1,300 research outputs found
Podcast: Towards a Tranformative Epistemology of Technology Education
No full textThis podcast, recorded by the author of the paper, discusses some of the key thinking and ideas in: Morrison-Love, D. (2016) Towards a transformative epistemology of technology education. Journal of Philosophy of Education, Vol 50, Issue 4 (In Press). Core ideas include the relationship between technical activity, materials and the metaphorical paradigm of technology as an enhancement to human capability. Ultimately, it is argued that pupils’ technological knowledge arises in no small part, from their navigation of an ontological pathway through which they realise solutions to problems in a physical form
Growth management and open space protection in Arizona : current tools and progress
No full textabstract: Four major statewide "tools" to help manage growth and preserve open space have been put to work in Arizona over the past five years. These include the Arizona Preserve Initiative and the closely-related Proposition 303, as well as the Growing Smarter Act and its "addendum," Growing Smarter Plus. All four tools are based in large part on a concept known as "smart growth," which is generally considered to be a set of growth management measures that attempt to strike a balance among issues of economics, environment, and quality of life. Taken together, these four growth management tools make significant changes in the way that (a) city and county governments plan and regulate their lands, (b) citizens play a role in land use issues, (c) state trust lands are managed, and (d) open space may be acquired and preserved. Many of these changes will have long-term effects for the state. This paper provides a brief overview of each of the four growth management/open space tools, a preliminary accounting of major activities each one has stimulated, and a perspective on what can be expected for the future as expressed by a selection of growth planners and other leaders of growth management in Arizona.Copyright by the Arizona Board of Regents for and on behalf of Arizona State University and its Morrison Institute for Public Polic
Improper Ferroelectricity: An Electronically Driven Improper Ferroelectric: Tungsten Bronzes as Microstructural Analogs for the Hexagonal Manganites (Adv. Mater. 40/2019)
No full textThe rapidly emerging field of domain wall nanoelectronics exploits the different functionality of ferroelectric domain walls relative to the bulk. In article number 1903620, Finlay D. Morrison and co-workers present a new improper ferroelectric with the hexagonal tungsten bronze structure. This material displays the same complex labyrinthine domain structure, including six-fold “cloverleaf” domain vertices, as the widely studied hexagonal manganites. These domain structures have generated much interest due to their rich functionality associated with a high density of charged domain walls
A politics of conversion: nihilism and love in Toni Morrison's fiction
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Letras.O estudo Uma Política de Conversão: Niilismo e Amor na Ficção de Toni Morrison começa com a idéia de que a Literatura Afro-Americana apresenta um sentido de auto-reflexividade e hibridismo, através do qual autobiografia dialoga com romance, o espiritual se funde com o político. A partir deste traço dialógico a auto-reflexividade é politicamente estabelecida entre niilismo e amor. Na política de conversão, o estudo analisa as formas como mulheres negras, individualmente ou em grupo, fogem da escravidão para a liberdade, avançam da individualidade para a coletividade, ou substituem niilismo por amor. Metodologicamente o estudo apresenta sete capítulos. O primeiro discute os aspectos dialógicos que ilustram as conexões entre narrativas espirituais, de escravos e ficção, entre espiritualidade e política. O segundo examina o diálogo entre a conversão, pregação pública e formação da comunidade em Diário e Experiências Religiosas de Lee. O capítulo sugere que ao afirmar espiritualidade e humanidade a narradora abre profundo espaço para a mulher negra reclamar direitos civis. O terceiro discute o diálogo no interior da política de conversão entre narrativa de escravos e ficção. Este diálogo lida com niilismo e amor em Incidentes de Jacobs e Amada, Sula e O Olho Mais Azul de Morrison. Para a análise de niilismo e amor valores individuais e coletivos são considerados em relação a cinco aspectos: ambiente e agente antagonistas, agente de apoio, propósito da personagem e resultado alcançado. É visível, no estudo, o apoio que certas mulheres recebem de suas comunidades para contra-atacar antagonistas. O apoio nem sempre resulta na superação do niilismo e, por isso, derrota temporária pode ocorrer antes que elas sejam reintegradas à comunidade, como acontece com Linda Brent. O quarto capítulo examina as fraquezas e as energias da política da conversão e a reintegração de Sethe Suggs à comunidade de Bluestone Road. O quinto avalia como a comunidade de Bottom tenta controlar a individualidade de Sula Peace e como um grupo de mulheres lideradas por Nel Wrights consegue resgatar o espírito de independência da heroína. O sexto mostra como a política da conversão das mulheres de Lorain é incapaz de garantir a saúde mental de Pecola Breedlove, mas consegue criar um papel mais consistente para o grupo. No sétimo, a conclusão examina da relação dialética entre niilismo e amor ou auto-amor nas experiências dos indivíduos e dos grupos. O estudo sugere que em Incidentes a busca de Linda Brent por liberdade envolve elementos de autodestruição e de autoempoderamento. Da mesma maneira, o estudo conclui que em Amada o amor que Sethe Suggs tem para as suas crianças mata a própria filha, enfatizando, assim, o desejo de livrá-la da escravidão. Igualmente em Sula, a individualidade de Sula Peace não apenas limita, mas também expande as experiências do grupo, levando-o à emancipação. Finalmente, em O Olho Mais Azul a luta de Pecola Breedlove por amor e beleza reflete auto-ódio ao mesmo tempo em que reconstrói a auto-apreciação de toda a comunidade
Vacancy ordering and polytypism in B-site deficient halide perovskites
No full textB-site deficient halide perovskites show promising optoelectronic properties as potential candidates for the replacement for conventional lead-based halide perovskites. To further understand the relationship between crystal structure and properties, it would be of great interest to explore B-site deficient halide perovskites with various vacancy distributions. This work focuses on the preparation and characterisation of novel B-site deficient halide perovskites with unusual vacancy ordering.
The successful preparation of Cs₄CuSb₂Cl₁₂ in 2017 provided insight into the study of cubic closed packed B-site deficient halide perovskites. Theoretical screening and experimental work were carried out in this study to explore other potential A₄B’²⁺B³⁺₂X₁₂ halide perovskites. One novel compound Cs₄MnBi₂Cl₁₂ was synthesised and analysed, with typical d-d transition induced photoluminescence (PL) at 602 nm activated by octahedral coordinated 3d⁵ Mn²⁺.
By manipulating the fraction of B-site vacancies, another novel B-site deficient halide perovskite Cs₁₀MnSb₆Cl₃₀ with unusual one-dimensional 10H (hcccc)₂ structure was synthesised and studied. A similar d-d transition induced PL was observed at 620 nm. However, an enhancement of the quantum yield in comparison with previously reported Cs₄MnSb₂Cl₁₂ suggested that this is due to the different vacancy ordering and reduced dimensionality of octahedral connectivity. Preliminary DFT calculations of the electronic structure of Cs₁₀MnSb₆Cl₃₀ suggested an indirect band gap of 2.69 eV for this compound.
By using azetidinium (Az⁺) as the A-site cation, one novel B-site deficient perovskite polytype with a 6H (hcc)₂ layered structure was observed in Az₃Sb₂Cl₉ and Az₃Sb₂Br₉. The unique vacancy distribution formed an intrinsically polar structure, which was further confirmed by the converse piezoelectric effect. Variable temperature structural analysis and property measurements revealed several phase transitions from the hexagonal prototypical structure to an orthorhombic superstructure between 300 K and 20 K for both compounds. A tuneable band gap and preferential site occupation of chlorine and bromine anions were also observed in the solid-solution Az₃Sb₂Cl₉₋ₓBrₓ.
The other azetidinium based halides were preliminarily investigated. Az₃Sb₂l₉, Az₃Bi₂Br₉ and Az₃Bi₂I₉ showed typical zero-dimensional 6H (hcc)₂ perovskite structure with isolated octahedral dimers; whereas Az₂BiCl₅ and Az₂BiBr₅ were found to adopt non-perovskite cis-connected chain structures
Reflecting on the role of emotions in the PhD process
No full textThis research project examined the role of emotions in the PhD process through an exploratory, qualitative, self reflective study by six recent or current PhD candidates. Despite differences in the nature of the PhD fields of study, and in the personal backgrounds of the participants, a number of common themes were recognised. We developed an interactive workshop for postgraduate students in which participants were asked to reflect on their emotional experiences in their own studies. The combined information from these sources was used to suggest some strategies for management of negative emotions that may arise during the PhD process. Of critical importance is the multiple roles of the PhD supervisor in helping manage the negative emotions that most PhD students inevitably experience at some stage in their candidature. Most important, though, is the role of self reflection in identifying potential emotional problems and their solutions; a process we recommend to PhD candidates and supervisors
Synthesis and structure-property relationships in selected metal fluorides
No full textThere has been an increase in the interest in fluoride materials over the
last decade. This interest has focused on multiferroic materials and kagome
lattices, to name but a few areas. This thesis focuses on the synthesis and
crystallographic characterisation of selected transition metal fluorides and
oxyfluorides. Work is presented on the tetragonal tungsten bronze solid
solutions of K[subscript(x)]FeF₃, where x = 0.58 and x ≈ 0.5, and the copper analogue,
K₃Cu₃Fe₂F₁₅; the kagome structure of Cs₂ZrCu₃F₁₂; and hydrothermal reactions
using vanadium, manganese, or molybdenum as the transition metals in the
formation of new fluorides and oxyfluorides.
The tetragonal tungsten bronze compounds K[subscript(x)]FeF₃ (x = 0.58 and x ≈ 0.5)
are both tetragonal at 500 K. In the variant with the lower K-content, there is a
clear phase separation into two tetragonal phases even at this temperature. The
K₀.₅₈FeF₃ sample separates into two distinct phases below 340 K to possess one
tetragonal and one orthorhombic phase. Then at roughly 300 K, both samples
undergo a phase transition where the tetragonal phase in the P4/mbm space
group in K₀.₅₈FeF₃ changes to an orthorhombic phase with a larger unit cell; and
the tetragonal phase in P4₂bc for the K₀.₅FeF₃ sample changes to the same
orthorhombic model, whilst the P4/mbm model remains unchanged. The
evolution of the lattice parameters and phase fractions is studied in detail using
synchrotron powder X-ray diffraction (sPXRD).
The kagome structure investigated, Cs₂ZrCu₃F₁₂, possesses the “ideal”
kagome lattice at room temperature, but previous work has suggested that
there is a phase transition at 225 K. The two structures are determined by
single crystal X-ray diffraction at 300 K and 125 K. Variable temperature
sPXRD studies are performed between these two temperature ranges to
determine the phase evolution as a function of temperature. The structure
changes from a rhombohedral to a monoclinic phase at low temperature. This
is the result of the buckling of the kagome layers at the phase transition. The
Zr⁴⁺ ion changes from 6 to 7 coordinate and this is seen as the main driving
force for the distortion of the kagome layer from its “ideal” planar arrangement.
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The phase transition is first-order as seen from the electrical impedance
measurements.
The hydrothermal reactions presented reveal seven new materials and
their crystal structures. Sr₂V₂F₁₀·H₂O is new and found to be isostructural to
Sr₂Fe₂F₁₀·H₂O. BaVO₂F₃ is a cubic material that is potentially piezoelectric. Two
hybrid organic inorganic manganese compounds are reported. The ladder
structure (C₃N₂H₅)[Mn₂F₆(H₂O)₂] crystallises in a polar space group and shows
promise as a candidate for multiferroic studies. The second hybrid material,
(C₇NH₁₆)₂[MnF₅(H₂O)]·2H₂O, crystallises in a centrosymmetric space group.
The Mo hybrid materials are all centrosymmetric and possess isolated
molybdenum-centred monomeric or dimeric octahedral units
Synthesis and structure-property relationships in rare earth doped bismuth ferrite
No full textThere has been significant interest in BiFeO₃ over the past decade. This interest has focused on the magnetic and electrical properties, which in the long term may prove useful in device applications.
This thesis focuses on the synthesis, electrical characterisation, and structural origin of the electrical properties of rare earth doped bismuth ferrite. Two systems have been studied: BiFeO₃ doped with lanthanum and neodymium (Bi₁₋ₓREₓFeO₃ RE= La, Nd). Specific examples have been highlighted focusing on a detailed structural analysis of a lanthanum doped bismuth ferrite, Bi₀.₅La₀.₅FeO₃, and a neodymium analogue, Bi₀.₇Nd₀.₃FeO₃. Both adopt an orthorhombic GdFeO₃-type structure (space group: Pnma) with G-type antiferromagnetism.
Structural variations were investigated by Rietveld refinement of temperature dependent powder neutron diffraction using a combination of both conventional “bond angle/bond length” and symmetry-mode analysis. The latter was particularly useful as it allowed the effects of A-site displacements and octahedral tilts/distortions to be considered separately. This in-depth structural analysis was complemented with ac-immittance spectroscopy using the multi-formulism approach of combined impedance and modulus data to correlate structural changes with the bulk electrical properties. This approach was essential due to the complex nature of the electrical response with contributions from different electroactive regions.
The structural variations occur due to a changing balance between magnetic properties and other bonding contributions in the respective systems. This results in changes in the magnitude of the octahedral tilts, and A-site displacements giving rise to phenomena such as negative thermal expansion and invariant lattice parameters i.e., the invar effect.
More specifically, analysis of Bi₀.₅La₀.₅FeO₃ highlights a structural link between changes in the relative dielectric permittivity and changes in the FeO₆ octahedral tilt magnitudes, accompanied by a structural distortion of the octahedra with corresponding A-site displacement along the c-axis; this behaviour is unusual due to an increasing in-phase tilt mode with increasing temperature. The anomalous orthorhombic distortion is driven by magnetostriction at the onset of antiferromagnetic ordering resulting in an Invar effect along the magnetic c-axis and anisotropic displacement of the A-site Bi³⁺ and La³⁺ along the a-axis. This contrasts with the neodymium analogue Bi₀.₇Nd₀.₃FeO₃ in which a combination of increasing A-site displacements in the ac-plane and decrease in both in-phase and anti-phase tilts combine with superexchange giving rise to negative thermal expansion at low temperature. The A-site displacements correlate with the orthorhombic strain.
By carefully changing the synthesis conditions, a significant change in bulk conductivity was observed for a number for Bi₁₋ₓLaₓFeO₃ compositions. A series of Bi₀.₆La0.₄FeO₃ samples are discussed, where changes in the second step of the synthesis result in significantly different bulk conductivities. This behaviour is also observed in other compositions e.g. Bi₀.₇₅La₀.₂₅FeO₃. Changes in the electrical behaviour as a function of temperature are discussed in terms of phase composition and concentration gradients of defects. Activation energies associated with the conduction process(es) in Bi₁₋ₓLaₓFeO₃ samples, regardless of composition, fall within one of two broad regimes, circa. 0.5 eV or 1.0 eV, associated with polaron hopping or migration of charge via oxygen vacancies, respectively.
The use of symmetry-mode analysis, in combination with conventional crystallographic analysis and electrical analysis using multi-formulism approach, presents a new paradigm for investigation of structure-property relationships in rare earth doped BiFeO₃
Memoirs of Adele Sarpy Morrison.
No full textGilt top edge.Author's autograph presentation copy."One hundred copies of this book have been privately printed for distribution among friends of the author."Mode of access: Internet
The efficacy of emamectin benzoate against infestations of sea lice, Lepeophtheirus salmonis, on farmed Atlantic salmon, Salmo salar L., in British Columbia
No full textAccession Number: 20103374704. Publication Type: Journal Article. Language: English. Number of References: 16 ref. Subject Subsets: Medical & Veterinary Entomology; Veterinary ScienceSource type: Electronic(1)http://search.ebscohost.com/login.aspx?direct=true&db=lah&AN=20103374704&site=ehost-live; http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2761.2010.01192.x/ful
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