72,977 research outputs found

    Preliminary Study on Treatment of Contaminated Groundwater from the Taylorville Gasifier Site

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    Groundwater and soil at the site of an abandoned coal gasification plant in Taylorville, Illinois have been contaminated with compounds associated with coal conversion process waters. A preliminary study to assess the feasibility of using ethanol as a means of increasing the solubility of compounds adsorbed within the soil matrix followed by treatment of the ethanol/groundwater extract in an expanded-bed anaerobic granular activated carbon (GAC) reactor was conducted. Results of the study indicate that compounds in the groundwater are highly adsorb able on GAC, and do not interfere with the anaerobic degradation of ethanol in the reactor. Soil extractions with varying ethanol/water ratios were able to remove many additional low water solubility compounds from the soil.ENR Contract Number HWR87035published or submitted for publicationis peer reviewe

    Magneto-elastic quantum fluctuations and phase transitions in the iron superconductors

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    We examine the relevance of magneto-elastic coupling to describe the complex magnetic and structural behaviour of the different classes of the iron superconductors. We model the system as a two-dimensional metal whose magnetic excitations interact with the distortions of the underlying square lattice. Going beyond mean field we find that quantum fluctuation effects can explain two unusual features of these materials that have attracted considerable attention. First, why iron telluride orders magnetically at a non-nesting wave-vector (π/2,π/2)(\pi/2, \pi/2) and not at the nesting wave-vector (π,0)(\pi, 0) as in the iron arsenides, even though the nominal band structures of both these systems are similar. And second, why the (π,0)(\pi, 0) magnetic transition in the iron arsenides is often preceded by an orthorhombic structural transition. These are robust properties of the model, independent of microscopic details, and they emphasize the importance of the magneto-elastic interaction.Comment: 4 pages, 3 figures; minor change

    Smoothed Affine Wigner Transform

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    We study a generalization of Husimi function in the context of wavelets. This leads to a nonnegative density on phase-space for which we compute the evolution equation corresponding to a Schr\"Aodinger equation

    Comments on Early Friends and the Work of Christ

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    Interaction Correction of Conductivity Near a Ferromagnetic Quantum Critical Point

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    We calculate the temperature dependence of conductivity due to interaction correction for a disordered itinerant electron system close to a ferromagnetic quantum critical point which occurs due to a spin density wave instability. In the quantum critical regime, the crossover between diffusive and ballistic transport occurs at a temperature T=1/[τγ(EFτ)2]T^{\ast}=1/[\tau \gamma (E_{F}\tau)^{2}], where γ\gamma is the parameter associated with the Landau damping of the spin fluctuations, τ\tau is the impurity scattering time, and EFE_{F} is the Fermi energy. For a generic choice of parameters, TT^{\ast} is few orders of magnitude smaller than the usual crossover scale 1/τ1/\tau. In the ballistic quantum critical regime, the conductivity has a T(d1)/3T^{(d-1)/3} temperature dependence, where dd is the dimensionality of the system. In the diffusive quantum critical regime we get T1/4T^{1/4} dependence in three dimensions, and ln2T\ln^2 T dependence in two dimensions. Away from the quantum critical regime we recover the standard results for a good metal.Comment: 15 pages, 8 figure

    The COOH terminus of the c-Abl tyrosine kinase contains distinct F- and G-actin binding domains with bundling activity

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    The myristoylated form of c-Abl protein, as well as the P210bcr/abl protein, have been shown by indirect immunofluorescence to associate with F-actin stress fibers in fibroblasts. Analysis of deletion mutants of c-Abl stably expressed in fibroblasts maps the domain responsible for this interaction to the extreme COOH-terminus of Abl. This domain mediates the association of a heterologous protein with F-actin filaments after microinjection into NIH 3T3 cells, and directly binds to F-actin in a cosedimentation assay. Microinjection and cosedimentation assays localize the actin-binding domain to a 58 amino acid region, including a charged motif at the extreme COOH-terminus that is important for efficient binding. F-actin binding by Abl is calcium independent, and Abl competes with gelsolin for binding to F- actin. In addition to the F-actin binding domain, the COOH-terminus of Abl contains a proline-rich region that mediates binding and sequestration of G-actin, and the Abl F- and G-actin binding domains cooperate to bundle F-actin filaments in vitro. The COOH terminus of Abl thus confers several novel localizing functions upon the protein, including actin binding, nuclear localization, and DNA binding. Abl may modify and receive signals from the F-actin cytoskeleton in vivo, and is an ideal candidate to mediate signal transduction from the cell surface and cytoskeleton to the nucleus
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