849 research outputs found

    Investigation of Corrosion Behavior of Bioactive Coverings on Commercially Pure Titanium and its Alloys

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    A microporous and macroporous bioactive coatings on boimedical titanium alloys (VT1-0, VT6, Ti-6Al-7Nb) were formed by a micro-arc oxidation method. The effect of the phase composition of microporous and macroporous coatings on corrosion behavior titanium and its alloys was investigated. The results show that phase composition of the coatings microporous presented only titanium oxides: anatase and rutile, at that the phase composition macroporous coatings consists of anatase, rutile and calcium phosphate compounds: tricalcium phosphate (TCP) α-Ca3(PO4)2 and calcium deficient hydroxyapatite Ca9HPO4(PO4)5OH. Corrosion behavior of MAO coatings was investigated in solution 0.9 % NaCl using potentiodynamic polarization tests. The microporous coatings exhibited a more highest corrosion resistance than macroporous coatings, it is connected with containing calcium phosphate compounds in macroporous coatings

    The Effective Action For Brane Localized Gauge Fields

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    The low energy effective action including gauge field degrees of freedom on a non-BPS p=2 brane embedded in a N=1, D=4 target superspace is obtained through the method of nonlinear realizations of the associated super-Poincare symmetries. The invariant interactions of the gauge fields and the brane excitation modes corresponding to the Nambu-Goldstone degrees of freedom resulting from the broken space translational symmetry and the target space supersymmetries are determined. Brane localized matter field interactions with the gauge fields are obtained through the construction of the combined gauge and super-Poincare covariant derivatives for the matter fields.Comment: 12 pages, no figure

    The electrical properties of coating obtained by vacuum arc deposition

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    AbstractThis paper investigates the electrical properties of the coating based on Ti–C–B system. The coating was obtained by vacuum-arc method by spraying of multi compound cathode prepared by reactive hot pressing of Ti, carbon black and amorphous B powder mixture.The electrical conductivity of the coating was measured in temperature range of 10–320K which was about σ=4.8·103Ω−1cm−1 in the entire temperature range. The carrier concentration measured was about n=1·1022 cm−3. The charge carriers’ mobility varies between 10 and −7 and changes sign at temperature about T=225K

    Investigation of Corrosion Behavior of Bioactive Coverings on Commercially Pure Titanium and its Alloys

    Get PDF
    A microporous and macroporous bioactive coatings on boimedical titanium alloys (VT1-0, VT6, Ti-6Al-7Nb) were formed by a micro-arc oxidation method. The effect of the phase composition of microporous and macroporous coatings on corrosion behavior titanium and its alloys was investigated. The results show that phase composition of the coatings microporous presented only titanium oxides: anatase and rutile, at that the phase composition macroporous coatings consists of anatase, rutile and calcium phosphate compounds: tricalcium phosphate (TCP) α-Ca3(PO4)2 and calcium deficient hydroxyapatite Ca9HPO4(PO4)5OH. Corrosion behavior of MAO coatings was investigated in solution 0.9 % NaCl using potentiodynamic polarization tests. The microporous coatings exhibited a more highest corrosion resistance than macroporous coatings, it is connected with containing calcium phosphate compounds in macroporous coatings

    Unitarity Corrections to the Proton Structure Functions through the Dipole Picture

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    We study the dipole picture for the description of the deep inelastic scattering, focusing on the structure functions which are driven directly by the gluon distribution. One performs estimates using the effective dipole cross section given by the Glauber-Mueller approach in QCD, which encodes the corrections due to the unitarity effects associated with the saturation phenomenon. We also address issues about frame invariance of the calculations when analysing the observables.Comment: 16 pages, 8 figures. Version to be published in Phys. Rev.

    Superscaling predictions for neutrino-induced charged-current charged pion production at MiniBooNE

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    Superscaling approximation (SuSA) predictions to neutrino-induced charged-current charged pion production in the \Delta-resonance region are explored under MiniBooNE experimental conditions. The results obtained within SuSA for the flux-averaged double-differential cross sections of the \pi+ production for the \nu_\mu+CH_2 reaction as a function of the muon kinetic energy and of the scattering angle, the cross sections averaged over the angle, the total cross section for the \pi+ production, as well as CC1\pi+ to CCQE cross section ratio are compared with the corresponding MiniBooNE experimental data. The SuSA predictions are in good agreement with data on neutrino flux average cross-sections, but a somewhat different dependence on the neutrino energy is predicted than the one resulting from the experimental analysis.Comment: 15 pages, 6 figures, accepted for publication in Physics Letters

    Two-temperature relaxation and melting after absorption of femtosecond laser pulse

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    The theory and experiments concerned with the electron-ion thermal relaxation and melting of overheated crystal lattice constitute the subject of this paper. The physical model includes two-temperature equation of state, many-body interatomic potential, the electron-ion energy exchange, electron thermal conductivity, and optical properties of solid, liquid, and two phase solid-liquid mixture. Two-temperature hydrodynamics and molecular dynamics codes are used. An experimental setup with pump-probe technique is used to follow evolution of an irradiated target with a short time step 100 fs between the probe femtosecond laser pulses. Accuracy of measurements of reflection coefficient and phase of reflected probe light are ~1% and \sim 1\un{nm}, respectively. It is found that, {\it firstly}, the electron-electron collisions make a minor contribution to a light absorbtion in solid Al at moderate intensities; {\it secondly}, the phase shift of a reflected probe results from heating of ion subsystem and kinetics of melting of Al crystal during 0 where tt is time delay between the pump and probe pulses measured from the maximum of the pump; {\it thirdly} the optical response of Au to a pump shows a marked contrast to that of Al on account of excitation of \textit{d}-electronsComment: 6th International Conference on Photo-Excited Processes and Applications 9-12 Sep 2008, Sapporo, Japan, http://www.icpepa6.com, the contributed paper will be published in Applied Surface Science(2009

    K -> pi pi and a light scalar meson

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    We explore the Delta-I= 1/2 rule and epsilon'/epsilon in K -> pi pi transitions using a Dyson-Schwinger equation model. Exploiting the feature that QCD penguin operators direct K^0_S transitions through 0^{++} intermediate states, we find an explanation of the enhancement of I=0 K -> pi pi transitions in the contribution of a light sigma-meson. This mechanism also affects epsilon'/epsilon.Comment: 7 pages, REVTE

    Meson-exchange currents and quasielastic neutrino cross sections in the SuperScaling Approximation model

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    We evaluate the quasielastic double differential neutrino cross sections obtained in a phenomenological model based on the superscaling behavior of electron scattering data. We compare our results with the recent experimental data for neutrinos of MiniBooNE and estimate the contribution of the vector meson-exchange currents in the 2p-2h sector.Comment: 6 pages, 4 figure

    A Twistor Formulation of the Non-Heterotic Superstring with Manifest Worldsheet Supersymmetry

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    We propose a new formulation of the D=3D=3 type II superstring which is manifestly invariant under both target-space N=2N=2 supersymmetry and worldsheet N=(1,1)N=(1,1) super reparametrizations. This gives rise to a set of twistor (commuting spinor) variables, which provide a solution to the two Virasoro constraints. The worldsheet supergravity fields are shown to play the r\^ole of auxiliary fields.Comment: 21p., LaTe
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