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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 6 (1994), S. 2956-2970 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A system of averaged equations describing the motion of a mixture of spherical compressible bubbles in an inviscid liquid is derived by the ensemble-averaging method introduced in an earlier paper [Zhang and Prosperetti, J. Fluid Mech. 267, 185 (1994)]. The averaging procedure introduces new terms in the equations, among which a contribution to the liquid stress tensor is of special interest. An extension of the well-known Rayleigh–Plesset equation to the case of bubbles interacting with the flow is also found. The general system of equations is closed in a rigorous manner in the dilute limit generalizing and correcting earlier averaged equations models. The results are illustrated by considering the problem of linear pressure wave propagation in a nonuniform bubbly liquid. Gradients of the bubble concentration are shown to dampen or amplify the wave strength.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 2955-2970 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The motion of bubbles dispersed in a liquid when a small-amplitude oscillatory motion is imposed on the mixture is examined in the limit of small frequency and viscosity. Under these conditions, for bubbles with a stress-free surface, the motion can be described in terms of added mass and viscous force coefficients. For bubbles contaminated with surface-active impurities, the introduction of a further coefficient to parametrize the Basset force is necessary. These coefficients are calculated numerically for random configurations of bubbles by solving the appropriate multibubble interaction problem exactly using a method of multipole expansion. Results obtained by averaging over several configurations are presented. Comparison of the results with those for periodic arrays of bubbles shows that these coefficients are, in general, relatively insensitive to the detailed spatial arrangement of the bubbles. On the basis of this observation, it is possible to estimate them via simple formulas derived analytically for dilute periodic arrays. The effect of surface tension and density of bubbles (or rigid particles in the case where the no-slip boundary condition is applicable) is also examined and found to be rather small.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The metronidazole resistance of Helicobacter pylori strains has increased rapidly.〈section xml:id="abs1-2"〉〈title type="main"〉Aim:To evaluate the efficacy and safety of new 1-week regimens containing ranitidine bismuth citrate, furazolidone and either amoxicillin or tetracycline.〈section xml:id="abs1-3"〉〈title type="main"〉Methods:One hundred and twenty patients with H. pylori-positive inactive duodenal ulcer or non-ulcer dyspepsia diagnosed by endoscopy were recruited randomly to receive one of two regimens for 7 days: ranitidine bismuth citrate, 350 mg b.d., furazolidone, 100 mg b.d., and either amoxicillin, 1000 mg b.d. (n=60), or tetracycline, 500 mg b.d. (n=60). H. pylori infection was identified by rapid urease testing and histology. 13C-Urea breath test was performed to evaluate the cure of H. pylori infection at least 4 weeks after completion of triple therapy.〈section xml:id="abs1-4"〉〈title type="main"〉Results:The eradication rates of H. pylori by ranitidine bismuth citrate–furazolidone–amoxicillin and ranitidine bismuth citrate–furazolidone–tetracycline regimens were 82% and 85% (P 〉 0.05), respectively, by intention-to-treat analysis, and 85% and 91% (P 〉 0.05), respectively, by per protocol analysis. Adverse effects were mild in both ranitidine bismuth citrate–furazolidone–amoxicillin and ranitidine bismuth citrate–furazolidone–tetracycline groups.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:One-week regimens containing ranitidine bismuth citrate, furazolidone and amoxicillin or tetracycline are well tolerated and effective for the eradication of H. pylori.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and computational fluid dynamics 7 (1995), S. 429-440 
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Three aspects of the finite radius of spherical particles in disperse two-phase flows are described. The first one is the relation between the exact volume fraction and the widely used approximation nv (n is the particle number density and v is the particle volume). The approximation affects the behavior of the effective equations at short wavelengths with possible consequences on stability and hyperbolicity. Secondly, the dilute theory of inviscid suspensions is corrected retaining the next leading order in the particle size and an application of this result to the linear problem is described. Thirdly, it is shown how several important properties of suspensions such as effective thermal conductivity and viscosity depend on the subtle effect of translation of the average fields over distances of the order of the particle size.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0649
    Keywords: 07.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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