erosion resistance was thus still not fully attained

  3. A material based approach to creating wear resistant surfaces for hot forging

    Science.gov (United States)

    Babu, Sailesh

    Tools and dies used in metal forming are characterized by extremely high temperatures at the interface, high local pressures and large metal to metal sliding. These harsh conditions result in accelerated wear of tooling. Lubrication of tools, done to improve metal flow drastically quenches the surface layers of the tools and compounds the tool failure problem. This phenomenon becomes a serious issue when parts forged at complex and are expected to meet tight tolerances. Unpredictable and hence uncontrolled wear and degradation of tooling result in poor part quality and premature tool failure that result in high scrap, shop downtime, poor efficiency and high cost. The objective of this dissertation is to develop a computer-based methodology for analyzing the requirements hot forging tooling to resist wear and plastic deformation and wear and predicting life cycle of forge tooling. Development of such is a system is complicated by the fact that wear and degradation of tooling is influenced by not only the die material used but also numerous process controls like lubricant, dilution ratio, forging temperature, equipment used, tool geometries among others. Phenomenological models available u1 the literature give us a good thumb rule to selecting materials but do not provide a way to evaluate pits performance in field. Once a material is chosen, there are no proven approaches to create surfaces out of these materials. Coating approaches like PVD and CVD cannot generate thick coatings necessary to withstand the conditions under hot forging. Welding cannot generate complex surfaces without several secondary operations like heat treating and machining. If careful procedures are not followed, welds crack and seldom survive forging loads. There is a strong need for an approach to selectively, reliably and precisely deposit material of choice reliably on an existing surface which exhibit not only good tribological properties but also good adhesion to the substrate

  4. Evaluation of effect of surface treatment on corrosion resistance of Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Martins, Emerson Alves

    2009-01-01

    Nd-Fe-B magnets produced by powder metallurgy are highly susceptible to corrosion due to their complex microstructure and intrinsic porosity due to their fabrication process. Moreover, these magnets have excellent magnetic properties and find many applications. In the nuclear area, permanent magnets based on rare earth transition-iron-boron (Ne-Fe-B) are used in the manufacture of magnetic media (magnetic levitation) for ultra-centrifuges used for isotopic enrichment of uranium employed in nuclear reactors. In dentistry these types of magnets are used to fix total and partial prostheses on implants; in orthodontics to correct dental malocclusion and make moves; in buco-maxillo-facial surgery for setting facial prostheses of large defects of the face. In electronic equipment, they are used in scales, locks, electric motors and particularly in the manufacturing of hard drives of computers. The objective of this study is to evaluate the corrosion resistance of the magnet tested and surface treatments that could replace chromating that generates toxic residues and present high cost of processing waste with treatments that are environmentally friendly. The evaluation of the corrosion resistance was carried out through the analysis potentiodynamic polarization curves, electrochemical impedance spectroscopy, monitoring of corrosion potential as a function of test time and scanning electron microscopy to try to correlate the magnet microstructure with its corrosion resistance. The results show that these magnets are highly susceptible to corrosion that occurs preferentially in the Nd-rich phase, located in the boundaries of the magnetic matrix phase (ψ). Treatment with silane, cerium, sam, Cr 6 + , tricationic phosphate followed by bath of chromium trioxide and in NaH 2 PO 4 solution for 24 hours followed by bath of zinc sulphate did not improve the corrosion resistance of the magnet. Among the treatments used, immersion in NaH 2 PO 4 solution for 24 hours pH=3.8 was the

  5. Abrasion Resistance of Nano Silica Modified Roller Compacted Rubbercrete: Cantabro Loss Method and Response Surface Methodology Approach

    Science.gov (United States)

    Adamu, Musa; Mohammed, Bashar S.; Shafiq, Nasir

    2018-04-01

    Roller compacted concrete (RCC) when used for pavement is subjected to skidding/rubbing by wheels of moving vehicles, this causes pavement surface to wear out and abrade. Therefore, abrasion resistance is one of the most important properties of concern for RCC pavement. In this study, response surface methodology was used to design, evaluate and analyze the effect of partial replacement of fine aggregate with crumb rubber, and addition of nano silica on the abrasion resistance of roller compacted rubbercrete (RCR). RCR is the terminology used for RCC pavement where crumb rubber was used as partial replacement to fine aggregate. The Box-Behnken design method was used to develop the mixtures combinations using 10%, 20%, and 30% crumb rubber with 0%, 1%, and 2% nano silica. The Cantabro loss method was used to measure the abrasion resistance. The results showed that the abrasion resistance of RCR decreases with increase in crumb rubber content, and increases with increase in addition of nano silica. The analysis of variance shows that the model developed using response surface methodology (RSM) has a very good degree of correlation, and can be used to predict the abrasion resistance of RCR with a percentage error of 5.44%. The combination of 10.76% crumb rubber and 1.59% nano silica yielded the best combinations of RCR in terms of abrasion resistance of RCR.

  6. Effect of surface treatment on the interfacial contact resistance and corrosion resistance of Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Yang, Meijun; Zhang, Dongming

    2014-01-01

    The bipolar plate is an important component of the PEMFC (polymer electrolyte membrane fuel cell) because it supplies the pathway of electron flow between each unit cell. Fe–Ni–Cr alloy is considered as a good candidate material for bipolar plate, but it is limited to use as a bipolar plate due to its high ICR (interfacial contact resistance) and corrosion problem. In order to explore a cost-effective method on surface modification, various chemical and electrochemical treatments are performed on Fe–Ni–Cr alloy to acquire the effect of the surface modification on the ICR and corrosion behavior. The ICR and corrosion resistance of Fe–Ni–Cr alloy can be effectively controlled by the chemical treatment of immersion in the mixed acid solution with 10 vol% HNO 3 , 2 vol% HCl and 1 vol% HF for 10 min at 65 °C and then was placed in 30 vol% HNO 3 solution for 5 min. The chemical treatment is more effective on reducing ICR and improving corrosion resistance than that of electrochemical methods (be carried out in the 2 mol/L H 2 SO 4 solution with the electrical potential from −0.4 V to 0.6 V) for Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells. - Highlights: • The procedure of the surface treatments on Fe–Ni–Cr alloy as bipolar plate was described in detail. • Effects of various surface treatments on the interfacial contact resistivity and corrosion behavior were discussed. • The mechanism of the surface modification was particularly analyzed

  7. Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell

    Directory of Open Access Journals (Sweden)

    Akira Kitamura

    2008-10-01

    Full Text Available Tributyltin (TBT released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (109.3 ± 0.2 colony-forming units mL-1 adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 108.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 106.8 TBT molecules is adsorbed by a single cell.

  8. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi.

    Science.gov (United States)

    Lando, Gabriela Albara; Marconatto, Letícia; Kessler, Felipe; Lopes, William; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

    2017-07-18

    Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU) are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae , when the films were pre-treated with Ultraviolet (UV) irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), scanning electron microscopy (SEM), and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  9. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

    Directory of Open Access Journals (Sweden)

    Gabriela Albara Lando

    2017-07-01

    Full Text Available Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR, scanning electron microscopy (SEM, and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  10. Using an equation based on flow stress to estimate structural integrity of annealed Type 304 stainless steel plate and pipes containing surface defects

    International Nuclear Information System (INIS)

    Reuter, W.G.; Place, T.A.

    1981-01-01

    An accurate assessment of the influence of defects on structural component integrity is needed. Generally accepted analytical techniques are not available for the very ductile materials used in many nuclear reactor components. Some results are presented from a test programme to obtain data by which to evaluate proposed models. Plate and pipe specimens containing surface flaws were fabricated from annealed Type 304 stainless steel and tested at room temperature. An evaluation of an empirical equation based on flow stress is presented. In essentially all instances the flow stress is not a constant but varies as a function of the size of the surface flaw. (author)

  11. Correlation between morphology, electron band structure, and resistivity of Pb atomic chains on the Si(5 5 3)-Au surface

    International Nuclear Information System (INIS)

    Jałochowski, M; Kwapiński, T; Łukasik, P; Nita, P; Kopciuszyński, M

    2016-01-01

    Structural and electron transport properties of multiple Pb atomic chains fabricated on the Si(5 5 3)-Au surface are investigated using scanning tunneling spectroscopy, reflection high electron energy diffraction, angular resolved photoemission electron spectroscopy and in situ electrical resistance. The study shows that Pb atomic chains growth modulates the electron band structure of pristine Si(5 5 3)-Au surface and hence changes its sheet resistivity. Strong correlation between chains morphology, electron band structure and electron transport properties is found. To explain experimental findings a theoretical tight-binding model of multiple atomic chains interacting on effective substrate is proposed. (paper)

  12. Fabrication of wear-resistant silicon microprobe tips for high-speed surface roughness scanning devices

    Science.gov (United States)

    Wasisto, Hutomo Suryo; Yu, Feng; Doering, Lutz; Völlmeke, Stefan; Brand, Uwe; Bakin, Andrey; Waag, Andreas; Peiner, Erwin

    2015-05-01

    Silicon microprobe tips are fabricated and integrated with piezoresistive cantilever sensors for high-speed surface roughness scanning systems. The fabrication steps of the high-aspect-ratio silicon microprobe tips were started with photolithography and wet etching of potassium hydroxide (KOH) resulting in crystal-dependent micropyramids. Subsequently, thin conformal wear-resistant layer coating of aluminum oxide (Al2O3) was demonstrated on the backside of the piezoresistive cantilever free end using atomic layer deposition (ALD) method in a binary reaction sequence with a low thermal process and precursors of trimethyl aluminum and water. The deposited Al2O3 layer had a thickness of 14 nm. The captured atomic force microscopy (AFM) image exhibits a root mean square deviation of 0.65 nm confirming the deposited Al2O3 surface quality. Furthermore, vacuum-evaporated 30-nm/200-nm-thick Au/Cr layers were patterned by lift-off and served as an etch mask for Al2O3 wet etching and in ICP cryogenic dry etching. By using SF6/O2 plasma during inductively coupled plasma (ICP) cryogenic dry etching, micropillar tips were obtained. From the preliminary friction and wear data, the developed silicon cantilever sensor has been successfully used in 100 fast measurements of 5- mm-long standard artifact surface with a speed of 15 mm/s and forces of 60-100 μN. Moreover, the results yielded by the fabricated silicon cantilever sensor are in very good agreement with those of calibrated profilometer. These tactile sensors are targeted for use in high-aspect-ratio microform metrology.

  13. Development of Advanced Wear and Corrosion Resistant Systems Through Laser Surface Alloying and Materials Simulations

    Energy Technology Data Exchange (ETDEWEB)

    R. P. Martukanitz and S. Babu

    2007-05-03

    Laser surfacing in the form of cladding, alloying, and modifications are gaining widespread use because of its ability to provide high deposition rates, low thermal distortion, and refined microstructure due to high solidification rates. Because of these advantages, laser surface alloying is considered a prime candidate for producing ultra-hard coatings through the establishment or in situ formation of composite structures. Therefore, a program was conducted by the Applied Research Laboratory, Pennsylvania State University and Oak Ridge National Laboratory to develop the scientific and engineering basis for performing laser-based surface modifications involving the addition of hard particles, such as carbides, borides, and nitrides, within a metallic matrix for improved wear, fatigue, creep, and corrosion resistance. This has involved the development of advanced laser processing and simulation techniques, along with the refinement and application of these techniques for predicting and selecting materials and processing parameters for the creation of new surfaces having improved properties over current coating technologies. This program has also resulted in the formulation of process and material simulation tools capable of examining the potential for the formation and retention of composite coatings and deposits produced using laser processing techniques, as well as positive laboratory demonstrations in producing these coatings. In conjunction with the process simulation techniques, the application of computational thermodynamic and kinetic models to design laser surface alloying materials was demonstrated and resulted in a vast improvement in the formulation of materials used for producing composite coatings. The methodology was used to identify materials and to selectively modify microstructures for increasing hardness of deposits produced by the laser surface alloying process. Computational thermodynamic calculations indicated that it was possible to induce the

  14. Ray-tracing traveltime tomography versus wave-equation traveltime inversion for near-surface seismic land data

    KAUST Repository

    Fu, Lei; Hanafy, Sherif M.

    2017-01-01

    . This initial starting model can be obtained by inverting traveltimes with ray-tracing traveltime tomography (RT) or wave-equation traveltime (WT) inversion. We have found that WT can provide a more accurate tomogram than RT by inverting the first

  15. Solid oxide fuel cell cathode infiltrate particle size control and oxygen surface exchange resistance determination

    Science.gov (United States)

    Burye, Theodore E.

    Over the past decade, nano-sized Mixed Ionic Electronic Conducting (MIEC) -- micro-sized Ionic Conducting (IC) composite cathodes produced by the infiltration method have received much attention in the literature due to their low polarization resistance (RP) at intermediate (500-700°C) operating temperatures. Small infiltrated MIEC oxide nano-particle size and low intrinsic MIEC oxygen surface exchange resistance (Rs) have been two critical factors allowing these Nano-Micro-Composite Cathodes (NMCCs) to achieve high performance and/or low temperature operation. Unfortunately, previous studies have not found a reliable method to control or reduce infiltrated nano-particle size. In addition, controversy exists on the best MIEC infiltrate composition because: 1) Rs measurements on infiltrated MIEC particles are presently unavailable in the literature, and 2) bulk and thin film Rs measurements on nominally identical MIEC compositions often vary by up to 3 orders of magnitude. Here, two processing techniques, precursor nitrate solution desiccation and ceria oxide pre-infiltration, were developed to systematically produce a reduction in the average La0.6Sr0.4Co0.8Fe 0.2O3-delta (LSCF) infiltrated nano-particle size from 50 nm to 22 nm. This particle size reduction reduced the SOFC operating temperature, (defined as the temperature where RP=0.1 Ocm 2) from 650°C to 540°C. In addition, Rs values for infiltrated MIEC particles were determined for the first time through finite element modeling calculations on 3D Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) reconstructions of electrochemically characterized infiltrated electrodes.

  16. Multidrug-Resistant and Extended Spectrum Beta-Lactamase-Producing Escherichia coli in Dutch Surface Water and Wastewater.

    Directory of Open Access Journals (Sweden)

    Hetty Blaak

    Full Text Available The goal of the current study was to gain insight into the prevalence and concentrations of antimicrobial resistant (AMR Escherichia coli in Dutch surface water, and to explore the role of wastewater as AMR contamination source.The prevalence of AMR E. coli was determined in 113 surface water samples obtained from 30 different water bodies, and in 33 wastewater samples obtained at five health care institutions (HCIs, seven municipal wastewater treatment plants (mWWTPs, and an airport WWTP. Overall, 846 surface water and 313 wastewater E. coli isolates were analysed with respect to susceptibility to eight antimicrobials (representing seven different classes: ampicillin, cefotaxime, tetracycline, ciprofloxacin, streptomycin, sulfamethoxazole, trimethoprim, and chloramphenicol.Among surface water isolates, 26% were resistant to at least one class of antimicrobials, and 11% were multidrug-resistant (MDR. In wastewater, the proportions of AMR/MDR E. coli were 76%/62% at HCIs, 69%/19% at the airport WWTP, and 37%/27% and 31%/20% in mWWTP influents and effluents, respectively. Median concentrations of MDR E. coli were 2.2×10(2, 4.0×10(4, 1.8×10(7, and 4.1×10(7 cfu/l in surface water, WWTP effluents, WWTP influents and HCI wastewater, respectively. The different resistance types occurred with similar frequencies among E. coli from surface water and E. coli from municipal wastewater. By contrast, among E. coli from HCI wastewater, resistance to cefotaxime and resistance to ciprofloxacin were significantly overrepresented compared to E. coli from municipal wastewater and surface water. Most cefotaxime-resistant E. coliisolates produced ESBL. In two of the mWWTP, ESBL-producing variants were detected that were identical with respect to phylogenetic group, sequence type, AMR-profile, and ESBL-genotype to variants from HCI wastewater discharged onto the same sewer and sampled on the same day (A1/ST23/CTX-M-1, B23/ST131/CTX-M-15, D2/ST405/CTX-M-15.In

  17. Surface composition, microstructure and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

    International Nuclear Information System (INIS)

    Li, P.; Lei, M.K.; Zhu, X.P.

    2011-01-01

    High-intensity pulsed ion beam (HIPIB) irradiation of AZ31 magnesium alloy is performed and electrochemical corrosion experiment of irradiated samples is carried out by using potentiodynamic polarization technology in order to explore the effect of HIPIB irradiation on corrosion resistance of magnesium alloy. The surface composition, cross-sectional morphology and microstructure are characterized by using electron probe microanalyzer, optical microscope and transmission electron microscope, respectively. The results indicated that HIPIB irradiation leads to a significant improvement in corrosion resistance of magnesium alloy, in terms of the considerable increase in both corrosion potential and pitting breakdown potential. The microstructural refinement and surface purification induced by HIPIB irradiation are responsible for the improved corrosion resistance. - Research Highlights: → A modified layer about 30 μm thick is obtained by HIPIB irradiation. → Selective ablation of element/impurity phase having lower melting point is observed. → More importantly, microstructural refinement occurred on the irradiated surface. → The modified layer exhibited a significantly improved corrosion resistance. → Improved corrosion resistance is ascribed to the combined effect induced by HIPIB.

  18. Effects of laser polishing on surface microstructure and corrosion resistance of additive manufactured CoCr alloys

    Science.gov (United States)

    Wang, W. J.; Yung, K. C.; Choy, H. S.; Xiao, T. Y.; Cai, Z. X.

    2018-06-01

    Laser polishing of 3D printed metal components has drawn great interest in view of its potential applications in the dental implant industries. In this study, corrosion resistance, surface composition and crystalline structure of CoCr alloys were investigated. The corrosion resistance, micromorphology, composition, phase transformations and crystalline structures of samples were characterized using an electrochemical analyzer, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. The results indicate that high laser powers and low object distances within a certain range can facilitate the formation of complex oxide films, which exhibits high corrosion resistance. Further, object distances have a significant influence on cooling rates during the solidification of the melt pool in laser polishing, and fast cooling generates vast amounts of vacancies and defects, which result in the crystalline phase transformation from γ to ε. Consequently, the formed oxides play an important role in corrosion resistance on the outer layer, and inner layer with γ phase also helps keep the CoCr alloys in a stable structure with high resistant to corrosion. The two process parameters in laser polishing, laser power and object distances, are demonstrated as being important for controlling the surface microstructures and corrosion resistance of the additive manufactured CoCr alloy components.

  19. Nanosecond laser surface modification of AISI 304L stainless steel: Influence the beam overlap on pitting corrosion resistance

    International Nuclear Information System (INIS)

    Pacquentin, Wilfried; Caron, Nadège; Oltra, Roland

    2014-01-01

    Surface modifications of AISI 304L stainless steel by laser surface melting (LSM) were investigated using a nanosecond pulsed laser-fibre doped by ytterbium at different overlaps. The objective was to study the change in the corrosion properties induced by the treatment of the outer-surface of the stainless steel without modification of the bulk material. Different analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and glow discharge optical emission spectrometry (GDOES) were used to characterize the laser-melted surface. The corrosion resistance was evaluated in a chloride solution at room temperature by electrochemical tests. The results showed that the crystallographic structure, the chemical composition, the properties of the induced oxide layer and consequently the pitting corrosion resistance strongly depend on the overlap rate. The most efficient laser parameters led to an increase of the pitting potential by more than 300 mV, corresponding to a quite important improvement of the corrosion resistance. This latter was correlated to chromium enrichment (47 wt.%) at the surface of the stainless steel and the induced absence of martensite and ferrite phases. However, these structural and chemical modifications were not sufficient to explain the change in corrosion behaviour: defects and adhesion of the surface oxide layer must have been taken into consideration.

  20. Influence of the post-weld surface treatment on the corrosion resistance of the duplex stainless steel 1.4062

    Science.gov (United States)

    Rosemann, P.; Müller, C.; Baumann, O.; Modersohn, W.; Halle, T.

    2017-03-01

    The duplex stainless steel 1.4062 (X2CrNiN22-2) is used as alternative material to austenitic stainless steels in the construction industry. The corrosion resistance of welded seams is influenced by the base material, the weld filler material, the welding process and also by the final surface treatment. The scale layer next to the weld seam can be removed by grinding, pickling, electro-polished or blasting depending on the application and the requested corrosion resistance. Blasted surfaces are often used in industrial practice due to the easier and cheaper manufacturing process compared to pickled or electro-polished surfaces. Furthermore blasting with corundum-grain is more effective than blasting with glass-beads which also lower the process costs. In recent years, stainless steel surfaces showed an unusually high susceptibility to pitting corrosion after grinding with corundum. For this reason, it is now also questioned critically whether the corrosion resistance is influenced by the applied blasting agent. This question was specifically investigated by comparing grinded, pickled, corundum-grain- and glass-bead-blasted welding seams. Results of the SEM analyses of the blasting agents and the blasted surfaces will be presented and correlated with the different performed corrosion tests (potential measurement, KorroPad-test and pitting potential) on welding seams with different surface treatments.

  1. Soliton solutions to the fifth-order Korteweg-de Vries equation and their applications to surface and internal water waves

    Science.gov (United States)

    Khusnutdinova, K. R.; Stepanyants, Y. A.; Tranter, M. R.

    2018-02-01

    We study solitary wave solutions of the fifth-order Korteweg-de Vries equation which contains, besides the traditional quadratic nonlinearity and third-order dispersion, additional terms including cubic nonlinearity and fifth order linear dispersion, as well as two nonlinear dispersive terms. An exact solitary wave solution to this equation is derived, and the dependence of its amplitude, width, and speed on the parameters of the governing equation is studied. It is shown that the derived solution can represent either an embedded or regular soliton depending on the equation parameters. The nonlinear dispersive terms can drastically influence the existence of solitary waves, their nature (regular or embedded), profile, polarity, and stability with respect to small perturbations. We show, in particular, that in some cases embedded solitons can be stable even with respect to interactions with regular solitons. The results obtained are applicable to surface and internal waves in fluids, as well as to waves in other media (plasma, solid waveguides, elastic media with microstructure, etc.).

  2. Electromagnetic Field Analysis of an Electric Dipole Antenna Based on a Surface Integral Equation in Multilayered Dissipative Media

    Directory of Open Access Journals (Sweden)

    Yidong Xu

    2017-07-01

    Full Text Available In this paper, a novel method based on the Poggio–Miller–Chang-Harrington–Wu–Tsai (PMCHWT integral equation is presented to study the electromagnetic fields excited by vertical or horizontal electric dipoles in the presence of a layered region which consists of K-layered dissipative media and the air above. To transform the continuous integral equation into a block tridiagonal matrix with the feature of convenient solution, the Rao–Wilton–Glisson (RWG functions are introduced as expansion and testing functions. The electromagnetic fields excited by an electric dipole are calculated and compared with the available results, where the electric dipole antenna is buried in the non-planar air–sea–seabed, air–rock–earth–mine, and multilayered sphere structures. The analysis and computations demonstrate that the method exhibits high accuracy and solving performance in the near field propagation region.

  3. Effects of plasma treatment time on surface characteristics of indium-tin-oxide film for resistive switching storage applications

    International Nuclear Information System (INIS)

    Chen, Po-Hsun; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Shih, Chih-Cheng; Wu, Cheng-Hsien; Yang, Chih-Cheng; Chen, Wen-Chung; Lin, Jiun-Chiu; Wang, Ming-Hui; Zheng, Hao-Xuan; Chen, Min-Chen; Sze, Simon M.

    2017-01-01

    In this paper, we implement a post-oxidation method to modify surface characteristics of indium tin oxide (ITO) films by using an O_2 inductively coupled plasma (ICP) treatment. Based on field emission-scanning electron microscope (FE-SEM) and atomic force microscope (AFM) analysis, we found that the surface morphologies of the ITO films become slightly flatter after the O_2 plasma treatment. The optical characteristics and X-ray diffraction (XRD) experiments of either pure ITO or O_2 plasma treated ITO films were also verified. Even though the XRD results showed no difference from bulk crystallizations, the oxygen concentrations increased at the film surface after O_2 plasma treatment, according to the XPS inspection results. Moreover, this study investigated the effects of two different plasma treatment times on oxygen concentration in the ITO films. The surface sheet resistance of the plasma treated ITO films became nearly non-conductive when measured with a 4-point probe. Finally, we applied the O_2 plasma treated ITO films as the insulator in resistive random access memory (RRAM) to examine their potential for use in resistive switching storage applications. Stable resistance switching characteristics were obtained by applying the O_2 plasma treatment to the ITO-based RRAM. We also confirmed the relationship between plasma treatment time and RRAM performance. These material analyses and electrical measurements suggest possible advantages in using this plasma treatment technique in device fabrication processes for RRAM applications.

  4. Effects of plasma treatment time on surface characteristics of indium-tin-oxide film for resistive switching storage applications

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Po-Hsun [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Chang, Ting-Chang, E-mail: tcchang3708@gmail.com [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Chang, Kuan-Chang, E-mail: kcchang@pkusz.edu.cn [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); School of Electronic and Computer Engineering, Peking University, Shenzhen 518055 (China); Tsai, Tsung-Ming; Pan, Chih-Hung; Shih, Chih-Cheng; Wu, Cheng-Hsien; Yang, Chih-Cheng; Chen, Wen-Chung; Lin, Jiun-Chiu; Wang, Ming-Hui [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Zheng, Hao-Xuan; Chen, Min-Chen [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Sze, Simon M. [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 300, Taiwan, ROC (China)

    2017-08-31

    In this paper, we implement a post-oxidation method to modify surface characteristics of indium tin oxide (ITO) films by using an O{sub 2} inductively coupled plasma (ICP) treatment. Based on field emission-scanning electron microscope (FE-SEM) and atomic force microscope (AFM) analysis, we found that the surface morphologies of the ITO films become slightly flatter after the O{sub 2} plasma treatment. The optical characteristics and X-ray diffraction (XRD) experiments of either pure ITO or O{sub 2} plasma treated ITO films were also verified. Even though the XRD results showed no difference from bulk crystallizations, the oxygen concentrations increased at the film surface after O{sub 2} plasma treatment, according to the XPS inspection results. Moreover, this study investigated the effects of two different plasma treatment times on oxygen concentration in the ITO films. The surface sheet resistance of the plasma treated ITO films became nearly non-conductive when measured with a 4-point probe. Finally, we applied the O{sub 2} plasma treated ITO films as the insulator in resistive random access memory (RRAM) to examine their potential for use in resistive switching storage applications. Stable resistance switching characteristics were obtained by applying the O{sub 2} plasma treatment to the ITO-based RRAM. We also confirmed the relationship between plasma treatment time and RRAM performance. These material analyses and electrical measurements suggest possible advantages in using this plasma treatment technique in device fabrication processes for RRAM applications.

  5. Facile fabrication of superhydrophobic surface with excellent mechanical abrasion and corrosion resistance on copper substrate by a novel method.

    Science.gov (United States)

    Su, Fenghua; Yao, Kai

    2014-06-11

    A novel method for controllable fabrication of a superhydrophobic surface with a water contact angle of 162 ± 1° and a sliding angle of 3 ± 0.5° on copper substrate is reported in this Research Article. The facile and low-cost fabrication process is composed from the electrodeposition in traditional Watts bath and the heat-treatment in the presence of (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane (AC-FAS). The superhydrophobicity of the fabricated surface results from its pine-cone-like hierarchical micro-nanostructure and the assembly of low-surface-energy fluorinated components on it. The superhydrophobic surface exhibits high microhardness and excellent mechanical abrasion resistance because it maintains superhydrophobicity after mechanical abrasion against 800 grit SiC sandpaper for 1.0 m at the applied pressure of 4.80 kPa. Moreover, the superhydrophobic surface has good chemical stability in both acidic and alkaline environments. The potentiodynamic polarization and electrochemical impedance spectroscopy test shows that the as-prepared superhydrophobic surface has excellent corrosion resistance that can provide effective protection for the bare Cu substrate. In addition, the as-prepared superhydrophobic surface has self-cleaning ability. It is believed that the facile and low-cost method offer an effective strategy and promising industrial applications for fabricating superhydrophobic surfaces on various metallic materials.

  6. Impact of an Environmental Cleaning Intervention on the Presence of Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococci on Surfaces in Intensive Care Unit Rooms

    Science.gov (United States)

    Goodman, Eric R.; Platt, Richard; Bass, Richard; Onderdonk, Andrew B.; Yokoe, Deborah S.; Huang, Susan S.

    2009-01-01

    OBJECTIVES To evaluate the adequacy of discharge room cleaning and the impact of a cleaning intervention on the presence of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) on environmental surfaces in intensive care unit (ICU) rooms. DESIGN Prospective environmental study. SETTING AND SAMPLE Convenience sample of ICU rooms in an academic hospital. METHODS AND INTERVENTION The intervention consisted of (1) a change from the use of pour bottles to bucket immersion for applying disinfectant to cleaning cloths, (2) an educational campaign, and (3) feedback regarding adequacy of discharge cleaning. Cleaning of 15 surfaces was evaluated by inspecting for removal of a preapplied mark, visible only with an ultraviolet lamp (“black light”). Six surfaces were cultured for MRSA or VRE contamination. Outcomes of mark removal and culture positivity were evaluated by χ2 testing and generalized linear mixed models, clustering by room. RESULTS The black-light mark was removed from 44% of surfaces at baseline, compared with 71% during the intervention (P <.001). The intervention increased the likelihood of removal of black-light marks after discharge cleaning (odds ratio, 4.4; P < .001), controlling for ICU type (medical vs surgical) and type of surface. The intervention reduced the likelihood of an environmental culture positive for MRSA or VRE (proportion of cultures positive, 45% at baseline vs 27% during the intervention; adjusted odds ratio, 0.4; P = .02). Broad, flat surfaces were more likely to be cleaned than were doorknobs and sink or toilet handles. CONCLUSIONS Increasing the volume of disinfectant applied to environmental surfaces, providing education for Environmental Services staff, and instituting feedback with a black-light marker improved cleaning and reduced the frequency of MRSA and VRE contamination. PMID:18624666

  7. A review of the clinical implications of anti-infective biomaterials and infection-resistant surfaces.

    Science.gov (United States)

    Campoccia, Davide; Montanaro, Lucio; Arciola, Carla Renata

    2013-11-01

    Infection is currently regarded as the most severe and devastating complication associated to the use of biomaterials. The important social, clinical and economic impacts of implant-related infections are promoting the efforts to obviate these severe diseases. In this context, the development of anti-infective biomaterials and of infection-resistant surfaces is being regarded as the main strategy to prevent the establishment of implant colonisation and biofilm formation by bacteria. In this review, the attention is focused on the biomaterial-associated infections, from which the need for anti-infective biomaterials originates. Biomaterial-associated infections differ markedly for epidemiology, aetiology and severity, depending mainly on the anatomic site, on the time of biomaterial application, and on the depth of the tissues harbouring the prosthesis. Here, the diversity and complexity of the different scenarios where medical devices are currently utilised are explored, providing an overview of the emblematic applicative fields and of the requirements for anti-infective biomaterials. © 2013 Elsevier Ltd. All rights reserved.

  8. Resistance to disinfection of a polymicrobial association contaminating the surface of elastomeric dental impressions.

    Science.gov (United States)

    Giammanco, Giovanni M; Melilli, Dario; Rallo, Antonio; Pecorella, Sonia; Mammina, Caterina; Pizzo, Giuseppe

    2009-04-01

    The aim of this study was to evaluate the ability to resist disinfection of a polymicrobial association contaminating the surface of dental impressions obtained with two different elastomers: a polyether (Impregum) and an addition-polymerized silicone (Elite). Impressions were contaminated with a mixture of three biofilm-forming microorganisms (Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans) and disinfected immediately after contamination, or after microbial layers were allowed to develop during a six-hour storage. Two commercial disinfectants were tested: MD 520 containing 0.5% glutaraldehyde and Sterigum Powder without glutaraldehyde. Residual contamination was recovered by mechanical rinsing immediately after disinfection and after a six-hour storage of disinfected impressions, and assessed by colony counting. Both disinfectants tested were shown to be effective in reducing the microbial presence on the impression materials, achieving at least a 102 reduction of microbial counts compared to water rinsing. However, Sterigum was generally less effective on the Elite elastomer and could not grant disinfection on six-hour aged P. aeruginosa and C. albicans microbial layers. The results of this study suggest that the materials used for the impressions influence the efficacy of disinfection. Disinfectants should be tested according to conditions encountered in everyday clinical practice and the need for immediate disinfection of impressions should be clearly indicated by manufacturers.

  9. Surface resistances of 5-cm-diameter YBCO films prepared by MOD for microwave applications

    International Nuclear Information System (INIS)

    Manabe, T.; Sohma, M.; Yamaguchi, I.; Tsukada, K.; Kondo, W.; Kamiya, K.; Tsuchiya, T.; Mizuta, S.; Kumagai, T.

    2006-01-01

    Large-area high-T c superconducting films with low surface resistances R s are required for use in microwave applications such as band pass filters. In this paper, preparation of 5-cm-diameter YBCO films on LaAlO 3 (LAO) and CeO 2 -buffered sapphire (CbS) substrates by metalorganic deposition (MOD) using a fluorine-free coating solution and their superconducting properties are described. The optimum firing conditions for YBCO films greatly depend on the substrate materials; a heating rate at ramp as high as 200 deg. C /min is necessary for films on LAO whereas a lower heating rate, e.g., 20 deg. C /min, is required for films on CbS. Accordingly, the suitable furnace systems for these substrates have been varied. As a result, a YBCO film with high J c (77 K) of 2.7 MA/cm 2 and a low R s (12 GHz, 77 K) of 0.54 mΩ was prepared on LAO by using an infrared image furnace. On the other hand, a YBCO film with a higher J c (77 K) of 4.0 MA/cm 2 and the same R s (12 GHz, 77 K) of 0.54 mΩ was prepared on CbS by using a tube furnace

  10. Study of the surface resistance of superconducting niobium films at 1.5 GHz

    CERN Document Server

    Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Peck, M A; Russo, R; Valente, A M

    1999-01-01

    A systematic study of superconducting properties of niobium films sputtered on the inner wall of radiofrequency cavities is presented. The measured quantities include in particular the response to 1.5 GHz microwaves, the critical temperature, the penetration depth and the magnetic penetration field. In addition to films grown in different gas discharges (Xe, Kr, Ar and Ar/Ne mixtures) and to films grown on substrates prepared under different conditions, the study also includes bulk niobium cavities. The surface resistance is analysed in terms of its dependence on temperature, on RF field and, when relevant, on the density of trapped fluxons. A simple parameterisation is found to give a good fit to the data. Once allowance for the presence of impurities and defects is made by means of a single parameter, the electron mean free path, good agreement with BCS theory is observed. The fluxon-induced losses are studied in detail and their dependence on RF field, on temperature and on the density of trapped fluxons i...

  11. Nanostructure Formations and Improvement in Corrosion Resistance of Steels by Means of Pulsed Electron Beam Surface Treatment

    Directory of Open Access Journals (Sweden)

    K. M. Zhang

    2013-01-01

    Full Text Available The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nanostructure formations of steels by using a low energy high pulsed electron beam (LEHCPEB treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels.

  12. A modified surface-resistance approach for representing bare-soil evaporation: wind tunnel experiments under various atmospheric conditions

    International Nuclear Information System (INIS)

    Yamanaka, T.; Takeda, A.; Sugita, F.

    1997-01-01

    A physically based (i.e., nonempirical) representation of surface-moisture availability is proposed, and its applicability is investigated. This method is based on the surface-resistance approaches, and it uses the depth of evaporating surface rather than the water content of the surface soil as the determining factor of surface-moisture availability. A simple energy-balance model including this representation is developed and tested against wind tunnel experiments under various atmospheric conditions. This model can estimate not only the latent heat flux but also the depth of the evaporating surface simultaneously by solving the inverse problem of energy balance at both the soil surface and the evaporating surface. It was found that the depth of the evaporating surface and the latent heat flux estimated by the model agreed well with those observed. The agreements were commonly found out under different atmospheric conditions. The only limitation of this representation is that it is not valid under conditions of drastic change in the radiation input, owing to the influence of transient phase transition of water in the dry surface layer. The main advantage of the approach proposed is that it can determine the surface moisture availability on the basis of the basic properties of soils instead of empirical fitting, although further investigations on its practical use are needed

  13. Experimental research on microhardness and wear resistances of pure Cu subjected to surface dynamic plastic deformation by ultrasonic impact

    Science.gov (United States)

    Chen, Zhaoxia; He, Yangming

    2018-04-01

    Dynamic plastic deformation (DPD) has been induced in the surface of pure Cu by ultrasonic impact treating (UIT) with the varied impact current and coverage percentage. The microstructures of the treated surface were analyzed by a scanning electron microscope (SEM). And the wear resistance of pure Cu was experimentally researched both with the treated and untreated specimens. The effect of DPD on the hardness was also investigated using microhardness tester. The results show that the grains on the top surfaces of pure Cu are highly refined. The maximum depth of the plastic deformation layer is approximately 1400 µm. The larger the current and coverage percentage, the greater of the microhardness and wear resistance the treated surface layer of pure Cu will be. When the impact current is 2 A and coverage percentage is 300%, the microhardness and wear resistance of the treated sample is about 276.1% and 68.8% higher than that of the untreated specimen, respectively. But the properties of the treated sample deteriorate when the UIT current is 3 A and the coverage percentage is 300% because of the formation of a new phase forms in the treated surface.

  14. Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

    Science.gov (United States)

    Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

    2015-09-02

    We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed.

  15. Analysis of the dual phase lag bio-heat transfer equation with constant and time-dependent heat flux conditions on skin surface

    Directory of Open Access Journals (Sweden)

    Ziaei Poor Hamed

    2016-01-01

    Full Text Available This article focuses on temperature response of skin tissue due to time-dependent surface heat fluxes. Analytical solution is constructed for DPL bio-heat transfer equation with constant, periodic and pulse train heat flux conditions on skin surface. Separation of variables and Duhamel’s theorem for a skin tissue as a finite domain are employed. The transient temperature responses for constant and time-dependent boundary conditions are obtained and discussed. The results show that there is major discrepancy between the predicted temperature of parabolic (Pennes bio-heat transfer, hyperbolic (thermal wave and DPL bio-heat transfer models when high heat flux accidents on the skin surface with a short duration or propagation speed of thermal wave is finite. The results illustrate that the DPL model reduces to the hyperbolic model when τT approaches zero and the classic Fourier model when both thermal relaxations approach zero. However for τq = τT the DPL model anticipates different temperature distribution with that predicted by the Pennes model. Such discrepancy is due to the blood perfusion term in energy equation. It is in contrast to results from the literature for pure conduction material, where the DPL model approaches the Fourier heat conduction model when τq = τT . The burn injury is also investigated.

  16. Diversity, distribution and quantification of antibiotic resistance genes in goat and lamb slaughterhouse surfaces and meat products.

    Directory of Open Access Journals (Sweden)

    Leyre Lavilla Lerma

    Full Text Available The distribution and quantification of tetracycline, sulfonamide and beta-lactam resistance genes were assessed in slaughterhouse zones throughout meat chain production and the meat products; this study represents the first to report quantitatively monitor antibiotic resistance genes (ARG in goat and lamb slaughterhouse using a culture independent approach, since most studies focused on individual bacterial species and their specific resistance types. Quantitative PCR (qPCR revealed a high prevalence of tetracycline resistance genes tetA and tetB in almost all slaughterhouse zones. Sulfonamide resistance genes were largely distributed, while beta-lactam resistance genes were less predominant. Statistical analysis revealed that resistant bacteria, in most cases, were spread by the same route in almost all slaughterhouse zones, except for tetB, blaCTX and blaTEM genes, which occurred in few zones as isolated 'hot spots.' The sum of all analyzed ARG indicated that slaughterhouse surfaces and end products act as reservoirs of ARG, mainly tet genes, which were more prevalent in slaughtering room (SR, cutting room (CR and commercial meat products (MP. Resistance gene patterns suggest they were disseminated throughout slaughterhouse zones being also detected in commercial meat products, with significant correlations between different sampling zones/end products and total resistance in SR, CR and white room (WR zones, and also refrigerator 4 (F4 and MP were observed. Strategically controlling key zones in slaughterhouse (SR, CR and WR by adequate disinfection methods could strategically reduce the risks of ARG transmission and minimize the issues of food safety and environment contamination.

  17. Diversity, distribution and quantification of antibiotic resistance genes in goat and lamb slaughterhouse surfaces and meat products.

    Science.gov (United States)

    Lavilla Lerma, Leyre; Benomar, Nabil; Knapp, Charles W; Correa Galeote, David; Gálvez, Antonio; Abriouel, Hikmate

    2014-01-01

    The distribution and quantification of tetracycline, sulfonamide and beta-lactam resistance genes were assessed in slaughterhouse zones throughout meat chain production and the meat products; this study represents the first to report quantitatively monitor antibiotic resistance genes (ARG) in goat and lamb slaughterhouse using a culture independent approach, since most studies focused on individual bacterial species and their specific resistance types. Quantitative PCR (qPCR) revealed a high prevalence of tetracycline resistance genes tetA and tetB in almost all slaughterhouse zones. Sulfonamide resistance genes were largely distributed, while beta-lactam resistance genes were less predominant. Statistical analysis revealed that resistant bacteria, in most cases, were spread by the same route in almost all slaughterhouse zones, except for tetB, blaCTX and blaTEM genes, which occurred in few zones as isolated 'hot spots.' The sum of all analyzed ARG indicated that slaughterhouse surfaces and end products act as reservoirs of ARG, mainly tet genes, which were more prevalent in slaughtering room (SR), cutting room (CR) and commercial meat products (MP). Resistance gene patterns suggest they were disseminated throughout slaughterhouse zones being also detected in commercial meat products, with significant correlations between different sampling zones/end products and total resistance in SR, CR and white room (WR) zones, and also refrigerator 4 (F4) and MP were observed. Strategically controlling key zones in slaughterhouse (SR, CR and WR) by adequate disinfection methods could strategically reduce the risks of ARG transmission and minimize the issues of food safety and environment contamination.

  18. A FMM-FFT accelerated hybrid volume surface integral equation solver for electromagnetic analysis of re-entry space vehicles

    KAUST Repository

    Yü cel, Abdulkadir C.; Gomez, Luis J.; Liu, Yang; Bagci, Hakan; Michielssen, Eric

    2014-01-01

    Space vehicles that re-enter the atmosphere often experience communication blackout. The blackout occurs when the vehicle becomes engulfed in plasma produced by interactions between the vehicle surface and the atmosphere. The plasma often

  19. Improvement of pitting corrosion resistance of AISI 304L stainless steel by nano-pulsed laser surface melting

    International Nuclear Information System (INIS)

    Pacquentin, W.; Blanc, C.; Caron, N.; Thro, P.Y.; Cheniere, A.; Tabarant, M.; Moutiers, G.; Miserque, F.; Plouzennec, H.; Oltra, R.

    2013-01-01

    The stainless steel 304L is widely used, however, in particular conditions, it may be sensitive to pitting corrosion. Nano-pulsed laser surface melting is a surface treatment which allows improving the corrosion resistance of this steel. This treatment consists in focusing a laser beam on the surface of the material, involving its quite immediately melting through a few microns depth, then an ultra-fast solidification occurs with cooling rate about 1011 K/s. The laser parameters control the modifications of the physico-chemical properties. In particular, we studied the influence of the impacts overlap of an ytterbium laser-fiber on the corrosion resistance of a 304L stainless steel in conditions of an aerated and agitated solution of NaCl (concentration of 30 g/L). We obtained an increase of the pitting potential of 220 mV, highlighting an improvement of the corrosion resistance. The study of the chemical and structural modifications is not enough to explain the improvement of the corrosion resistance. Other phenomena must be taken into account, as the quality of the oxide layer, in terms of physico-chemical and mechanical properties. (authors)

  20. Assessment of slipping resistance of footwear and floor surfaces. Influence of manufacture and utilization of the products.

    Science.gov (United States)

    Leclercq, S; Tisserand, M; Saulnier, H

    1995-02-01

    The slipping resistance of footwear or floor surfaces is a characteristic which it is vital to be able to quantify. Work is being carried out at the International Standard Organization (ISO) and at the European Committee for Standardization (CEN) into the slip resistance of both work shoes and protective footwear, involving analysis of the latest developments in both the validity of measuring methods and the extent of the influence of certain experimental parameters on the slip resistance. Two industrial factors, independent of the measuring process but essential to the determination of the coefficient of friction of the models have been experimentally studied, namely the effect of the manufacture of the footwear or floor surfaces on the scattering of the specific coefficient of friction of a referenced model and the effect on the coefficient of friction of mechanical wear and tear on the soles as a result of their use respectively. Work into slipping on industrial floor surfaces is less advanced. Yet, problems raised call for the same approach than for problems linked to slipping resistance of footwear, and applications will be also at first related to standardized measurement conditions.

  1. Effect of internal short fibers, steel reinforcement, and surface layer on impact and penetration resistance of concrete

    Directory of Open Access Journals (Sweden)

    Ali Abd_Elhakam Aliabdo

    2013-09-01

    Full Text Available This paper presents an experimental program to investigate the impact and penetration resistance of concrete. The research work is divided into two approaches. These approaches are effect of concrete constituents and effect of surface layer. Effect of concrete aggregate type, w/c ratio, fiber type, fiber shape, fiber volume fraction, and steel reinforcement is considered in the first approach. The second approach includes using fiber reinforced concrete and glass fiber reinforced polymer as surface layers. The evaluating tests include standard impact test according to ASTM D 1557 and suggested simulated penetration test to measure the impact and penetration resistance of concrete. The test results of plain and fibrous concrete from ASTM D 1557 method indicated that steel fiber with different configurations and using basalt have a great positive effect on impact resistance of concrete. Moreover, the simulated penetration test indicates that steel fibers are more effective than propylene fibers, type of coarse aggregate has negligible effect, and steel fiber volume fraction has a more significant influence than fiber shape for reinforced concrete test panels. Finally, as expectable, surface properties of tested concrete panels have a significant effect on impact and penetration resistance.

  2. Effects of electropolishing surface treatment on the cyclic fatigue resistance of BioRace nickel-titanium rotary instruments.

    Science.gov (United States)

    Lopes, Hélio P; Elias, Carlos N; Vieira, Victor T L; Moreira, Edson J L; Marques, Raquel V L; de Oliveira, Julio C Machado; Debelian, Gilberto; Siqueira, José F

    2010-10-01

    This study evaluated the influence of electropolishing surface treatment on the number of cycles to fracture of BioRace rotary nickel-titanium endodontic instruments. BioRace size BR5C instruments with or without electropolishing surface treatment were used in an artificial curved canal under rotational speed of 300 rpm until fracture. Fractured surfaces and the helical shafts of fractured instruments were analyzed by scanning electron microscopy (SEM). Polished instruments displayed a significantly higher number of cycles to fracture when compared with nonpolished instruments (P ductile morphologic characteristics. Evaluation of the separated fragments after cyclic fatigue testing showed the presence of microcracks near the fracture surface. Polished instruments exhibited fine cracks that assumed an irregular path (zigzag crack pattern), whereas nonpolished instruments showed cracks running along the machining grooves. Electropolishing surface treatment of BioRace endodontic instruments significantly increased the cyclic fatigue resistance. Copyright © 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  3. Quasiclassical Theory of Spin Dynamics in Superfluid ^3He: Kinetic Equations in the Bulk and Spin Response of Surface Majorana States

    Science.gov (United States)

    Silaev, M. A.

    2018-06-01

    We develop a theory based on the formalism of quasiclassical Green's functions to study the spin dynamics in superfluid ^3He. First, we derive kinetic equations for the spin-dependent distribution function in the bulk superfluid reproducing the results obtained earlier without quasiclassical approximation. Then, we consider spin dynamics near the surface of fully gapped ^3He-B-phase taking into account spin relaxation due to the transitions in the spectrum of localized fermionic states. The lifetimes of longitudinal and transverse spin waves are calculated taking into account the Fermi-liquid corrections which lead to a crucial modification of fermionic spectrum and spin responses.

  4. Dependence of the residual surface resistance of superconducting radio frequency cavities on the cooling dynamics around T{sub c}

    Energy Technology Data Exchange (ETDEWEB)

    Romanenko, A., E-mail: aroman@fnal.gov; Grassellino, A., E-mail: annag@fnal.gov; Melnychuk, O.; Sergatskov, D. A. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)

    2014-05-14

    We report a strong effect of the cooling dynamics through T{sub c} on the amount of trapped external magnetic flux in superconducting niobium cavities. The effect is similar for fine grain and single crystal niobium and all surface treatments including electropolishing with and without 120 °C baking and nitrogen doping. Direct magnetic field measurements on the cavity walls show that the effect stems from changes in the flux trapping efficiency: slow cooling leads to almost complete flux trapping and higher residual resistance, while fast cooling leads to the much more efficient flux expulsion and lower residual resistance.

  5. Dependence of the residual surface resistance of superconducting radio frequency cavities on the cooling dynamics around Tc

    Science.gov (United States)

    Romanenko, A.; Grassellino, A.; Melnychuk, O.; Sergatskov, D. A.

    2014-05-01

    We report a strong effect of the cooling dynamics through Tc on the amount of trapped external magnetic flux in superconducting niobium cavities. The effect is similar for fine grain and single crystal niobium and all surface treatments including electropolishing with and without 120 °C baking and nitrogen doping. Direct magnetic field measurements on the cavity walls show that the effect stems from changes in the flux trapping efficiency: slow cooling leads to almost complete flux trapping and higher residual resistance, while fast cooling leads to the much more efficient flux expulsion and lower residual resistance.

  6. Chronological change of electrical resistance in GeCu2Te3 amorphous film induced by surface oxidation

    International Nuclear Information System (INIS)

    Saito, Yuta; Shindo, Satoshi; Sutou, Yuji; Koike, Junichi

    2014-01-01

    Unusual chronological electrical resistance change behavior was investigated for amorphous GeCu 2 Te 3 phase change material. More than a 1 order decrease of electrical resistance was observed in the air even at room temperature. The resistance of the amorphous film gradually increased with increasing temperature and then showed a drop upon crystallization. Such unusual behavior was attributed to the oxidation of the amorphous GeCu 2 Te 3 film. From the compositional depth profile measurement, the GeCu 2 Te 3 film without any capping layer was oxidized in air at room temperature and the formed oxide was mainly composed of germanium oxide. Consequently, a highly-conductive Cu-rich layer was formed in the vicinity of the surface of the film, which reduced the total resistance of the film. The present results could provide insight into the chronological change of electrical resistance in amorphous chalcogenide materials, indicating that not only relaxation of the amorphous, but also a large atomic diffusion contributes to the chronological resistance change. (paper)

  7. Resistivity and Seismic Surface Wave Tomography Results for the Nevşehir Kale Region: Cappadocia, Turkey

    Science.gov (United States)

    Coşkun, Nart; Çakır, Özcan; Erduran, Murat; Arif Kutlu, Yusuf

    2014-05-01

    The Nevşehir Kale region located in the middle of Cappadocia with approximately cone shape is investigated for existence of an underground city using the geophysical methods of electrical resistivity and seismic surface wave tomography together. Underground cities are generally known to exist in Cappadocia. The current study has obtained important clues that there may be another one under the Nevşehir Kale region. Two-dimensional resistivity and seismic profiles approximately 4-km long surrounding the Nevşehir Kale are measured to determine the distribution of electrical resistivities and seismic velocities under the profiles. Several high resistivity anomalies with a depth range 8-20 m are discovered to associate with a systematic void structure beneath the region. Because of the high resolution resistivity measurement system currently employed we were able to isolate the void structure from the embedding structure. Low seismic velocity zones associated with the high resistivity depths are also discovered. Using three-dimensional visualization techniques we show the extension of the void structure under the measured profiles.

  8. A resistance representation of schemes for evaporation from bare and partly plant-covered surfaces for use in atmospheric models

    Energy Technology Data Exchange (ETDEWEB)

    Mihailovic, D.T.; Pielke, R.A.; Rajkovic, B.; Lee, T.J.; Jeftic, M. (Novi Sad Univ. (Yugoslavia) Colorado State Univ., Fort Collins (United States) Belgrade Univ. (Yugoslavia))

    1993-06-01

    In the parameterization of land surface processes, attention must be devoted to surface evaporation, one of the main processes in the air-land energy exchange. One of the most used approaches is the resistance representation which requires the calculation of aerodynamic resistances. These resistances are calculated using K theory for different morphologies of plant communities; then, the performance of the evaporation schemes within the alpha, beta, and their combination approaches that parameterize evaporation from bare and partly plant-covered soil surfaces are discussed. Additionally, a new alpha scheme is proposed based on an assumed power dependence alpha on volumetric soil moisture content and its saturated value. Finally, the performance of the considered and the proposed schemes is tested based on time integrations using real data. The first set was for 4 June 1982, and the second for 3 June 1981 at the experimental site in Rimski Sancevi, Yugoslavia, on chernozem soil, as representative for a bare, and partly plant-covered surface, respectively. 63 refs.

  9. Preparation and characterization of soy protein films with a durable water resistance-adjustable and antimicrobial surface.

    Science.gov (United States)

    Li, Shuzhao; Donner, Elizabeth; Xiao, Huining; Thompson, Michael; Zhang, Yachuan; Rempel, Curtis; Liu, Qiang

    2016-12-01

    A water resistant surface was first obtained by immobilizing hydrophobic copolymers, poly (styrene-co-glycidyl methacrylate) (PSG), with functional groups on soy protein isolate (SPI) films. XPS and AFM results showed that PSG copolymers were immobilized on the film by chemical bonding, and formed a rough surface with some bumps because of the segregation of two different phases on PSG copolymers. Water resistance of the modified films could be adjusted dramatically by further immobilizing different amounts of guanidine-based antimicrobial polymers, poly (hexamethylene guanidine hydrochloride) (PHMG) on the resulting hydrophobic surface. The introduction of hydrophilic PHMG on the resulting surface generated many micropores, which potentially increased the water uptake of the modified films. Furthermore, the modified SPI films showed higher thermostability compared to native SPI film and broad-spectrum antimicrobial activity by contact killing, attributed to the presence of PHMG on the surface. The modified SPI film with a multi-functional surface showed potential for applications in the packaging and medical fields. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  10. Nano structure Formations and Improvement in Corrosion Resistance of Steels by Means of Pulsed Electron Beam Surface Treatment

    International Nuclear Information System (INIS)

    Zhang, K.M.; Zou, J.X.; Zou, J.X.; Grosdidier, T.; Zou, J.X.; Grosdidier, T.; Grosdidier, T.

    2013-01-01

    The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels

  11. The effect of electron-surface scattering and thiol adsorption on the electrical resistivity of gold ultrathin films

    International Nuclear Information System (INIS)

    Henriquez, Ricardo; Del Campo, Valeria; Gonzalez-Fuentes, Claudio; Correa-Puerta, Jonathan; Moraga, Luis; Flores, Marcos; Segura, Rodrigo; Donoso, Sebastián; Marín, Francisca; Bravo, Sergio; Häberle, Patricio

    2017-01-01

    Highlights: • We prepared ultra thin films (10 nm) on mica on top of a chromium seedlayer (<1 nm). • We prepared samples with different topographies controlling the substrate temperature. • We studied the contribution of the different scattering mechanims on the resistivity. • We developed a discernment method based on thiol adsorption. - Abstract: In order to study the effect of electron-surface scattering in gold ultrathin films (∼10 nm), we have prepared a set of Au samples on mica on top of a chromium seedlayer (<1 nm). Chromium is added as a metallic surfactant which enables surpassing the electric percolation threshold for substrate temperatures above room temperature. We prepared samples with the same thickness but different topographies setting different substrate temperatures. These modifications modulate the contributions of the different electronic scattering mechanisms to the film resistivity. A second set of gold thin films deposited on mica at room temperature, with different thicknesses between 8 and 100 nm, was also prepared to compare the resisitivities of both sets through Mayadas and Shatzkes theory. We found that in samples with thicknesses below 15 nm, the electron-surface scattering is indeed the dominant mechanism influencing the film resistivity. To obtain further evidence of this prevalence, we developed a discrimination method based on thiol adsorption. The film with the highest resistivity increase is the sample in which electron-surface scattering is dominant. With this method, we observed that a large enhancement of the electron-surface scattering not only occurs in samples with large diameters grains, but also if the film has a reduced surface roughness.​

  12. The effect of electron-surface scattering and thiol adsorption on the electrical resistivity of gold ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Henriquez, Ricardo, E-mail: ricardo.henriquez@usm.cl [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Del Campo, Valeria; Gonzalez-Fuentes, Claudio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Correa-Puerta, Jonathan [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Curauma, Valparaíso (Chile); Moraga, Luis [Universidad Central de Chile, Toesca 1783, Santiago 8370178 (Chile); Flores, Marcos [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Segura, Rodrigo [Instituto de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso (Chile); Donoso, Sebastián; Marín, Francisca; Bravo, Sergio; Häberle, Patricio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile)

    2017-06-15

    Highlights: • We prepared ultra thin films (10 nm) on mica on top of a chromium seedlayer (<1 nm). • We prepared samples with different topographies controlling the substrate temperature. • We studied the contribution of the different scattering mechanims on the resistivity. • We developed a discernment method based on thiol adsorption. - Abstract: In order to study the effect of electron-surface scattering in gold ultrathin films (∼10 nm), we have prepared a set of Au samples on mica on top of a chromium seedlayer (<1 nm). Chromium is added as a metallic surfactant which enables surpassing the electric percolation threshold for substrate temperatures above room temperature. We prepared samples with the same thickness but different topographies setting different substrate temperatures. These modifications modulate the contributions of the different electronic scattering mechanisms to the film resistivity. A second set of gold thin films deposited on mica at room temperature, with different thicknesses between 8 and 100 nm, was also prepared to compare the resisitivities of both sets through Mayadas and Shatzkes theory. We found that in samples with thicknesses below 15 nm, the electron-surface scattering is indeed the dominant mechanism influencing the film resistivity. To obtain further evidence of this prevalence, we developed a discrimination method based on thiol adsorption. The film with the highest resistivity increase is the sample in which electron-surface scattering is dominant. With this method, we observed that a large enhancement of the electron-surface scattering not only occurs in samples with large diameters grains, but also if the film has a reduced surface roughness.​.

  13. Atmospheric sensitivity to land surface changes: comparing the impact of albedo, roughness, and evaporative resistance on near-surface air temperature using an idealized land model.

    Science.gov (United States)

    Lague, M. M.; Swann, A. L. S.; Bonan, G. B.

    2017-12-01

    Past studies have demonstrated how changes in vegetation can impact the atmosphere; however, it is often difficult to identify the exact physical pathway through which vegetation changes drive an atmospheric response. Surface properties (such as vegetation color, or height) control surface energy fluxes, which feed back on the atmosphere on both local and global scales by modifying temperatures, cloud cover, and energy gradients. Understanding how land surface properties influence energy fluxes is crucial for improving our understanding of how vegetation change - past, present, and future - impacts the atmosphere, global climate, and people. We explore the sensitivity of the atmosphere to perturbations of three land surface properties - albedo, roughness, and evaporative resistance - using an idealized land model coupled to an Earth System Model. We derive a relationship telling us how large a change in each surface property is required to drive a local 0.1 K change in 2m air temperature. Using this idealized framework, we are able to separate the influence on the atmosphere of each individual surface property. We demonstrate that the impact of each surface property on the atmosphere is spatially variable - that is, a similar change in vegetation can have different climate impacts if made in different locations. This analysis not only improves our understanding of how the land system can influence climate, but also provides us with a set of theoretical limits on the potential climate impact of arbitrary vegetation change (natural or anthropogenic).

  14. The recovery of a time-dependent point source in a linear transport equation: application to surface water pollution

    International Nuclear Information System (INIS)

    Hamdi, Adel

    2009-01-01

    The aim of this paper is to localize the position of a point source and recover the history of its time-dependent intensity function that is both unknown and constitutes the right-hand side of a 1D linear transport equation. Assuming that the source intensity function vanishes before reaching the final control time, we prove that recording the state with respect to the time at two observation points framing the source region leads to the identification of the source position and the recovery of its intensity function in a unique manner. Note that at least one of the two observation points should be strategic. We establish an identification method that determines quasi-explicitly the source position and transforms the task of recovering its intensity function into solving directly a well-conditioned linear system. Some numerical experiments done on a variant of the water pollution BOD model are presented

  15. Protein adsorption resistant surface on polymer composite based on 2D- and 3D-controlled grafting of phospholipid moieties

    International Nuclear Information System (INIS)

    Hoshi, Toru; Matsuno, Ryosuke; Sawaguchi, Takashi; Konno, Tomohiro; Takai, Madoka; Ishihara, Kazuhiko

    2008-01-01

    To prepare the biocompatible surface, a phosphorylcholine (PC) group was introduced on this hydroxyl group generated by surface hydrolysis on the polymer composite composed of polyethylene (PE) and poly (vinyl acetate) (PVAc) prepared by supercritical carbon dioxide. Two different procedures such as two-dimensional (2D) modification and three-dimensional (3D) modification were applied to obtain the steady biocompatible surface. 2D modification was that PC groups were directly anchored on the surface of the polymer composite. 3D modification was that phospholipid polymer was grafted from the surface of the polymer composite by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC). The surfaces were characterized by X-ray photoelectron spectroscopy, dynamic water contact angle measurements, and atomic force microscope. The effects of the poly(MPC) chain length on the protein adsorption resistivity were investigated. The protein adsorption on the polymer composite surface with PC groups modified by 2D or 3D modification was significantly reduced as compared with that on the unmodified PE. Further, the amount of protein adsorbed on the 3D modified surface that is poly(MPC)-grafted surface decreased with an increase in the chain length of the poly(MPC). The surface with an arbitrary structure and the characteristic can be constructed by using 2D and 3D modification. We conclude that the polymer composites of PE/PVAc with PC groups on the surface are useful for fabricating biomedical devices due to their good mechanical and surface properties

  16. Slipping on pedestrian surfaces: methods for measuring and evaluating the slip resistance.

    Science.gov (United States)

    Wetzel, Christoph; Windhövel, Ulrich; Mewes, Detlef; Ceylan, Orhan

    2015-01-01

    Tripping, slipping and falling accidents are among the types of accident with a high incidence. This article describes the requirements concerning slip resistance, as well as the state of the art of slip resistance measurement standards in the European Community and the USA. The article also describes how risk assessment can be performed in the field.

  17. Robust numerical methods for boundary-layer equations for a model problem of flow over a symmetric curved surface

    NARCIS (Netherlands)

    A.R. Ansari; B. Hossain; B. Koren (Barry); G.I. Shishkin (Gregori)

    2007-01-01

    textabstractWe investigate the model problem of flow of a viscous incompressible fluid past a symmetric curved surface when the flow is parallel to its axis. This problem is known to exhibit boundary layers. Also the problem does not have solutions in closed form, it is modelled by boundary-layer

  18. Local instant conservation equations

    International Nuclear Information System (INIS)

    Delaje, Dzh.

    1984-01-01

    Local instant conservation equations for two-phase flow are derived. Derivation of the equation starts from the recording of integral laws of conservation for a fixed reference volume, containing both phases. Transformation of the laws, using the Leibniz rule and Gauss theory permits to obtain the sum of two integrals as to the volume and integral as to the surface. Integrals as to the volume result in local instant differential equations, in particular derivatives for each phase, and integrals as to the surface reflect local instant conditions of a jump on interface surface

  19. Influence of Surface Pretreatment on the Corrosion Resistance of Cold-Sprayed Nickel Coatings in Acidic Chloride Solution

    Science.gov (United States)

    Scendo, Mieczyslaw; Zorawski, Wojciech; Staszewska-Samson, Katarzyna; Makrenek, Medard; Goral, Anna

    2018-03-01

    Corrosion resistance of the cold-sprayed nickel coatings deposited on the Ni surface (substrate) without and with abrasive grit-blasting treatment of the substrate was investigated. The corundum powder with different grain sizes was used. The corrosive environment contained an acidic chloride solution. The mechanism of the corrosion of nickel was suggested and discussed. Corrosion electrochemical parameters were determined by electrochemical methods. The corrosion effect of a nickel coating depends on the grain size used to prepare the substrate. The nickel coating after the medium grit-blasting treatment of the substrate was found to be the most corrosion resistant. However, the smallest resistance on the corrosion effect should be attributed to the nickel coating on the substrate after the coarse grit-blasting treatment.

  20. Fracture resistance of dental nickel-titanium rotary instruments with novel surface treatment: Thin film metallic glass coating.

    Science.gov (United States)

    Chi, Chih-Wen; Deng, Yu-Lun; Lee, Jyh-Wei; Lin, Chun-Pin

    2017-05-01

    Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure. Copyright © 2016. Published by Elsevier B.V.

  1. Fabrication of ZIF-8@SiO2 Micro/Nano Hierarchical Superhydrophobic Surface on AZ31 Magnesium Alloy with Impressive Corrosion Resistance and Abrasion Resistance.

    Science.gov (United States)

    Wu, Cuiqing; Liu, Qi; Chen, Rongrong; Liu, Jingyuan; Zhang, Hongsen; Li, Rumin; Takahashi, Kazunobu; Liu, Peili; Wang, Jun

    2017-03-29

    Superhydrophobic coatings are highly promising for protecting material surfaces and for wide applications. In this study, superhydrophobic composites, comprising a rhombic-dodecahedral zeolitic imidazolate framework (ZIF-8@SiO 2 ), have been manufactured onto AZ31 magnesium alloy via chemical etching and dip-coating methods to enhance stability and corrosion resistance. Herein, we report on a simple strategy to modify hydrophobic hexadecyltrimethoxysilan (HDTMS) on ZIF-8@SiO 2 to significantly improve the property of repelling water. We show that various liquids can be stable on its surface and maintain a contact angle higher than 150°. The morphologies and chemical composition were characterized by means of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FI-IR). In addition, the anticorrosion and antiattrition properties of the film were assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization and HT, respectively. Such a coating shows promising potential as a material for large-scale fabrication.

  2. Kinetic model framework for aerosol and cloud surface chemistry and gas-particle interactions - Part 1: General equations, parameters, and terminology

    Science.gov (United States)

    Pöschl, U.; Rudich, Y.; Ammann, M.

    2007-12-01

    Aerosols and clouds play central roles in atmospheric chemistry and physics, climate, air pollution, and public health. The mechanistic understanding and predictability of aerosol and cloud properties, interactions, transformations, and effects are, however, still very limited. This is due not only to the limited availability of measurement data, but also to the limited applicability and compatibility of model formalisms used for the analysis, interpretation, and description of heterogeneous and multiphase processes. To support the investigation and elucidation of atmospheric aerosol and cloud surface chemistry and gas-particle interactions, we present a comprehensive kinetic model framework with consistent and unambiguous terminology and universally applicable rate equations and parameters. It enables a detailed description of mass transport and chemical reactions at the gas-particle interface, and it allows linking aerosol and cloud surface processes with gas phase and particle bulk processes in systems with multiple chemical components and competing physicochemical processes. The key elements and essential aspects of the presented framework are: a simple and descriptive double-layer surface model (sorption layer and quasi-static layer); straightforward flux-based mass balance and rate equations; clear separation of mass transport and chemical reactions; well-defined and consistent rate parameters (uptake and accommodation coefficients, reaction and transport rate coefficients); clear distinction between gas phase, gas-surface, and surface-bulk transport (gas phase diffusion, surface and bulk accommodation); clear distinction between gas-surface, surface layer, and surface-bulk reactions (Langmuir-Hinshelwood and Eley-Rideal mechanisms); mechanistic description of concentration and time dependences (transient and steady-state conditions); flexible addition of unlimited numbers of chemical species and physicochemical processes; optional aggregation or resolution

  3. Electrical resistivity dynamics beneath a fractured sedimentary bedrock riverbed in response to temperature and groundwater–surface water exchange

    Directory of Open Access Journals (Sweden)

    C. M. Steelman

    2017-06-01

    Full Text Available Bedrock rivers occur where surface water flows along an exposed rock surface. Fractured sedimentary bedrock can exhibit variable groundwater residence times, anisotropic flow paths, and heterogeneity, along with diffusive exchange between fractures and rock matrix. These properties of the rock will affect thermal transients in the riverbed and groundwater–surface water exchange. In this study, surface electrical methods were used as a non-invasive technique to assess the scale and temporal variability of riverbed temperature and groundwater–surface water interaction beneath a sedimentary bedrock riverbed. Conditions were monitored at a semi-daily to semi-weekly interval over a full annual period that included a seasonal freeze–thaw cycle. Surface electromagnetic induction (EMI and electrical resistivity tomography (ERT methods captured conditions beneath the riverbed along a pool–riffle sequence of the Eramosa River in Canada. Geophysical datasets were accompanied by continuous measurements of aqueous specific conductance, temperature, and river stage. Time-lapse vertical temperature trolling within a lined borehole adjacent to the river revealed active groundwater flow zones along fracture networks within the upper 10 m of rock. EMI measurements collected during cooler high-flow and warmer low-flow periods identified a spatiotemporal riverbed response that was largely dependent upon riverbed morphology and seasonal groundwater temperature. Time-lapse ERT profiles across the pool and riffle sequence identified seasonal transients within the upper 2 and 3 m of rock, respectively, with spatial variations controlled by riverbed morphology (pool versus riffle and dominant surficial rock properties (competent versus weathered rock rubble surface. While the pool and riffle both exhibited a dynamic resistivity through seasonal cooling and warming cycles, conditions beneath the pool were more variable, largely due to the formation of river

  4. Effects of the different frequencies and loads of ultrasonic surface rolling on surface mechanical properties and fretting wear resistance of HIP Ti–6Al–4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, G., E-mail: ligang_scut@outlook.com; Qu, S.G., E-mail: qusg@scut.edu.cn; Pan, Y.X.; Li, X.Q.

    2016-12-15

    Highlights: • Effects of MUSR frequency and load on surface properties of HIP Ti-6Al-4V investigated. • The grains in surface-modified layer were refined and appeared twins and many dense dislocations. • The hardened layer depth and surface residual stress of MUSR- treated samples were significantly improved. • MUSR- treated samples showed the good fretting friction and wear resistance. • The best microstructure and properties of surface-modified layer obtained by sample treated by 30 kHz and 900 N. - Abstract: The main purpose of this paper was to investigate the effects of the different frequencies and loads of multi-pass ultrasonic surface rolling (MUSR) on surface layer mechanical properties, microstructure and fretting friction and wear characteristics of HIP (hot isostatic pressing) Ti–6Al–4 V alloy. Some microscopic analysis methods (SEM, TEM and EDS) were used to characterize the modified surface layer of material after MUSR treatment. The results indicated that the material in sample surface layer experienced a certain extent plastic deformation, and accompanied by some dense dislocations and twins generation. Moreover surface microhardness and residual stress of samples treated by MUSR were also greatly improved compared with the untreated. The fretting friction and wear properties of samples treated by MUSR in different conditions are tested at 10 and 15 N in dry friction conditions. It could be found that friction coefficient and wear volume loss were significantly declined in the optimal result. The main wear mechanism of MUSR-treated samples included abrasive wear, adhesion and spalling.

  5. Effect of surface fields on the dynamic resistance of planar HgCdTe mid-wavelength infrared photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    He, Kai; Wang, Xi; Zhang, Peng; Chen, Yi-Yu [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhou, Song-Min; Xie, Xiao-Hui; Lin, Chun, E-mail: chun-lin@mail.sitp.ac.cn; Ye, Zhen-Hua; Wang, Jian-Xin; Zhang, Qin-Yao, E-mail: qinyao@mail.sitp.ac.cn [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Yang [Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-05-28

    This work investigates the effect of surface fields on the dynamic resistance of a planar HgCdTe mid-wavelength infrared photodiode from both theoretical and experimental aspects, considering a gated n-on-p diode with the surface potential of its p-region modulated. Theoretical models of the surface leakage current are developed, where the surface tunnelling current in the case of accumulation is expressed by modifying the formulation of bulk tunnelling currents, and the surface channel current for strong inversion is simulated with a transmission line method. Experimental data from the fabricated devices show a flat-band voltage of V{sub FB}=−5.7 V by capacitance-voltage measurement, and then the physical parameters for bulk properties are determined from the resistance-voltage characteristics of the diode working at a flat-band gate voltage. With proper values of the modeling parameters such as surface trap density and channel electron mobility, the theoretical R{sub 0}A product and corresponding dark current calculated from the proposed model as functions of the gate voltage V{sub g} demonstrate good consistency with the measured values. The R{sub 0}A product remarkably degenerates when V{sub g} is far below or above V{sub FB} because of the surface tunnelling current or channel current, respectively; and it attains the maximum value of 5.7×10{sup 7} Ω · cm{sup 2} around the transition between surface depletion and weak inversion when V{sub g}≈−4 V, which might result from reduced generation-recombination current.

  6. Ray-tracing traveltime tomography versus wave-equation traveltime inversion for near-surface seismic land data

    KAUST Repository

    Fu, Lei

    2017-05-11

    Full-waveform inversion of land seismic data tends to get stuck in a local minimum associated with the waveform misfit function. This problem can be partly mitigated by using an initial velocity model that is close to the true velocity model. This initial starting model can be obtained by inverting traveltimes with ray-tracing traveltime tomography (RT) or wave-equation traveltime (WT) inversion. We have found that WT can provide a more accurate tomogram than RT by inverting the first-arrival traveltimes, and empirical tests suggest that RT is more sensitive to the additive noise in the input data than WT. We present two examples of applying WT and RT to land seismic data acquired in western Saudi Arabia. One of the seismic experiments investigated the water-table depth, and the other one attempted to detect the location of a buried fault. The seismic land data were inverted by WT and RT to generate the P-velocity tomograms, from which we can clearly identify the water table depth along the seismic survey line in the first example and the fault location in the second example.

  7. Influence of gas-powder laser cladding’s technological parameters on structural characteristics of corrosion-resistant steels’ restored surface layer

    Science.gov (United States)

    Krylova, S. E.; Oplesnin, S. P.; Goltyapin, M. I.

    2018-03-01

    The results of the developed industrial technology for surface restoration of corrosion-resistant steels by laser surfacing are presented in the article. A comparative analysis of the microstructure of the welded wear-resistant layer, the fusion zone with the base material and the diffusion zone for different technological surfacing regimes are given. Dyrometric studies and nondestructive testing of the deposited layer for defects were performed

  8. Self-assembled thin film of imidazolium ionic liquid on a silicon surface: Low friction and remarkable wear-resistivity

    International Nuclear Information System (INIS)

    Gusain, Rashi; Kokufu, Sho; Bakshi, Paramjeet S.; Utsunomiya, Toru; Ichii, Takashi; Sugimura, Hiroyuki; Khatri, Om P.

    2016-01-01

    Graphical abstract: - Highlights: • Ionic liquid thin film is deposited on a silicon surface via covalent interaction. • Chemical and morphological features of ionic liquid thin film are probed by XPS and AFM. • Ionic liquid thin film exhibited low and steady friction along with remarkable wear-resistivity. - Abstract: Imidazolium-hexafluorophosphate (ImPF_6) ionic liquid thin film is prepared on a silicon surface using 3-chloropropyltrimethoxysilane as a bifunctional chemical linker. XPS result revealed the covalent grafting of ImPF_6 thin film on a silicon surface. The atomic force microscopic images demonstrated that the ImPF_6 thin film is composed of nanoscopic pads/clusters with height of 3–7 nm. Microtribological properties in terms of coefficient of friction and wear-resistivity are probed at the mean Hertzian contact pressure of 0.35–0.6 GPa under the rotational sliding contact. The ImPF_6 thin film exhibited low and steady coefficient of friction (μ = 0.11) along with remarkable wear-resistivity to protect the underlying silicon substrate. The low shear strength of ImPF_6 thin film, the covalent interaction between ImPF_6 ionic liquid thin film and underlying silicon substrate, and its regular grafting collectively reduced the friction and improved the anti-wear property. The covalently grafted ionic liquid thin film further shows immense potential to expand the durability and lifetime of M/NEMS based devices with significant reduction of the friction.

  9. Correlation between antibiotic and biocide resistance in mesophilic and psychrotrophic Pseudomonas spp. isolated from slaughterhouse surfaces throughout meat chain production.

    Science.gov (United States)

    Lavilla Lerma, Leyre; Benomar, Nabil; Casado Muñoz, María del Carmen; Gálvez, Antonio; Abriouel, Hikmate

    2015-10-01

    The aim of this study was to evaluate biocide susceptibility in mesophilic and psychrotrophic pseudomonads isolated from surfaces of a goat and lamb slaughterhouse, which was representative of the region. To determine biocide resistance in pseudomonads, we determined for the first time the epidemiological cut-off values (ECOFFs) of benzalkonium, cetrimide, chlorhexidine, hexachlorophene, P3 oxonia, polyhexamethylene guanidine hydrochloride (PHMG), topax 66 and triclosan being generally very similar in different Pseudomonas spp. with some exceptions. Thus, resistance of pseudomonads was mainly shown to triclosan, and in lesser extent to cetrimide and benzalkonium chloride depending on the species, however they were highly susceptible to industrial formulations of biocides. By means of statistical analysis, positive correlations between antibiotics, biocides and both antimicrobials in pseudomonads were detected suggesting a co- or cross resistance between different antimicrobials in goat and lamb slaughterhouse environment. Cross-resistance between biocides and antibiotics in pseudomonads were especially detected between PHMG or triclosan and different antibiotics depending on the biocide and the population type. Thus, the use of those biocides as disinfectant in slaughterhouse zones must be carefully evaluated because of the selection pressure effect of antimicrobials on the emergence of resistant bacteria which could be spread to the consumer. It is noteworthy that specific industrial formulations such as topax 66 and oxonia P3 showed few correlations with antibiotics (none or 1-2 antibiotics) which should be taken into consideration for disinfection practices in goat and lamb slaughterhouse. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Prevalence of bacteria resistant to antibiotics and/or biocides on meat processing plant surfaces throughout meat chain production.

    Science.gov (United States)

    Lavilla Lerma, Leyre; Benomar, Nabil; Gálvez, Antonio; Abriouel, Hikmate

    2013-02-01

    In order to investigate the prevalence of resistant bacteria to biocides and/or antibiotics throughout meat chain production from sacrifice till end of production line, samples from various surfaces of a goat and lamb slaughterhouse representative of the region were analyzed by the culture dependent approach. Resistant Psychrotrophs (n=255 strains), Pseudomonas sp. (n=166 strains), E. coli (n=23 strains), Staphylococcus sp. (n=17 strains) and LAB (n=82 represented mainly by Lactobacillus sp.) were isolated. Resistant psychrotrophs and pseudomonads (47 and 29%, respectively) to different antimicrobials were frequently detected in almost all areas of meat processing plant regardless the antimicrobial used, although there was a clear shift in the spectrum of other bacterial groups and for this aim such resistance was determined according to several parameters: antimicrobial tested, sampling zone and the bacterial group. Correlation of different parameters was done using a statistical tool "Principal component analysis" (PCA) which determined that quaternary ammonium compounds and hexadecylpyridinium were the most relevant biocides for resistance in Pseudomonas sp., while ciprofloxacin and hexachlorophene were more relevant for psychrotrophs, LAB, and in lesser extent Staphylococcus sp. and Escherichia coli. On the other hand, PCA of sampling zones determined that sacrifice room (SR) and cutting room (CR) considered as main source of antibiotic and/or biocide resistant bacteria showed an opposite behaviour concerning relevance of antimicrobials to determine resistance being hexadecylpyridinium, cetrimide and chlorhexidine the most relevant in CR, while hexachlorophene, oxonia 6P and PHMG the most relevant in SR. In conclusion, rotational use of the relevant biocides as disinfectants in CR and SR is recommended in an environment which is frequently disinfected. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Surface resistivity test evaluation as an indicator of the chloride permeability of concrete.

    Science.gov (United States)

    2012-12-01

    Many agencies have adopted the standard tests for electrical : indication of concretes ability to resist chloride ion penetration : (AASHTO T 277 and ASTM C1202), commonly known as the rapid : chloride permeability test (RCPT), in their specificat...

  12. Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO2 composite coating

    Science.gov (United States)

    Obadele, Babatunde Abiodun; Andrews, Anthony; Mathew, Mathew T.; Olubambi, Peter Apata; Pityana, Sisa

    2015-08-01

    Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H2SO4 solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO2 cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO2 particles. The results obtained show that addition of ZrO2 improves the corrosion resistance property of TiNi coating but decrease the tribocorrosion resistance property. The surface hardening effect induced by ZrO2 addition, combination of high hardness of Ti2Ni phase could be responsible for the mechanical degradation and chemical wear under sliding conditions.

  13. Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO2 composite coating

    International Nuclear Information System (INIS)

    Obadele, Babatunde Abiodun; Andrews, Anthony; Mathew, Mathew T.; Olubambi, Peter Apata; Pityana, Sisa

    2015-01-01

    Highlights: • The tribocorrosion behaviour of TiNiZrO 2 composite is investigated. • The effect of ZrO 2 on the microstructure is discussed. • The effect of the combined action of wear and chemical process is reported. • ZrO 2 addition improved the tribocorrosion property of Ti6Al4V. - Abstract: Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H 2 SO 4 solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO 2 cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO 2 particles. The results obtained show that addition of ZrO 2 improves the corrosion resistance property of TiNi coating but decrease the tribocorrosion resistance property. The surface hardening effect induced by ZrO 2 addition, combination of high hardness of Ti 2 Ni phase could be responsible for the mechanical degradation and chemical wear under sliding conditions

  14. Er,Cr:YSGG Laser Energy Delivery: Pulse and Power Effects on Enamel Surface and Erosive Resistance.

    Science.gov (United States)

    de Oliveira, Renan Mota; de Souza, Vinicius Matsuzaki; Esteves, Camila Machado; de Oliveira Lima-Arsati, Ynara Bosco; Cassoni, Alessandra; Rodrigues, José Augusto; Brugnera Junior, Aldo

    2017-11-01

    High power lasers have been suggested as a useful tool for dental caries and erosion prevention due to the increase of enamel acid resistance. to evaluate the effect of Er,Cr:YSGG (erbium,chromium:yttrium, scandium, gallium, garnet) laser irradiation pulse frequency and power on enamel surface and acid erosion resistance. By combining pulse frequency (5-75 Hz) and power settings (0.10-1.00 W), 20 irradiated groups and one nonirradiated control group were tested. A total of 63 bovine enamel blocks (n = 3/group) were prepared for surface hardness and roughness evaluation, performed in three phases: baseline, after irradiation, and after erosive challenge. Enamel blocks were irradiated with Er,Cr:YSGG laser with MZ8 tip (iPlus; Waterlase, Biolase, CA) for 30 sec according to experimental group and submitted. Erosive challenge consisted of four cycles alternating immersion in 0.01 M HCl (5 mL/mm 2 ; 2 min; at 37°C) and immersion in artificial saliva for 3 h. Analysis of variance (three-way ANOVA), Tukey's test, and Pearson correlation were performed for the statistical analysis (p hardness. After erosive challenge, 5 and 75 W groups showed increase in surface hardness; 0.25, 0.5, 0.75, and 1 W groups showed minor alterations in surface roughness. the irradiation of Er,Cr:YSGG laser with different parameters of power and pulse frequency settings may alter enamel surface and erosive resistance differently. Pulse frequency of 30 Hz and power of 0.50 W was considered the best parameter to prevent enamel acid erosion.

  15. On Dust Charging Equation

    OpenAIRE

    Tsintsadze, Nodar L.; Tsintsadze, Levan N.

    2008-01-01

    A general derivation of the charging equation of a dust grain is presented, and indicated where and when it can be used. A problem of linear fluctuations of charges on the surface of the dust grain is discussed.

  16. Preparation of protein- and cell-resistant surfaces by hyperthermal hydrogen induced cross-linking of poly(ethylene oxide).

    Science.gov (United States)

    Bonduelle, Colin V; Lau, Woon M; Gillies, Elizabeth R

    2011-05-01

    The functionalization of surfaces with poly(ethylene oxide) (PEO) is an effective means of imparting resistance to the adsorption of proteins and the attachment and growth of cells, properties that are critical for many biomedical applications. In this work, a new hyperthermal hydrogen induced cross-linking (HHIC) method was explored as a simple one-step approach for attaching PEO to surfaces through the selective cleavage of C-H bonds and subsequent cross-linking of the resulting carbon radicals. In order to study the effects of the process on the polymer, PEO-coated silicon wafers were prepared and the effects of different treatment times were investigated. Subsequently, using an optimized treatment time and a modified butyl polymer with increased affinity for PEO, the technique was applied to butyl rubber surfaces. All of the treated surfaces exhibited significantly reduced protein adsorption and cell growth relative to control surfaces and compared favorably with surfaces that were functionalized with PEO using conventional chemical methods. Thus HHIC is a simple and effective means of attaching PEO to non-functional polymer surfaces.

  17. [The influence of autoclave sterilization on surface characteristics and cyclic fatigue resistance of 3 nickel-titanium rotary instruments].

    Science.gov (United States)

    Li, Xiang-fen; Zheng, Ping; Xu, Li; Su, Qin

    2015-12-01

    To investigate the effects of autoclave sterilization on surface characteristics and cyclic fatigue resistance of 3 types of nickel-titanium rotary instruments (K3, Mtwo, ProTaper). Three brands of NiTi rotary endodontic instruments of the same size (tip diameter 0.25 mm and constant 0.06 taper) were selected: K3, Mtwo and Protaper (F2). 24 instruments for each brand were used to evaluate the effects of autoclave sterilization on inner character in the as-received condition and after subjection to 0, 1, 5, and 10 sterilization cycles (6 for each group). Time to fracture (TtF) from the start of the test to the moment of file breakage and the length of the fractured fragment were recorded. Means and standard deviations of TtF and fragment length were calculated. The data was analyzed with SPSS13.0 software package. Another 12 NiTi rotary instruments for each brand were used, 6 subjected to 10 autoclave sterilization cycles and the other as control. Scanning electron microscope was used to observe the changes in surface topography and inner character. For cyclic fatigue resistance, when sterilization was not performed, K3 showed the highest value of TtF means and ProTaper the lowest. The differences between each brand were statistically significant (Pinstruments were intensified greatly after 10 cycles of sterilization. Cycle fatigue resistance is different among instruments of different brands. Autoclave sterilization may increase fatigue resistance of the 3 brands. Autoclave sterilization may increase the surface roughness and inner defects in cross section.

  18. The Interface Structure of High-Temperature Oxidation-Resistant Aluminum-Based Coatings on Titanium Billet Surface

    Science.gov (United States)

    Xu, Zhefeng; Rong, Ju; Yu, Xiaohua; Kun, Meng; Zhan, Zhaolin; Wang, Xiao; Zhang, Yannan

    2017-10-01

    A new type of high-temperature oxidation-resistant aluminum-based coating, on a titanium billet surface, was fabricated by the cold spray method, at a high temperature of 1050°C, for 8 h, under atmospheric pressure. The microstructure of the exposed surface was analyzed via optical microscopy, the microstructure of the coating and elemental diffusion was analyzed via field emission scanning electron microscopy, and the interfacial phases were identified via x-ray diffraction. The Ti-Al binary phase diagram and Gibbs free energy of the stable phase were calculated by Thermo-calc. The results revealed that good oxidation resistant 50-μm-thick coatings were successfully obtained after 8 h at 1050°C. Two layers were obtained after the coating process: an Al2O3 oxidation layer and a TiAl3 transition layer on the Ti-based substrate. The large and brittle Al2O3 grains on the surface, which can be easily spalled off from the surface after thermal processing, protected the substrate against oxidation during processing. In addition, the thermodynamic calculation results were in good agreement with the experimental data.

  19. Laser surface alloying of aluminium with WC+Co+NiCr for improved wear resistance

    CSIR Research Space (South Africa)

    Nath, S

    2012-03-01

    Full Text Available from any defects like micro-porosities or cracks. Furthermore, the average surface roughness was increased from 7.5 ?m to 15 ?m when the scan speed of laser was decreased from 0.04 to 0.012 m/s. The increased surface roughness at a lower scan speed... width from one corner to other evidences that there is no deflection of laser beam. Presence of micro-pores was also observed on the surface with the presence of few unmelted particles on the surface causing formation of rough surface. The defect...

  20. Nano-TiO2-based photocatalytic disinfection of environmental surfaces contaminated by meticillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Petti, S; Messano, G A

    2016-05-01

    Traditional cleaning and disinfection methods are inefficient for complete decontamination of hospital surfaces from meticillin-resistant Staphylococcus aureus (MRSA). Additional methods, such as nano-TiO2-based photocatalytic disinfection (PCD), could be helpful. To evaluate anti-MRSA activity of PCD on polyvinyl chloride (PVC) surfaces in natural-like conditions. Two identical PVC surfaces were used, and nano-TiO2 was incorporated into one of them. The surfaces were contaminated with MRSA isolated from hospitalized patients using a mist sprayer to simulate the mode of environmental contamination caused by a carrier. MRSA cell density was assessed before contamination until 180min after contamination using Rodac plates. The differences between test and control surfaces in terms of MRSA density and log MRSA density reduction were assessed using parametric and non-parametric statistical tests. Five strains were tested, and each strain was tested five times. The highest median MRSA densities [46.3 and 43.1 colony-forming units (cfu)/cm(2) for control and test surfaces, respectively] were detected 45min after contamination. Median MRSA densities 180min after contamination were 10.1 and 0.7cfu/cm(2) for control and test surfaces, respectively (Pdisinfectant activity remained stable throughout the 25 testing occasions, despite between-test cleaning and disinfection. The anti-MRSA activity of PCD was compatible with the benchmark for surface hygiene in hospitals (surfaces. However, for clinical surfaces, PCD should be regarded as supplemental to conventional decontamination procedures, rather than an alternative. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  1. Effect of filling surface-treated pyrolytic char on resistivity of rubber films

    Directory of Open Access Journals (Sweden)

    Pattraporn Yamkaya

    2015-03-01

    Full Text Available In this research, natural rubber (NR films filled with pyrolytic tire char, carbon black N234 and N330 were compared for their electrical resistivity. The filler loading was varied to be 5, 10, 15, 20 and 25% of dry rubber content. The effect of surfactant which is 2 %w/v sodium dodecyl sulfate (SDS was also investigated. In the experiments, it was necessary to disperse the pyrolytic char in ethyl alcohol while disperse carbon black (CB in ammonium hydroxide solution prior to mixing with the rubber latex and the filled NR film was prepared by casting the mixture on a plate. It was found that increasing the amount of pyrolytic char in the NR film could lower its resistivity. The surfactant, SDS, could help better dispersion of both CB and pyrolytic char, thereby decreasing the resistivity. In a separate experiment where hexane vapor was absorbed in NR film without surfactant, in the first 30 seconds, the rate of increasing resistivity of the CB-filled film was not seen as clearly as that of pyrolytic-char-filled film. For the films with surfactant, the slow increase in resistivity of the NR films filled with N330 and pyrolytic char during adsorbing hexane vapor was observed.

  2. Flocked nylon swabs versus RODAC plates for detection of multidrug-resistant organisms on environmental surfaces in intensive care units.

    Science.gov (United States)

    Okamoto, K; Rhee, Y; Schoeny, M; Lolans, K; Cheng, J; Reddy, S; Weinstein, R A; Hayden, M K; Popovich, K J

    2018-01-01

    To compare two culture methods [nylon fiber flocked swabs with broth enrichment versus RODAC ('replicate organism detection and counting') plates] for recovery of multidrug-resistant organisms, 780 environmental surfaces in 63 rooms of patients on contact precautions in four intensive care units at one hospital were examined. Among sites that had at least one positive culture, swab culture with broth enrichment detected the target organisms more frequently than RODAC plates (37.5% vs 26.0%, P = 0.06). There was moderate agreement between the two methods (κ = 0.44) with agreement better for small or flat surfaces compared to large or irregular surfaces. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  3. Novel strategy in increasing stability and corrosion resistance for super-hydrophobic coating on aluminum alloy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yin Bo [Department of Applied Physics, Chongqing University, Chongqing, 400044 (China); Fang Liang, E-mail: fangliangcqu@yahoo.com.cn [Department of Applied Physics, Chongqing University, Chongqing, 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing, 400044 (China); Tang Anqiong; Huang Qiuliu; Hu Jia; Mao Jianhui [Department of Applied Physics, Chongqing University, Chongqing, 400044 (China); Bai, Ge; Bai, Huan [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing, 400044 (China)

    2011-10-15

    A novel super-hydrophobic coating was prepared by chemical modification on the anodized aluminum alloy surface. The surface structure was characterized by water contact angle measurement, scanning electron microscopy (SEM), and the composition was measured by X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the super-hydrophobic coating was evaluated by the polarization curve and the electrochemical impedance spectroscopy (EIS). It was found that the static water contact angle on the surface of super-hydrophobic coating was as high as 167.7 {+-} 1.2 deg., and the sliding angle was 5 deg. The super-hydrophobic coating resulted in excellent corrosion resistance property and the super-hydrophobic coating showed a good stability.

  4. Traffic accidents and road surface skidding resistance : an investigation into the statistical relationship between the skidding resistance of the road surface and relative road risk. Summary of the research report of Sub-committee V of the Working Group on Tyres, Road Surfaces and Skidding Accidents of the Institute for Road Safety Research, SWOV

    NARCIS (Netherlands)

    Schlösser, L.H.M

    1975-01-01

    This study forms part of an extended research programme of the Working Group on Tyres, Road-surfaces and Skidding accidents. According to the terms of reference a statistical relationship had to be established between the skidding resistance of a road-surface and the number of accidents per million

  5. Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Huihui; Qian, Bin; Zhang, Wei [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); Lan, Minbo, E-mail: minbolan@ecust.edu.cn [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2016-02-15

    Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm{sup 2}, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

  6. Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Yuan, Huihui; Qian, Bin; Zhang, Wei; Lan, Minbo

    2016-01-01

    Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm"2, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

  7. Investigation of γ-(2,3-Epoxypropoxypropyltrimethoxy Silane Surface Modified Layered Double Hydroxides Improving UV Ageing Resistance of Asphalt

    Directory of Open Access Journals (Sweden)

    Canlin Zhang

    2017-01-01

    Full Text Available γ-(2,3-Epoxypropoxypropyltrimethoxy silane surface modified layered double hydroxides (KH560-LDHs were prepared and used to improve the ultraviolet ageing resistance of asphalt. The results of X-ray photoelectron spectrometry (XPS indicated that KH560 has been successfully grafted onto the surface of LDHs. The agglomeration of LDHs particles notably reduced after KH560 surface modification according to scanning electron microscopy (SEM, which implied that the KH560 surface modification was helpful to promote the dispersibility of LDHs in asphalt. Then, the influence of KH560-LDHs and LDHs on the physical and rheological properties of asphalt before and after UV ageing was thoroughly investigated. The storage stability test showed that the difference in softening point (ΔS of LDHs modified asphalt decreased from 0.6 °C to 0.2 °C at an LDHs content of 1% after KH560 surface modification, and the tendency became more pronounced with the increase of LDH content, indicating that KH560 surface modification could improve the stability of LDHs in asphalt. After UV ageing, the viscous modulus (G’’ of asphalt significantly reduced, and correspondingly, the elastic modulus (G’ and rutting factor (G*/sin δ rapidly increased. Moreover, the asphaltene increased and the amount of “bee-like” structures of the asphalt decreased. Compared with LDHs, KH560-LDHs obviously restrained performance deterioration of the asphalt, and helped to relieve the variation of the chemical compositions and morphology of asphalt, which suggested that the improvement of KH560-LDHs on UV ageing resistance of asphalt was superior to LDHs.

  8. Assessing thermal conductivity of composting reactor with attention on varying thermal resistance between compost and the inner surface.

    Science.gov (United States)

    Wang, Yongjiang; Niu, Wenjuan; Ai, Ping

    2016-12-01

    Dynamic estimation of heat transfer through composting reactor wall was crucial for insulating design and maintaining a sanitary temperature. A model, incorporating conductive, convective and radiative heat transfer mechanisms, was developed in this paper to provide thermal resistance calculations for composting reactor wall. The mechanism of thermal transfer from compost to inner surface of structural layer, as a first step of heat loss, was important for improving insulation performance, which was divided into conduction and convection and discussed specifically in this study. It was found decreasing conductive resistance was responsible for the drop of insulation between compost and reactor wall. Increasing compost porosity or manufacturing a curved surface, decreasing the contact area of compost and the reactor wall, might improve the insulation performance. Upon modeling of heat transfers from compost to ambient environment, the study yielded a condensed and simplified model that could be used to conduct thermal resistance analysis for composting reactor. With theoretical derivations and a case application, the model was applicable for both dynamic estimation and typical composting scenario. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. The effect of morphology and surface composition on radiation resistance of heterogeneous material CdS-PbS

    Energy Technology Data Exchange (ETDEWEB)

    Malyar, I. V., E-mail: imalyar@yandex.ru; Stetsyura, S. V., E-mail: stetsyurasv@info.sgu.ru [Chernyshevsky Saratov State University (Russian Federation)

    2011-07-15

    As a result of a complex study of the heterophase photosensitive material CdS-PbS by the methods of scanning electron microscopy and Auger spectrometry, it has been found that the radiation resistance of this material depends on the morphology and phase composition at its surface. It is shown that, as the temperature of annealing is increased, aggregations with predominant content of PbS grow; simultaneously, the composition of these aggregations varies as a consequence of the reaction of substitution of sulfur atoms with oxygen atoms. The latter of the aforementioned processes brings about a decrease in the radiation resistance of the heterophase photosensitive material CdS-PbS, which is accounted for by a decrease in the gettering due to appearance of an intermediate oxidized layer between PbS and CdS. An increase in the sizes and number of spherical aggregations at the surface, which consist of crystallites with predominant content of PbS, brings about an increase in the radiation resistance.

  10. High-Q operation of superconducting rf cavities: Potential impact of thermocurrents on the rf surface resistance

    Directory of Open Access Journals (Sweden)

    J.-M. Vogt

    2015-04-01

    Full Text Available For many new accelerator applications, superconducting radio frequency systems are the enabling technology. In particular for CW applications, much effort is being expended to minimize the power dissipation (surface resistance of niobium cavities. Starting in 2009, we suggested a means of reducing the residual resistance by performing a thermal cycle [O. Kugeler et al., in Proceedings of the 14th International Conference on RF Superconductivity (2009, p. 352], a procedure of warming up a cavity after initial cooldown to about 20 K and cooling it down again. In subsequent studies [J. M. Vogt, O. Kugeler, and J. Knobloch, Phys. Rev. ST Accel. Beams 16, 102002 (2013], this technique was used to manipulate the residual resistance by more than a factor of 2. It was postulated that thermocurrents during cooldown generate additional trapped magnetic flux that impacts the cavity quality factor. Here, we present a more extensive study that includes measurements of two additional passband modes and that confirms the effect. In this paper, we also discuss simulations that support the claim. While the layout of the cavity LHe tank system is cylindrically symmetric, we show that the temperature dependence of the material parameters results in a nonsymmetric current distribution. Hence a significant amount of magnetic flux can be generated at the rf surface.

  11. Stainless Steel Foil with Improved Creep-Resistance for Use in Primary Surface Recuperators for Gas Turbine Engines

    International Nuclear Information System (INIS)

    Browning, P.F.; Fitzpatrick, M.; Grubb, J.F.; Klug, R.C.; Maziasz, P.J.; Montague, J.P.; Painter, R.A.; Swindeman, R.W.

    1998-01-01

    Primary surface recuperators (PSRs) are compact heat-exchangers made from thin-foil type 347 austenitic stainless steel, which boost the efficiency of land-based gas turbine engines. Solar Turbines uses foil folded into a unique corrugated pattern to maximize the primary surface area for efficient heat transfer between hot exhaust gas on one side, and the compressor discharge air on the other side of the foil. Allegheny-Ludlum produces 0.003 - 0.0035 in. thick foil for a range of current turbine engines using PSRs that operate at up to 660 degrees C. Laboratory-scale processing modification experiments recently have demonstrated that dramatic improvements can be achieved in the creep resistance of such typical 347 stainless steel foils. The modified processing enables fine NbC carbide precipitates to develop during creep at 650-700 degrees C, which provides strength even with a fine grain size. Such improved creep-resistance is necessary for advanced turbine systems that will demand greater materials performance and reliability at higher operating conditions. The next challenges are to better understand the nature of the improved creep resistance in these 347 stainless steel foil, and to achieve similar improvements with scale-up to commercial foil production

  12. Electrical resistivity surface for FeO-Fe2O3-P2O5 glasses

    Science.gov (United States)

    Vaughan, J. G.; Kinser, D. L.

    1975-01-01

    The dc electrical properties and microstructure of x(FeO-Fe2O3)-(100-x)P2O5 glasses were investigated up to a maximum of x = 75 mol %. Results indicate that, in general, the minimum resistivity of the glass does not occur at equal Fe(2+) and Fe(3+) concentrations, although for the special case where x = 55 mol % the minimum does occur at Fe(2+)/Fe total = 0.5, as reported by other investigators. Evidence presented shows that the position of the minimum resistivity is a function of total iron content. The minimum shifts to glasses richer in Fe(2+) at higher total iron concentrations.

  13. A FMM-FFT accelerated hybrid volume surface integral equation solver for electromagnetic analysis of re-entry space vehicles

    KAUST Repository

    Yücel, Abdulkadir C.

    2014-07-01

    Space vehicles that re-enter the atmosphere often experience communication blackout. The blackout occurs when the vehicle becomes engulfed in plasma produced by interactions between the vehicle surface and the atmosphere. The plasma often is concentrated in a relatively thin shell around the vehicle, with higher densities near its nose than rear. A less structured, sometimes turbulent plasma wake often trails the vehicle. The plasma shell severely affects the performance of side-mounted antennas as it alters their characteristics (frequency response, gain patterns, axial ratio, and impedance) away from nominal, free-space values, sometimes entirely shielding the antenna from the outside world. The plasma plume/turbulent wake similarly affect the performance of antennas mounted at the back of the vehicle. The electromagnetic characteristics of the thin plasma shell and plume/turbulent wake heavily depend on the type of re-entry trajectory, the vehicle\\'s speed, angles of attack, and chemical composition, as well as environmental conditions. To analyze the antennas\\' performance during blackout and to design robust communication antennas, efficient and accurate simulation tools for charactering the antennas\\' performance along the trajectory are called for.

  14. Re-Inversion of Surface Electrical Resistivity Tomography Data from the Hanford Site B-Complex

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Timothy C.; Wellman, Dawn M.

    2013-05-01

    This report documents the three-dimensional (3D) inversion results of surface electrical resistivity tomography (ERT) data collected over the Hanford Site B-Complex. The data were collected in order to image the subsurface distribution of electrically conductive vadose zone contamination resulting from both planned releases of contamination into subsurface infiltration galleries (cribs, trenches, and tile fields), as well as unplanned releases from the B, BX, and BY tank farms and/or associated facilities. Electrically conductive contaminants are those which increase the ionic strength of pore fluids compared to native conditions, which comprise most types of solutes released into the subsurface B-Complex. The ERT data were collected and originally inverted as described in detail in report RPP-34690 Rev 0., 2007, which readers should refer to for a detailed description of data collection and waste disposal history. Although the ERT imaging results presented in that report successfully delineated the footprint of vadose zone contamination in areas outside of the tank farms, imaging resolution was not optimized due to the inability of available inversion codes to optimally process the massive ERT data set collected at the site. Recognizing these limitations and the potential for enhanced ERT characterization and time-lapse imaging at contaminated sites, a joint effort was initiated in 2007 by the U.S. Department of Energy – Office of Science (DOE-SC), with later support by the Office of Environmental Management (DOE-EM), and the U.S. Department of Defense (DOD), to develop a high-performance distributed memory parallel 3D ERT inversion code capable of optimally processing large ERT data sets. The culmination of this effort was the development of E4D (Johnson et al., 2010,2012) In 2012, under the Deep Vadose Zone Applied Field Research Initiative (DVZ-AFRI), the U.S. Department of Energy – Richland Operations Office (DOE-RL) and CH2M Hill Plateau Remediation

  15. Modulation of resistive switching characteristics for individual BaTiO3 microfiber by surface oxygen vacancies

    Science.gov (United States)

    Miao, Zhilei; Chen, Lei; Zhou, Fang; Wang, Qiang

    2018-01-01

    Different from traditional thin-film BaTiO3 (BTO) RRAM device with planar structure, individual microfiber-shaped RRAM device, showing promising application potentials in the micro-sized non-volatile memory system, has not been investigated so far to demonstrate resistive switching behavior. In this work, individual sol-gel BTO microfiber has been formed using the draw-bench method, followed by annealing in different atmospheres of air and argon, respectively. The resistive switching characteristics of the individual BTO microfiber have been investigated by employing double-probe SEM measurement system, which shows great convenience to test local electrical properties by modulating the contact sites between the W probes and the BTO microfiber. For the sample annealed in air, the average resistive ON/OFF ratio is as high as 108, enhanced about four orders in comparison with the counterpart that annealed in Argon. For the sample annealed in argon ambience, the weakened resistive ON/OFF ratio can be attributed to the increased presence of oxygen vacancies in the surface of BTO fibers, and the underlying electrical conduction mechanisms are also discussed.

  16. An oxygen-insensitive degradable resist for fabricating metallic patterns on highly curved surfaces by UV-nanoimprint lithography.

    Science.gov (United States)

    Hu, Xin; Huang, Shisong; Gu, Ronghua; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

    2014-10-01

    In this paper, an oxygen-insensitive degradable resist for UV-nanoimprint is designed, com-prising a polycyclic degradable acrylate monomer, 2,10-diacryloyloxymethyl-1,4,9,12-tetraoxa-spiro [4.2.4.2] tetradecane (DAMTT), and a multifunctional thiol monomer pentaerythritol tetra(3-mercaptopropionate) (PETMP). The resist can be quickly UV-cured in the air atmosphere and achieve a high monomer conversion of over 98%, which greatly reduce the adhesion force between the resist and the soft mold. High conversion, in company with an adequate Young's modulus (about 1 GPa) and an extremely low shrinkage (1.34%), promises high nanoimprint resolution of sub-50 nm. The cross-linked resist is able to break into linear molecules in a hot acid solvent. As a result, metallic patterns are fabricated on highly curved surfaces via the lift off process without the assistance of a thermoplastic polymer layer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Surface integral formulation of Maxwell's equations for simulation of non-destructive testing by eddy currents. Preliminary study on the implementation of the fast multipole method

    International Nuclear Information System (INIS)

    Lim, T.

    2011-01-01

    To simulate numerically a non-destructive by eddy current testing (NDT-CF), the sensor response can be modeled through a semi-analytical approach by volume integral equations. Faster than the finite element method, this approach is however restricted to the study of plane or cylindrical parts (without taking into account the edge effects) because of the complexity of the expression of the dyadic Green function for more general configurations. However, there is an industrial demand to extend the capabilities of the CF model in complex configurations (deformed plates, edges effects...). We were thus brought to formulate the electromagnetic problem differently, by setting ourselves the goal of maintaining a semi-analytical approach. The surface integral equation (SIE) expresses the volume problem by an equivalent transmission one at the interfaces (2D) between homogeneous sub-domains. This problem is approached by a linear system (by the method of moments), whose number of unknowns is reduced due to the nature of the surfacic mesh. Therefore, this system can be solved by a direct solver for small configurations. That enabled us to treat several various positions of the sensor for only one inversion of the impedance matrix. The numerical results obtained using this formulation involve plates with consideration of edge effects such as edge and corner. They are consistent with results obtained by the finite element method. For larger configurations, we conducted a preliminary study for the adaptation of an acceleration method of the matrix vector product involved in an iterative solver (fast multipole method or FMM) to define the conditions under which the FMM calculation works correctly (accuracy, convergence...) in the NDT's domain. A special attention has been given to the choice of basis functions (which have to satisfy an Hdiv conforming property) and on the evaluation of near interactions (which are weakly singular). (author) [fr

  18. Building unique surface structure on aramid fibers through a green layer-by-layer self-assembly technique to develop new high performance fibers with greatly improved surface activity, thermal resistance, mechanical properties and UV resistance

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Lifang; Yuan, Li; Guan, Qingbao; Gu, Aijuan, E-mail: ajgu@suda.edu.cn; Liang, Guozheng, E-mail: lgzheng@suda.edu.cn

    2017-07-31

    Highlights: • A green technology is setup to build unique surface structure on aramid fiber (AF). • The method is layer-by-layer self-assembling SiO{sub 2} and layered double hydroxide. • The surface of AF is adjustable by controlling the self-assembly cycle number. • New AF has excellent surface activity, anti-UV, thermal and mechanical properties. • The origin behind attractive performances of new AFs was intensively studied. - Abstract: Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of aramid fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO{sub 2} and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91–95%, about 29–14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and

  19. Elements of partial differential equations

    CERN Document Server

    Sneddon, Ian Naismith

    1957-01-01

    Geared toward students of applied rather than pure mathematics, this volume introduces elements of partial differential equations. Its focus is primarily upon finding solutions to particular equations rather than general theory.Topics include ordinary differential equations in more than two variables, partial differential equations of the first and second orders, Laplace's equation, the wave equation, and the diffusion equation. A helpful Appendix offers information on systems of surfaces, and solutions to the odd-numbered problems appear at the end of the book. Readers pursuing independent st

  20. Surface potential measurement on contact resistance of amorphous-InGaZnO thin film transistors by Kelvin probe force microscopy

    Science.gov (United States)

    Han, Zhiheng; Xu, Guangwei; Wang, Wei; Lu, Congyan; Lu, Nianduan; Ji, Zhuoyu; Li, Ling; Liu, Ming

    2016-07-01

    Contact resistance plays an important role in amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). In this paper, the surface potential distributions along the channel have been measured by using Kelvin probe force microscopy (KPFM) on operating a-IGZO TFTs, and sharp potential drops at the edges of source and drain were observed. The source and drain contact resistances can be extracted by dividing sharp potential drops with the corresponding drain to source current. It is found that the contact resistances could not be neglected compared with the whole channel resistances in the a-IGZO TFT, and the contact resistances decrease remarkably with increasing gate biased voltage. Our results suggest that the contact resistances can be controlled by tuning the gate biased voltage. Moreover, a transition from gradual channel approximation to space charge region was observed through the surface potential map directly when TFT operating from linear regime to saturation regime.

  1. Corrosion resistance and durability of superhydrophobic surface formed on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution.

    Science.gov (United States)

    Ishizaki, Takahiro; Masuda, Yoshitake; Sakamoto, Michiru

    2011-04-19

    The corrosion resistant performance and durability of the superhydrophobic surface on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution were investigated using electrochemical and contact angle measurements. The durability of the superhydrophobic surface in corrosive 5 wt% NaCl aqueous solution was elucidated. The corrosion resistant performance of the superhydrophobic surface formed on magnesium alloy was estimated by electrochemical impedance spectroscopy (EIS) measurements. The EIS measurements and appropriate equivalent circuit models revealed that the superhydrophobic surface considerably improved the corrosion resistant performance of magnesium alloy AZ31. American Society for Testing and Materials (ASTM) standard D 3359-02 cross cut tape test was performed to investigate the adhesion of the superhydrophobic film to the magnesium alloy surface. The corrosion formation mechanism of the superhydrophobic surface formed on the magnesium alloy was also proposed. © 2011 American Chemical Society

  2. Direct observations of surface water-groundwater interaction using electrical resistivity tomography

    NARCIS (Netherlands)

    Noell, Ursula; Wießner, Claudia; Ganz, Christina; Westhoff, Martijn

    2011-01-01

    Electrical resistivity tomography is a helpful tool to observe the infiltration process in and through the soil. Array 3-D measurements and 3-D inversion schemes are required for reliable interpretation of heterogeneous subsurface structures. Smoothing of the inversion can be minimized by using

  3. Concrete surface with nano-particle additives for improved wearing resistance to increasing truck traffic.

    Science.gov (United States)

    2012-07-01

    This study focused on the use of nanotechnology in concrete to improve the wearing resistance of concrete. The nano : materials used were polymer cross-linked aerogels, carbon nanotubes, and nano-SiO2, nano-CaCO3, and nano-Al2O3 : particles. As an in...

  4. Spatial and temporal monitoring of soil moisture using surface electrical resistivity tomography in Mediterranean soils

    NARCIS (Netherlands)

    Alamry, Abdulmohsen S.; van der Meijde, Mark; Noomen, Marleen; Addink, Elisabeth A.|info:eu-repo/dai/nl/224281216; van Benthem, Rik; de Jong, Steven M.|info:eu-repo/dai/nl/120221306

    2017-01-01

    ERT techniques are especially promising in (semi-arid) areas with shallow and rocky soils where other methods fail to produce soil moisture maps and to obtain soil profile information. Electrical Resistivity Tomography (ERT) was performed in the Peyne catchment in southern France at four sites

  5. Semi-transparent gold film as simultaneous surface heater and resistance thermometer for nucleate boiling studies

    International Nuclear Information System (INIS)

    Oker, E.; Merte, H. Jr.

    1981-01-01

    A large (22 x 25 mm) semi-transparent thin film of gold, approximately 400 A in thickness, is deposited on a glass substrate for simultaneous use as a heat source and resistance thermometer. Construction techniques and calibration procedures are described, and a sample application to a transient boiling process is included with simultaneous high speed photographs taken through the thin film from beneath

  6. Klebsiella sp. FIRD 2, a TBT-resistant bacterium isolated from contaminated surface sediment along Strait of Johor Malaysia.

    Science.gov (United States)

    Abubakar, Abdussamad; Mustafa, Muskhazli B; Johari, Wan Lutfi Wan; Zulkifli, Syaizwan Zahmir; Ismail, Ahmad; Mohamat-Yusuff, Ferdaus Binti

    2015-12-15

    A possible tributyltin (TBT)-degrading bacterium isolated from contaminated surface sediment was successfully identified as Klebsiella sp. FIRD 2. It was found to be the best isolate capable of resisting TBT at a concentration of 1000 μg L(-1). This was a concentration above the reported contaminated level at the sampling station, 790 μg L(-1). Further studies revealed that the isolate was Gram negative and resisted TBT concentrations of up to 1500 μg L(-1) in a Minimal Salt Broth without the addition of any carbon source within the first 48 h of incubation. It is expected that additional work could be conducted to check the degradation activity of this new isolate and possibly improve the degradation capacity in order to contribute to finding a safe and sustainable remediation solution of TBT contamination. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Erosion resistant anti-ice surfaces generated by ultra short laser pulses

    NARCIS (Netherlands)

    Del Cerro, D.A.; Römer, G.R.B.E.; Huis in't Veld, A.J.

    2010-01-01

    Wetting properties of a wide range of materials can be modified by accurate laser micromachining with ultra short laser pulses. Controlling the surface topography in a micro and sub-micrometer scale allows the generation of water-repellent surfaces, which remain dry and prevent ice accumulation

  8. A novel method to prepare superhydrophobic, UV resistance and anti-corrosion steel surface

    KAUST Repository

    Isimjan, Tayirjan T.; Wang, Taoye; Rohani, Sohrab M F

    2012-01-01

    . The resulting surfaces were modified by the low free energy chemical PTES (1H,1H,2H,2H-Perfluorodecyltriethoxysilane). The experimental results of wettability exhibit that such modified surfaces have a strong repulsive force to water droplets, their static

  9. Multilayer Choline Phosphate Molecule Modified Surface with Enhanced Cell Adhesion but Resistance to Protein Adsorption.

    Science.gov (United States)

    Chen, Xingyu; Yang, Ming; Liu, Botao; Li, Zhiqiang; Tan, Hong; Li, Jianshu

    2017-08-22

    Choline phosphate (CP), which is a new zwitterionic molecule, and has the reverse order of phosphate choline (PC) and could bind to the cell membrane though the unique CP-PC interaction. Here we modified a glass surface with multilayer CP molecules using surface-initiated atom-transfer radical polymerization (SI-ATRP) and the ring-opening method. Polymeric brushes of (dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by SI-ATRP from the glass surface. Then the grafted PDMAEMA brushes were used to introduce CP groups to fabricate the multilayer CP molecule modified surface. The protein adsorption experiment and cell culture test were used to evaluate the biocompatibility of the modified surfaces by using human umbilical veinendothelial cells (HUVECs). The protein adsorption results demonstrated that the multilayer CP molecule decorated surface could prevent the adsorption of fibrinogen and serum protein. The adhesion and proliferation of cells were improved significantly on the multilayer CP molecule modified surface. Therefore, the biocompatibility of the material surface could be improved by the modified multilayer CP molecule, which exhibits great potential for biomedical applications, e.g., scaffolds in tissue engineering.

  10. Influence of desiccation procedures on the surface wettability and corrosion resistance of porous aluminium anodic oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Meng, E-mail: ZhengMeng@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-Ku, Sapporo 060-8628 (Japan); Sakairi, Masatoshi [Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-Ku, Sapporo 060-8628 (Japan); Jha, Himendra [Technische Universitaet Muenchen, Lichtenbergstrasse 4, D-85748 Garching (Germany)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Simple desiccation treatment without coating or etching produces hydrophobicity of porous anodic oxide film. Black-Right-Pointing-Pointer Treatment time can be shortened by controlling desiccation condition. Black-Right-Pointing-Pointer Surface microstructure is the key point to determine the wettability. Black-Right-Pointing-Pointer The hydrophobic surfaces show better corrosion resistance than oxide aluminium. - Abstract: A hydrophobic oxide film was formed on aluminium by anodizing followed by desiccation treatment. Films subjected to gradual heating and cooling exhibit larger water contact angles than samples exposed to fast heating and cooling at the same temperature. From SEM and Auger Electron Spectroscopic observations, the low wettability surface shows a regular porous morphology with no significant chemical composition differences due to the different treatments. The desiccation process improves the corrosion resistance, shown by immersion in NaCl. The change in morphology by the desiccation processes is considered a main reason to lower the wettability, which further affects the corrosion properties.

  11. Surface TRAIL decoy receptor-4 expression is correlated with TRAIL resistance in MCF7 breast cancer cells

    International Nuclear Information System (INIS)

    Sanlioglu, Ahter D; Dirice, Ercument; Aydin, Cigdem; Erin, Nuray; Koksoy, Sadi; Sanlioglu, Salih

    2005-01-01

    Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) selectively induces apoptosis in cancer cells but not in normal cells. Despite this promising feature, TRAIL resistance observed in cancer cells seriously challenged the use of TRAIL as a death ligand in gene therapy. The current dispute concerns whether or not TRAIL receptor expression pattern is the primary determinant of TRAIL sensitivity in cancer cells. This study investigates TRAIL receptor expression pattern and its connection to TRAIL resistance in breast cancer cells. In addition, a DcR2 siRNA approach and a complementary gene therapy modality involving IKK inhibition (AdIKKβKA) were also tested to verify if these approaches could sensitize MCF7 breast cancer cells to adenovirus delivery of TRAIL (Ad5hTRAIL). TRAIL sensitivity assays were conducted using Molecular Probe's Live/Dead Cellular Viability/Cytotoxicity Kit following the infection of breast cancer cells with Ad5hTRAIL. The molecular mechanism of TRAIL induced cell death under the setting of IKK inhibition was revealed by Annexin V binding. Novel quantitative Real Time RT-PCR and flow cytometry analysis were performed to disclose TRAIL receptor composition in breast cancer cells. MCF7 but not MDA-MB-231 breast cancer cells displayed strong resistance to adenovirus delivery of TRAIL. Only the combinatorial use of Ad5hTRAIL and AdIKKβKA infection sensitized MCF7 breast cancer cells to TRAIL induced cell death. Moreover, novel quantitative Real Time RT-PCR assays suggested that while the level of TRAIL Decoy Receptor-4 (TRAIL-R4) expression was the highest in MCF7 cells, it was the lowest TRAIL receptor expressed in MDA-MB-231 cells. In addition, conventional flow cytometry analysis demonstrated that TRAIL resistant MCF7 cells exhibited substantial levels of TRAIL-R4 expression but not TRAIL decoy receptor-3 (TRAIL-R3) on surface. On the contrary, TRAIL sensitive MDA-MB-231 cells displayed very low levels of surface TRAIL-R4

  12. Potential of electrical resistivity tomography and muon density imaging to study spatio-temporal variations in the sub-surface

    Science.gov (United States)

    Lesparre, Nolwenn; Cabrera, Justo; Courbet, Christelle

    2015-04-01

    We explore the capacity of electrical resistivity tomography and muon density imaging to detect spatio-temporal variations of the medium surrounding a regional fault crossing the underground platform of Tournemire (Aveyron, France). The studied Cernon fault is sub-vertical and intersects perpendicularly the tunnel of Tournemire and extends to surface. The fault separates clay and limestones layers of the Dogger from limestones layers of the Lias. The Cernon fault presents a thickness of a ten of meters and drives water from an aquifer circulating at the top of the Dogger clay layer to the tunnel. An experiment combining electrical resistivity imaging and muon density imaging was setup taking advantage of the tunnel presence. A specific array of electrodes were set up, adapted for the characterization of the fault. Electrodes were placed along the tunnel as well as at the surface above the tunnel on both sides of the fault in order to acquire data in transmission across the massif to better cover the sounded medium. Electrical resistivity is particularly sensitive to water presence in the medium and thus carry information on the main water flow paths and on the pore space saturation. At the same time a muon sensor was placed in the tunnel under the fault region to detect muons coming from the sky after their crossing of the rock medium. Since the muon flux is attenuated as function of the quantity of matter crossed, muons flux measurements supply information on the medium average density along muons paths. The sensor presents 961 angles of view so measurements performed from one station allows a comparison of the muon flux temporal variations along the fault as well as in the medium surrounding the fault. As the water saturation of the porous medium fluctuates through time the medium density might indeed present sensible variations as shown by gravimetric studies. During the experiment important rainfalls occurred leading variations of the medium properties

  13. Self-assembled thin film of imidazolium ionic liquid on a silicon surface: Low friction and remarkable wear-resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Gusain, Rashi [CSIR-Indian Institute of Petroleum, Mohkampur, Dehardun 248005 (India); Academy of Scientific and Innovative Research, New Delhi 110025 (India); Kokufu, Sho [Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501 (Japan); Bakshi, Paramjeet S. [CSIR-Indian Institute of Petroleum, Mohkampur, Dehardun 248005 (India); Utsunomiya, Toru; Ichii, Takashi; Sugimura, Hiroyuki [Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501 (Japan); Khatri, Om P., E-mail: opkhatri@iip.res.in [CSIR-Indian Institute of Petroleum, Mohkampur, Dehardun 248005 (India); Academy of Scientific and Innovative Research, New Delhi 110025 (India)

    2016-02-28

    Graphical abstract: - Highlights: • Ionic liquid thin film is deposited on a silicon surface via covalent interaction. • Chemical and morphological features of ionic liquid thin film are probed by XPS and AFM. • Ionic liquid thin film exhibited low and steady friction along with remarkable wear-resistivity. - Abstract: Imidazolium-hexafluorophosphate (ImPF{sub 6}) ionic liquid thin film is prepared on a silicon surface using 3-chloropropyltrimethoxysilane as a bifunctional chemical linker. XPS result revealed the covalent grafting of ImPF{sub 6} thin film on a silicon surface. The atomic force microscopic images demonstrated that the ImPF{sub 6} thin film is composed of nanoscopic pads/clusters with height of 3–7 nm. Microtribological properties in terms of coefficient of friction and wear-resistivity are probed at the mean Hertzian contact pressure of 0.35–0.6 GPa under the rotational sliding contact. The ImPF{sub 6} thin film exhibited low and steady coefficient of friction (μ = 0.11) along with remarkable wear-resistivity to protect the underlying silicon substrate. The low shear strength of ImPF{sub 6} thin film, the covalent interaction between ImPF{sub 6} ionic liquid thin film and underlying silicon substrate, and its regular grafting collectively reduced the friction and improved the anti-wear property. The covalently grafted ionic liquid thin film further shows immense potential to expand the durability and lifetime of M/NEMS based devices with significant reduction of the friction.

  14. Effect of irrigation on surface roughness and fatigue resistance of controlled memory wire nickel-titanium instruments.

    Science.gov (United States)

    Cai, J-J; Tang, X-N; Ge, J-Y

    2017-07-01

    To investigate the effect of irrigation on the surface roughness and fatigue resistance of HyFlex and M3 controlled memory (CM) wire nickel-titanium instruments. Two new files of each brand were analysed by atomic force microscopy (AFM). Then, the instruments were dynamically immersed in either 5.25% sodium hypochlorite (NaOCl) or 17% ethylene diamine tetraacetic acid (EDTA) solution for 10 min, followed by AFM analysis. The roughness average (Ra) and root mean square (RMS) values were analysed statistically using an independent sample t-test. Then, 36 files of each brand were randomly assigned to three groups (n = 12). Group 1 (the control group) was composed of new instruments. Groups 2 and 3 were dynamically immersed in 5.25% NaOCl and 17% EDTA solutions for 10 min, respectively. The number of rotations to failure for various groups was analysed using the one-way analysis of variance software. For M3 files, the Ra and RMS values significantly increased (P  0.05) NaOCl. The resistance to cyclic fatigue of both HyFlex and M3 files did not significantly decrease (P > 0.05) by immersing in 5.25% NaOCl and 17% EDTA solutions. Except the HyFlex files immersed in NaOCl, the surface roughness of other files exposed to irrigants increased. However, a change in the surface tomography of CM wire instruments caused by contact with irrigants for 10 min did not trigger a decrease in cyclic fatigue resistance. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  15. Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis

    International Nuclear Information System (INIS)

    Assis, Sergio Luiz de

    2006-01-01

    In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

  16. Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO{sub 2} composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Obadele, Babatunde Abiodun, E-mail: obadele4@gmail.com [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Andrews, Anthony [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Materials Engineering, Kwame Nkrumah University of Science and Technology, Kumasi-Ghana (Ghana); Mathew, Mathew T. [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of orthopedics, Rush University Medical Center, Chicago, IL 60612 (United States); Olubambi, Peter Apata [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Pityana, Sisa [Institute for NanoEngineering Research, Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); National Laser Center, Council for Scientific and Industrial Research, Pretoria (South Africa)

    2015-08-01

    Highlights: • The tribocorrosion behaviour of TiNiZrO{sub 2} composite is investigated. • The effect of ZrO{sub 2} on the microstructure is discussed. • The effect of the combined action of wear and chemical process is reported. • ZrO{sub 2} addition improved the tribocorrosion property of Ti6Al4V. - Abstract: Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H{sub 2}SO{sub 4} solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO{sub 2} cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO{sub 2} particles. The results obtained show that addition of ZrO{sub 2} improves the corrosion resistance property of TiNi coating but decrease the tribocorrosion resistance property. The surface hardening effect induced by ZrO{sub 2} addition, combination of high hardness of Ti{sub 2}Ni phase could be responsible for the mechanical degradation and chemical wear under sliding conditions.

  17. One-step electrodeposition process to fabricate corrosion-resistant superhydrophobic surface on magnesium alloy.

    Science.gov (United States)

    Liu, Qin; Chen, Dexin; Kang, Zhixin

    2015-01-28

    A simple, one-step method has been developed to construct a superhydrophobic surface by electrodepositing Mg-Mn-Ce magnesium plate in an ethanol solution containing cerium nitrate hexahydrate and myristic acid. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were employed to characterize the surfaces. The shortest electrodeposition time to obtain a superhydrophobic surface was about 1 min, and the as-prepared superhydrophobic surfaces had a maximum contact angle of 159.8° and a sliding angle of less than 2°. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5 wt % aqueous solutions of NaCl, Na2SO4, NaClO3, and NaNO3. Besides, the chemical stability and mechanical durability of the as-prepared superhydrophobic surface were also examined. The presented method is rapid, low-cost, and environmentally friendly and thus should be of significant value for the industrial fabrication of anticorrosive superhydrophobic surfaces and should have a promising future in expanding the applications of magnesium alloys.

  18. Development of low-friction and wear-resistant surfaces for low-cost Al hot stamping tools

    Directory of Open Access Journals (Sweden)

    Dong Y.

    2015-01-01

    Full Text Available In this study, advanced surfaces and coatings have been developed using plasma thermochemical treatment, PVD coating, electroless Ni-BN plating and duplex surface engineering to produce low-friction and wear-resistant surfaces for cast iron stamping tools. Their microstructural and nano-mechanical properties were systematically analysed and the tribological behaviour of these new surfaces and coatings were evaluated. The experimental results have shown that under dry sliding condition, the tribological behaviour of aluminium differed great from that of steel regardless of the counterpart material. Highly reactive aluminium had a strong tendency to solder with tool surfaces during dry sliding. However, the lubricity of gray cast irons can be significantly improved by Ni-BN and DLC coatings. The coefficient of friction reduced from about 0.5 for untreated cast irons to about 0.2 sliding against aluminium. Duplex treatment combining plasma nitrocarburising with low-friction coatings showed superior durability than both DLC and Ni-BN coatings.

  19. Provision of wear resistance and fatigue strength of surfaces during electroerosive processing

    Science.gov (United States)

    Fedonin, O. N.; Syanov, S. Yu; Papikyan, A. M.

    2018-03-01

    This article is a generalization of the results of theoretical studies of the effect of erosion control regimes on the operational properties of mold-forming parts of molds. The main problem is the provision of wear resistance and fatigue strength in the electroerosion processing of these types of products. The analysis showed that the fatigue strength is affected by the processing regimes and the coefficient after the erosion treatment. The index of wear resistance is determined both by the treatment modes and by the physical-mechanical properties of the billet materials. To ensure the operational performance of products, it is necessary to establish the physical picture of the processing of complex profile parts by finding the optimum eroding regime.

  20. Effect of DC Plasma Electrolytic Oxidation on Surface Characteristics and Corrosion Resistance of Zirconium

    Directory of Open Access Journals (Sweden)

    Maciej Sowa

    2018-05-01

    Full Text Available Zr is a valve metal, the biocompatibility of which is at least on par with Ti. Recently, numerous attempts of the formation of bioactive coatings on Zr by plasma electrolytic oxidation (PEO in solutions that were based on calcium acetate and calcium β-glycerophosphate were made. In this study, the direct current (DC PEO of commercially pure zirconium in the solutions that contained Ca(H2PO22, Ca(HCOO2, and Mg(CH3COO2 was investigated. The treatment was conducted at 75 mA/cm2 up to 200, 300, or 400 V. Five process stages were discerned. The treatment at higher voltages resulted in the formation of oxide layers that had Ca/P or (Mg+Ca/P ratios that were close to that of hydroxyapatite (Ca/P = 1.67, determined by SEM/EDX. The corrosion resistance studies were performed using electrochemical impedance spectroscopy (EIS and DC polarization methods. R(Q[R(QR] circuit model was used to fit the EIS data. In general, the coatings that were obtained at 200 V were the most corrosion resistant, however, they lacked the porous structure, which is typical for PEO coatings, and is sought after in the biomedical applications. The treatment at 400 V resulted in the formation of the coatings that were more corrosion resistant than those that were obtained at 300 V. This was determined mainly by the prevailing plasma regime at the given process voltage. The pitting resistance of Zr was also improved by the treatment, regardless of the applied process conditions.

  1. A molecular study on bacterial resistance to arsenic-toxicity in surface and underground waters of Latium (Italy).

    Science.gov (United States)

    Davolos, Domenico; Pietrangeli, Biancamaria

    2013-10-01

    Latium, a region in central Italy, is known for its extensive volcanic areas that make a significant contribution to the arsenic (As) contamination of freshwater environments, even though some degree of As water pollution may be caused by human activities. The information available on indigenous As-resistant prokaryotes in aquatic environments of Latium is, however, still limited. In this study, we describe new bacteria that are resistant to arsenic toxicity and were isolated from the surface waters of Lake Vico and the Sacco River, two groundwater systems in Latium, as well as from bottled natural mineral water from the same region. The 16S rRNA gene sequence analysis for the As-resistant strains in lake and river waters points to a prevalence of β- and γ-Proteobacteria, while α-Proteobacteria, Firmicutes and Bacteroidetes are represented to a lesser extent. By contrast, solely γ-Proteobacteria were isolated from groundwater samples. The presence of Actinobacteria was documented exclusively in bottled mineral water. In addition, we conducted a DNA sequence-based study on the gene codifying arsB, an As(III) efflux membrane protein pump related to arsenic resistance, for all the As-resistant bacterial isolates. A phylogenetic analysis was carried out on the newly sequenced 16S rRNA genes and arsB in the present study as well as on an additional 16S rRNA/arsB dataset we obtained previously from Lake Albano, from the Tiber and from a well in Bassano Romano located in Latium (Davolos and Pietrangeli, 2011). Overall, the phylogenetic diversity of As-resistant bacteria in underground water was very limited if compared with lentic and lotic waters. Lastly, our molecular data support the hypothesis that the horizontal gene transfer of ars in As-containing freshwater environments is not limited to closely-related genomes, but also occurs between bacteria that are distant from an evolutionary viewpoint, thereby indicating that such genetic events may be considered a

  2. Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

    Energy Technology Data Exchange (ETDEWEB)

    Gajek, M; Lis, J; Partyka, J; Wojczyk, M, E-mail: mgajek@agh.edu.pl [AGH University of Science and Technology, Faculty of Materials Science and Ceramic, al. Mickiewicza 30, 30-059 Cracow (Poland)

    2011-10-29

    The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al{sub 2}O{sub 3}-SiO{sub 2}, have been presented. The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO{sub 2}, ZrO{sub 2}, V{sub 2}O{sub 5} on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined. The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6{approx}8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm{sup 2} (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5{approx}6 GPa and the wear resistance values range from 120 to 200 mg, has been proved. Starting glasses (frits) and glazes of the ternary system MgO-SiO{sub 2}-Al{sub 2}O{sub 3}, were examined with use of DTA, XRD and SEM methods.

  3. Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

    Science.gov (United States)

    Gajek, M.; Lis, J.; Partyka, J.; Wójczyk, M.

    2011-10-01

    The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al2O3-SiO2, have been presented. The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO2, ZrO2, V2O5 on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined. The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6~8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm2 (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5~6 GPa and the wear resistance values range from 120 to 200 mg, has been proved. Starting glasses (frits) and glazes of the ternary system MgO-SiO2-Al2O3, were examined with use of DTA, XRD and SEM methods.

  4. Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

    International Nuclear Information System (INIS)

    Gajek, M; Lis, J; Partyka, J; Wojczyk, M

    2011-01-01

    The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al 2 O 3 -SiO 2 , have been presented. The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO 2 , ZrO 2 , V 2 O 5 on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined. The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6∼8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm 2 (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5∼6 GPa and the wear resistance values range from 120 to 200 mg, has been proved. Starting glasses (frits) and glazes of the ternary system MgO-SiO 2 -Al 2 O 3 , were examined with use of DTA, XRD and SEM methods.

  5. Surge-Resistant Nanocomposite Enameled Wire Using Silica Nanoparticles with Binary Chemical Compositions on the Surface

    Directory of Open Access Journals (Sweden)

    Jeseung Yoo

    2015-01-01

    Full Text Available We developed polyesterimide (PEI nanocomposite enameled wires using surface-modified silica nanoparticles with binary chemical compositions on the surface. The modification was done using silanes assisted by ultrasound, which facilitated high density modification. Two different trimethoxysilanes were chosen for the modification on the basis of resemblance of chemical compositions on the silica surface to PEI varnish. The surface-modified silica was well dispersed in PEI varnish, which was confirmed by optical observation and viscosity measurement. The glass transition temperature of the silica-PEI nanocomposite increased with the silica content. The silica-dispersed PEI varnish was then used for enameled wire fabrication. The silica-PEI nanocomposite enameled wire exhibited a much longer lifetime compared to that of neat PEI enameled wire in partial discharge conditions.

  6. Corrosion resistance of hsla steel after various surface treatments in chloride environment

    Czech Academy of Sciences Publication Activity Database

    Borko, K.; Pastorek, F.; Fintová, Stanislava; Hadzima, B.

    2016-01-01

    Roč. 18, č. 4 (2016), s. 99-102 ISSN 1335-4205 Institutional support: RVO:68081723 Keywords : Corrosion properties * Iron phosphating * S355J steel Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  7. Laser surface alloying of aluminium with WC+Co+NiCr for improved wear resistance

    CSIR Research Space (South Africa)

    Nath, S

    2012-03-01

    Full Text Available Department of Metallurgical & Materials Engineering, IIT Kharagpur, West Bengal, India 2National Laser Centre, CSIR, Pretoria, South Africa Abstract In the present study, laser surface alloying of aluminium with WC+Co+NiCr (in the ratio of 70... be used for dispersion of ceramic materials into metallic matrix and hence, form a ceramic dispersed metal matrix composite on metallic substrate [3]. The advantages of laser surface alloying include refinement of the microstructure, uniform dispersion...

  8. Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base.

    Science.gov (United States)

    Shinawi, Lana Ahmed

    2017-05-01

    The application of computer-aided design computer-aided manufacturing (CAD CAM) technology in the fabrication of complete dentures, offers numerous advantages as it provides optimum fit and eliminates polymerization shrinkage of the acrylic base. Additionally, the porosity and surface roughness of CAD CAM resins is less compared to conventionally processed resins which leads to a decrease in the adhesion of bacteria on the denture base, which is associated with many conditions including halitosis and aspiration pneumonia in elderly denture wearers. To evaluate the influence of tooth brushing with dentifrices on CAD CAM resin blocks in terms of abrasion resistance, surface roughness and scanning electron photomicrography. This experimental study was carried out at the Faculty of Dentistry of King Abdulaziz University during 2016. A total of 40 rectangular shaped polymerized CAD CAM resin samples were subjected to 40.000 and 60.000 brushing strokes under a 200-gram vertical load simulating three years of tooth brushing strokes using commercially available denture cleaning dentifrice. Data were analyzed by SPSS version 20, using descriptive statistics and ANOVA. ANOVA test revealed a statistical significant weight loss of CAD CAM acrylic resin denture base specimens following 40.000 and 60.000 brushing strokes as well as a statistical significant change (p=0.0.5) in the surface roughness following brushing. The CAD CAM resin samples SEM baseline imaging revealed a relatively smooth homogenous surface, but following 40,000 and 60,000 brushing strokes, imaging displayed the presence of small scratches on the surface. CAD CAM resin displayed a homogenous surface initially with low surface roughness that was significantly affected following simulating three years of manual brushing, but despite the significant weight loss, the findings are within the clinically acceptable limits.

  9. Targeting glucosylceramide synthase induction of cell surface globotriaosylceramide (Gb3) in acquired cisplatin-resistance of lung cancer and malignant pleural mesothelioma cells

    Energy Technology Data Exchange (ETDEWEB)

    Tyler, Andreas, E-mail: andreas.tyler@medbio.umu.se [Department of Medical Biosciences, Umeå University, S-901 85 Umea (Sweden); Johansson, Anders [Department of Odontology, Umeå University, S-901 85 Umea (Sweden); Karlsson, Terese [Department of Radiation Sciences, Oncology, S-901 85 Umea (Sweden); Gudey, Shyam Kumar; Brännström, Thomas; Grankvist, Kjell; Behnam-Motlagh, Parviz [Department of Medical Biosciences, Umeå University, S-901 85 Umea (Sweden)

    2015-08-01

    Background: Acquired resistance to cisplatin treatment is a caveat when treating patients with non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM). Ceramide increases in response to chemotherapy, leading to proliferation arrest and apoptosis. However, a tumour stress activation of glucosylceramide synthase (GCS) follows to eliminate ceramide by formation of glycosphingolipids (GSLs) such as globotriaosylceramide (Gb3), the functional receptor of verotoxin-1. Ceramide elimination enhances cell proliferation and apoptosis blockade, thus stimulating tumor progression. GSLs transactivate multidrug resistance 1/P-glycoprotein (MDR1) and multidrug resistance-associated protein 1 (MRP1) expression which further prevents ceramide accumulation and stimulates drug efflux. We investigated the expression of Gb3, MDR1 and MRP1 in NSCLC and MPM cells with acquired cisplatin resistance, and if GCS activity or MDR1 pump inhibitors would reduce their expression and reverse cisplatin-resistance. Methods: Cell surface expression of Gb3, MDR1 and MRP1 and intracellular expression of MDR1 and MRP1 was analyzed by flow cytometry and confocal microscopy on P31 MPM and H1299 NSCLC cells and subline cells with acquired cisplatin resistance. The effect of GCS inhibitor PPMP and MDR1 pump inhibitor cyclosporin A for 72 h on expression and cisplatin cytotoxicity was tested. Results: The cisplatin-resistant cells expressed increased cell surface Gb3. Cell surface Gb3 expression of resistant cells was annihilated by PPMP whereas cyclosporin A decreased Gb3 and MDR1 expression in H1299 cells. No decrease of MDR1 by PPMP was noted in using flow cytometry, whereas a decrease of MDR1 in H1299 and H1299res was indicated with confocal microscopy. No certain co-localization of Gb3 and MDR1 was noted. PPMP, but not cyclosporin A, potentiated cisplatin cytotoxicity in all cells. Conclusions: Cell surface Gb3 expression is a likely tumour biomarker for acquired cisplatin

  10. Quantitative risk analysis for potentially resistant E. coli in surface waters caused by antibiotic use in agricultural systems.

    Science.gov (United States)

    Limayem, Alya; Martin, Elizabeth M

    2014-01-01

    Antibiotics are frequently used in agricultural systems to promote livestock health and to control bacterial contaminants. Given the upsurge of the resistant fecal indicator bacteria (FIB) in the surface waters, a novel statistical method namely, microbial risk assessment (MRA) was performed, to evaluate the probability of infection by resistant FIB on populations exposed to recreational waters. Diarrheagenic Escherichia coli, except E. coli O157:H7, were selected for their prevalence in aquatic ecosystem. A comparative study between a typical E. coli pathway and a case scenario aggravated by antibiotic use has been performed via Crystal Ball® software in an effort to analyze a set of available inputs provided by the US institutions including E. coli concentrations in US Great Lakes through using random sampling and probability distributions. Results from forecasting a possible worst-case scenario dose-response, accounted for an approximate 50% chance for 20% of the exposed human populations to be infected by recreational water in the U.S. However, in a typical scenario, there is a 50% chance of infection for only 1% of the exposed human populations. The uncertain variable, E. coli concentration accounted for approximately 92.1% in a typical scenario as the major contributing factor of the dose-response model. Resistant FIB in recreational waters that are exacerbated by a low dose of antibiotic pollutants would increase the adverse health effects in exposed human populations by 10 fold.

  11. Kalman filters for assimilating near-surface observations into the Richards equation - Part 2: A dual filter approach for simultaneous retrieval of states and parameters

    Science.gov (United States)

    Medina, H.; Romano, N.; Chirico, G. B.

    2014-07-01

    This study presents a dual Kalman filter (DSUKF - dual standard-unscented Kalman filter) for retrieving states and parameters controlling the soil water dynamics in a homogeneous soil column, by assimilating near-surface state observations. The DSUKF couples a standard Kalman filter for retrieving the states of a linear solver of the Richards equation, and an unscented Kalman filter for retrieving the parameters of the soil hydraulic functions, which are defined according to the van Genuchten-Mualem closed-form model. The accuracy and the computational expense of the DSUKF are compared with those of the dual ensemble Kalman filter (DEnKF) implemented with a nonlinear solver of the Richards equation. Both the DSUKF and the DEnKF are applied with two alternative state-space formulations of the Richards equation, respectively differentiated by the type of variable employed for representing the states: either the soil water content (θ) or the soil water matric pressure head (h). The comparison analyses are conducted with reference to synthetic time series of the true states, noise corrupted observations, and synthetic time series of the meteorological forcing. The performance of the retrieval algorithms are examined accounting for the effects exerted on the output by the input parameters, the observation depth and assimilation frequency, as well as by the relationship between retrieved states and assimilated variables. The uncertainty of the states retrieved with DSUKF is considerably reduced, for any initial wrong parameterization, with similar accuracy but less computational effort than the DEnKF, when this is implemented with ensembles of 25 members. For ensemble sizes of the same order of those involved in the DSUKF, the DEnKF fails to provide reliable posterior estimates of states and parameters. The retrieval performance of the soil hydraulic parameters is strongly affected by several factors, such as the initial guess of the unknown parameters, the wet or dry

  12. Environmental Impact of Tributyltin-Resistant Marine Bacteria in the Indigenous Microbial Population of Tributyltin-Polluted Surface Sediments.

    Science.gov (United States)

    Mimura, Haruo; Yagi, Masahiro; Yoshida, Kazutoshi

    2017-01-01

     We compared the TBT-resistant ability of resting cells prepared from isolates that formed colonies on nutrient agar plates containing 100 µM tributyltin (TBT) chloride, such as Photobacterium sp. TKY1, Halomonas sp. TKY2, and Photobacterium sp. NGY1, with those from taxonomically similar type strains. Photobacterium sp. TKY1 showed the highest ability among those three isolates. The number of surviving Photobacterium sp. TKY1 cells was hardly decreased after 1 h of exposure to 100 µM TBTCl, regardless of the number of resting cells in the range from 10 9.4 to 10 4.2 CFU mL -1 . In such an experimental condition, the maximum number of TBT molecules available to associate with a single cell was estimated to be approximately 6.0 x 10 11.8 . Resting cells prepared from type strains Photobacterium ganghwense JCM 12487 T and P. halotolerans LMG 22194 T , which have 16S rDNA sequences highly homologous with those of Photobacterium sp. TKY1, showed sensitivity to TBT, indicating that TBT-resistant marine bacterial species are not closely related in spite of their taxonomic similarity. We also estimated the impact of TBT-resistant bacterial species to indigenous microbial populations of TBT-polluted surface sediments. The number of surviving TBT-sensitive Vibrio natriegens ATCC 14048 T cells, 10 6.2±0.3 CFU mL -1 , was reduced to 10 4.4±0.4 CFU mL -1 when TBT-resistant Photobacterium sp. TKY1 cells, 10 9.1±0.2 CFU mL -1 , coexisted with 10 9.4±0.2 CFU mL -1 of V. natriegens ATCC 14048 T cells in the presence of 100 µM TBTCl. These results indicate that the toxicity of TBT to TBT-sensitive marine bacterial populations might be enhanced when a TBT-resistant marine bacterial species inhabits TBT-polluted surface sediments.

  13. Acids and alkali resistant sticky superhydrophobic surfaces by one-pot electropolymerization of perfluoroalkyl alkyl pyrrole.

    Science.gov (United States)

    Nicolas, Mael

    2010-03-15

    Over the past few years, electropolymerization of semifluorinated monomers like thiophene or pyrrole has been used as a gentle and effective method to generate, in one step, stable superhydrophobic surfaces. The synthetic route mostly involves the coupling reaction between a carboxylic acid and an alcohol, using a carboxy group-activated reagent and a catalyst. As a consequence, the electroformed surfaces present high liquid repellency due to the concomitant effect of roughness and low surface energy. Nevertheless, the ester connector can be cleaved under acidic and basic conditions, preventing its use under a range of environmental conditions. To overcome this drawback, a new perfluoroalkyl alkyl pyrrole has been synthesized, the fluorinated segment being connected to the electropolymerizable part via an alkyl chain, and electropolymerized, leading to surfaces that exhibit a static contact angle with water superior to 150 degrees and no sliding angle, over a wide pH range and with a long lifetime. This represents the first example of a pure conducting polymer surface with sticky superhydrophobicity not only in pure water but also in corrosive solutions such as acids and bases, giving rise to new prospects in practical applications. 2009 Elsevier Inc. All rights reserved.

  14. Characterization of a Staphylococcus aureus surface virulence factor that promotes resistance to oxidative killing and infectious endocarditis.

    Science.gov (United States)

    Malachowa, Natalia; Kohler, Petra L; Schlievert, Patrick M; Chuang, Olivia N; Dunny, Gary M; Kobayashi, Scott D; Miedzobrodzki, Jacek; Bohach, Gregory A; Seo, Keun Seok

    2011-01-01

    Staphylococcus aureus is a prominent human pathogen and a leading cause of community- and hospital-acquired bacterial infections worldwide. Herein, we describe the identification and characterization of the S. aureus 67.6-kDa hypothetical protein, named for the surface factor promoting resistance to oxidative killing (SOK) in this study. Sequence analysis showed that the SOK gene is conserved in all sequenced S. aureus strains and homologous to the myosin cross-reactive antigen of Streptococcus pyogenes. Immunoblotting and immunofluorescence analysis showed that SOK was copurified with membrane fractions and was exposed on the surface of S. aureus Newman and RN4220. Comparative analysis of wild-type S. aureus and an isogenic deletion strain indicated that SOK contributes to both resistance to killing by human neutrophils and to oxidative stress. In addition, the S. aureus sok deletion strain showed dramatically reduced aortic valve vegetation and bacterial cell number in a rabbit endocarditis model. These results, plus the suspected role of the streptococcal homologue in certain diseases such as acute rheumatic fever, suggest that SOK plays an important role in cardiovascular and other staphylococcal infections.

  15. Contribution to surface physicochemical factors to stress corrosion resistance in stainless steels

    International Nuclear Information System (INIS)

    Gras, Jean-Marie

    1974-01-01

    The author of this research thesis first presents and discusses the various aspects of stress corrosion cracking of Fe-Cr-Ni alloys of high purity: experimental conditions (alloy elaboration, sample preparation), corrosion results (Schaeffer diagram, crack morphology, intergranular corrosion), influence of addition elements in ferritic alloys. He reports an electrochemical study of stainless steels in magnesium chloride (experimental conditions, influence of metallurgic and environmental parameters on polarization resistance, current-voltage curves), and an analytical study of layers formed in the magnesium chloride

  16. Device for electrochemical detection of metal sample surface resistance and passivation against corrosion in electrolyte

    International Nuclear Information System (INIS)

    Urbancik, L.; Bar, J.; Nemec, J.; Sima, A.

    1986-01-01

    The device consists of a teflon vessel with sealing and an opening below the electrolyte level. Into it is submerged an electrode connected to a dc voltage supply whose other pole is connected to a sample of the metal which is pressed to the opening in the sealing with a flexible strap. The teflon vessel and the sealing are integral. The device is simpler and less costly than those manufactured so far. The operating capability of damaged sealing may be renewed by simple mechanical working. The device may be used for detecting the resistance and passivation of steam generator metal tubes. (J.B.). 1 fig

  17. Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell

    OpenAIRE

    Mimura, Haruo; Sato, Ryusei; Sasaki, Yu; Furuyama, Yuichi; Taniike, Akira; Yoshida, Kazutoshi; Kitamura, Akira

    2008-01-01

    Tributyltin (TBT) released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (109.3 ± 0.2 colony-forming units mL-1) adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 108.2. The value was reduced to about one-fif...

  18. Enhanced biofouling resistance of polyethersulfone membrane surface modified with capsaicin derivative and itaconic acid

    International Nuclear Information System (INIS)

    Wang, Jian; Gao, Xueli; Wang, Qun; Sun, Haijing; Wang, Xiaojuan; Gao, Congjie

    2015-01-01

    Graphical abstract: - Highlights: • PES membrane was modified with a capsaicin derivative. • UV-assisted graft polymerization was carried out on membrane surface. • The capsaicin derivative modified membrane shows better antibiofouling property. - Abstract: The culprit of biofouling is the reproduction of viable microorganisms on the membrane surface. Recently, functionalization of membrane surface with natural antibacterial agents has drawn great attention. This work presents the fabrication of antibiofouling polyethersulfone (PES) ultrafiltration (UF) membranes by UV-assisted photo grafting of capsaicin derivative (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide, HMBA) and itaconic acid (IA) on the surface of PES membrane. Results of FTIR-ATR, water static contact angle (WSCA) and atomic force microscopy (AFM) analysis confirmed the successful grafting of HMBA and IA on the membrane surface. We investigated the antifouling and antibacterial properties of these membranes using BSA and Escherichia coli as the test model, respectively. During a 150-min test, the modified membranes show much lower flux decline (42.7% for PES-g-1H0I, 22.2% for PES-g-1H1I and 7.7% for PES-g-1H5I) when compared with the pristine membrane (flux declined by 77%). The modified membranes exhibit excellent antibacterial activity (nearly 100%) when UV irradiation time was 6 min. The morphological study suggested that the E. coli on the pristine membrane showed a regular and smooth surface while that on the modified membrane was disrupted, which validated the antibacterial activity of the modified membranes.

  19. Enhanced biofouling resistance of polyethersulfone membrane surface modified with capsaicin derivative and itaconic acid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Xueli, E-mail: gxl_ouc@126.com [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Wang, Qun; Sun, Haijing; Wang, Xiaojuan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Congjie, E-mail: gaocjie@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China)

    2015-11-30

    Graphical abstract: - Highlights: • PES membrane was modified with a capsaicin derivative. • UV-assisted graft polymerization was carried out on membrane surface. • The capsaicin derivative modified membrane shows better antibiofouling property. - Abstract: The culprit of biofouling is the reproduction of viable microorganisms on the membrane surface. Recently, functionalization of membrane surface with natural antibacterial agents has drawn great attention. This work presents the fabrication of antibiofouling polyethersulfone (PES) ultrafiltration (UF) membranes by UV-assisted photo grafting of capsaicin derivative (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide, HMBA) and itaconic acid (IA) on the surface of PES membrane. Results of FTIR-ATR, water static contact angle (WSCA) and atomic force microscopy (AFM) analysis confirmed the successful grafting of HMBA and IA on the membrane surface. We investigated the antifouling and antibacterial properties of these membranes using BSA and Escherichia coli as the test model, respectively. During a 150-min test, the modified membranes show much lower flux decline (42.7% for PES-g-1H0I, 22.2% for PES-g-1H1I and 7.7% for PES-g-1H5I) when compared with the pristine membrane (flux declined by 77%). The modified membranes exhibit excellent antibacterial activity (nearly 100%) when UV irradiation time was 6 min. The morphological study suggested that the E. coli on the pristine membrane showed a regular and smooth surface while that on the modified membrane was disrupted, which validated the antibacterial activity of the modified membranes.

  20. Integral equations

    CERN Document Server

    Moiseiwitsch, B L

    2005-01-01

    Two distinct but related approaches hold the solutions to many mathematical problems--the forms of expression known as differential and integral equations. The method employed by the integral equation approach specifically includes the boundary conditions, which confers a valuable advantage. In addition, the integral equation approach leads naturally to the solution of the problem--under suitable conditions--in the form of an infinite series.Geared toward upper-level undergraduate students, this text focuses chiefly upon linear integral equations. It begins with a straightforward account, acco

  1. Application of the surface azimuthal electrical resistivity survey method to determine patterns of regional joint orientation in glacial tills

    Science.gov (United States)

    Carlson, D.

    2010-01-01

    Joints within unconsolidated material such as glacial till can be primary avenues for the flow of electrical charge, water, and contaminants. To facilitate the siting and design of remediation programs, a need exists to map anisotropic distribution of such pathways within glacial tills by determining the azimuth of the dominant joint set. The azimuthal survey method uses standard resistivity equipment with a Wenner array rotated about a fixed center point at selected degree intervals that yields an apparent resistivity ellipse. From this ellipse, joint set orientation can be determined. Azimuthal surveys were conducted at 21 sites in a 500-km2 (193 mi2) area around Milwaukee, Wisconsin, and more specifically, at sites having more than 30 m (98 ft) of glacial till (to minimize the influence of underlying bedrock joints). The 26 azimuthal surveys revealed a systematic pattern to the trend of the dominant joint set within the tills, which is approximately parallel to ice flow direction during till deposition. The average orientation of the joint set parallel with the ice flow direction is N77??E and N37??E for the Oak Creek and Ozaukee tills, respectively. The mean difference between average direct observation of joint set orientations and average azimuthal resistivity results is 8??, which is one fifth of the difference of ice flow direction between the Ozaukee and Oak Creek tills. The results of this study suggest that the surface azimuthal electrical resistivity survey method used for local in situ studies can be a useful noninvasive method for delineating joint sets within shallow geologic material for regional studies. Copyright ?? 2010 The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  2. Impact of nitrogen doping of niobium superconducting cavities on the sensitivity of surface resistance to trapped magnetic flux

    Science.gov (United States)

    Gonnella, Dan; Kaufman, John; Liepe, Matthias

    2016-02-01

    Future particle accelerators such as the SLAC "Linac Coherent Light Source-II" (LCLS-II) and the proposed Cornell Energy Recovery Linac require hundreds of superconducting radio-frequency (SRF) niobium cavities operating in continuous wave mode. In order to achieve economic feasibility of projects such as these, the cavities must achieve a very high intrinsic quality factor (Q0) to keep cryogenic losses within feasible limits. To reach these high Q0's in the case of LCLS-II, nitrogen-doping of niobium cavities has been selected as the cavity preparation technique. When dealing with Q0's greater than 1 × 1010, the effects of ambient magnetic field on Q0 become significant. Here, we show that the sensitivity to RF losses from trapped magnetic field in a cavity's walls is strongly dependent on the cavity preparation. Specifically, standard electropolished and 120 °C baked cavities show a sensitivity of residual resistance from trapped magnetic flux of ˜0.6 and ˜0.8 nΩ/mG trapped, respectively, while nitrogen-doped cavities show a higher sensitivity of residual resistance from trapped magnetic flux of ˜1 to 5 nΩ/mG trapped. We show that this difference in sensitivities is directly related to the mean free path of the RF surface layer of the niobium: shorter mean free paths lead to less sensitivity of residual resistance to trapped magnetic flux in the dirty limit (ℓ ≪ ξ0), while longer mean free paths lead to lower sensitivity of residual resistance to trapped magnetic flux in the clean limit (ℓ ≫ ξ0). These experimental results are also shown to have good agreement with recent theoretical predictions for pinned vortex lines oscillating in RF fields.

  3. Influence of multi-wavelength laser irradiation of enamel and dentin surfaces at 0.355, 2.94, and 9.4 μm on surface morphology, permeability, and acid resistance.

    Science.gov (United States)

    Chang, Nai-Yuan N; Jew, Jamison M; Simon, Jacob C; Chen, Kenneth H; Lee, Robert C; Fried, William A; Cho, Jinny; Darling, Cynthia L; Fried, Daniel

    2017-12-01

    Ultraviolet (UV) and infrared (IR) lasers can be used to specifically target protein, water, and mineral, respectively, in dental hard tissues to produce varying changes in surface morphology, permeability, reflectivity, and acid resistance. The purpose of this study was to explore the influence of laser irradiation and topical fluoride application on the surface morphology, permeability, reflectivity, and acid resistance of enamel and dentin to shed light on the mechanism of interaction and develop more effective treatments. Twelve bovine enamel surfaces and twelve bovine dentin surfaces were irradiated with various combinations of lasers operating at 0.355 (Freq.-tripled Nd:YAG (UV) laser), 2.94 (Er:YAG laser), and 9.4 μm (CO 2 laser), and surfaces were exposed to an acidulated phosphate fluoride gel and an acid challenge. Changes in the surface morphology, acid resistance, and permeability were measured using digital microscopy, polarized light microscopy, near-IR reflectance, fluorescence, polarization sensitive-optical coherence tomography (PS-OCT), and surface dehydration rate measurements. Different laser treatments dramatically influenced the surface morphology and permeability of both enamel and dentin. CO 2 laser irradiation melted tooth surfaces. Er:YAG and UV lasers, while not melting tooth surfaces, showed markedly different surface roughness. Er:YAG irradiation led to significantly rougher enamel and dentin surfaces and led to higher permeability. There were significant differences in acid resistance among the various treatment groups. Surface dehydration measurements showed significant changes in permeability after laser treatments, application of fluoride and after exposure to demineralization. CO 2 laser irradiation was most effective in inhibiting demineralization on enamel while topical fluoride was most effective for dentin surfaces. Lasers Surg. Med. 49:913-927, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  4. Damage resistance of AR-coated germanium surfaces for nanosecond CO2 laser pulses

    International Nuclear Information System (INIS)

    Newnam, B.E.; Gill, D.H.

    1977-01-01

    An evaluation of the state-of-the-art of AR coatings on gallium-doped germanium, used as a saturable absorber at 10.6 μm, has been conducted. Both 1-on-1 and N-on-1 laser damage thresholds were measured with 1.2 ns pulses on bare and coated surfaces. Only front surface damage was observed. With few exceptions, the thresholds for coated surfaces were centered at 0.49 +- 0.3 J/cm 2 . Bare Ge had a threshold ranging from 0.65 to 0.70 J/cm 2 . No significant differences due to substrate polish, crystallinity or doping level were evident and multiple-shot conditioning resulted in the same threshold as for single shot tests. From an analysis of standing-wave electric fields, damage for AR-coated Ge appeared to be limited by the surface properties of Ge. Measurements at both 1.2 and 70 ns indicated that the threshold (J/cm 2 ) of both coated and uncoated Ge increases as the square root of the pulse-width

  5. Surface Functionalization of Epoxy-Resist- Based Microcantilevers with Iron Oxide Nanocrystals

    DEFF Research Database (Denmark)

    Ingrosso, Chiara; Sardella, E.; Keller, Stephan Sylvest

    2010-01-01

    A functionalization procedure is integrated in the fabrication of micromechanical SU-8 cantilevers in order to chemically bind organic-capped Fe2O3 NCs at the photoresist surface, under visible light, ambient atmosp here and room temperature. The achieved highly interconnected NC multilayer netwo...... is demonstrated an active layer for real-time detection of acetone vapor molecules....

  6. Resistance of pathogenic bacteria on the surface of stainless steel depending on attachment form and efficacy of chemical sanitizers.

    Science.gov (United States)

    Bae, Young-Min; Baek, Seung-Youb; Lee, Sun-Young

    2012-02-15

    Various bacteria including food spoilage bacteria and pathogens can form biofilms on different food processing surfaces, leading to potential food contamination or spoilage. Therefore, the survival of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus, Cronobacter sakazakii) in different forms (adhered cells, biofilm producing in TSB, biofilm producing at RH 100%) on the surface of stainless steel and stored at various relative humidities (RH 23%, 43%, 68%, 85%, and 100%) at room temperature for 5 days was investigated in this study. Additionally, the efficacy of chemical sanitizers (chlorine-based and alcohol-based commercial sanitizers) on inhibiting various types of biofilms of E. coli O157:H7 and S. aureus on the surface of stainless steel was investigated. The number of pathogens on the surface of stainless steel in TSB stored at 25°C for 7 days or RH 100% at 25°C for 7 days was significantly increased and resulted in the increase of 3 log(10) CFU/coupon after 1 day, and these levels were maintained for 7 days. When stainless steel coupons were stored at 25°C for 5 days, the number of pathogens on the surface of stainless steel was significantly reduced after storage at RH 23%, 43%, 68%, and 85%, but not at 100%. When the bacteria formed biofilms on the surface of stainless steel in TSB after 6 days, the results were similar to those of the attached form. However, levels of S. aureus and C. sakazakii biofilms were more slowly reduced after storage at RH 23%, 43%, 68%, and 85% for 5 days than were those of the other pathogens. Formation of biofilms stored at RH 100% for 5 days displayed the highest levels of resistance to inactivation. Treatment with the alcohol sanitizer was very effective at inactivating attached pathogens or biofilms on the surface of stainless steel. Reduction levels of alcohol sanitizer treatment ranged from 1.91 to 4.77 log and from 4.35 to 5.35 log CFU/coupon in E. coli

  7. Decrease of the surface resistance in superconducting niobium resonator cavities by the microwave field

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Dhakal, Pashupati [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Gurevich, Alexander V. [Old Dominion University, Norfolk, VA (United States)

    2014-03-03

    Measurements of the quality factor, Q, of Nb superconducting microwave resonators often show that Q increases by {approx_equal} 10%–30% with increasing radio-frequency (rf) field, H, up to {approx} 15-20 mT. Recent high temperature heat treatments can amplify this rf field-induced increase of Q up to {approx_equal} 50%–100% and extend it to much higher fields, but the mechanisms of the enhancement of Q(H) remain unclear. Here, we suggest a method to reveal these mechanisms by measuring temperature dependencies of Q at different rf field amplitudes. We show that the increase of Q(H) does not come from a field dependent quasi-particles activation energy or residual resistance, but rather results from the smearing of the density of state by the rf field.

  8. Analysis of surface insulation resistance related failures in electronics by circuit simulation

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Joshy, Salil; Jellesen, Morten Stendahl

    2017-01-01

    conduction medium. Findings-This paper provides a summary of the effects of contamination with various weak organic acids representing the active components in no-clean solder flux residue, and demonstrates the effect of humidity and contamination on the possible malfunctions and errors in electronic...... of the circuits using a range of empirical leakage resistance values combined with the knowledge of the humidity and contamination profile of the electronics can be used for the robust design of a device, which is also important for electronic products relying on low current consumption for long battery lifetime....... Originality/value-Examples provide a basic link between the combined effect of humidity and contamination and the performance of electronic circuits. The methodology shown provides the possibility of addressing the climatic reliability of an electronic device at the early stage of device design by using...

  9. Resistance of superhydrophobic and oleophobic surfaces to varied temperature applications on 316L SS

    Science.gov (United States)

    Shams, Hamza; Basit, Kanza; Saleem, Sajid; Siddiqui, Bilal A.

    316L SS also called Marine Stainless Steel is an important material for structural and marine applications. When superhydrophobic and oleophobic coatings are applied on 316L SS it shows significant resistance to wear and corrosion. This paper aims to validate the coatings manufacturer's information on optimal temperature range and test the viability of coating against multiple oil based cleaning agents. 316L SS was coated with multiple superhydrophic and oleohobic coatings and observed under SEM for validity of adhesion and thickness and then scanned under FFM to validate the tribological information. The samples were then dipped into multiple cleaning agents maintained at the range of operating temperatures specified by the manufacturer. Coating was observed for deterioration over a fixed time intervals through SEM and FFM. A comparison was drawn to validate the most critical cleaning agent and the most critical temperature at which the coating fails to leave the base substrate exposed to the environment.

  10. Final Technical Report: Development of an Abrasion-Resistant Antisoiling Coating for Front-Surface Reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Gee, Randy C. [Sundog Solar Technology, Arvada, CO (United States)

    2017-07-18

    A high-performance reflective film has been successfully developed for Concentrating Solar Power (CSP) solar concentrators. Anti-soiling properties and abrasion resistance have been incorporated into the reflector to reduce reflector cleaning costs and to enhance durability. This approach has also resulted in higher reflectance and improved specularity. From the outset of this project we focused on the use of established high-volume roll-to-roll manufacturing techniques to achieve low manufacturing costs on a per ubit area basis. Roll-to-roll manufacturng equipment has a high capital cost so there is an entire industry devoted to roll-to-roll “toll” manufacturing, where the equipment is operated “around the clock” to produce a multitude of products for a large variety of uses. Using this approach, the reflective film can be manufactured by toll coaters/converters on an as-needed basis.

  11. Acute Exercise-Associated Skin Surface Temperature Changes after Resistance Training with Different Exercise Intensities

    Directory of Open Access Journals (Sweden)

    Martin Weigert

    2018-01-01

    Full Text Available Background: Studies showed, that changes in muscular metabolic-associated heat production and blood circulation during and after muscular work affect skin temperature (T but the results are inconsistent and the effect of exercise intensity is unclear. Objective: This study investigated the intensity-dependent reaction of T on resistance training. Methods: Ten male students participated. After acclimatization (15 min, the participants completed 3x10 repetitions of unilateral biceps curl with 30, 50 or 70% of their one-repetition-maximum (1RM in a randomized order. Skin temperature of the loaded and unloaded biceps was measured at rest (Trest, immediately following set 1, 2 and 3 (TS1,TS2,TS3 and 30 minutes post exercise (T1 - T30 with an infrared camera. Results: Two-way ANOVA detected a significant effect of the measuring time point on T (Trest to T30 of the loaded arm for 30% (Eta²=0.85, 50% (Eta²=0.88 and 70% 1RM (Eta²=0.85 and of the unloaded arm only for 30% 1RM (Eta²=0.41 (p0.05. The T values at the different measuring time points (Trest - T30 did not differ between the intensities at any time point. The loaded arm showed a mean maximum T rise to Trest of 1.8°C and on average, maximum T was reached approximately 5 minutes after the third set.  Conclusion: This study indicate a rise of T, which could be independent of the exercise intensity. Infrared thermography seems to be applicable to identify the primary used functional muscles in resistance training but this method seems not suitable to differentiate between exercise intensity from 30 to 70% 1RM.

  12. Influence of surface treatments on corrosion resistance of stainless steels. Residual stresses in metals

    International Nuclear Information System (INIS)

    Berge, J. Philippe

    1968-05-01

    In a first part, this research thesis proposes presentation of the definition of a surface condition: chemical characteristics such as passivity and contamination, physical characteristics (obtained through micrographic methods, X ray diffusion, magnetic methods), and micro-geometrical characteristics. The author notably discusses the measurement of characteristics either by appropriate conventional methods or by an original method in the case of passivity. In a second part, the author reports the study of the influence of surface condition on different types of corrosion of stainless steels in chemical environments (corrosion in sulphuric acid, intergranular corrosion, stress corrosion cracking in magnesium chloride, pitting corrosion) and of high temperature oxidation (corrosion in pressurized water, oxidation in dry vapour or in carbon dioxide)

  13. Lead-free, bronze-based surface layers for wear resistance in axial piston hydraulic pumps

    Energy Technology Data Exchange (ETDEWEB)

    Vetterick, Gregory Alan [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Concerns regarding the safety of lead have provided sufficient motivation to develop substitute materials for the surface layer on a thrust bearing type component known as a valve plate in axial piston hydraulic pumps that consists of 10% tin, 10% lead, and remainder cooper (in wt. %). A recently developed replacement material, a Cu-10Sn-3Bi (wt.%) P/M bronze, was found to be unsuitable as valve plate surface layer, requiring the development of a new alloy. A comparison of the Cu-1-Sn-10Pb and Cu-10Sn-3Bi powder metal valve plates showed that the differences in wear behavior between the two alloys arose due to the soft phase bismuth in the alloy that is known to cause both solid and liquid metal embrittlement of copper alloys.

  14. Increased Wear Resistance of Surfaces of Rotation Bearings Methods Strengthening-Smoothing Processing

    Directory of Open Access Journals (Sweden)

    A.A. Tkachuk

    2016-05-01

    Full Text Available Trends of modern engineering put forward higher requirements for quality bearings. This is especially true on production of bearings for special purposes with high speeds of rotation and resource. Much more opportunities in the technology management quality surface layers appear in the application of smoothing-strengthening methods, based on superficial plastic deformation. Working models of cutting lathes, grinders and tool smoothing sequence revealed the formation of operational parameters in the technological cycle of roller rings. The model of the dynamics of elastic deformation of the work piece tool helps identify actions radial force in the contact “surface – indenter.” Using mathematical modelling resolved a number of issues relevant process.

  15. Magnetic field integral equation analysis of interaction between a surface plasmon polariton and a circular dielectric cavity embedded in the metal.

    Science.gov (United States)

    Chremmos, Ioannis

    2009-12-01

    A rigorous integral equation (IE) analysis of the interaction between a surface plasmon polariton (SPP) and a circular dielectric cavity embedded in a metal half-space is presented. The device is addressed as the plasmonic counterpart of the established integrated optics filter comprising a whispering gallery (WG) resonator coupled to a waveguide. The mathematical formulation is that of a transverse magnetic scattering problem. Using a magnetic-type Green's function of the two-layer medium with boundary conditions that cancel the line integral contributions along the interface, an IE for the magnetic field inside the cavity is obtained. The IE is treated through an entire-domain method of moments (MoM) with cylindrical-harmonic basis functions. The entries of the MoM matrix are determined analytically by utilizing the inverse Fourier transform of Green's function and the Jacobi-Anger formula for interchanging between plane and cylindrical waves. Complex analysis techniques are applied to determine the transmitted, reflected, and radiated field quantities in series forms. The numerical results show that the scattered SPPs' spectra exhibit pronounced wavelength selectivity that is related to the excitation of WG-like cavity modes. It seems feasible to exploit the device as a bandstop or reflective filter or even as an efficient radiating element. In addition, the dependence of transmission on the cavity refractive index endows this structure with a sensing functionality.

  16. Kalman filters for assimilating near-surface observations in the Richards equation - Part 2: A dual filter approach for simultaneous retrieval of states and parameters

    Science.gov (United States)

    Medina, H.; Romano, N.; Chirico, G. B.

    2012-12-01

    We present a dual Kalman Filter (KF) approach for retrieving states and parameters controlling soil water dynamics in a homogenous soil column by using near-surface state observations. The dual Kalman filter couples a standard KF algorithm for retrieving the states and an unscented KF algorithm for retrieving the parameters. We examine the performance of the dual Kalman Filter applied to two alternative state-space formulations of the Richards equation, respectively differentiated by the type of variable employed for representing the states: either the soil water content (θ) or the soil matric pressure head (h). We use a synthetic time-series series of true states and noise corrupted observations and a synthetic time-series of meteorological forcing. The performance analyses account for the effect of the input parameters, the observation depth and the assimilation frequency as well as the relationship between the retrieved states and the assimilated variables. We show that the identifiability of the parameters is strongly conditioned by several factors, such as the initial guess of the unknown parameters, the wet or dry range of the retrieved states, the boundary conditions, as well as the form (h-based or θ-based) of the state-space formulation. State identifiability is instead efficient even with a relatively coarse time-resolution of the assimilated observation. The accuracy of the retrieved states exhibits limited sensitivity to the observation depth and the assimilation frequency.

  17. Carbapenem-Resistant Acinetobacter baumannii: Concomitant Contamination of Air and Environmental Surfaces.

    Science.gov (United States)

    Shimose, Luis A; Masuda, Eriko; Sfeir, Maroun; Berbel Caban, Ana; Bueno, Maria X; dePascale, Dennise; Spychala, Caressa N; Cleary, Timothy; Namias, Nicholas; Kett, Daniel H; Doi, Yohei; Munoz-Price, L Silvia

    2016-07-01

    OBJECTIVE To concomitantly determine the differential degrees of air and environmental contamination by Acinetobacter baumannii based on anatomic source of colonization and type of ICU layout (single-occupancy vs open layout). DESIGN Longitudinal prospective surveillance study of air and environmental surfaces in patient rooms. SETTING A 1,500-bed public teaching hospital in Miami, Florida. PATIENTS Consecutive A. baumannii-colonized patients admitted to our ICUs between October 2013 and February 2014. METHODS Air and environmental surfaces of the rooms of A. baumannii-colonized patients were sampled daily for up to 10 days. Pulsed-field gel electrophoresis (PFGE) was used to type and match the matching air, environmental, and clinical A. baumannii isolates. RESULTS A total of 25 A. baumannii-colonized patients were identified during the study period; 17 were colonized in the respiratory tract and 8 were colonized in the rectum. In rooms with rectally colonized patients, 38.3% of air samples were positive for A. baumannii; in rooms of patients with respiratory colonization, 13.1% of air samples were positive (P=.0001). In rooms with rectally colonized patients, 15.5% of environmental samples were positive for A. baumannii; in rooms of patients with respiratory colonization, 9.5% of environmental samples were positive (P=.02). The rates of air contamination in the open-layout and single-occupancy ICUs were 17.9% and 21.8%, respectively (P=.5). Environmental surfaces were positive in 9.5% of instances in open-layout ICUs versus 13.4% in single-occupancy ICUs (P=.09). CONCLUSIONS Air and environmental surface contaminations were significantly greater among rectally colonized patients; however, ICU layout did not influence the rate of contamination. Infect Control Hosp Epidemiol 2016;37:777-781.

  18. Physiochemical Control of Composition and Location for Fundamental Studies of Biofouling Resistant, High Fouling Release Surfaces

    Science.gov (United States)

    2016-06-22

    glass and substrate allowing capillary forces to uniformly spread the reactants over the surface. Reduction projection reproduces the image from an...image (see Figure 2). Correspondingly, silicon (m/z = 29) was detected exclusively in regions of the SiO2 substrate where the photomask blocked the...initiator-functionalized SiO2 substrate through a binary photomask. Brown circles indicate polymerization initiators. (b and c) Optical micrographs of

  19. Resisting and pinning of a nanodrop by trenches on a hysteresis-free surface

    Science.gov (United States)

    Chang, Cheng-Chung; Wu, Cyuan-Jhang; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2016-10-01

    The encounter of a nanodrop with a trench on a hysteresis-free surface is explored by many-body dissipative particle dynamics to show the effect of surface roughness on droplet wetting. A free nanodrop exhibits Brownian motion and the diffusivity decays exponentially with the liquid-solid contact area. In contrast, as the nanodrop sits on a trench, its random motion is constrained. Work must be done to overcome the energy barriers for the transition between free and trapped states. The potential energy landscape is thus constructed based on the force-displacement plot. It is shown that the trench acts as a hydrophobic blemish for capture but like a hydrophilic blemish for escape. A drop always breaks up after detachment from a hydrophilic trench. Therefore, the drop tends to bypass a small trench when it meets one. The macroscopic experiments are performed by fabricating liquid-infused surfaces with extremely low contact angle hysteresis. The experimental observations agree qualitatively with simulation outcomes.

  20. Differences in friction and torsional resistance in athletic shoe-turf surface interfaces.

    Science.gov (United States)

    Heidt, R S; Dormer, S G; Cawley, P W; Scranton, P E; Losse, G; Howard, M

    1996-01-01

    This study evaluated the shoe-surface interaction of 15 football shoes made by 3 manufacturers in both anterior translation and rotation using a specially designed pneumatic testing system. The shoes included traditional cleated football shoes, "court" shoes (basketball-style shoes), molded-cleat shoes, and turf shoes. Under an 11.35-kg (25-pound) axial load, all shoes were tested on synthetic turf under wet and dry conditions and on natural stadium grass. Test-retest reliability, as calculated using the Pearson Product-Moment Correlation test, was 0.85 for force of translation and 0.55 for the moment of rotation. The wet versus dry surface values on translation were significantly different for rotation about the tibial axis. Spatting, which is protective taping of the ankle and heel applied on the outside of the shoe, resulted in a reduction of forces generated in both translation and rotation. No overall difference between shoes on grass versus AstroTurf was noted. However, there were significant differences for cleated and turf shoes. Shoes tested in conditions for which they were not designed exhibited reproducible excessive or extreme minimal friction characteristics that may have safety implications. On the basis of this study, we urge shoe manufacturers to display suggested indications and playing surface conditions for which their shoes are recommended.

  1. Study of the surface crystallization and resistance to dissolution of niobium phosphate glasses for nuclear waste immobilization

    International Nuclear Information System (INIS)

    Vieira, Heveline

    2008-01-01

    The surface crystallization and the dissolution rate of three phosphate glass compositions containing different amounts of niobium oxide were studied. The glasses were named Nb30, Nb37, and Nb44 according to the nominal content of niobium oxide in the glass composition. The three compositions were evaluated keeping the P 2 O 5 /K 2 O ratio constant and varying the amount of Nb 2 O 5 . These glasses were produced by melting appropriate chemical compounds at 1500 deg C for 0.5 hour. The crystalline phases which were nucleated on the glass surface after heat treatment were determined by X-ray diffraction. The crystalline structures depend on the amount of niobium oxide in the glass composition. The crystal morphologies were observed by using an optical microscope, and their characteristics are specific for each kind of crystalline phase. The crystal growth rate and the surface nuclei density were determined for each glass composition, and they depend on each crystalline phase nucleated on the surface. From the differential thermal analysis curves it was determined that the Nb44 glass containing 46.5 mol por cent of niobium oxide is the most thermally stable against crystallization when compared to the Nb30 and Nb37 glasses. According to the activation energies determined for crystal growth on the surface of each glass type, the Nb44 glass can also be considered the most resistant one against crystallization. The dissolution rate for the Nb44 glass after 14 days immersed in an aqueous solution with pH equals to 7 at 90 deg C is the lowest (9.0 x 10 -7 g. cm -2 . day -1 ) when compared to the other two glass compositions. The dissolution rates in acidic and neutral solutions of all studied glasses meet the international standards for materials which can be used in the immobilization of nuclear wastes. (author)

  2. Water resistance and surface morphology of synthetic fabrics covered by polysiloxane/acrylate followed by electron beam irradiation

    CERN Document Server

    El-Naggar, A M; Mohammed, S S; Alam, E A

    2003-01-01

    Different synthetic fabrics were treated by electron beam surface coating with two formulations based on polydimethylsiloxane (PDMS) and polystyrene (PS) or poly(methyl methacrylate) (PMMA) oligomers. The water resistance properties were investigated in terms of the percentage of water repellency and absorption. Also, the surface coated fabrics were examined by scanning electron microscopy/microscope (SEM) connected to an energy dispersive X-ray (EDX) unit to determine the percentage atomic contents of elements. The results showed that the adhesion of the polysiloxane formulation to the surface depends largely on the kind of acrylate oligomer and textile fabric as indicated by the EDX analysis for silicon. In this regard, PDMS/PS formulation is more compatible with polyester and nylon-6 fabrics than PDMS/PMMA one. However, it was found that PDMS/PMMA formulation is more compatible with cotton/polyester blend than PDMS/PS. The SEM micrographs give further supports to the EDX analysis. On the basis of the perce...

  3. Fabrication of Water Jet Resistant and Thermally Stable Superhydrophobic Surfaces by Spray Coating of Candle Soot Dispersion.

    Science.gov (United States)

    Qahtan, Talal F; Gondal, Mohammed A; Alade, Ibrahim O; Dastageer, Mohammed A

    2017-08-08

    A facile synthesis method for highly stable carbon nanoparticle (CNP) dispersion in acetone by incomplete combustion of paraffin candle flame is presented. The synthesized CNP dispersion is the mixture of graphitic and amorphous carbon nanoparticles of the size range of 20-50 nm and manifested the mesoporosity with an average pore size of 7 nm and a BET surface area of 366 m 2 g -1 . As an application of this material, the carbon nanoparticle dispersion was spray coated (spray-based coating) on a glass surface to fabricate superhydrophobic (water contact angle > 150° and sliding angle fabricated from direct candle flame soot deposition (candle-based coating). This study proved that water jet resistant and thermally stable superhydrophobic surfaces can be easily fabricated by simple spray coating of CNP dispersion gathered from incomplete combustion of paraffin candle flame and this technique can be used for different applications with the potential for the large scale fabrication.

  4. Magnetic evaluation of the external surface in cast heat-resistant steel tubes with different aging states

    Science.gov (United States)

    Arenas, Mónica P.; Silveira, Rosa M.; Pacheco, Clara J.; Bruno, Antonio C.; Araujo, Jefferson F. D. F.; Eckstein, Carlos B.; Nogueira, Laudemiro; de Almeida, Luiz H.; Rebello, João M. A.; Pereira, Gabriela R.

    2018-06-01

    Heat-resistant austenitic stainless steels have become the principal alloys for use in steam reformer tubes in the petrochemical industry due to its mechanical properties. These tubes are typically exposed to severe operational conditions leading to microstructural transformations such as the aging phenomenon. The combination of high temperatures and moderate stresses causes creep damages, being necessary to monitor its structural condition by non-destructive techniques. The tube external wall is also subjected to oxidizing atmospheres, favoring the formation of an external surface, composed by an oxide scale and a chromium depleted zone. This external surface is usually not taken into account in the tube evaluation, which can lead to erroneous estimations of the service life of these components. In order to observe the magnetic influence of this layer, two samples, exposed to different operational temperatures, were characterized by non-destructive eddy current testing (ECT), scanning DC-susceptometer and magnetic force microscopy (MFM). It was found that the external surface thickness influences directly in the magnetic response of the samples.

  5. Dependence of trapped-flux-induced surface resistance of a large-grain Nb superconducting radio-frequency cavity on spatial temperature gradient during cooldown through Tc

    Science.gov (United States)

    Huang, Shichun; Kubo, Takayuki; Geng, R. L.

    2016-08-01

    Recent studies by Romanenko et al. revealed that cooling down a superconducting cavity under a large spatial temperature gradient decreases the amount of trapped flux and leads to reduction of the residual surface resistance. In the present paper, the flux expulsion ratio and the trapped-flux-induced surface resistance of a large-grain cavity cooled down under a spatial temperature gradient up to 80 K /m are studied under various applied magnetic fields from 5 to 20 μ T . We show the flux expulsion ratio improves as the spatial temperature gradient increases, independent of the applied magnetic field: our results support and enforce the previous studies. We then analyze all rf measurement results obtained under different applied magnetic fields together by plotting the trapped-flux-induced surface resistance normalized by the applied magnetic field as a function of the spatial temperature gradient. All the data can be fitted by a single curve, which defines an empirical formula for the trapped-flux-induced surface resistance as a function of the spatial temperature gradient and applied magnetic field. The formula can fit not only the present results but also those obtained by Romanenko et al. previously. The sensitivity rfl of surface resistance from trapped magnetic flux of fine-grain and large-grain niobium cavities and the origin of d T /d s dependence of Rfl/Ba are also discussed.

  6. Modeling the influence of a reduced equator-to-pole sea surface temperature gradient on the distribution of water isotopes in the Eocene

    Science.gov (United States)

    Speelman, E. N.; Sewall, J. O.; Noone, D. C.; Huber, M.; Sinninghe Damsté, J. S.; Reichart, G.

    2009-12-01

    Proxy-based climate reconstructions suggest the existence of a strongly reduced equator-to-pole temperature gradient during most of the Early Eocene. With the realization that the Eocene Arctic Ocean was covered with enormous quantities of the free floating freshwater fern Azolla, new questions related to Eocene (global) hydrological cycling facilitating these blooms arose. Changes in hydrological cycling, as a consequence of a reduced temperature gradient, are expected to be most clearly reflected in the isotopic composition (D, 18O) of precipitation. The interpretation of water isotopic records to quantitatively estimate past precipitation patterns is, however, hampered by the lack of detailed information on changes in their spatial and temporal distribution. Using the isotope-enabled global circulation model, Community Atmosphere Model v.3 (isoCAM3), relationships between water isotopes and past climates can be simulated. Here we examine the influence of a reduced meridional sea surface temperature gradient on the spatial distribution of precipitation and its isotopic composition in an Eocene setting. Overall, our combination of Eocene climate forcings, with superimposed TEX86-derived SST estimates and elevated pCO2 concentrations, produces a climate that agrees well with proxy data in locations around the globe. It shows the presence of an intensified hydrological cycle with precipitation exceeding evaporation in the Arctic region. The Eocene model runs with a significantly reduced equator-to-pole temperature gradient in a warmer more humid world predict occurrence of less depleted precipitation, with δD values ranging only between 0 and -140‰ (as opposed to the present-day range of 0 to -300‰). Combining new results obtained from compound specific isotope analyses on terrestrially derived n-alkanes extracted from Eocene sediments, and model calculations, shows that the model not only captures the main features, but reproduces isotopic values

  7. Differential equations

    CERN Document Server

    Tricomi, FG

    2013-01-01

    Based on his extensive experience as an educator, F. G. Tricomi wrote this practical and concise teaching text to offer a clear idea of the problems and methods of the theory of differential equations. The treatment is geared toward advanced undergraduates and graduate students and addresses only questions that can be resolved with rigor and simplicity.Starting with a consideration of the existence and uniqueness theorem, the text advances to the behavior of the characteristics of a first-order equation, boundary problems for second-order linear equations, asymptotic methods, and diff

  8. Surface Contaminant Control Technologies to Improve Laser Damage Resistance of Optics

    Directory of Open Access Journals (Sweden)

    Xiaofeng Cheng

    2014-01-01

    Full Text Available The large high-power solid lasers, such as the National Ignition Facility (NIF of America and the Shenguang-III (SG-III laser facility of China, can output over 2.1 MJ laser pulse for the inertial confinement fusion (ICF experiments. Because of the enhancement of operating flux and the expansion of laser driver scale, the problem of contamination seriously influences their construction period and operation life. During irradiation by intense laser beams, the contaminants on the metallic surface of beam tubes can be transmitted to the optical surfaces and lead to damage of optical components. For the high-power solid-state laser facilities, contamination control focuses on the slab amplifiers, spatial filters, and final-optical assemblies. In this paper, an effective solution to control contaminations including the whole process of the laser driver is put forward to provide the safe operation of laser facilities, and the detailed technical methods of contamination control such as washing, cleanliness metrology, and cleanliness protecting are also introduced to reduce the probability of laser-induced damage of optics. The experimental results show that the cleanliness level of SG-III laser facility is much better to ensure that the laser facility can safely operate at high energy flux.

  9. Multifunctional Nano-engineered Polymer Surfaces with Enhanced Mechanical Resistance and Superhydrophobicity

    Science.gov (United States)

    Hernández, Jaime J.; Monclús, Miguel A.; Navarro-Baena, Iván; Viela, Felipe; Molina-Aldareguia, Jon M.; Rodríguez, Isabel

    2017-03-01

    This paper presents a multifunctional polymer surface that provides superhydrophobicity and self-cleaning functions together with an enhancement in mechanical and electrical performance. These functionalities are produced by nanoimprinting high aspect ratio pillar arrays on polymeric matrix incorporating functional reinforcing elements. Two distinct matrix-filler systems are investigated specifically, Carbon Nanotube reinforced Polystyrene (CNT-PS) and Reduced Graphene Oxide reinforced Polyvinylidene Difluoride (RGO-PVDF). Mechanical characterization of the topographies by quantitative nanoindentation and nanoscratch tests are performed to evidence a considerable increase in stiffness, Young’s modulus and critical failure load with respect to the pristine polymers. The improvement on the mechanical properties is rationalized in terms of effective dispersion and penetration of the fillers into the imprinted structures as determined by confocal Raman and SEM studies. In addition, an increase in the degree of crystallization for the PVDF-RGO imprinted nanocomposite possibly accounts for the larger enhancement observed. Improvement of the mechanical ruggedness of functional textured surfaces with appropriate fillers will enable the implementation of multifunctional nanotextured materials in real applications.

  10. “I am a place”: Aletheia as aesthetic and political resistance in Margaret Atwood's Surfacing

    Directory of Open Access Journals (Sweden)

    Joakim Wrethed

    2015-07-01

    Full Text Available The article investigates the aesthetic and political power of Margaret Atwood's 1972 novel Surfacing. It argues that the novel's perennial vitality is partly explained by Jacques Rancière's theory about the aesthetic regime of art that highlights the tension between art for art's sake and art as a political instrument. By means of phenomenological methodology and concepts, mainly derived from Martin Heidegger and Maurice Merleau-Ponty, the examination uncovers an experiential aesthetics intimately intertwined with the protagonist's perceptions throughout the narrative. These perceptions and impressions are permeated by a sense of semi-religious revelation. But here they are primarily seen from an epistemological perspective through the dominance of immediacy (denoted by the Greek aletheia over verificational dimensions (denoted by the Roman veritas. These predominantly sensory aspects of Surfacing make up the aesthetic nerve that is linked to the political impact of the work. Aletheia functions as a promise of emancipation since it transcends the political division of the sensory, that is, art for art's sake and art as life. But, Atwood's work also upholds this separation since aletheia is ultimately autonomous, which in turn sustains the autonomy of the novel. It is claimed that the persistent status of Surfacing—and thereby its sustained political impact—is ultimately due to its aesthetic integrity. The novel's more explicit political concerns of ecocriticism and feminism are secondary in relation to the force of aletheia.

  11. A review of the biomaterials technologies for infection-resistant surfaces.

    Science.gov (United States)

    Campoccia, Davide; Montanaro, Lucio; Arciola, Carla Renata

    2013-11-01

    Anti-infective biomaterials need to be tailored according to the specific clinical application. All their properties have to be tuned to achieve the best anti-infective performance together with safe biocompatibility and appropriate tissue interactions. Innovative technologies are developing new biomaterials and surfaces endowed with anti-infective properties, relying either on antifouling, or bactericidal, or antibiofilm activities. This review aims at thoroughly surveying the numerous classes of antibacterial biomaterials and the underlying strategies behind them. Bacteria repelling and antiadhesive surfaces, materials with intrinsic antibacterial properties, antibacterial coatings, nanostructured materials, and molecules interfering with bacterial biofilm are considered. Among the new strategies, the use of phages or of antisense peptide nucleic acids are discussed, as well as the possibility to modulate the local immune response by active cytokines. Overall, there is a wealth of technical solutions to contrast the establishment of an implant infection. Many of them exhibit a great potential in preclinical models. The lack of well-structured prospective multicenter clinical trials hinders the achievement of conclusive data on the efficacy and comparative performance of anti-infective biomaterials. © 2013 Elsevier Ltd. All rights reserved.

  12. Diamond-like carbon coatings enhance scratch resistance of bearing surfaces for use in joint arthroplasty: hard substrates outperform soft.

    Science.gov (United States)

    Roy, Marcel E; Whiteside, Leo A; Katerberg, Brian J

    2009-05-01

    The purpose of this study was to test the hypotheses that diamond-like carbon (DLC) coatings will enhance the scratch resistance of a bearing surface in joint arthroplasty, and that a hard ceramic substrate will further enhance scratch resistance by reducing plastic deformation. We tested these hypotheses by applying a hard DLC coating to medical-grade cobalt chromium alloy (CoCr) and magnesia-stabilized zirconia (Mg-PSZ) femoral heads and performing scratch tests to determine the loads required to cause cohesive and adhesive fracture of the coating. Scratch tracks of DLC-coated and noncoated heads were then scanned by optical profilometry to determine scratch depth, width, and pile-up (raised edges), as measures of susceptibility to scratching. DLC-coated CoCr specimens exhibited cohesive coating fracture as wedge spallation at an average load of 9.74 N, whereas DLC-coated Mg-PSZ exhibited cohesive fracture as arc-tensile cracks and chipping at a significantly higher average load of 41.3 N (p coating fracture, DLC-CoCr delaminated at an average load of 35.2 N, whereas DLC-Mg-PSZ fractured by recovery spallation at a significantly higher average load of 46.8 N (p DLC-CoCr and DLC-Mg-PSZ specimens exhibited significantly shallower scratches and less pile-up than did uncoated specimens (p DLC-Mg-PSZ better resisted plastic deformation, requiring significantly higher loads for cohesive and adhesive coating fracture. These findings supported both of our hypotheses. (c) 2008 Wiley Periodicals, Inc.

  13. Anodized porous titanium coated with Ni-CeO{sub 2} deposits for enhancing surface toughness and wear resistance

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaowei, E-mail: zhouxiaowei901@163.com; Ouyang, Chun

    2017-05-31

    Highlights: • Structural design of anodized nanoporous Ti was introduced for bonding pinholes to achieve a metallurgical bonding interface. • Anodized porous Ti substrate was activated by electroless Ni-P film to be acted as transitional layer to deposit Ni-CeO{sub 2} nanocomposite coatings. • An analytical model was validated for predicting the Ce-rich worn products as a self-lubricant phase for monitoring wear mechanisms. - Abstract: In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO{sub 2} nanocomposite coatings. Regarding TiO{sub 2} barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO{sub 2} deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO{sub 2} nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO{sub 2} nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devote