40 research outputs found

    Collaborative ownership in cross-cultural educational digital library design

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    This paper details research into building a Collaborative Educational Resource Design model by investigating two contrasting Kenyan / UK design case-studies and an evaluation of end-users and designers’ perceptions of digital libraries and their usage patterns. The two case-studies compared are; case study 1 based on formal learning in an African university digital library. Case study 2 is centered on informal learning in an ongoing rural community digital library system which has a collaborative design model that is being designed, developed and reviewed within the UK and Africa. A small scale in-depth evaluation was done with 21 participants in case-study 1 but related to and with implications for the second case-study. In-depth user issues of access, ownership, control and collaboration are detailed and reviewed in relation to design implications. Adams & Blandford’s ‘information journey’ framework is used to evaluate high-level design effects on usage patterns. Digital library design support roles and cultural issues are discussed further

    Translational Symmetries in the Linear-Chain Semiconductors K\u3csub\u3e4\u3c/sub\u3e[Pt\u3csub\u3e2\u3c/sub\u3e(P\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e5\u3c/sub\u3eH\u3csub\u3e2\u3c/sub\u3e)\u3csub\u3e4\u3c/sub\u3eX]•nH\u3csub\u3e2\u3c/sub\u3eO (X = Cl, Br, I)

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    The solid-state structures of the linear-chain semiconductors K4[Pt2(P2O5H2)4X]•nH2O (X = Cl, Br, I), abbreviated Pt2Cl, Pt2Br, and Pt2I, have been studied. The X-ray crystal structures of Pt2Cl at 300 and 22 K and of Pt2Br at 19 K are reported. These structures show that Pt2Cl is a composite of alternating units of Pt2 and Pt2Cl2 with (AABCCB)n translational symmetry. The X-ray structure of Pt2Br, on the other hand, shows equivalent Pt-Pt bonds and two slightly different Pt-Br bonds. Raman data confirm the composite Pt2/Pt2Cl2 structure for Pt2Cl and indicate that the Pt2Br species is comprised of dimeric units with nearly equal Pt-Pt bonds. The Pt2Br structure is viewed as involving a slight distortion from idealized (AAB)n toward (AABCCB)n translational symmetry. Structural studies of Pt2I were attempted; however, all crystals were twinned. Magnetic susceptibility, microwave conductivity, ESCA, and reflectance spectroscopy measurements are reported for Pt2Br; the material is a semiconductor, with a = 10-3Ω-1 cm-1 at 300 K, a bandgap of 0.08 eV, and a bandwidth greater than 0.05 eV. © 1988, American Chemical Society. All rights reserved
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