NASA Scientific and Technical Aerospace Reports

instability modes in comparison with the results obtained with either Dirichlet or Neumann conditions.
Author
Boundary Conditions; Boundary Layer Transition; Flow Distortion
20040111394 Michigan Univ., Ann Arbor, MI, USA
Two-Photon Flow Cytometry
Zhog, Cheng Frank; Ye, Jing Yong; Norris, Theodore B.; Myc, Andrzej; Cao, Zhengyl; Bielinska, Anna; Thomas, Thommey;
Baker, James R., Jr.; [2004]; 1 pp.; In English
Contract(s)/Grant(s): NAS2-02069; No Copyright; Avail: Other Sources
Flow cytometry is a powerful technique for obtaining quantitative information from fluorescence in cells. Quantitation is
achieved by assuring a high degree of uniformity in the optical excitation and detection, generally by using a highly controlled
flow such as is obtained via hydrodynamic focusing. In this work, we demonstrate a two-beam, two- channel detection and
two-photon excitation flow cytometry (T(sup 3)FC) system that enables multi-dye analysis to be performed very simply, with
greatly relaxed requirements on the fluid flow. Two-photon excitation using a femtosecond near-infrared (NIR) laser has the
advantages that it enables simultaneous excitation of multiple dyes and achieves very high signal-to-noise ratio through
simplified filtering and fluorescence background reduction. By matching the excitation volume to the size of a cell, single-cell
detection is ensured. Labeling of cells by targeted nanoparticles with multiple fluorophores enables normalization of the
fluorescence signal and thus ratiometric measurements under nonuniform excitation. Quantitative size measurements can also
be done even under conditions of nonuniform flow via a two-beam layout. This innovative detection scheme not only
considerably simplifies the fluid flow system and the excitation and collection optics, it opens the way to quantitative
cytometry in simple and compact microfluidics systems, or in vivo. Real-time detection of fluorescent microbeads in the
vasculature of mouse ear demonstrates the ability to do flow cytometry in vivo. The conditions required to perform quantitative
in vivo cytometry on labeled cells will be presented.
Author
Cytometry; Fluid Flow; Photons; Detection; Fluorescence
20040111427 National Center for Microgravity Research on Fluids and Combusiton, Cleveland, OH, USA
Thermocapillary Convection Due to a Stationary Bubble - A Paradox
Balasubramaniam, R.; Subramanian, R. S.; [2003]; 2 pp.; In English; Annual Meeting American Institute of Chemical
Engineers, 13-14 Oct. 2003, Ann Arbor, MI, USA
Contract(s)/Grant(s): NCC3-975; 101-58-09; No Copyright; Avail: CASI; A01, Hardcopy
We analyze the velocity and temperature fields at steady state due to thermocapillary convection around a gas bubble that
is stationary in a liquid. A linear temperature field is imposed in the undisturbed liquid. Our interest is in investigating the effect
of convective transport of momentum and energy on the velocity and temperature fields. We assume the pertinent physical
properties to be constant, and that buoyant convection is negligible. Suitably defined Reynolds and Marangoni numbers are
assumed to be small compared with unity. When both the Reynolds and Marangoni numbers are set equal to zero, a solution
can be found. In this solution, far from the bubble, the velocity field decays as the inverse of the distance from the bubble,
and the disturbance temperature field decays as the inverse of the square of this distance. We now attempt to obtain a solution
when the Reynolds number is zero, but the Marangoni number is small, but non-zero, by a perturbation expansion in the
Marangoni number. When the temperature field is expanded in a regular perturbation series in the Marangoni number, we show
that the problem for the first correction field is ill-posed. The governing equation for this perturbation field contains an
inhomogeneity, and the corresponding particular solution neither decays far from the bubble, nor can be canceled by a
homogeneous solution. Additional information is included in the original extended abstract.
Author (revised)
Bubbles; Thermocapillary Migration; Marangoni Convection; Steady State; Momentum Transfer
20040111470 Academy of Sciences of the Ukraine, Kiev
Aerodynamic Applications of Boundary Layer Control Using Embedded Streamwise Vortices
Yurchenko, Nina F.; Jul. 2003; 77 pp.; In English; Original contains color illustrations
Report No.(s): AD-A425398; EOARD-STCU-01-8002; No Copyright; Avail: CASI; A05, Hardcopy
The objective of the proposed work is to show feasibility and effectiveness of inherent streamwise vortices to control
characteristics of boundary layers through modification of their space-time scales as well as to develop an engineering
approach to generation and maintenance of a favorable vortical structure near a wall. To account for flow conditions taking
114