We describe azimuthal light scattering spectroscopy (phi/LSS), a novel technique for assessing epithelial-cell nuclear morphology. The difference between the spectra measured at azimuthal angles phi = 0 degrees and phi = 90 degrees preferentially isolates the single backscattering contribution due to large (approximately 10 microm) structures such as epithelial cell nuclei by discriminating against scattering from smaller organelles and diffusive background. We demonstrate the feasibility of using phi/LSS for cancer detection by showing that spectra from cancerous colon tissue exhibit significantly greater azimuthal asymmetry than spectra from normal colonic tissues.
Flow over a circular cylinder with its axis aligned with the free stream was investigated experimentally. Both upstream and downstream faces of the cylinder are sharply truncated. The fineness ratio (length to diameter ratio) was varied and the behavior of the leading-edge separating shear layer and its effect on the wake were studied in water using both flow visualization and PIV techniques. For the moderately large fineness ratio, the shear layer reattaches with subsequent boundary layer growth, whereas over a shorter cylinder the shear layer remains detached. This causes differences in the wake recirculation region and the immediate wake patterns. The shear layer structure was analyzed using the proper orthogonal decomposition (POD). The model in the water channel was sting-mounted and in some cases the effect of model support was detected in the wake measurements. To avoid such disturbance from the model support, an experiment was initiated in air using a magnetic model support and balance system. The drag variation with fineness ratio is presented and discussed in light of the flowfield measurements.
Porous polyethylene oxide-b-polyfluorooctylmethacrylate (PEO-b-PFOMA) diblock copolymer films were drop cast onto substrates from Freon (1,1,2-trichlorotrifluoroethane) in a humid atmosphere. The pores in the films exhibit long range hexagonal order in some cases, depending on the PFOMA-to-PEO molecular weight ratio. Films with the best ordered pores were formed with PFOMA-to-PEO ratios of 70 kDa:2kDa. The pores in the polymer films derive from water droplets that condense as Freon evaporates. The polymer stabilizes the water droplets, or "breath figures," which act as an immiscible template that molds the porous film. Increased polymer hydrophobicity reduces the water wettability of the air/Freon interface, which in turn decreases water droplet nucleation, thus influencing the final pore size and spatial order in the polymer films. We describe how water droplet nucleation influences the final pore size and packing order in the polymer films.