183 research outputs found

    Threshold concepts: Impacts on teaching and learning at tertiary level

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    This project explored teaching and learning of hard-to-learn threshold concepts in first-year English, an electrical engineering course, leadership courses, and in doctoral writing. The project was envisioned to produce disciplinary case studies that lecturers could use to reflect on and refine their curriculum and pedagogy, thereby contributing to discussion about the relationship between theory and methodology in higher education research (Shay, Ashwin, & Case, 2009). A team of seven academics investigated lecturersā€™ awareness and emergent knowledge of threshold concepts and associated pedagogies and how such pedagogies can afford opportunities for learning. As part of this examination the lecturers also explored the role of threshold concept theory in designing curricula and sought to find the commonalities in threshold concepts and their teaching and learning across the four disciplines. The research highlights new ways of teaching threshold concepts to help students learn concepts that are fundamental to the disciplines they are studying and expand their educational experiences. Given that much of the international research in this field focuses on the identification of threshold concepts and debates their characteristics (Barradell, 2013; Flanagan, 2014; Knight, Callaghan, Baldock, & Meyer, 2013), our exploration of what happens when lecturers use threshold concept theory to re-envision their curriculum and teaching helps to address a gap within the field. By addressing an important theoretical and practical approach the project makes a considerable contribution to teaching and learning at the tertiary level in general and to each discipline in particular

    Mutations in shaking-B prevent electrical synapse formation in the Drosophila giant fiber system

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    The giant fiber system (GFS) is a simple network of neurons that mediates visually elicited escape behavior in Drosophila. The giant fiber (GF), the major component of the system, is a large, descending interneuron that relays visual stimuli to the motoneurons that innervate the tergotrochanteral jump muscle (TTM) and dorsal longitudinal flight muscles (DLMs). Mutations in the neural transcript from the shaking-B locus abolish the behavioral response by disrupting transmission at some electrical synapses in the GFS. This study focuses on the role of the gene in the development of the synaptic connections. Using an enhancer-trap line that expresses lacZ in the GFs, we show that the neurons develop during the first 30 hr of metamorphosis. Within the next 15 hr, they begin to form electrical synapses, as indicated by the transfer of intracellularly injected Lucifer yellow. The GFs dye-couple to the TTM motoneuron between 30 and 45 hr of metamorphosis, to the peripherally synapsing interneuron that drives the DLM motoneurons at approximately 48 hr, and to giant commissural interneurons in the brain at approximately 55 hr. Immunocytochemistry with shaking-B peptide antisera demonstrates that the expression of shaking-B protein in the region of GFS synapses coincides temporally with the onset of synaptogenesis; expression persists thereafter. The mutation shak-B2, which eliminates protein expression, prevents the establishment of dye coupling shaking-B, therefore, is essential for the assembly and/or maintenance of functional gap junctions at electrical synapses in the GFS

    Development and biological evaluation of Iinkjet printed drug coatings on intravascular stent

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    Inkjetā€“printing technology was used to apply biodegradable and biocompatible polymeric coatings of poly(D, L lactide) with the antiproliferative drugs simvastatin (SMV) and paclitaxel (PCX) on coronary metal stents. A piezoelectric dispenser applied coating patterns of very fine droplets (300 xL) and ink jetting was optimized to develop uniform, accurate and reproducible coatings of high yields on the stent strut. The drug loaded polymeric coatings were assed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and transition thermal microscopy (TTM) where a phase separation was observed for SMV/PLA layers while PCX showed a uniform distribution within the polymer layers. Cytocompatibility studies of PLA coatings showed excellent cell adhesion with no decrease of cell viability and proliferation. In vivo stent implantation studies showed significant intra stent restenosis (ISR) for PXC/PLA and PLA plain coatings similar to marketed Presillion (bare metal) and Cypher (drug eluting) stents. The investigation of several cytokine levels after seven days of stent deployment showed no inflammatory response and hence no in vivo cytotoxicity related to PLA coatings. Inkjet printing can be employed as a robust coating technology for the development of drug eluting stents compared to the current conventional approaches

    Layered Al2O3-SiO2 and Al2O3-Ta2O5 thin-film composites for high dielectric strength, deposited by pulsed direct current and radio frequency magnetron sputtering

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    Multilayer thin films have the potential to act as high dielectric strength insulation for wire and microelectronics. In this study, films consisting of 2, 4 or 8 layers, composed of Al2O3 with SiO2 or Ta2O5, were prepared via pulsed direct current and radio frequency magnetron sputtering to a thickness of between 152 and 236ā€Ænm. The dielectric strengths of all films exceeded the 310 VĪ¼māˆ’1 achieved for PDC Al2O3. Maximum dielectric strengths were obtained for four layer composites; Al2O3-SiO2-Al2O3-SiO2 (466 VĪ¼māˆ’1) and Al2O3-Ta2O5-Al2O3-Ta2O5 (513 VĪ¼māˆ’1), each containing two PDC-Al2O3 and two RF-SiO2/Ta2O5 layers. Whilst the average dielectric strength was higher in the Ta2O5 composites, they suffered from higher leakage prior to breakdown with ca. 6.5ā€ÆnA compared to ca. 0.1ā€ÆnA for SiO2 composites. The mechanical properties of the composites were poorer due to increased intrinsic coating stress. Samples exhibited complete interfacial delamination with maximum coating adhesion strengths of 22 and 25ā€ÆMPa. The variance resulted from larger coefficient of thermal expansion for Ta2O5 compared to SiO2. Sputtered composites of Al2O3 and either SiO2 or Ta2O5 had high breakdown strength with reasonable adhesion and could be suitable for insulating copper conductors in the aerospace and automotive industries

    Time dependent decomposition of ammonia borane for the controlled production of 2D hexagonal boron nitride.

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    Ammonia borane (AB) is among the most promising precursors for the large-scale synthesis of hexagonal boron nitride (h-BN) by chemical vapour deposition (CVD). Its non-toxic and non-flammable properties make AB particularly attractive for industry. AB decomposition under CVD conditions, however, is complex and hence has hindered tailored h-BN production and its exploitation. To overcome this challenge, we report in-depth decomposition studies of AB under industrially safe growth conditions. In situ mass spectrometry revealed a time and temperature-dependent release of a plethora of NxBy-containing species and, as a result, significant changes of the N:B ratio during h-BN synthesis. Such fluctuations strongly influence the formation and morphology of 2D h-BN. By means of in situ gas monitoring and regulating the precursor temperature over time we achieve uniform release of volatile chemical species over many hours for the first time, paving the way towards the controlled, industrially viable production of h-BN
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