Turbulence-induced preferential concentration of solid particles in microgravity conditions

A box of near-isotropic, particle-laden turbulence was flown aboard NASA's reduced gravity aircraft in order to measure the turbulence-induced preferential concentration of solid particles in microgravity. Three particle sets of Stokes numbers based on the fluid Kolmogorov time scale of approximately 0.5, 5, and 50 were tested for relative amounts of preferential concentration. Eight fans in each corner of a Lexan box generated fluid turbulence. Particle concentrations were measured using an imaging system consisting of a camera viewing perpendicular to a white light sheet. Post-processing of video images found largest concentration gradients for the intermediate-sized particles of Stokes number 5, closely followed by the Stokes number 0.5 particles. The experimental results agreed well with the trends seen in direct numerical simulations. The quantitative effects of turbulence modulation by the presence of particles were not measured in the experiment, but were most likely present. Received: 10 February 2000 / Accepted: 9 November 2001     

Isospectral superdeformed bands in the N = 46 nuclei 88Mo and 89Tc

Superdeformed bands in ⁸⁸Mo and ⁸⁹Tc were populated using ⁴⁰Ca-induced fusion-evaporation reactions on ⁵⁸Ni at a beam energy of 185MeV. Gamma-rays emitted in the reactions were detected using the Gammasphere spectrometer, in coincidence with charged particles detected by the Microball array. A new superdeformed band was assigned to the nucleus ⁸⁸Mo, leading to a revisit of earlier configuration assignments for superdeformed structures in this nucleus. In particular, the theoretical interpretation of a pair of identical (isospectral) superdeformed bands in ⁸⁸Mo/⁸⁹Tc is discussed. The configurations that are assigned to the four SD bands belonging to ⁸⁸Mo have properties that are predicted to be significantly affected by pair correlations.Received: 1 October 2003, Revised: 30 January 2004, Published online: 21 September 2004PACS: 21.10.Re Collective levels - 21.60.Cs Shell model - 23.20.Lv transitions and level energies - 27.50. + e K. Lagergren: Present address: Department of Physics, Florida State University, Tallahassee, FL 32306, USA;A. Görgen: Present address: DAPNIA/SPhN, CEA Saclay, F-91191 Gif-sur-Yvette Cedex, France.     

Yrast band spectroscopy of155Gd and157Dy

The yrast bands of¹⁵⁵Gd and¹⁵⁷Dy have been observed to high spins (I～25–40). The systematic properties of the N=91 isotones with particular reference to the second i_13/2 neutron and first h_11/2 proton alignments are discussed.     

On the character of three 8+ states in 192Pb

Three low-lying 8⁺ states have been identified in ¹⁹²Pb . A newly observed cascade of $ \gamma$ -rays built directly on the 8⁺ ₁ state is compared to the previously identified, weakly rotational band above the 11^- $ \pi$ i _13/2 , h _9/2 isomer in the same nucleus, and to analogous structures in ¹⁹⁴Pb . The similarity of all four structures lends support to the suggestion that the 8⁺ ₁ configurations are of a similar oblate deformation to the 11^- isomers. The excitation energies of all three 8⁺ states in ¹⁹²Pb and ¹⁹⁰Pb are compared to systematics. The possibility that one of the 8⁺ states in ¹⁹²Pb is associated with a prolate shape is discounted.     

DuPont Qualicon BAX System assay for genus Listeria 24E

The new BAX System PCR Assay for Genus Listeria 24E was evaluated for detecting Listeria spp. in frankfurters, spinach, cooked shrimp, queso fresco cheese, and on stainless steel surfaces with a single-stage enrichment in BAX System 24 Listeria Enrichment Broth (24 LEB). Method comparison studies performed on samples with low-level inoculates showed that the BAX System demonstrates a sensitivity equivalent or superior to the U.S. Food and Drug Administration's Bacteriological Analytical Manual and the U.S. Department of Agriculture-Food Safety and Inspection Service culture methods, but with a significantly shorter time to result. Tests to evaluate inclusivity and exclusivity returned no false-negative and no false-positive results on a diverse panel of isolates, and tests for lot-to-lot variability and tablet stability demonstrated consistent performance. Ruggedness studies determined that none of the factors examined, within the range of deviations from specified parameters examined, affect the performance of the assay.     

Quadrupole moments of superdeformed bands in 193Tl

Lifetimes of states in the two strongest superdeformed (SD) bands in ¹⁹³Tl were measured using the Doppler-shift attenuation method. The reaction ¹⁷⁶Yb(²³Na,6n)¹⁹³Tl at a beam energy of 129 MeV was used and γ-rays were detected by the Gammasphere array. Quadrupole moments of 18.3(10) eb and 17.4(10) eb were extracted for SD bands 1 and 2, respectively, using the fractional Doppler-shifts of the SD transitions. The previously reported linking transitions of these SD bands to normal deformed near yrast levels could not be confirmed. No other candidates for linking transitions could be established. Received: 27 April 1999