966 research outputs found

    One-dimensional radiation-hydrodynamic simulations of imploding spherical plasma liners with detailed equation-of-state modeling

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    This work extends the one-dimensional radiation-hydrodynamic imploding spherical argon plasma liner simulations of T. J. Awe et al. [Phys. Plasmas 18, 072705 (2011)] by using a detailed tabular equation-of-state (EOS) model, whereas Awe et al. used a polytropic EOS model. Results using the tabular EOS model give lower stagnation pressures by a factor of 3.9-8.6 and lower peak ion temperatures compared to the polytropic EOS results. Both local thermodynamic equilibrium (LTE) and non-LTE EOS models were used in this work, giving similar results on stagnation pressure. The lower stagnation pressures using a tabular EOS model are attributed to a reduction in the liner's ability to compress arising from the energy sink introduced by ionization and electron excitation, which are not accounted for in a polytropic EOS model. Variation of the plasma liner species for the same initial liner geometry, mass density, and velocity was also explored using the LTE tabular EOS model, showing that the highest stagnation pressure is achieved with the highest atomic mass species for the constraints imposed.Comment: 21 pages, 3 tables, 7 figures, accepted for publication by Phys. Plasmas (9/24/2012

    Phase chemistry in the Ca-Mn-Sb-O system at 1160-1250 °C

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    Phase equilibrium in the Ca-Mn-Sb-O system was studied in air at the temperature range from 1160 to 1250°C and a pseudo-quaternary phase diagram for the system CaO-MnO-Mn2O3-Sb2O5 is presented. The following compounds were discovered: new antimonate Ca 7Sb2O12 with a perovskite-like structure, solid solutions Mn2-xCaxSb2O7 (0 ≤ x ≤ 1.6) with a 3T-weberite structure, and Ca2-xMn xSb2O7 (0 ≤ x ≤ 0.23) with a 2O-weberite structure, as well as solid solutions Ca2Mn1+xSb 1-xO6 with monoclinic (0 ≤ x ≤ 0.67) and orthorhombic (0.75 ≤ x ≤ 1) perovskite structures. The existence of a number of double and ternary oxides and solid solutions on the basis of Sb 5+ and Mn2+, Mn3+, Mn4+ and with mixed manganese valence is confirmed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    Modification of the zirconia ceramics by different calcium phosphate coatings:comparative study

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    The aim of this study was to characterize different calcium phosphate coatings and evaluate in vitro cell response of these materials to ceramics implants. The physical and chemical properties of calcium phosphate coatings formed by RF-magnetron sputtering of calcium phosphate tribasic, hydroxyapatite, calcium phosphate monobasic, calcium phosphate dibasic dihydrate and calcium pyrophosphate powders were characterized. Cell adhesion and cell viability were examined on calcium phosphate coatings using mesenchymal stem cells. The results of cytotoxicity measurements of the calcium phosphate coatings revealed that only the coating obtained by RF-magnetron sputtering of the calcium phosphate dibasic dihydrate and calcium phosphate tribasic powders possessed lower cell viability than the zirconia substrate. The coating formed by sputtering of the calcium phosphate tribasic powder demonstrated more cells adhered onto its surface compared with other calcium phosphate coatings

    Aspects of phi-meson production in proton-proton collisions

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    We analyze near-threshold cross section data for the reaction pp->pp phi published by the DISTO collaboration and recent, still preliminary results presented by the ANKE Collaboration. We formulate a procedure to evaluate the OZI ratio at low energies by taking into account corrections from the kinematics and the final-state interaction. Combining the new data with the few measurements available at higher energies we give a limit for the OZI rule violation and estimate the possible contribution from a five-quark baryonic resonance coupled to the phi-p system.Comment: 6 pages, 4 figure

    Photoproduction evidence for and against hidden-strangeness states near 2 GeV

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    Experimental evidence from coherent diffractive proton scattering has been reported for two narrow baryonic resonances which decay predominantly to strange particles. These states, with masses close to 2.0 GeV would, if confirmed, be candidates for hidden strangeness states with unusual internal structure. In this paper we examine the literature on strangeness photoproduction, to seek additional evidence for or against these states. We find that one state is not confirmed, while for the other state there is some mild supporting evidence favoring its existence. New experiments are called for, and the expected photoproduction lineshapes are calculated.Comment: 9 pages, RevTex, five postscript figures, submitted to PR

    Fabrication and properties of L-arginine-doped PCL electrospun composite scaffolds

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    The article describes fabrication and properties of composite fibrous scaffolds obtained by electrospinning of the solution of poly({\epsilon}-caprolactone) and arginine in common solvent. The influence of arginine content on structure, mechanical, surface and biological properties of the scaffolds was investigated. It was found that with an increase of arginine concentration diameter of the scaffold fibers was reduced, which was accompanied by an increase of scaffold strength and Young modulus. It was demonstrated that porosity and water contact angle of the scaffold are independent from arginine content. The best cell adhesion and viability was shown on scaffolds with arginine concentration from 0.5 to 1 % wt

    Hot dense capsule implosion cores produced by z-pinch dynamic hohlraum radiation

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    Hot dense capsule implosions driven by z-pinch x-rays have been measured for the first time. A ~220 eV dynamic hohlraum imploded 1.7-2.1 mm diameter gas-filled CH capsules which absorbed up to ~20 kJ of x-rays. Argon tracer atom spectra were used to measure the Te~ 1keV electron temperature and the ne ~ 1-4 x10^23 cm-3 electron density. Spectra from multiple directions provide core symmetry estimates. Computer simulations agree well with the peak compression values of Te, ne, and symmetry, indicating reasonable understanding of the hohlraum and implosion physics.Comment: submitted to Phys. Rev. Let

    Immunological assessment of plant-derived avian flu H5/HA1 variants.

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    Polypeptide variants of the HA1 antigenic domain of the H5N1 avian influenza virus hemagglutinin (HA) molecule were produced in plants using transient and stable expression systems and fused with His/c-myc tags or with mouse or human Fc antibody fragments. The resulting peptides were purified and used for intramuscular immunization of mice. While the recombinant HA1 variants induced a significant serum humoral immune response in the mice, none of the HA1 preparations induced virus-neutralizing antibodies. Fusion with the Fc fragment improved overall yield of the constructs and allowed purification requiring only a single step, but led to no detectable fusion-related enhancement of immunogenicity or quality of immune response
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