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.
The ability of chitin fermentation products to promote tetrachloroethene (PCE) reduction was evaluated in a continuous-flow column system to identify how different electron donors affect reductive dechlorination. Natural chitin fermentation products were initially used to support PCE reduction. Acetate (3.5mM) was the dominant fermentation product, followed by propionate (0.1mM), butyrate (0.1mM), and hydrogen (100nM). After chlorinated ethene concentration profiles reached pseudo steady state, the ability of individual fermentation products (acetate, acetate+propionate, propionate, or formate) to support PCE reduction was evaluated. None of the fermentation products tested stimulated dechlorination as well as the suite generated from chitin (kPCE=6.9day−1); however, acetate-stimulated PCE dechlorination the best (kPCE=5.3day−1), followed by formate (kPCE=2.4day−1), acetate+propionate (kPCE=1.8day−1), and propionate (kPCE=1.2day−1). Similar trends were observed for the PCE daughter products trichloroethene and dichloroethene. Free energies of individual fatty acid reactions were calculated and shown to be useful predictors of dechlorination performance, except for the case of acetate+propionate. Hence, acetate is the dominant fatty acid controlling dechlorination in the chitin-enhanced system, propionate appears to have an inhibitory effect when present with acetate alone, and other unidentified nutrients produced during chitin fermentation likely contribute to dechlorination activity as well.
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.
Chitin, corncobs, and a mixture of chitin and corncobs were tested as potential electron donor sources for stimulating the reductive dechlorination of tetrachloroethene (PCE). Semi-batch, sand-packed columns were used to evaluate the donors with aerobic and anaerobic groundwaters containing varying degrees of alkalinity. In all experiments, acetate and butyrate were the dominant fatty acids produced, although propionate, valerate, formate, and succinate were also detected. From a multivariable regression analysis on the data, the presence of chitin, limestone, and dechlorinating culture inoculum were determined to be the most positive predictors of dechlorination activity. Chitin fermentation products supported the degradation of PCE to trichloroethene (TCE), cis-1,2-dichloroethene (DCE), and vinyl chloride (VC), even in columns containing PCE DNAPL, whereas dechlorination activity was not observed in any of the columns containing corncobs alone. The longevity and efficiency of chitin as an electron donor source demonstrates its potential usefulness for passive, in situ field applications.