41,128 results for 2010

  • Marine biogeochemical cycling of cadmium and its isotopes: Studies of the South Pacific Ocean, Mediterranean Sea and Black Sea

    George, Ejin (2017)

    Doctoral thesis
    University of Otago

    Cadmium (Cd) is utilised by phytoplankton in the ocean, especially under zinc (Zn)- and iron (Fe)-limited conditions, and is a crucial yet underconstrained component of the ocean’s biological pump, regulating ocean-atmosphere CO2 levels, and thereby global climate. Moreover, the depth distribution of Cd in the oceans mimics that of the major nutrient phosphate (PO4), therefore a well correlated relationship between oceanic Cd and PO4 is widely used to infer past nutrient cycling in the ocean based on the Cd/Ca ratios of foraminifera. However, spatial variabilities in the Cd-PO4 relationship question the reliability of this proxy. Therefore, an improved understanding of the biogeochemical behaviour of Cd in the oceans is needed. In this regard, the Cd stable isotope system offers the potential to provide new insights into the oceanic cycling of Cd because each process imparts a unique isotopic signature to the water column. In the last decade, improved analytical techniques have enabled the natural Cd isotopic shifts in the marine system to be unravelled in some areas of the world’s oceans. The results to date for high-Cd waters indicate that the Cd isotope system offers potential as a proxy of past productivity changes by providing further evidence for the biological importance of Cd. However, observations for low-Cd waters are limited to a few isolated data points, and additional datasets for Cd-depleted, as well as Cd-replete, waters are needed to further constrain Cd’s biogeochemical role in the oceans. In this study, paired dissolved Cd concentration and Cd isotopic measurements were performed with high-precision on waters collected during the GEOTRACES GP-13 zonal section in the South Pacific Ocean, and waters and sediments sampled during the GA04N section in the Black and Mediterranean Seas, using multiple-collector ICP-MS (MC-ICPMS) and techniques in double-spiking. Both oceanic regions are characterized by extremely low sub-picomolar (pM) concentrations of Cd across some depth gradients, requiring the analysis of sub-nanogram quantities of Cd that are 20-fold smaller than typical Cd load sizes (10-15 ng). To this end, new analytical protocols were devised, and the robustness of these analytical methods was evaluated by undertaking a series of different experiments before measuring the GP-13 and GA04N samples. Reliable Cd isotopic measurements could be obtained for samples containing as little as 0.4 ng of Cd with a precision of ± 3.5 Ɛ, while larger Cd load sizes yielded a precision of ± 0.5 Ɛ. The South Pacific subtropical gyre is the most oligotrophic gyre in the global ocean and a unique area to study the Cd isotope systematics associated with phytoplankton productivity under ultra-low nutrient concentrations, including those for Cd, that exist in this region. The Cd concentration and Cd isotopic composition were negatively correlated across the thermocline depth range, extending from 1500 to 150 m depth, due to active biological uptake in surface waters, and the preferential uptake of lighter Cd isotopes over heavier isotopes by phytoplankton, with remineralisation of Cd at depth. This process is best described by Cd isotope fractionation under open system conditions with continuous Cd replenishment and a fractionation factor of 1.0006 ± 0.0002, in contrast to closed system conditions without Cd replenishment that are typically assumed for the open ocean settings. Additionally, an unexpected positive correlation was observed between Cd concentration and Cd isotopic composition in the upper mixed layer of the South Pacific Ocean, from 150 to 15 m depth, suggesting the dominant role of mixing with Cd sourced from atmospheric deposition in these oligotrophic waters. In the surface waters of the South Pacific Ocean, the Cd isotopic signature was positively correlated with dissolved manganese (Mn) and Fe and negatively correlated with dissolved Zn as observed previously in the high-Cd Southern Ocean and suggests the influence of different uptake pathways (Mn and Zn uptake systems) on Cd uptake and Cd isotopic composition, even under ultra-low Cd levels. The permanently anoxic Black Sea is an ideal natural laboratory to study the behaviour of Cd and its isotopes under the different redox zonations that exist in the water column under oxygen-deficient conditions. In the upper oxic zone of the Black Sea, from the surface to 70 m depth, biological utilisation of Cd modulates the Cd isotope systematics. The observed Cd isotopic fractionation in this zone is defined equally well by both open and closed system fractionation conditions with fractionation factors of 1.0008 ± 0.0002 and 1.0005 ± 0.0001 respectively. In the nitrogenous zone, between 70 and 100 m depth, the Cd isotopic composition was approximately constant, despite a significant 10-fold depletion of Cd with depth, most likely due to Cd adsorption to Mn and Fe oxide particles in this sub-oxic zone. The Cd isotopic composition shifted towards heavier values below 100 m depth due to CdS precipitation in the deep sulphidic layer of the Black Sea, which occurs in the presence of free sulphide in the water column, and produced a fractionation factor of 1.0003 ± 0.0002. This implies that the Cd isotopic composition of the oxygen-lean Archean ocean, spanning the first 2 billion years of Earth’s history, may have been isotopically heavier than today, indicating that the Cd isotope system may be a valuable tracer of anoxic combined with sulphidic levels in the past oceans. Surface Cd concentrations are enriched in the Mediterranean Sea compared to the surface concentrations of the Atlantic and Pacific Oceans. The depth distribution of Cd in the northern Mediterranean Sea shows significant variations between the eastern and western Mediterranean basins (EMED and WMED, respectively). In the WMED, Cd follows a nutrient-type depth distribution. However, a better correlation of Cd with salinity compared to the major nutrient PO4 suggests that mixing is likely to be the main factor controlling the vertical Cd distribution in the WMED. In contrast, the Cd depth distribution is homogenous in the EMED and dissolved Cd does not show any significant correlation with either salinity or PO4. The similar endmember Cd concentrations of different deep water masses existing in the EMED might explain the homogenous dissolved Cd distribution. These results will inform a planned Cd isotope study of the Mediterranean Sea.  

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  • Correlating tephras and cryptotephras using glass compositional analyses and numerical and statistical methods: review and evaluation

    Lowe, David J.; Pearce, Nicholas J.G.; Jorgensen, Murray A.; Kuehn, Stephen C.; Tryon, Christian A.; Hayward, Chris L. (2017)

    Journal article
    University of Waikato

    We define tephras and cryptotephras and their components (mainly ash-sized particles of glass ± crystals in distal deposits) and summarize the basis of tephrochronology as a chronostratigraphic correlational and dating tool for palaeoenvironmental, geological, and archaeological research. We then document and appraise recent advances in analytical methods used to determine the major, minor, and trace elements of individual glass shards from tephra or cryptotephra deposits to aid their correlation and application. Protocols developed recently for the electron probe microanalysis of major elements in individual glass shards help to improve data quality and standardize reporting procedures. A narrow electron beam (diameter ~3-5 μm) can now be used to analyze smaller glass shards than previously attainable. Reliable analyses of ‘microshards’ (defined here as glass shards <10 μm) can be subject to significant element fractionation during analysis, but the systematic relationship of such fractionation with glass composition suggests that analyses for some elements at these resolutions may be quantifiable. In undertaking analyses, either by microprobe or LA-ICP-MS, reference material data acquired using the same procedure, and preferably from the same analytical session, should be presented alongside new analytical data. In part 2 of the review, we describe, critically assess, and recommend ways in which tephras or cryptotephras can be correlated (in conjunction with other information) using numerical or statistical analyses of compositional data. Statistical methods provide a less subjective means of dealing with analytical data pertaining to tephra components (usually glass or crystals/phenocrysts) than heuristic alternatives. They enable a better understanding of relationships among the data from multiple viewpoints to be developed and help quantify the degree of uncertainty in establishing correlations. In common with other scientific hypothesis testing, it is easier to infer using such analysis that two or more tephras are different rather than the same. Adding stratigraphic, chronological, spatial, or palaeoenvironmental data (i.e. multiple criteria) is usually necessary and allows for more robust correlations to be made. A two-stage approach is useful, the first focussed on differences in the mean composition of samples, or their range, which can be visualised graphically via scatterplot matrices or bivariate plots coupled with the use of statistical tools such as distance measures, similarity coefficients, hierarchical cluster analysis (informed by distance measures or similarity or cophenetic coefficients), and principal components analysis (PCA). Some statistical methods (cluster analysis, discriminant analysis) are referred to as ‘machine learning’ in the computing literature. The second stage examines sample variance and the degree of compositional similarity so that sample equivalence or otherwise can be established on a statistical basis. This stage may involve discriminant function analysis (DFA), support vector machines (SVMs), canonical variates analysis (CVA), and ANOVA or MANOVA (or its two-sample special case, the Hotelling two-sample T² test). Randomization tests can be used where distributional assumptions such as multivariate normality underlying parametric tests are doubtful. Compositional data may be transformed and scaled before being subjected to multivariate statistical procedures including calculation of distance matrices, hierarchical cluster analysis, and PCA. Such transformations may make the assumption of multivariate normality more appropriate. A sequential procedure using Mahalanobis distance and the Hotelling two-sample T² test is illustrated using glass major element data from trachytic to phonolitic Kenyan tephras. All these methods require a broad range of high-quality compositional data which can be used to compare ‘unknowns’ with reference (training) sets that are sufficiently complete to account for all possible correlatives, including tephras with heterogeneous glasses that contain multiple compositional groups. Currently, incomplete databases are tending to limit correlation efficacy. The development of an open, online global database to facilitate progress towards integrated, high-quality tephrostratigraphic frameworks for different regions is encouraged.

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  • Forget me not : critical intervention of Tōtara North’s decaying industrial heritage

    Scally, Braeden (2016)

    Thesis
    Unitec

    This research project is a design-led investigation into how the people of Tōtara North could engage with their town’s forgotten industrial heritage while moving into the 21st century. Situated on the shores of the remote coastal town, the now derelict Lane & Brown Timber Mill and Shipbuilding Yard is the last standing example of a once functioning kauri timber mill. With the first change in ownership in over a century in 2004, the township’s industrial heritage is disintegrating back into the ground where kauri once grew. In the past, the native forests provided a connection between the people of the town and their relationship to the place. The resulting disjunction has led to an uncertain future for the occupants and their once globally significant industrial heritage. This project aims to stop this negative cycle and rejuvenate the industrial nature of the site whilst also providing people with a reason to stay. Informed by the past industrial process, which connected land and sea, the new programme seeks to reverse the path of production, from sea to land, reviving the past whilst also exploring alternative methods for future development. Through the dredging of the harbour’s excessive silt build up, a case for manufacturing adobe mud brick and a research centre for alternative earth construction is proposed, repurposing the kauri sediment from the seabed in order to construct a new future for the people of Tōtara North. The project questions the fate of our small historic towns, investigating the role of the architect and of heritage conservation in this context. Through an understanding of both tangible and intangible heritage, the reimagined sheds explore the design potential for representing heritage based upon three initiatives: building the stories, provoking unique intervention, and repurposing the past. Each initiative entails a response to the site at both macro and micro scales, extending past barriers and constraints of the norm to inspire the people, re-establishing their identity and connection to the heritage of the place. As a result, the local people and the wider public are able to dynamically engage with their past.

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  • Deployment of hydrogen technologies in New Zealand

    Leaver, Jonathan; Gardiner, A.; Spencer, J. (2017-07-11T00:07:32Z)

    Conference paper
    Unitec

    In 2013 the implementation in New Zealand of hydrogen technology took a significant step forward when the private sector company H2NZ facilitated the establishment of a nationally focused Hydrogen Technology Development Committee (HTDC) based at Unitec (NZ) to provide commercially viable renewable hydrogen based energy solutions. The scope for deployment of hydrogen technologies initially encompasses transport, stationary equipment and heating. A New Zealand Branch of the International Hydrogen Energy Association will be established as a promotion and information dissemination entity. Concomitantly commercial activities are being managed by H2NZ; education and research by Unitec; and expert advice and facilitation of commercialisation by Callaghan Innovation, a government agency. Industry partners are engaged at all levels to maximise potential for commercialisation. In December 2013 H2NZ through the HTDC launched the development of two projects. These are a hydrogen powered quad bike and a zero grid energy residential house incorporating on-site hydrogen storage. Both are planned to be built by the end of 2014. In addition H2NZ is facilitating the commercialisation of UniSyD techno-economic system dynamics modeling software through collaboration between the joint intellectual property owners Unitec and the University of Iceland (UI), and the New Zealand National Energy Research Institute.

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  • Blurring the lines [:How can blurring the lines between theatre and performance create an alternative multipurpose performance space(s) which revitalises dormant urban spaces within the Aotea Quarter?]

    Rodrigues, Neil Craig (2016)

    Thesis
    Unitec

    The Aotea Quarter has been identified by the Auckland City Council as the cultural heart of Auckland. The Quarter currently lacks necessities, such as adequate connections between major public squares, and a current lack of connection between the cultural and arts facilities. These links and connections prevent the Quarter from fulfilling its true potential as Auckland’s leading cultural hub. The weak and ineffective connections are caused by the inactive edges and undeveloped dormant urban spaces (such as council owned car parks) within the Quarter. This research project builds on the Aotea Quarter Framework plan to revitalise the Quarter. The primary focus is making a substantive contribution to the creation of a Theatre District within the Aotea Quarter. Outdoor theatre and street performance exemplifies human interaction, as emotions and reactions are not hidden away in the darkness of the auditorium but rather exposed in daylight and defenceless if the performer approaches. It creates a bond between the performer and audience, and between the audience members themselves. Through blurring the boundaries between theatre and performance, the project proposes multipurpose outdoor performance spaces. The design creates purposeful visual and physical links and connections with the theatres in the vicinity. Simultaneously, the project looks at the urban design problems caused by the construction of Mayoral Drive. The design aims to strengthen the corner of Mayoral Drive and Queen Street and improve the connection between Aotea Square and Myers Park. People are a city’s biggest attraction and we will naturally gravitate to exuberant and lively places. The thoroughfares are designed to attract people by creating the opportunity for impromptu performances and rehearsal spaces, while forming links with the existing performing arts venues.

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  • The nature of leadership dilemmas in technical vocational education and training in Papua New Guinea

    Demi, Markus (2017)

    Thesis
    Unitec

    Effective leadership is essential in securing the highest possible quality for Technical Vocational Education and Training in Papua New Guinea (TVETPNG). In this education sector, senior managers and officers are challenged with finding solutions to educational problems that stand in the way of high student achievement and find this expectation very challenging. The body of knowledge related to problem-solving that was reviewed for this research confirms a view that the effectiveness of leaders is contingent upon their capability to resolve complex problems, and specifically those problems that have the characteristics of a leadership dilemma. These dilemmas reflect a tension between the needs of the organisation and the needs of the individual and create the most challenging problems for leaders. This study further investigated the nature of these dilemmas and challenges for senior managers and officers in resolving them in the context of TVET-PNG. An interpretive approach was adopted for this qualitative study involving the indepth investigation of the experiences and practices of senior managers and senior officers of TVET education in PNG. The study involved the use of two research methods. Firstly, semi-structured interviews were used to explore perceptions from the senior managers’ perspective. Secondly, questionnaires were used to obtain the perspectives of the senior officers. The data was analysed thematically and findings revealed that leadership dilemmas were seen as problems that had not been effectively addressed in the past and hence persisted. These were indeed challenging problems because the senior leaders were not clear about the nature of the problem themselves. Thus, these problems were either avoided, referred or deferred.The study further suggests the need for senior managers and senior officers of TVET education in PNG to engage in management development in order to identify the existence of leadership dilemmas in the workplace and come up with possible context relevant solutions to address them in a more appropriate way.

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  • An Investigation into Establishing (Motivating) Operations

    Jackson, Surrey Merryn Kate (2017)

    Doctoral thesis
    University of Waikato

    Motivating Operations (MOs) are a fundamental concept in behavioural psychology. Despite this, empirical research into MOs is lacking. The overall aim of this thesis is to contribute to the experimental literature base for MOs. Experiment 2.1 used an already published video analysis methodology to assess the morphology of food motivated pecks made to a computer screen by hens, after the hens had been trained to emit the peck using either an autoshaping or handshaping procedure. The intention of this was to then be able to use the video analysis to assess the effect of altering two MOs related to two different reinforcers (e.g., food and water) at one time, on morphology. The study showed that both methods produced similarly formed pecks despite the variability inherent in the handshaping procedure. It was then concluded it is the nature of the reinforcer that gives rise to morphology not the autoshaping procedure per se which gives rise to a particular form of elicited responses. The aim of Experiment 3.1 and 3.2 was to develop a procedure for restricting access to water in laying hens, in order to motivate them sufficiently to respond for water reinforcers. Experiment 3.1 assessed the effect that gradually decreasing time and amount of water access had on food-restricted hens’ water consumption and health. It was found that hens could be restricted to one hr access of water (restricted to the maximum amount that hens would consume when access was ad libitum) without adverse effects to health being apparent. However, when the hens were subsequently exposed to FR schedules with a low response requirement in Experiment 3.2, they did not respond consistently. This indicated that the level of restriction was insufficient to motivate responding and this finding, combined with the difficulty of obtaining ethical approval, meant that the proposed experiments utilising water deprivation as an MO had to be abandoned. Experiment 4.1 used the autoshaping paradigm to assess the acquisition of food motivated pecks to a stimulus, at two different levels of bodyweight (75% and 95%). An infra-red screen was used to analyse performance separately from learning effects by examining activity levels (location and amount of pecks). It was found that that higher numbers of effective pecks were made by hens maintained at 75% free-feeding bodyweight than hens maintained at 95% (different MO conditions). There were also higher levels of ineffective pecks in the 75% group. Experiment 5.1 investigated relative preference for stimuli correlated with different MO conditions: high deprivation (no pre-feeding), or low deprivation (pre-feeding), when subjects were maintained at either 75% or 95% of free-feeding bodyweight. The results showed that 6/10 hens demonstrated an increased preference for the stimulus paired with high deprivation conditions (no pre-feeding) when measured by log ratios of responses, and had faster response rates on this stimulus. Overall, the 75% bodyweight hens had faster response rates than the 95% hens (as in Experiment 4.1), and 8/10 hens responded faster on the stimulus that was paired with no pre-feeding. It was also found, as per Experiment 4.1, that higher numbers of effective pecks were made by hens maintained at 75% free-feeding bodyweight than hens maintained at 95% (different MO conditions). Experiments 6.1 and 6.2 extended the findings of the thesis thus far in that concurrent VI VI schedules were used to assess the effect of bodyweight and pre-feeding as MOs on steady state responding. In total 16 conditions were run exposing hens to three different VI pairs: VI-12, VI-60 (5:1); VI-20, VI-20 (1:1); and VI-60, VI-12 (1:5). Bodyweight values of 85%, 95%, 100%, and 85% with pre-feeding of 40 cc wheat delivered 40 minutes prior to experimental sessions were manipulated between hens finishing a series of the three VI pairs. It was found that 4/6 hens had higher absolute and relative response rates when bodyweight was made lower. For 3/6 of these hens, increasing bodyweight increased sensitivity as measured by the parameter a; this was more distinct when the Generalised Matching Law was applied to response rather than time locations for these hens. Frequency distributions of IRTs showed that for the hens that tended to show increasing sensitivity as bodyweights increased there were more IRTs in bins greater than 0.4 s. This was reflected on the log-survivor plots as the limbs were shallower when bodyweights were higher, indicating that more between-bout responses were occurring. It was also found that pre-feeding increased sensitivity as measured by the parameter a for all hens; this was more noticeable when the GML was applied to response rather than time allocations. Although overall response rates tended to resemble those for the 85% bodyweight condition and remain higher than the 95% and 100% bodyweight conditions, the distribution of left and right response rates showed that hens matched better to the prevailing reinforcer rates when they were pre-fed, than when they were not pre-fed. Overall, the main findings were: (1) that reducing bodyweights increased amounts of species-specific behaviour; and (2) that reducing bodyweight causes increases in response rate. These findings could explain why changes in preference for stimuli paired with high levels of deprivation are observed during SDVL procedures, and why increased sensitivity to available reinforcement at lower levels of deprivation found in studies utilising the GML have been observed in previous studies. These findings contribute to the empirical data informing the behavioural treatment of motivation and have applied implications. Reinforcement and punishment procedures such as extinction or differential reinforcement of alternative behaviours may no longer be necessary when MOs are manipulated.

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  • Spontaneous activity drives local synaptic plasticity in vivo

    Winnubst, J; Cheyne, Juliette; Niculescu, D; Lohmann, C (2015-07)

    Journal article
    The University of Auckland Library

    Spontaneous activity fine-tunes neuronal connections in the developing brain. To explore the underlying synaptic plasticity mechanisms, we monitored naturally occurring changes in spontaneous activity at individual synapses with whole-cell patch-clamp recordings and simultaneous calcium imaging in the mouse visual cortex in vivo. Analyzing activity changes across large populations of synapses revealed a simple and efficient local plasticity rule: synapses that exhibit low synchronicity with nearby neighbors ( fashion through proBDNF/p75(NTR) signaling to refine neuronal connectivity.

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  • Technical report two: Analysis of curriculum documents

    Ballantyne, N; Beddoe, Elizabeth; Hay, K; Maidment, JM; Walker, S; Ngan, L (2016)

    Report
    The University of Auckland Library

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  • Transformative aspirations and realities in Physical Education teacher education

    Ovens, Alan (2017)

    Book item
    The University of Auckland Library

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  • Field, capital and professional identity: Social work in health care

    Beddoe, Elizabeth (2017)

    Book item
    The University of Auckland Library

    This chapter explores social work identity in health settings, a significant field of practice in many parts of the world, including North America and Australasia. The influence of the French sociologist Pierre Bourdieu???s philosophical framework is explored in a consideration of professional identity. His concepts, ???field??? and ???capital??? are used to analyse the influence of power relations, utilising an additional concept of ???professional capital???. Social work may be perceived as successful in health contexts as it is not as subject to media and critical public scrutiny as children???s social work is, but health social workers still often express feelings of marginalisation (Beddoe, 2013a). In Bourdieu???s terms, social work may be viewed as a collective of ???agents??? occupying a field, playing out their roles in a ???structured social space, a field of forces??? (Bourdieu, 1998, p. 40). In such fields there may be palpable competition between actors for the accumulation of different kinds of capital and it is here perhaps that social work identity is less secure.

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  • Report on reader attitudes and behaviour

    Morris, Paula; Robertson, C (2016)

    Report
    The University of Auckland Library

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  • Technical report three: TISWEANZ Taxonomy

    Ballantyne, N; Beddoe, Elizabeth; Hay, K; Maidment, JM; Ngan, L; Walker, S (2016)

    Report
    The University of Auckland Library

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  • Report on citizenship law: New Zealand

    McMillan, K; Hood, Anna (2016)

    Report
    The University of Auckland Library

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  • Technical report one: Methods for the creation of terms for indexing social work education in Aotearoa New Zealand (TISWEANZ)

    Ballantyne, N; Beddoe, Elizabeth; Hay, K; Maidment, JM; Ngan, L; Walker, S (2016)

    Report
    The University of Auckland Library

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  • The good without the bad: Selective chelators for beryllium encapsulation

    Perera, Lakshika C (2017)

    Doctoral thesis
    The University of Auckland Library

    Beryllium is an indispensable metal. Its unmatched combination of unique properties such as extreme strength, low density and high machinability has made it vital in the automotive, nuclear, space, medical, defence sectors and other consumer industries. However, beryllium is considered the most toxic non-radioactive element on the planet. It is also a class one carcinogen and the cause of chronic beryllium disease (CBD). Surprisingly, this fact has not deterred its use in manufacturing. Therefore it is imperative that chemical agents be developed for better detection and remediation of beryllium in the environment and as therapies for individuals exposed to this element. The goal of this research was to develop strong, selective chelating agents for the encapsulation of beryllium. Furthermore a greater ex-ploration of beryllium fundamental coordination chemistry was under-taken with an investigation of binding preferences of the Be2+ cation. The introduction begins with a brief overview of beryllium solu-tion chemistry. Following this is a comprehensive review of the Be2+ coordination chemistry with an investigation into existing organic and inorganic ligands with an emphasis on hard nitrogen and oxygen donor containing ligands. This then moves on to a brief description of the selected ligand design based on the fundamental coordination prefer-ences of Be2+. The main ligand motif will be based on a di-pyridyl sca???old with selected chelating pendant groups, allowing the formation of tetradentate complexes which can form the desired six-membered chelate rings with Be2+ cations. Chapter Two explored the synthesis of a ligand based a dipyrrin pendant group. The corresponding dipyrromethane was used as the starting point. While coupling of this dipyrromethane directly on to a dipyridyl sca???old was unsuccessful, the same dipyrromethane con-taining a one pyridyl group in the form of an acyl-pyridyl unit served as a reasonably good candidate for the successful coupling of the last pyridine group. Furthermore, synthesis of a modi???ed dipyrrin ligand with the inclusion of hydrogen-bonding buttressing groups was also attempted. Chapter Three explored the synthesis of a ligand containing a mo-tif based on a hydroxy-phenyl imidazole moiety. The hydroxyphenyl imidazole moiety was synthesised and used as a starting point. The brominated analogue of the hydroxyphenyl imidazole moiety was suc-cessfully coupled to a di-pyridyl sca???old containing a nitrogen at the center sca???old position through a modi???ed Ullman type reaction. DFT studies of the ligands synthesised and preliminary complexation studies were conducted using boron and aluminium ions as safe analogues and are described in chapters Four and Five. ESI-MS studies were also used for the study of the Be-ligand complexes, allowing their synthesis on a small scale and minimising exposure to beryllium.

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  • On the analysis of quasi-periodic systems and a novel ???deterministic??? explanation of the stochastic resonance phenomenon

    Blekhman, I; Sorokin, Vladislav (2017)

    Conference item
    The University of Auckland Library

    The present paper is concerned with the analysis of quasi-periodic systems which represent an important class of dynamical systems frequently encountered in applications. The related problems appear, e.g. in the analysis of parametric amplifiers based on resonant micro- and nanoscale systems, wave propagation in nearly periodic structures and composite materials, etc. The conventional methods of linear and nonlinear dynamics, e.g. asymptotic methods and approximate approaches based on Floquet theory, often appear to be not applicable for solving such problems. The present paper addresses the application of the Oscillatory Strobodynamics approach and the Method of Varying Amplitudes for these problems with the notable effects being revealed. In particular, a novel ???deterministic??? explanation to the phenomenon of stochastic resonance is proposed.

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  • Designing graphene supercapacitor electrodes

    Farquhar, Anna K. (2017)

    Doctoral thesis
    University of Canterbury Library

    Graphene, a two-dimensional material comprised of sp2-hybridised carbon atoms, has significant potential in energy storage as an electrode material for supercapacitors. Unfortunately, strong intermolecular forces between the graphene sheets results in aggregation during assembly and use, reducing the accessible surface area and experimentally available capacitance. Prevention of aggregation during electrode assembly and cycling will allow the development of graphene materials with better energy storage capability. In this thesis work, molecular spacers grafted to few-layer graphene (FLG) were investigated as a way of preventing aggregation of the graphene sheets. Molecular spacers were grafted to FLG using three strategies: the spontaneous reaction with aryldiazonium salts, the Diels Alder reaction of an aryne, and the addition of an amine. The aryldiazonium reaction was studied using five different salts. The results indicated that at least two reaction pathways are operative for the spontaneous reaction, giving a multilayer film with both -C-C- and -N=N- linkages. Furthermore, the experimental protocol allowed the modified FLG to be collected with the film either sandwiched between the FLG and the substrate, or exposed to the electrolyte. In the sandwiched orientation two nitrophenyl reduction peaks were sometimes seen and larger surface concentrations were measured, behaviour that has not been reported previously for films grafted onto carbon materials from aryldiazonium salts. The Diels- Alder reaction, which relied on the generation of an aryne from an anthranilic acid precursor, provided an efficient route to monolayer growth. The amine addition reaction provided an alternative route modifying FLG, though a Michael-like addition or partial intercalation. Supercapacitor electrodes were assembled from aryldiazonium modified FLG using a layer-by-layer (LBL) strategy. The grafted film could efficiently separate the FLG sheets during assembly and prevent restacking during cycling, with the full surface area remaining accessible even after 20,000 galvanostatic charge discharge cycles. Furthermore, the grafted film did not diminish the total capacitance of the FLG or hinder ion movement to the surface of the sheets. To further enhance the capacitance of the FLG, pseudocapacitive metal hydroxide films were electrochemically deposited on the FLG sheets prior to LBL assembly, which enhanced the total areal capacitance of the system. This thesis work successfully developed a novel LBL protocol that allowed electrodes comprised of stacks of FLG to be assembled without diminishing the total accessible surface area and therefore capacitance of each graphene sheet, which is an essential step in the development of energy storage devices from graphene.

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  • Fire Dynamics Simulator (FDS) Pyrolysis Model Analysis of Heavy Goods Vehicle Fires in Road Tunnels

    Wang, Xiaoyun (2017)

    Doctoral thesis
    University of Canterbury Library

    Heavy goods vehicle (HGV) fires cause more serious fire safety problems than other vehicle fires in road tunnels due to the large fire size. The fire size is a critical parameter in road tunnel fire safety design and this parameter varies considerably under different environmental conditions. It is impractical to experimentally measure heat release rate (HRR) for HGV fires under different tunnel conditions because of the large experimental cost. There is a desire to use a cost-effective computational fluid dynamics (CFD) modelling method to study tunnel fires, such as fire dynamics simulator (FDS). The pyrolysis model in FDS can predict HRR based on fuel properties and environmental conditions. Therefore, the FDS pyrolysis model is adopted in this research to simulate a large-scale tunnel simulated HGV cargo experiment, which was carried out on behalf of the Land Transport Authority (LTA), Singapore. There are three major objectives in this research: to understand fuel properties for the application of the pyrolysis model; to understand influence of forced ventilation on the HRR of tunnel fires; and to assess the predictive capability of the pyrolysis model in FDS to simulate tunnel fires. The material properties of the fuels (plastic and wood) adopted in the LTA experiment are investigated. A simple hand calculation method using multiple-component schemes is proposed in this research to analyse the kinetic properties for the LTA materials through a series of material-scale experiments. Favourable FDS predictions of decomposition behaviour are obtained based on the derived kinetic properties. Following the studies of the kinetic properties, a manual optimisation process is used to determine other thermal properties for the application of the FDS pyrolysis model. The results from FDS simulations for a series of cone calorimeter experiments reveal that the use of component schemes and thermal property settings are critical in accurately predicting burning behaviour in FDS. A series of small-scale tunnel experiments are conducted which is scaled at a ratio of 1:20 on the basis of the LTA large-scale tunnel experiment. Medium density fireboard (MDF) cribs are used as fuel source to investigate the influence of forced ventilation on tunnel fires. It is found that the forced ventilation affects fire spread rate and burning efficiency which ultimately affects the peak HRR. In addition, the influence of forced ventilation on burning efficiency is affected by the crib length. A mathematical model to predict peak HRR for crib fires is proposed based on the observed influences on crib fires from these different factors. The ultimate objective is to assess the ability of the FDS pyrolysis model to predict the HRR in the small-scale and large-scale tunnel experiments. In the simulations, the decomposition reactions are described. The ventilation influences on burning efficiency are accounted for through heat of combustion. Unfortunately, FDS considerably under predicts the HRR and fire growth behaviour for both experiments. These results suggest that the FDS pyrolysis model is unable to predict fire burning behaviour for complex fuels with sufficient accuracy to be used in practical tunnel design. Overall, this research reveals an effective hand calculation method to derive kinetic properties; a manual optimisation process to determine thermal properties; a mathematical model to describe forced ventilation influence on fire size and to further estimate peak HRR for tunnel crib fires. In addition, the results from the application of FDS pyrolysis model to simulate tunnel fires reveal that the pyrolysis model is unable to accurately predict fire burning behaviour for complex fuels.

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  • Mapping the Twitter linkages between American politicians and hate groups

    Sahioun, Rania (2017)

    Masters thesis
    University of Canterbury Library

    Big Data is a growing field after social media allowed developers to collect and store data using various platforms. The present research utilises Twitter data and Apache Spark to extend and develop an easy to implement method to test a contemporary question of interest. Specifically, I focus on Donald Trump’s campaign for the President of the USA. Donald Trump’s campaign had been very controversial from the start, following his hostile views expressed toward immigrants and minorities. During this time, media pundits and the public spent much time debating whether Trump’s campaign was motivated by hate or other factors. The present work examines whether Donald Trump had unique appeal to hate groups by examining the twitter linkages between several American political leaders (Donald Trump, Hillary Clinton, Bernie Sanders, Ted Cruz, and Paul Ryan) with American hate groups. The results show that users who often retweet Donald Trump are more likely to frequently retweet American hate groups such as Neo Nazis, White Nationalists, anti-immigrant, anti-Muslim, anti-LGBT, and anti-government groups, more than any other politician. While other Republican politicians were also linked to anti-immigrant, anti-Muslim, and anti-LGBT groups, it was to a lesser extent than Trump. This data suggests Trump may have had unique appeal to American hate groups.

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