4,861 research outputs found

    Decorating Metal Oxide Surfaces with Fluorescent Chlorosulfonated Corroles

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    We have prepared 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrole (1), 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrolatoaluminum(III) (1-Al), and 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrolatogallium(III) (1-Ga). The metal complexes 1-Al and 1-Ga were isolated and characterized by electronic absorption and NMR spectroscopies, as well as by mass spectrometry. Relative emission quantum yields for 1, 1-Al, and 1-Ga, determined in toluene, are 0.094, 0.127, and 0.099, respectively. Reactions between 1, 1-Al, and 1-Ga and TiO2 nanoparticles (NPs) result in corrole–TiO_2 NP conjugates. The functionalized NP surfaces were investigated by solid-state Fourier transform infrared and X-ray photoelectron spectroscopies and by confocal fluorescence imaging. The fluorescence images for 1-Al–TiO_2 and 1-Ga–TiO_2 suggest a promising application of these NP conjugates as contrast agents for noninvasive optical imaging

    Dilatancy transition in a granular model

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    We introduce a model of granular matter and use a stress ensemble to analyze shearing. Monte Carlo simulation shows the model to exhibit a second order phase transition, associated with the onset of dilatancy.Comment: Future versions can be obtained from: http://www.ma.utexas.edu/users/radin/papers/shear2.pd

    Structure of unbound neutron-rich 9^{9}He studied using single-neutron transfer

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    The 8He(d,p) reaction was studied in inverse kinematics at 15.4A MeV using the MUST2 Si-CsI array in order to shed light on the level structure of 9He. The well known 16O(d,p)17O reaction, performed here in reverse kinematics, was used as a test to validate the experimental methods. The 9He missing mass spectrum was deduced from the kinetic energies and emission angles of the recoiling protons. Several structures were observed above the neutron-emission threshold and the angular distributions were used to deduce the multipolarity of the transitions. This work confirms that the ground state of 9He is located very close to the neutron threshold of 8He and supports the occurrence of parity inversion in 9He.Comment: Exp\'erience GANIL/SPIRAL1/MUST

    MATE, a single front-end ASIC for silicon strip, Si(Li) and CsI detectors

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    MATE (Must ASIC for Time and Energy) will process signals delivered from the hodoscope MUST2. The hodoscope consists of six large area telescopes (100 cm²), each made up of a double sided Si strip detector followed by a Si(Li) and Csi crystal. MATE has sixteen channels and can deliver three types of analogue information per channel; time of flight and energy loss of the detected particle; value of leakage DC current per channel. MATE also gives a trigger logical signal corresponding to the cross over of an adjustable threshold value. The analogue information is transmitted as differential current through twisted pair to the acquisition system based on VXI-C. The slow control is assured via the I2C industrial protocol. The first version of MATE for Si(strip) is available. An update of MATE will allow it to be used for the Si(Li) and Csi detectors. MATE is a novel R&D project for nuclear physics which includes both energy and time measurements with good resolution and high energy dynamic range

    Transport properties of heterogeneous materials derived from Gaussian random fields: Bounds and Simulation

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    We investigate the effective conductivity (σe\sigma_e) of a class of amorphous media defined by the level-cut of a Gaussian random field. The three point solid-solid correlation function is derived and utilised in the evaluation of the Beran-Milton bounds. Simulations are used to calculate σe\sigma_e for a variety of fields and volume fractions at several different conductivity contrasts. Relatively large differences in σe\sigma_e are observed between the Gaussian media and the identical overlapping sphere model used previously as a `model' amorphous medium. In contrast σe\sigma_e shows little variability between different Gaussian media.Comment: 15 pages, 14 figure
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