735 research outputs found
Annealed lower tails for the energy of a polymer
We consider the energy of a randomly charged polymer. We assume that only
charges on the same site interact pairwise. We study the lower tails of the
energy, when averaged over both randomness, in dimension three or more. As a
corollary, we obtain the correct temperature-scale for the Gibbs measure.Comment: 27 page
Nosocomial outbreak of imipenem-resistant Pseudomonas aeruginosa producing VIM-2 metallo-β-lactamase in a kidney transplantation unit
<p>Abstract</p> <p>Background</p> <p>Twenty four non replicate imipenem resistant <it>P. aeruginosa </it>were isolated between January and November 2008, in the kidney transplantation unit of Charles Nicolle Hospital of Tunis (Tunisia). This study was conducted in order to establish epidemiological relationship among them and to identify the enzymatic mechanism involved in imipenem resistance.</p> <p>Methods</p> <p>Analysis included antimicrobial susceptibility profile, phenotypic (imipenem-EDTA synergy test) and genotypic detection of metallo-β-lactamase (MBL) (PCR), O-serotyping and pulsed-field gel electrophoresis.</p> <p>Results</p> <p>All strains showed a high level of resistance to all antimicrobials tested except to colistin. The presence of MBL showed concordance between phenotypic and genotypic methods. Sixteen isolates were identified as VIM-2 MBL-producers and 13 of them were serotype O4 and belonged to a single pulsotype (A).</p> <p>Conclusions</p> <p>This study describes an outbreak of VIM-2-producing <it>P. aeruginosa </it>in a kidney transplantation unit. Clinical spread of <it>bla</it><sub>VIM-2 </sub>gene is a matter of great concern for carbapenem resistance in Tunisia.</p
Utilities of saccharinyl acetyl isothiocyanate in synthesis of non-condensed polynuclear heterocyclic compounds of expected biological activity
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First-principles prediction of redox potentials in transition-metal compounds with LDA+U
First-principles calculations within the Local Density Approximation (LDA) or
Generalized Gradient Approximation (GGA), though very successful, are known to
underestimate redox potentials, such as those at which lithium intercalates in
transition metal compounds. We argue that this inaccuracy is related to the
lack of cancellation of electron self-interaction errors in LDA/GGA and can be
improved by using the DFT+ method with a self-consistent evaluation of the
parameter. We show that, using this approach, the experimental lithium
intercalation voltages of a number of transition metal compounds, including the
olivine LiMPO (M=Mn, Fe Co, Ni), layered LiMO (Co,
Ni) and spinel-like LiMO (M=Mn, Co), can be reproduced
accurately.Comment: 19 pages, 6 figures, Phys. Rev. B 70, 235121 (2004
Microwave spectrum, structure, barrier to internal rotation, dipole moment, and deuterium quadupole coupling constants of the ethylene–sulfur dioxide complex
The microwave spectra of the complex between ethylene and sulfur dioxide and nine of its isotopic species have been observed in a Fourier transform microwave spectrometer. The spectra exhibit a and c dipole selection rules; transitions of the normal species and several of the isotopically substituted species occur as tunneling doublets. The complex has a stacked structure with Cs symmetry; the C2H4 and SO2 moieties both straddle the mirror plane with the C2 axis of SO2 crossed at 90 ° to the carbon–carbon bond axis (i.e., only the S atom lies in the symmetry plane). The distance between the centers of mass (Rcm) of C2H4 and SO2 is 3.504(1) Å and the deviation of their planes from perpendicular to Rcm is 21(2) ° and 12(2) °, respectively. The tunneling splittings arise from a rotation of the ethylene subunit in its molecular plane. The barrier to internal rotation is 30(2) cm−1. The dipole moment of the complex is 1.650(3)D. The deuterium nuclear quadrupole coupling constants for C2H3D⋅SO2 are χaa=−0.119(1) MHz, χbb=0.010(1) MHz, and χcc=0.109(1) MHz. The binding energy is estimated to be 490 cm−1 from the pseudo‐diatomic approximation. A distributed multipole electrostatic model is explored to rationalize the structure and binding energies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70892/2/JCPSA6-93-10-7030-1.pd
Submersed Micropatterned Structures Control Active Nematic Flow, Topology and Concentration
Coupling between flows and material properties imbues rheological matter with
its wide-ranging applicability, hence the excitement for harnessing the
rheology of active fluids for which internal structure and continuous energy
injection lead to spontaneous flows and complex, out-of-equilibrium dynamics.
We propose and demonstrate a convenient, highly tuneable method for controlling
flow, topology and composition within active films. Our approach establishes
rheological coupling via the indirect presence of fully submersed
micropatterned structures within a thin, underlying oil layer. Simulations
reveal that micropatterned structures produce effective virtual boundaries
within the superjacent active nematic film due to differences in viscous
dissipation as a function of depth. This accessible method of applying
position-dependent, effective dissipation to the active films presents a
non-intrusive pathway for engineering active microfluidic systems.Comment: 13 pages; 5 main-text-figures; 3-supplemental-figure
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