8518308
Pb(II) distributions at biofilm–metal oxide interfaces
The distribution of aqueous Pb(II) sorbed at the interface between Burkholderia cepacia biofilms and hematite (α-Fe2O3) or corundum (α-Al2O3) surfaces has been probed by using an application of the long-period x-ray standing wave technique. Attached bacteria and adsorbed organic matter may interfere with sorption processes on metal oxide surfaces by changing the characteristics of the electrical double layer at the solid–solution interface, blocking surface sites, or providing a variety of new sites for metal binding. In this work, Pb Lα fluorescence yield profiles for samples equilibrated with 10−7 to 10−3.8 M Pb(II) were measured and modeled to determine quantitatively the partitioning of Pb(II) at the biofilm–metal oxide interface. Our data show that the reactive sites on the metal oxide surfaces were not passivated by the formation of a monolayer biofilm. Instead, high-energy surface sites on the metal oxides form the dominant sink for Pb(II) at submicromolar concentrations, following the trend α-Fe2O3 (0001) > α-Al2O3 (11̄02) > α-Al2O3 (0001), despite the greater site density within the overlying biofilms. At [Pb] > 10−6 M, significant Pb uptake by the biofilms was observed.
134906969
Synchrotron-based studies of microbe-metal ion-mineral interactions
121451303
Molecular beam epitaxial growth and properties of CoFe2O4 on MgO(001)
Abstract We have grown single-crystal Co ferrite (CoFe 2 O 4 ) on MgO(0 0 1) by oxygen-plasma-assisted molecular beam epitaxy (OPA-MBE), and have characterized the composition, structure, surface morphology, and magnetic properties by a number of methods. The as-grown OPA-MBE material forms a perfect inverse spinel, in which all Co is in the 2+ formal oxidation state, and occupies octahedral sites within the cation sublattice. The OPA-MBE film surfaces are very flat, with mean roughnesses of only a few A, and exhibit large, stable magnetic domains. The measured moment per unit volume is 250 emu/cm 3 , and the saturation magnetization for films in the 1000 A film thickness range is ∼60% of that of bulk Co ferrite. The material also exhibits strain-dependent magnetic anisotropy that can be understood by considering the various contributions to the total magnetic energy. The overall quality of epitaxial Co ferrite grown on MgO by OPA-MBE is superior in every respect to that obtained using pulsed laser deposition as the growth method.
14037638
Event-by-Event Physics at the CERN SPS
Event-by-event physics in nuclear collisions has been an active field of research for more than a decade. Jet production in p-p and e-e collisions and flow in heavy-ion collisions have been extensively studied at LEP, CSPS, TEVATRON, BEVALAC and AGS among other facilities. Jets and flow are large-amplitude and/or large-scale effects which are detectable despite the rather small particle multiplicities per event from these collision systems. Multiplicities have been limited by small system size (p-p, e-e) or low energy densities (heavy ions). Both jet and flow phenomena are manifestations of symmetry reduction or increased correlation with respect to a nominally thermalized system of produced particles.
121880014
Internal pair conversion in heavy nuclei
29108617
The University of Washington Superconducting Booster Linac
We have begun construction of a superconducting linac designed to accelerate ions from protons through about mass 60. Injected by our 9 MV-terminal tandem van de Graaff accelerator, the linac is expected to double the proton energy and quadruple the energies of heavier ions. The resonators are lead plated copper quarter wave structures. The overall layout and expected performance of the accelerator will be presented, along with a brief status report.
118557363
Azimuth quadrupole component spectra on transverse rapidity y(t) for identified hadrons from Au-Au collisions at s(NN)**(1/2) = 200-GeV
I present the first isolation of azimuth quadrupole components from published $v_2(p_t)$ data (called elliptic flow) as spectra on transverse rapidity $y_t$ for identified pions, kaons and lambdas/protons from minimum-bias Au-Au collisions at 200 GeV. The form of the spectra on $y_t$ indicates that the three hadron species are emitted from a common boosted source with boost $\Delta y_{t0} \sim 0.6$. The quadrupole spectra have a L\'evy form similar to the soft component of the single-particle spectrum, but with significantly reduced ($\sim 0.7\times$) slope parameters $T$. Comparison of quadrupole spectra with single-particle spectra suggests that the quadrupole component comprises a small fraction ($< 5$%) of the total hadron yield, contradicting the hydrodynamic picture of a thermalized, flowing bulk medium. The form of $v_2(p_t)$ is, within a constant factor, the product of $p'_t$ ($p_t$ in the boost frame) times the ratio of quadrupole spectrum to single-particle spectrum. That ratio in turn implies that above 0.5 GeV/c the form of $v_2(p_t)$ is dominated by the hard component of the single-particle spectrum (interpreted as due to minijets). It is therefore unlikely that so-called {\em constituent-quark scaling} attributed to $v_2$ is relevant to soft hadron production mechanisms (e.g., chemical freezeout).