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Structural and electrical characterisation of some ABO₃ perovskites
Get PDFPowder X-ray diffraction and Raman spectroscopy have been used to characterise the electrolyte materials La₁₋ₓSrₓGaO₃₋δ (x = 0-0.2) and LaGa₁₋yMyO₃₋δ (y = 0-0.2, M = Cr, Mg). XRD of La₁₋ₓSrₓGaO₃₋δ (x = 0-0.2) showed the secondary phase of SrGa₃O₇ at >5 mol% Sr. The cell deformed with increasing Sr dopant concentration. In the XRD patterns of LaGa₁₋yCryO₃₋δ (y = 0-0.2) the cell also deformed with increasing Cr dopant concentration. The peak at ca. 32° showed a second peak at 32.37°, likely to be due to a phase change, since the peaks did not alter in relative intensity with increase in dopant concentration (above x = 0). LaGa₁₋yMgyO₃₋δ (y = 0-0.2) showed, from the powder X-ray diffraction pattern, the formation of the secondary phase of La₄Ga₂O₉ at >5 mol% Mg. Raman spectra of LaGaO₃ showed 18 features at room temperature, and 14 at -196 °C with the disappearance of the band at 92 cm⁻¹. Raman spectra of the doped material, LaGa₁₋yMgyO₃₋δ at y = 0-0.2 showed the formation of a secondary phase of La₄Ga₂O₉ with bands at 243, 295 and 356 cm⁻¹ which become more predominant at 20 mol % Mg.
LaFeO₃ was prepared using a reverse-strike coprecipitation method. The Raman spectrum of LaFeO₃ were obtained at both low-temperature and room temperature, with 9 bands observed of a predicted 24 Raman active modes. Mode assignment was determined from comparison of the Raman profile and band position with perovskites with the same structure, namely, SmAlO₃ and LaGaO₃ and are as follows: 102 (B₁g ), ca.140 (B₂g), 150 (B₁g), 176 (Ag), 227 (B₃g), 261 (Ag), 289 (Ag), 413 (Ag), 429 (B₃g). LaFe₁₋ₓMgₓO₃ was prepared using a reverse-strike coprecipitation method. The XRD patterns obtained at room temperature showed single phase, but also included small amounts of impurity of La₂O₃ and La₂MgOₓ. Lattice calculations based on FeLaO₃ showed that Mg dopant concentration had a minor effect on the overall unit cell volume, with the minimum volume achieved being 241.68ų at 1450 °C, 15%Mg concentration. In summary, Mg-doped LaFeO₃ produced a single phase material in the range 0-20 mol% Mg as observed from X-ray diffraction. However, a small amount of impurities in each of the samples was observed, containing La₂O₃ and La₂MgOₓ. The presence of the impurities suggested that an extra calcination step be included in the processing of the material.
LaGdO₃ was fabricated using reverse strike co-precipitation method and sintered at temperature of 1350, 1400 and 1450 °C. X-ray diffraction showed the presence of a single monoclinic phase. Raman spectroscopy showed a spectrum similar for that reported for the B-type rare earth oxide Gd₂O₃ and the band positions of the low temperature Raman spectrum were assigned in comparison with this. A total of 18 bands were identified. Intense broad profile in the region 1000-2000 cm⁻¹ was observed for LaGdO₃, likely due to fluorescent/luminescent bands.
The acceptor-doped perovskite proton conductor SrCe₁₋ₓYₓO₃₋δ (x=0.025 to 0.20, δ = x/2) was prepared and characterised using X-ray diffraction and AC impedance spectroscopy, and the effect of the yttrium dopant concentration on structure and electrical properties has been investigated. X-ray diffraction studies showed a decrease in lattice volume with increasing yttrium content. Electrical conductivity studies were made as a function of oxygen partial pressure, and a partial pressure of water vapour of 0.001 and 0.01 atm. The total conductivity was separated into different components by fitting procedures and regions of ionic and p-type conduction were identified. At 800°C, and at the water vapour partial pressure of 0.01 atm, the ionic conductivity showed a maximum at a doping level of x = 0.10, reaching a value of 5 mS/cm. The conductivity component appearing at low oxygen partial pressure, which according to recent studies may be regarded as protonic rather than n-type, decreased with doping, while the p-type component at high oxygen partial pressure increased
A pilot study of application of the Stroke Riskometer mobile app for assessment of the course and clinical outcomes of COVID-19 among hospitalised patients
Get PDFEarly determination of COVID-19 severity and health outcomes could facilitate better treatment of patients. Different methods and tools have been developed for predicting outcomes of COVID-19, but they are difficult to use in routine clinical practice. Methods: We conducted a prospective cohort study of inpatients aged 20-92 years, diagnosed with COVID-19 to determine whether their individual 5-year absolute risk of stroke at the time of hospital admission predicts the course of COVID-19 severity and mortality. The risk of stroke was determined by the Stroke Riskometer mobile application. Results: We examined 385 patients hospitalised with COVID-19 (median age 61 years). The participants were categorised based on COVID-19 severity: 271 (70.4%) to the “Not severe” and 114 (29.6%) to the “Severe” groups. The median risk of stroke the next day after hospitalisation was significantly higher among patients in the Severe group (2.83 [95% CI 2.35-4.68]) vs the Not severe group (1.11 [95% CI 1.00–1.29]). The median risk of stroke and median systolic blood pressure (SBP) were significantly higher among non-survivors (12.04 [95% CI 2.73-21.19]) and (150 [95% CI 140-170]) vs survivors (1.31 [95% CI 1.14-1.52]), 134 [95% CI 130-135]), respectively. Those who spent more than 2.5 hours a week on physical activity were 3.1 times more likely to survive from COVID-19. Those who consumed more than one standard alcohol drink a day, or suffered with atrial fibrillation, or had poor memory were 2.5, 2.3, and 2.6 times more likely not to survive from COVID-19, respectively. Conclusions: High risk of stroke, physical inactivity, alcohol intake, high SBP, and atrial fibrillation are associated with severity and mortality of COVID-19. Our findings suggest that the Stroke Riskometer app could be used as a simple predictive tool of COVID-19 severity and mortality
Changing hearts and minds: Investigating transformative praxis from participating in the Poutama Pounamu Blended Learning
Get PDFThe Poutama Pounamu Blended Learning offers a unique bicultural opportunity to critically examine ourselves within the fabric of our society. This metaphoric fabric includes an inequitable education system which was shaped by, and designed to support, an oppressive colonial agenda. Within this education system, which has methodically assimilated and underserved its indigenous Māori children, holding a mirror up to ourselves as teachers to examine our own beliefs, values and practices is absolutely critical but very rarely done. The Blended Learning’s carefully considered underpinnings of Critical and Kaupapa Māori theories provide the tools to raise consciousness. A conscientised educator can recognise, understand and deconstruct prejudice, bias and racism when it reveals itself. This process is achieved by resisting systems and practices that perpetuate the marginalisation of Māori in favour of power-balancing transformative praxis which works to value language, culture and identity as assets in education.
This thesis describes the enduring implications of participating in the Poutama Pounamu Blended Learning by focusing on a number of educators in English-Medium state schools - the very context where our Māori children struggle the most to fit in and prove their potential. These educators suggest that this is an indigenised, evidence based, transformative education reform programme which has changed their lives and the lives of many others who have participated within this project. It has empowered and liberated Māori, Pākehā and Tauiwi participants alike by modelling the nurturing and liberating cultural relationships for responsive pedagogy that all students in Aotearoa should be experiencing. This is a pedagogy which can open hearts and minds and nurture a mauri ora pathway to educational freedom and success
Insensitivity to anorexigenic effects of naltrexone in the VPA rat model of autism
Get PDFAutism spectrum disorder (ASD) is a complex disorder whose etiology lies in, among others, abnormal neural processing, and improper neural circuitry development. This results in a plethora of aberrant behaviors, including those driven by the brain’s reward system and by the endogenous mediators of reward, for example opioids. One of the maladaptive consequences of pathophysiology of the reward system is excessive consumption of palatable foods in people with autism and in ASD model animals, such as valproic acid (VPA)-induced ASD rats. Here, I hypothesized that overconsumption of palatable diets in the VPA ASD rat is caused by abnormal functioning of the opioid circuitry. To investigate this, first I determined sensitivity of sucrose liquid-fed or high?fat high-sugar chow (HFHS)-fed VPA vs non-VPA control rats to the anorexigenic properties of the opioid receptor antagonist, naltrexone (NTX), a drug that reduces eating for palatability, but does not affect feeding for calories. In the follow up immunohistochemical study involving a marker of neuronal activity, c-Fos, I examined differences in brain activation after an injection of the same dose of NTX in VPAs vs non-VPA controls. As expected, NTX did not affect energy-driven consumption of bland chow in non-VPA controls or VPAs. NTX did, however, decrease intake of palatable sucrose water and HFHS chow. Importantly, while 1 mg/kg NTX was sufficient to reduce eating for palatability in non-VPA controls, a 10-mg NTX dose was needed to achieve the same effect in VPAs. c-Fos analysis in the non–VPA controls showed significant differences in neuronal activation in the paraventricular nucleus (PVN), supraoptic nucleus (SON), arcuate nucleus (ARC), Dorsomedial hypothalamus (DMH), central nucleus of the amygdala (CeA), and nucleus accumbens shell (NAc – shell). The VPA animals showed a difference only in the CeA. Collectively these data show different responsiveness to NTX at the behavioural (feeding) and brain activation iii (c-Fos) level, likely indicative of dysregulation of the opioid signaling and – more broadly – reward processing, in the autistic brain
Convergence in floodplain pond communities indicates different pathways to community assembly
Get PDFDisturbance can strongly influence ecosystems, yet much remains unknown about the relative importance of key processes (selection, drift, and dispersal) in the recovery of ecological communities following disturbance. We combined field surveys with a field experiment to elucidate mechanisms governing the recovery of aquatic macroinvertebrates in habitats of an alluvial floodplain following flood disturbance. We monitored macroinvertebrates in 24 natural parafluvial habitats over 60 days after a major flood, as well as the colonization of 24 newly-built ponds by macroinvertebrates over 45 days in the same floodplain. We examined the sources of environmental variation and their relative effects on aquatic assemblages using a combination of null models and Mantel tests. We also used a joint species distribution model to investigate the importance of primary metacommunity structuring processes during recovery: selection, dispersal, and drift. Contrary to expectations, we found that beta diversity actually decreased among natural habitats over time after the flood or the creation of the ponds, instead of increasing. This result was despite environmental predictors showing contrasting patterns for explaining community variation over time in the natural habitats compared with the experimental ponds. Flood heterogeneity across the floodplain and spatial scale differences between the experimental ponds and the natural habitats seemingly constrained the balance between deterministic and stochastic processes driving the ecological convergence of assemblages over time. While environmental selection was the dominant structuring process in both groups, biotic interactions also had a prominent influence on community assembly. These findings have profound implications towards understanding metacommunity structuring in riverscapes that includes common linkages between disturbance heterogeneity, spatial scale properties, and community composition
Inequities in Covid-19 Omicron infections and hospitalisations for Māori and Pacific people in Te Manawa Taki Midland region, New Zealand
Get PDFCovid-19 impacts population health equity. While mRNA vaccines protect against serious illness and death, little New Zealand (NZ) data exists about the impact of Omicron - and effectiveness of vaccination - on different population groups. We aim to examine the impact of Omicron on Māori, Pacific and Other ethnicities and how this interacts with age and vaccination status in the Te Manawa Taki Midland region of NZ. Daily Covid-19 infection and hospitalisation rates (01/02/2022 - 29/06/2022) were calculated for Māori, Pacific and Other ethnicities for six age bands. A multivariate logistic regression model quantified the effects of ethnicity, age, and vaccination on hospitalisation rates. Per-capita Omicron cases were highest and occurred earliest among Pacific (9 per 1,000) and Māori (5 per 1,000) people and were highest among 12-24 year-olds (7 per 1,000). Hospitalisation was significantly more likely for Māori (OR=2.03), Pacific people (OR=1.75), over 75-year olds (OR=39.22), and unvaccinated people (OR=4.64). Length of hospitalisation is strongly related to age. Covid-19 vaccination reduces hospitalisations for older individuals and Māori and Pacific populations. Omicron inequitably impacted Māori and Pacific people through higher per-capita infection and hospitalisation rates. Older people are more likely to be hospitalised and for longer
The coherence of traumatic and non-traumatic memories: A tale of equivalence
Get PDFThere is contention in the scientific literature about the mechanisms by which our memories for traumatic events operate. In one view, the extremely negative nature of traumatic events results in incomplete encoding, leaving memories for these events incoherent. In this view, incoherence promotes distress and therefore must be targeted over the course of treatment to enable recovery. In another view, traumatic memories operate using the same basic set of mechanisms as memories for non-traumatic events; traumatic memories are not uniquely incoherent, and evidence does not support the idea that treatment boosts coherence in a way that supports recovery. But across the literature, several counter-explanations hinder our interpretation of the existing findings. Over five experiments, we addressed these counter-explanations. We found little evidence to suggest people’s memories for traumatic events were incoherent, both in absolute terms and in relation to memories for non-traumatic events. Across our experiments, coherence did not vary in a systematic way depending on whether a memory was traumatic or non- traumatic. Moreover, we found evidence to suggest the way people recalled a memory affected their sense of how coherent that memory was. We also found that repeatedly recalling a memory, as happens in some therapies for posttraumatic stress disorder (PTSD), did not boost coherence. Instead, the data suggest repeated recall prevented a sense of lost coherence seen in memories not repeatedly recalled. Furthermore, we consistently found that memory coherence was not related to the degree of posttraumatic stress a person reported about that event. Mini meta-analyses on the data gathered across these five experiments, and their associated pilot studies, converged on the conclusions that a) traumatic memories are just as coherent as their non-traumatic counterparts, and b) there is no relation between coherence and symptomatology. Considered together, these findings are consistent with a basic mechanisms account of traumatic memories, and have implications for our conceptualisation of PTSD and the therapies designed to treat it
Mothers, kids, and COVID: Suburban geographies of the COVID-19 pandemic
Get PDFThis thesis extends pandemic, health, and maternal geographies by examining how the emotions and actions of seven mothers during the COVID-19 pandemic influence the health outcomes of their children. The research seeks to explain mothers’ responses to, and lived experiences during, the COVID-19 pandemic in a coastal Bay of Plenty suburb in Aotearoa New Zealand. The research addresses three main questions: first, how have COVID-19 public health requirements altered mothers’ relationship with their homes and suburban communities? Second, how have mothers understood COVID-19 scientific knowledge and mis/dis information in relation to the vaccine for 5 to 11-year-old children? Third, how do mothers with their vaccinated and unvaccinated children navigate their suburban movements during COVID-19 public health requirements? The thesis aims to promote awareness of the influence and impact mothers can have on geographies of disease management.
Discussion around COVID-19 has been wide-ranging and varied on the geographical consequences of the pandemic, however, there is little that accounts for the role of mothers, children and their disrupted everyday geographies. Current discourses marginalise mothers in their role as caregiver and this research seeks to re-image mothers and make space for their alternative ways of generating and sharing knowledge. Seven mothers, with at least one child aged 5 to 11-years-old, participated in semi-structured interviews with an emotional mapping activity. The methodology is theoretically and empirically innovative and seeks to open up creative ways of conducting pandemic and health research.
My findings are organised into three areas: the idea of home as being both ‘safe’ and ‘unsafe’ for mothers during the pandemic; the consequence of ‘bubble’ living on the mobility of mothers and their children; and, how mothers’ behaviours changed over the course of the pandemic in relation to the rise of mis/dis information, with particular focus on information towards the vaccine for young children. I assert that the lived experiences of mothers during the pandemic have created space for increased confidence when making health-related decisions for their children. Some mothers have challenged the public health advice. The consequences of which are visible through the low uptake of the COVID-19 vaccine for children aged 5 to 11. Ultimately, this thesis shows how mothers can be at the forefront of disease management. Mothers who combine science and emotion to make decisions add to complex geographies of disease management. Understanding this may help frame effective strategies of preparedness and response to future pandemics
Preparation of phosphinate-based ionic liquids for rare earth recovery
Get PDFThe rare earth elements are vital components in many modern technologies, including green energy technology such as wind turbines and electric vehicles, however the extraction and separation of these elements remains a problem. Due to the similar chemical properties of these elements, achieving pure single elemental concentrations of the REEs is difficult, often requiring multiple steps in the separation process, as well as the use of large volumes of harmful organic solvents. With the demand of these elements projected to grow in the coming decades, greener and more efficient extraction and separation methods need to be developed.
In this work, a series of hydrophobic ionic liquids were prepared through simple neutralisation and protonation reactions. The successful synthesis and characterisation of camphyl phenyl phosphinic acid is also described and used as an anion precursor in IL preparation. Five phosphinate-based ionic liquids were successfully prepared and tested for the separation of the rare earth elements, as well as for cobalt/nickel separations. Both liquid-liquid extraction methods using a neat IL, and column chromatography methods using supported ionic liquids were tested. Results showed selectivity towards the heavy rare earth elements, achieving a La/Yb separation factor as high as 55.3. For the liquid-liquid extraction experiments, La extraction efficiencies of 99% were achieved for a majority of the tested ILs. For the Yb column extractions, high extraction efficiencies were also achieved, ranging from 85.5 - 99.9%. Repeated extractions of cobalt and nickel showed the stability of the column, with minimal decrease in extraction efficiencies over 10 repeated runs, and an average separation factor of 2.79 across these runs
Roald Dahl Rewritten: When will this madness end?
Get PDFThe author expresses frustration over recent changes made to Roald Dahl's children's books as part of what they perceive as "cancel culture." They mention growing up with Dahl's books and sharing them with their son, finding the stories timeless and enjoyable. The author questions why classic works are being altered in a time when literacy rates are declining and children who read for pleasure are rare.
The text highlights specific changes made to Dahl's books, such as Augustus Gloop no longer being described as fat, Mrs Twit's appearance being altered, and the Oompa-Loompas becoming gender-neutral. The author questions the necessity of these changes, arguing that spiders are often black and earthworms are often pink, and wonders if innocuous colors like black and pink are now considered inappropriate. They also point out the removal of the word "black" in describing tractors in Fantastic Mr. Fox and discuss the shift in language in The Witches to empower women.
The author disagrees with the changes and believes that they limit the imaginative world Dahl created. They express their intention to continue reading the original versions of Dahl's books with their son, appreciating the lively, edgy, and colorful nature of the stories.
In conclusion, the author expresses concern about the changes made to Roald Dahl's books, questioning the motivations behind them and advocating for the preservation of the original works for future generations to enjoy