58,301 research outputs found

    Structural, vibrational and thermal properties of densified silicates : insights from Molecular Dynamics

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    Structural, vibrational and thermal properties of densified sodium silicate (NS2) are investigated with classical molecular dynamics simulations of the glass and the liquid state. A systematic investigation of the glass structure with respect to density was performed. We observe a repolymerization of the network manifested by a transition from a tetrahedral to an octahedral silicon environment, the decrease of the amount of non-bridging oxygen atoms and the appearance of three-fold coordinated oxygen atoms (triclusters). Anomalous changes in the medium range order are observed, the first sharp diffraction peak showing a minimum of its full-width at half maximum according to density. The previously reported vibrational trends in densified glasses are observed, such as the shift of the Boson peak intensity to higher frequencies and the decrease of its intensity. Finally, we show that the thermal behavior of the liquid can be reproduced by the Birch-Murnaghan equation of states, thus allowing us to compute the isothermal compressibility

    Development of high-emittance scales on thoriated nickel-chromium-aluminum-base alloys

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    The surface regions of a DSNiCrAl alloy have been doped, by a pack diffusion process, with small amounts of Mn, Fe, or Co, and the effect of these dopants on the total normal emissivity of the scales produced by subsequent high temperature oxidation has been measured. While all three elements lead to a modest increase in emissivity, (up to 23% greater than the undoped alloy) only the change caused by manganese is thermally stable. However, this increased emissivity is within 85 percent of that of TDNiCr oxidized to form a chromia scale. The maganese-doped alloy is some 50 percent weaker than undoped DSNiCrAl after the doping treatment, and approximately 30 percent weaker after oxidation

    Making Sense of 'Joint Enterprise' for Murder: Legal Legitimacy or Instrumental Acquiescence?

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    AbstractThe legal doctrine of ‘joint enterprise’ has been heavily criticized for lacking legitimacy, primarily linked to distributive (in)justice. This paper draws on the narratives of ‘joint enterprise prisoners’ serving long life sentences for murder to address such concerns and extend the discussion to questions of ‘legal legitimacy’. Prisoners who were early in their sentences explicitly rejected the legal legitimacy of joint enterprise, while those at a later stage reported ‘accepting’ their conviction and demonstrated ‘consent’ by engaging with their sentence. We argue that rather than representing normative acceptance of the legal legitimacy of joint enterprise over time, this acceptance is a form of instrumental acquiescence associated with ‘dull compulsion’ ‘coping acceptance’ and personal meaning making.Isaac Newton Trus
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