2,418 research outputs found
Effect of damper on overall and blade-element performance of a compressor rotor having a tip speed of 1151 feet per second and an aspect ratio of 3.6
The overall and blade-element performance of two configurations of a moderately high aspect ratio transonic compressor rotor are presented. The subject rotor has conventional blade dampers. The performance is compared with a rotor utilizing dual wire friction dampers. At design speed the subject achieved a pressure ratio of 1.52 and efficiency of 0.89 at a near design weight flow of 72.1 pounds per second. The rotor with wire dampers gave consistently higher pressure ratios at each speed, but efficiencies for the two rotors were about the same. Stall margin for the subject rotor was 20.4 percent, but for the wire damped rotor only 4.0 percent
Characterization of cells of amniotic fluids by immunological identification of intermediate-sized filaments: Presence of cells of different tissue origin
Antibodies against intermediate-sized filaments, of the prekeratin or vimentin type, were used to investigate the presence of these filaments by indirect immunofluorescence microscopy in cultured and non-cultured amniotic fluid cells, in frozen sections of the placenta and in isolated cells of the amniotic epithelium. Two major classes of cells can be cultured from amniotic fluids, namely cells of epithelial origin containing filaments of the prekeratin type and cells of different origin which contain filaments of the vimentin type but are negative when tested with antibodies to epidermal prekeratin. The presence of prekeratin type filaments correlates with the morphology of colonies of amniotic fluid cell cultures in vitro as classified by Hoehn et al. (1974). Cells of E-type colonies are shown to be of epithelial origin. In contrast our data indicate a different origin of almost all cells of F-type colonies and of the large majority of cells of AF-type colonies. Cells of epithelial origin and positively stained with antibodies to epidermal prekeratin are occasionally scattered in F-type colonies and in variable percentages (up to 30%) in AF-type colonies. Surprisingly, cryostat sections of the amniotic epithelium and isolated groups of amniotic cells showed positive reactions with both antibodies to vimentin and prekeratin. The possibility that amniotic cells may be different from other epithelial cells in that they contain both types of filaments simultaneously already in situ is presently under investigation
Characterization of cells of amniotic fluids by immunological identification of intermediate-sized filaments: Presence of cells of different tissue origin
Antibodies against intermediate-sized filaments, of the prekeratin or vimentin type, were used to investigate the presence of these filaments by indirect immunofluorescence microscopy in cultured and non-cultured amniotic fluid cells, in frozen sections of the placenta and in isolated cells of the amniotic epithelium. Two major classes of cells can be cultured from amniotic fluids, namely cells of epithelial origin containing filaments of the prekeratin type and cells of different origin which contain filaments of the vimentin type but are negative when tested with antibodies to epidermal prekeratin. The presence of prekeratin type filaments correlates with the morphology of colonies of amniotic fluid cell cultures in vitro as classified by Hoehn et al. (1974). Cells of E-type colonies are shown to be of epithelial origin. In contrast our data indicate a different origin of almost all cells of F-type colonies and of the large majority of cells of AF-type colonies. Cells of epithelial origin and positively stained with antibodies to epidermal prekeratin are occasionally scattered in F-type colonies and in variable percentages (up to 30%) in AF-type colonies. Surprisingly, cryostat sections of the amniotic epithelium and isolated groups of amniotic cells showed positive reactions with both antibodies to vimentin and prekeratin. The possibility that amniotic cells may be different from other epithelial cells in that they contain both types of filaments simultaneously already in situ is presently under investigation
Relaxation of Surface Profiles by Evaporation Dynamics
We present simulations of the relaxation towards equilibrium of one
dimensional steps and sinusoidal grooves imprinted on a surface below its
roughening transition. We use a generalization of the hypercube stacking model
of Forrest and Tang, that allows for temperature dependent
next-nearest-neighbor interactions. For the step geometry the results at T=0
agree well with the t^(1/4) prediction of continuum theory for the spreading of
the step. In the case of periodic profiles we modify the mobility for the tips
of the profile and find the approximate solution of the resulting free boundary
problem to be in reasonable agreement with the T=0 simulations.Comment: 6 pages, Revtex, 5 Postscript figures, to appear in PRB 15, October
199
Polymer-Based Batteries â Flexible and Thin Energy Storage Systems
Batteries have become an integral part of everyday lifeâfrom small coin cells to batteries for mobile phones, as well as batteries for electric vehicles and an increasing number of stationary energy storage applications. There is a large variety of standardized battery sizes (e.g., the familiar AAâbattery or AAAâbattery). Interestingly, all these battery systems are based on a huge number of different cell chemistries depending on the application and the corresponding requirements. There is not one single battery type fulfilling all demands for all imaginable applications. One battery class that has been gaining significant interest in recent years is polymerâbased batteries. These batteries utilize organic materials as the active parts within the electrodes without utilizing metals (and their compounds) as the redoxâactive materials. Such polymerâbased batteries feature a number of interesting properties, like high power densities and flexible batteries fabrication, among many more
Topological Constraints at the Theta Point: Closed Loops at Two Loops
We map the problem of self-avoiding random walks in a Theta solvent with a
chemical potential for writhe to the three-dimensional symmetric
U(N)-Chern-Simons theory as N goes to 0. We find a new scaling regime of
topologically constrained polymers, with critical exponents that depend on the
chemical potential for writhe, which gives way to a fluctuation-induced
first-order transition.Comment: 5 pages, RevTeX, typo
Quantum lattice dynamical effects on the single-particle excitations in 1D Mott and Peierls insulators
As a generic model describing quasi-one-dimensional Mott and Peierls
insulators, we investigate the Holstein-Hubbard model for half-filled bands
using numerical techniques. Combining Lanczos diagonalization with Chebyshev
moment expansion we calculate exactly the photoemission and inverse
photoemission spectra and use these to establish the phase diagram of the
model. While polaronic features emerge only at strong electron-phonon
couplings, pronounced phonon signatures, such as multi-quanta band states, can
be found in the Mott insulating regime as well. In order to corroborate the
Mott to Peierls transition scenario, we determine the spin and charge
excitation gaps by a finite-size scaling analysis based on density-matrix
renormalization group calculations.Comment: 5 pages, 5 figure
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