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Now showing items 33 - 48 of 152

  • Migration of vacancies, He interstitials and He-vacancy clusters at grain boundaries in α-Fe

    F. Gao   H.L. Heinisch   R.J. Kurtz  

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  • Integrated Brownian Motions and Exact L2-Small Balls

    F. Gao   J. Hannig and T. Torcaso  

    We will introduce a class of m-times integrated Brownian motions. The exact asymptotic expansions for the $L_2$-small ball probabilities will be discussed for members of this class, of which the usual m-times integrated Brownian motion is an example. Another example will be what we call an Euler-integrated Brownian motion. We will also find very sharp estimates for the asymptotics of the eigenvalues of the covariance operator of integrated Brownian motions and will, therefore, obtain exact, not just logarithmic, asymptotics.
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  • Atomic simulation of ion–solid interaction in ceramics

    F. Gao   W.J. Weber  

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  • Early anti-apoptosis treatment reduces myocardial infarct size after a prolonged reperfusion

    F. Gao   L. Tao   W. Yan   E. Gao   H.-R. Liu   B. L. Lopez   T. A. Christopher and X. L. Ma  

    Objective: Significant myocardial apoptosis occurs in ischemia/reperfused hearts. However, the contribution of apoptosis to the development of myocardial injury remains controversial. The present study attempted to obtain evidence that inhibition of apoptosis at early reperfusion can reduce myocardial infarction after prolonged reperfusion. Methods: Adult male rats were subjected to 30 min ischemia and 4 (apoptosis assay) or 24 h (myocardial infarction determination) of reperfusion and treated with vehicle, SB 239063, insulin or insulin plus wortmannin. Results: Treatment with SB 239063 or insulin markedly decreased myocardial apoptosis (10.6 ± 1.5%and 7.9 ± 0.9%respectively, P vs. vehicle) and significantly reduced infarct size (43 ± 3.6%and 35 ± 2.9%, respectively, P vs. vehicle). Most interestingly, inhibition of insulin signaling with wortmannin to block insulin signaling not only blocked insulin's anti-apoptotic effect, but also abolished its infarct reduction property. Conclusion: These data indicate that apoptosis contributes to the development of myocardial infarction, and inhibition of apoptosis at early reperfusion reduces the myocardial infarction.
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  • Early anti-apoptosis treatment reduces myocardial infarct size after a prolonged reperfusion

    F. Gao   L. Tao   W. Yan   E. Gao   H.-R. Liu   B. L. Lopez   T. A. Christopher   X. L. Ma  

    Objective: Significant myocardial apoptosis occurs in ischemia/ reperfused hearts. However, the contribution of apoptosis to the development of myocardial injury remains controversial. The present study attempted to obtain evidence that inhibition of apoptosis at early reperfusion can reduce myocardial infarction after prolonged reperfusion. Methods: Adult male rats were subjected to 30 min ischemia and 4 (apoptosis assay) or 24 h (myocardial infarction determination) of reperfusion and treated with vehicle, SB 239063, insulin or insulin plus wortmannin. Results: Treatment with SB 239063 or insulin markedly decreased myocardial apoptosis (10.6 +/- 1.5% and 7.9 +/- 0.9% respectively, P 0.01 vs. vehicle) and significantly reduced infarct size (43 +/- 3.6% and 35 +/- 2.9%, respectively, P 0.01 vs. vehicle). Most interestingly, inhibition of insulin signaling with wortmannin to block insulin signaling not only blocked insulin's anti-apoptotic effect, but also abolished its infarct reduction property. Conclusion: These data indicate that apoptosis contributes to the development of myocardial infarction, and inhibition of apoptosis at early reperfusion reduces the myocardial infarction.
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  • Effects of substrate temperature on Bi0.8La0.2FeO3 thin films prepared by pulsed laser deposition

    F. Gao   X.Y. Qiu   Y. Yuan   B. Xu   Y.Y. Wen   F. Yuan   L.Y. Lv   J.-M. Liu  

    Bi 0.8La 0.2FeO 3 thin films on Pt/TiO 2/SiO 2/Si substrates at various substrate temperatures from 500 degC to 750 degC are prepared by pulsed laser deposition, and their microstructures and ferroelectric/magnetic properties are carefully investigated using various techniques. It is observed that the crystallographic orientation and Fe-ion valence state depend significantly on the substrate temperature, which consequently influences considerably on the ferroelectric and magnetic properties of the thin films. A considerable improvement of the ferroelectric and magnetic properties of the thin films can be achieved by optimizing the substrate temperature for deposition. [All rights reserved Elsevier].
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  • The surface and tribological chemistry of chlorine- and sulfur-containing lubricant additives

    F. Gao   P.V. Kotvis   W.T. Tysoe  

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  • Stress and strain concentrations of completely overlapped tubular joints under lap brace OPB load

    F. Gao  

    The stress and strain concentrations of a completely overlapped tubular joint specimen are experimentally investigated under lap brace out-of-plane bending (OPB) load. The experimental results showed that the strain distribution near the weld toe is fairly linear. The maximum strain concentration factor of the joint occurs at the through brace saddle near the lap brace. For the finite element (FE) analysis, both 8-node thick shell and 20-node solid elements are suitable for modelling the joint specimen. A set of parametric equations is proposed for predicting the stress concentration factor (SCF) of completely overlapped tubular joints based on 5184 FE models. The parametric equations are verified against the acceptance criteria of Fatigue Guidance Review Panel. The assessment of the proposed equations is based on the database of FE analysis and test results. The comparison of SCF showed that the existing T/Y-joint parametric equations for predicting the SCF of completely overlapped tubular joints are inappropriate under OPB load. [All rights reserved Elsevier]
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  • Stress and strain concentrations of completely overlapped tubular joints under lap brace OPB load

    F. Gao  

    The stress and strain concentrations of a completely overlapped tubular joint specimen are experimentally investigated under lap brace out-of-plane bending (OPB) load. The experimental results showed that the strain distribution near the weld toe is fairly linear. The maximum strain concentration factor of the joint occurs at the through brace saddle near the lap brace. For the finite element (FE) analysis, both 8-node thick shell and 20-node solid elements are suitable for modelling the joint specimen. A set of parametric equations is proposed for predicting the stress concentration factor (SCF) of completely overlapped tubular joints based on 5184 FE models. The parametric equations are verified against the acceptance criteria of Fatigue Guidance Review Panel. The assessment of the proposed equations is based on the database of FE analysis and test results. The comparison of SCF showed that the existing T/Y-joint parametric equations for predicting the SCF of completely overlapped tubular joints are inappropriate under OPB load.
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  • Laser pyrolysis of polymers and its relation to polymer fire behaviour

    F. Gao   D. Price   G.J. Milnes   B. Eling   C.I. Lindsay   P.T. McGrail  

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  • Damping of surface acoustic vibration induced by electrons trapped on SnO[sub 2] nanocrystal surface

    F. Gao   T. H. Li   X. L. Wu   Y. C. Cheng   J. C. Shen   P. K. Chu  

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  • Reaction of tributyl phosphate with oxidized iron: surface chemistry and tribological significance

    F. Gao   P. V. Kotvis   D. Stacchiola   W. T. Tysoe  

    The chemistry of tributyl phosphate on Fe 3O 4 was studied in ultrahigh vacuum using temperature-programmed desorption (TPD) and Auger spectroscopy. A portion of the tributyl phosphate desorbs intact with an activation energy of ~120 kJ/mol. The remainder decomposes either by P-O bond scission to deposit surface butoxy species or appears to dehydrogenate desorbing C 2 or C 3 compounds and depositing hydrogen and carbon on the surface. The resulting hydrogen reacts either with the oxide to desorb water or with butoxy species yielding 1-butanol. The remaining butoxy species are stable up to ~600 K where they decompose to desorb butanal via hydride elimination where again the hydrogen reacts with butoxy species to form 1-butanol or with the oxide to form water. The carbon deposited onto the surface further reduces the oxide to desorb as CO above ~750 K, although a small amount of carbon is detected on the surface using Auger spectroscopy. Substantially larger amounts of carbon are deposited onto the surface when Fe 3O 4 is exposed to tributyl phosphate at 300 K. where an Auger depth profile reveals that the carbon is located at the surface while the PO x species formed by tributyl phosphate decomposition diffuse rapidly into the oxide layer, leading to a film structure in which graphitic carbon is deposited onto a phosphorus-containing oxide layer
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  • Experimental and Numerical Analysis of an In-Plane Shear Specimen Designed for Ductile Fracture Studies

    F. Gao   L. Gui   Z. Fan  

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  • Thermodynamic Assessment of Phase Equilibria in the Sn-Ag-Ni System with Key Experimental Verification

    F. Gao   C.P. Wang   X.J. Liu   K. Ishida  

    The phase transformations of the Sn-Ag-Ni system were investigated by means of differential scanning calorimetry (DSC). Based on the experimental data of phase equilibria and thermodynamic properties determined by the present work and previous literature, the thermodynamic assessments of the Sn-Ag-Ni system were carried out using the calculation of phase diagrams (CALPHAD) method. The thermodynamic parameters for describing the phase equilibria were optimized, and reasonable agreement between the calculations and experimental data was obtained in the Sn-Ag-Ni ternary system.
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  • Three-dimensional images of the void structure in carbonized preforms

    F. Gao   J. W. Patrick   A. Walker  

    To obtain direct information on the void structure, this study used a silicon impregnation technique to fill targeted voids with silicon. After burning-off the carbon constituents, the remaining silicon skeleton has the form of the target voids. An unavoidable thin layer of SiC was formed by interaction of silicon and carbon at the boundaries between the original voids and carbon constituents of the composite during this process. Therefore the Si-SiC skeleton may be slightly thicker and may possibly show more interconnection than the actual structure of the target voids. However, scanning electron microscopy (SEM) revealed that most of the void features still remain, so the skeletons were further investigated as a preliminary step towards quantification of the three-dimensional structure of voids in two dimensional C/C composites
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  • Intrinsic Volumes of the Brownian Motion Body

    F. Gao   R. A. Vitale  

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