4,737 research outputs found

    Thermodynamics of the Flexible Metal-Organic Framework Material MIL-53(Cr) From First Principles

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    We use first-principles density functional theory total energy and linear response phonon calculations to compute the Helmholtz and Gibbs free energy as a function of temperature, pressure, and cell volume in the flexible metal-organic framework material MIL-53(Cr) within the quasiharmonic approximation. GGA and metaGGA calculations were performed, each including empirical van der Waals (vdW) forces under the D2, D3, or D3(BJ) parameterizations. At all temperatures up to 500 K and pressures from -30 MPa to 30 MPa, two minima in the free energy versus volume are found, corresponding to the narrow pore (npnp) and large pore (lplp) structures. Critical positive and negative pressures are identified, beyond which there is only one free energy minimum. While all results overestimated the stability of the npnp phase relative to the lplp phase, the best overall agreement with experiment is found for the metaGGA PBEsol+RTPSS+U+J approach with D3 or D3(BJ) vdW forces. For these parameterizations, the calculated free energy barrier for the npnp-lplp transition is only 3 to 6 kJ per mole of Cr4_4(OH)4_4(C8_8H4_4O4_4)4_4

    Re-enchanting the Chinese Sport Spectator - A Postmodern perspective on Sport Marketing in China

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    The cultural and philosophical heritage of modernism underpinning general marketing management theory imparts profound implications for organisations operating in professional sport. This theoretical paper uses the context of China’s professional football industry to argue that marketing may benefit from a more postmodern approach to marketing management

    Liberating the modern Chinese football fan: a theoretical perspective

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    The cultural and philosophical heritage of modernism underpinning general marketing management theory imparts profound implications for organisations operating in professional sport. This theoretical paper uses the context of China’s professional football industry to argue that marketing may benefit from a more postmodern approach to marketing management

    First Principles Calculations of Ionic Vibrational Frequencies in PbMg1/3Nb2/3O3

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    Lattice dynamics for several ordered supercells with composition PbMg1/3Nb2/3O (PMN) were calculated with first-principles frozen phonon methods. Nominal symmetries of the supercells studied are reduced by lattice instabilities. Lattice modes corresponding to these instabilities, equilibrium ionic positions, and infrared (IR) reflectivity spectra are reported.Comment: 6 pages; Fundamental physics of Ferroelectrics 200

    Who makes better use of technology for learning in D&T? Schools or university?

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    University teacher training departments have many functions in their role as Schools for Initial Teacher Education (ITE), these include accrediting qualified teacher status, teaching subject knowledge and pedagogy, and influencing change in a school subject's content and pedagogy. This paper discusses this latter area. It can be easy for teacher training in universities to become ivory towers, modelling new ideas for curriculum delivery and content in a 'bubble' away from the real world of the school classroom. A centre of design and technology (D&T) education at an English university has undertaken research-led developments in the use of web 2.0 technologies and technology enhanced learning (TEL), modelling how they can be used in the classroom. The research examined in this paper is the next stage of the centre's curriculum development to ensure the relevance of the university curriculum content and practices. Anecdotal evidence suggests that the use of TEL in secondary schools is inconsistent and sporadic with D&T teachers using TEL, with minimal awareness of research available, which could inform their practice. This impacts on the centre's trainee teachers as they begin teaching in schools during their final year of the course, with a possible unrealistic expectation of how TEL is used in schools, based on their university experiences

    Configuration dependence of physical properties of a ferroelectric solid solution

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    In this article, we motivate the detailed comparison of the physical properties of individual configurations of a ferroelectric solid solution as a means toward developing first principles models for these systems. We compare energies, dielectric constants epsilon_infinity, mode effective charges of local polar distortions, and the zero temperature piezoelectric behavior of several ordered Pb_3GeTe_4 supercells. Cluster expansions of these properties show the importance of second-neighbor effects, which can be related to symmetry-preserving relaxation and its effect on the symmetry breaking polar instabilities.Comment: 11 pages, LaTeX (aipproc), 1 eps figur
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