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  • 1
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    Chicago : Periodicals Archive Online (PAO)
    Journal of marketing research. 25:3 (1988:Aug.) 308 
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  • 2
    ISSN: 1573-5028
    Keywords: chloroplast rDNA ; termination region ; 4.5S rRNA ; rRNA processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Postimplant calcific degeneration is a frequent cause of clinical failures of glutaraldehyde cross-linked porcine bioprosthetic heart valves (BPHV). It was demonstrated previously that 2-amino oleic acid (AOA) used as a bioprosthesis treatment was highly effective in mitigating aortic valve cusp but not aortic wall calcification. Our main objective was to study the efficacy of various AOA exposure conditions for inhibiting calcification of both cusps and aortic wall tissues using rat subdermal implants. BPHV tissues were treated with a saturated AOA solution for different time intervals before experimentation. Aortic wall AOA levels were consistently lower than that of the cusps after the same exposure times. The diffusion of calcium ion across both cusp and aortic wall tissues was evaluated, and the results demonstrated that there was an AOA exposure time-dependent retardation of calcium ion penetration for cusp but not aortic wall. An 8-month extraction study was performed to determine the stability of AOA binding. When Tween 80 was used as an extraction medium, cusp and aortic wall retained 12.9 and 48.7%, respectively, of their initial AOA levels. AOA inhibition of calcification in rat subdermal implants (60 days) was found to be exposure time-dependent with maximum treatment time (120 h), resulting in the lowest calcium levels (20.1 ± 10.3 and 71.4 ± 5.4 μg/mg of cusp and aortic wall, respectively) as compared with control (219.1 ± 6.8 and 104.9 ± 8.5 μg/mg of cusp and aortic wall respectively). The significance of AOA binding on BPHV tissue was determined by either blocking or reducing BPHV's (cusp and aortic wall) free aldehyde residues with lysine or NaBH4, respectively, before AOA treatment. For aortic cusps, the AOA contents after 72 h were 98.3 ± 2.7, 34.2 ± 3.6, and 54.1 ± 3.0 nM/mg of tissue for AOA (control), lysine-pretreated (plus AOA) and NaBH4-pretreated (plus AOA) tissues, respectively. However, their calcium levels after 60 days of rat subdermal implant were all comparable (i. e., 48.1 ± 6.2, 38.2 ± 9.1, and 47.0 ± 15.0 μg calcium per mg of tissue). Similar results were observed on BPHV aortic wall. It can thus be concluded that AOA inhibition of BPHV calcification is exposure time-dependent, but the efficacy of AOA for aortic wall is less than that noted for aortic cusps, perhaps because of lower AOA bindings and differences in calcium diffusion kinetics. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the steady laminar flow past a sudden expansion at large Reynolds number R, the equations of motion reduce to the boundary-layer equations as R→∞ if the longitudinal length scale of the separated eddy increases linearly and indefinitely with R. In part I of this series [Phys. Fluids 29, 1353 (1986)], several sudden expansion geometries were considered, and in each case, when the inflow was uniform, steady solutions to the boundary-layer equations were found to exist provided that the expansion ratio remained above a critical value where the pressure gradient became singular near the reattachment point of the eddy. These results suggested that for uniform inflows and smaller values of the expansion ratio, the eddy length could not continue to increase linearly with R if the latter were sufficiently large. In the present work a global Newton method was employed to obtain finite-difference solutions to the steady Navier–Stokes equations up to R=1000 for a uniform inflow past a cascade of sudden expansions. The calculations show that for large values of the expansion ratio, the eddy length increases linearly with R, and that the main features of the flow approach those predicted by the boundary-layer solutions, including the existence of large pressure gradients near the reattachment point, as the expansion ratio is reduced toward the critical value. However, for smaller values of the expansion ratio where solutions to the boundary-layer equations could not be found, the steady solutions to the Navier–Stokes equations approach, with increasing R, the limit of an inviscid eddy O(1) in length, with the main features of the flow conforming to the theoretical model of Batchelor [J. Fluid Mech. 1, 388 (1956)] for an inviscid separated eddy behind a bluff body.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 955-963 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The deformation of a hairpin-shaped vortex filament under self-induction and in the presence of shear is studied numerically using the Biot–Savart law. It is shown that the tip region of an elongated hairpin vortex evolves into a vortex ring and that the presence of mean shear impedes the process. In addition, evolution of a finite-thickness vortex sheet under self-induction is investigated using the Navier–Stokes equations. The layer evolves into a hairpin vortex, which in turn produces a vortex ring of high Reynolds stress content. These results indicate a mechanism for the generation of ring vortices in turbulent shear flows, and a link between the experimental and numerical observation of hairpin vortices and the observation of Falco [Phys. Fluids 20, S124 (1977)] of ring vortices in the outer regions of turbulent boundary layers.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 52-58 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Turbulence structures in a wall-bounded shear layer during the bursting event detected by a conditional sampling technique are investigated using data obtained from large-eddy simulation of turbulent channel flow. Streamlines are constructed from the ensemble-averaged velocity field to illustrate the flow patterns associated with the bursting event. They exhibit the "splatting'' motions during the sweep event and the existence of a pair of counterrotating streamwise vortices during the ejection process.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 695-706 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A database obtained from direct numerical simulation of a turbulent channel flow is analyzed to extract the streamwise component of the propagation velocity V of velocity, vorticity, and pressure fluctuations from their space-time correlations. A surprising result is that V is approximately the same as the local mean velocity for most of the channel, except for the near-wall region. For y+≤15, V is virtually constant, implying that perturbations of all flow variables propagate like waves near the wall. In this region, V is 55% of the centerline velocity Uc for velocity and vorticity perturbations and 75% of Uc for pressure perturbations. This is equal to U at y+=15 for velocity and vorticity perturbations, and equal to U at y+=20 for pressure perturbations, indicating that the dynamics of the near-wall turbulence is controlled by turbulence structures present near y+(approximately-equal-to)15–20. Scale dependence of V is also examined by analyzing the bandpass-filtered flow fields. This paper contains comprehensive documentation on the propagation velocities, which should prove useful in the evaluation of Taylor's hypothesis. An attempt has been made to explain some of the data in terms of the current understanding of organized structures.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 775-777 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Numerical experiments were performed to clarify apparent differences between experimental observations and a theoretical prediction of the secondary instability in plane Poiseuille flow. It is shown that subharmonic breakdown is unlikely in natural transition as a result of the initial growth of what we call the "minus'' modes and consequent forcing of Orr–Sommerfeld modes present in the background noise. Subharmonic breakdown was achieved only when these minus modes were continuously suppressed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 2914-2917 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Direct numerical simulations of turbulent spots in plane Poiseuille and boundary-layer flows are performed. Mature, self-similar spots are obtained. The propagation velocities and spreading angles are found to compare well with corresponding experiments. The difference in shape of the two spots is also clearly discernible: the turbulent parts are contained within arrowhead regions that point in opposite directions for the two cases. The wing-tip region of the Poiseuille spot is also found to consist of a large-amplitude semiturbulent wave packet.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 88 (1966), S. 4203-4211 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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