title: Synthesis study of size-controlled noble metal nanoparticle systems of Re, Ir, and Os using AOT-reverse microemulsion based methodologies

authors: Soleimani Zohr Shiri, Mohammad

abstract: This thesis presents a novel methodology for synthesizing stable, very small nanoparticles (NPs) of rhenium (Re), iridium (Ir), and osmium (Os) using a reverse microemulsion (AOT-ME) system, with AOT as the negatively charged surfactant to form and stabilize the MEs. These noble metals are among the least studied in their NP form, making this research a valuable contribution to the field.
An important initial finding was the identification of a sulfite ion impurity in commercially sourced AOT, most likely introduced during industrial preparation. The reason for the apparent ability of AOT to reduce certain metals, such as Re, was previously unknown among researchers. Although this impurity is present in low concentrations, it became significant when larger quantities of AOT were used to stabilize ME systems, acting as an unintended/hidden reducing agent. While purification with activated carbon could reduce the impurity, it came at a considerable cost of the AOT reagent.
Using the AOT-ME system, Re, Ir, and Os NPs were successfully synthesized under ambient conditions with precise control over size and size distribution. Systematic investigation of synthesis parameters—including the water-to-surfactant concentration ratio (W factor) and temperature—revealed that these factors had a significant impact on NP size and stability. Across all three metals, the effect of the W factor was consistent, with higher W values generating larger, more polydisperse particles. While the AOT-ME system effectively maintained colloidal stability and controlled particle size for all three metals, it also played a specific role in slowing the tendency of Re NPs to oxidise into perrhenate.
A range of advanced characterization techniques, including UV-Vis spectroscopy, ESI-MS, FE-SEM/EDX, and HR-TEM, were employed to thoroughly analyse the synthesized NPs. UV-Vis confirmed the successful reduction of the metal precursors, while FE-SEM/EDX provided valuable information on surface morphology and elemental composition. HR-TEM offered detailed insights into the size and crystallinity of the NPs. Additionally, ESI-MS helped investigate the chemical stability of the colloidal aqueous solutions.
This thesis contributes to the field of noble metal NP synthesis by offering a reproducible method for controlling NP size and stability within AOT-ME systems. The findings provide valuable insights for optimizing synthesis protocols and broaden the potential applications of Re, Ir, and Os NPs in catalysis and materials science.

text: Synthesis study of size-controlled noble metal nanoparticle systems of Re, Ir, and Os using AOT-reverse microemulsion based methodologies This thesis presents a novel methodology for synthesizing stable, very small nanoparticles (NPs) of rhenium (Re), iridium (Ir), and osmium (Os) using a reverse microemulsion (AOT-ME) system, with AOT as the negatively charged surfactant to form and stabilize the MEs. These noble metals are among the least studied in their NP form, making this research a valuable contribution to the field.
An important initial finding was the identification of a sulfite ion impurity in commercially sourced AOT, most likely introduced during industrial preparation. The reason for the apparent ability of AOT to reduce certain metals, such as Re, was previously unknown among researchers. Although this impurity is present in low concentrations, it became significant when larger quantities of AOT were used to stabilize ME systems, acting as an unintended/hidden reducing agent. While purification with activated carbon could reduce the impurity, it came at a considerable cost of the AOT reagent.
Using the AOT-ME system, Re, Ir, and Os NPs were successfully synthesized under ambient conditions with precise control over size and size distribution. Systematic investigation of synthesis parameters—including the water-to-surfactant concentration ratio (W factor) and temperature—revealed that these factors had a significant impact on NP size and stability. Across all three metals, the effect of the W factor was consistent, with higher W values generating larger, more polydisperse particles. While the AOT-ME system effectively maintained colloidal stability and controlled particle size for all three metals, it also played a specific role in slowing the tendency of Re NPs to oxidise into perrhenate.
A range of advanced characterization techniques, including UV-Vis spectroscopy, ESI-MS, FE-SEM/EDX, and HR-TEM, were employed to thoroughly analyse the synthesized NPs. UV-Vis confirmed the successful reduction of the metal precursors, while FE-SEM/EDX provided valuable information on surface morphology and elemental composition. HR-TEM offered detailed insights into the size and crystallinity of the NPs. Additionally, ESI-MS helped investigate the chemical stability of the colloidal aqueous solutions.
This thesis contributes to the field of noble metal NP synthesis by offering a reproducible method for controlling NP size and stability within AOT-ME systems. The findings provide valuable insights for optimizing synthesis protocols and broaden the potential applications of Re, Ir, and Os NPs in catalysis and materials science.

year: 2025

title: Subjective cognitive complaints 8-Years after mild traumatic brain injury

authors: Duffy, Brittney

subjects: TBI

abstract: Mild traumatic brain injury (TBI) is common and can result in symptoms that persist for years after the initial injury. The symptoms following TBI are dynamic, and can result in cognitive, emotional, behavioural and physical symptoms, often collectively referred to as post-concussion symptoms. Persistent post-concussion symptoms impact education, employment, relationships and quality of life. The first aim of this study was to evaluate the long-term symptoms of adults eight- years after a mild TBI compared to a TBI-free group. The second aim of this study was to compare the prevalence and severity of post-concussion symptoms that were reported at 1-month post-injury, 12-months post-injury, and the symptoms reported now, at 8 years post-injury. Finally, the factors contributing to subjective cognitive complaints at 8-years post-injury were explored.
A population-based sample of 151 adults who sustained a mild TBI (mTBI) between 2010 and 2011 participated in this study. Additionally, 213 participants with no history of head injury took part. Both groups answered questions about current post-concussion symptoms using the Rivermead Post-Concussion Symptom Questionnaire (RPQ). The results of this study revealed the prevalence and severity of post- concussion symptoms was significantly greater in participants with mTBI at 8- years post-injury. Differences in cognitive symptoms were most prominent between groups, with the mTBI participants reporting significantly more cognitive complaints. When evaluating symptom-severity over time, we found no significant change in post-concussion symptoms from 12-months post-injury to 8-years. Older age at injury and increased symptoms of depression were associated with increased cognitive complaints at 8-years post-injury. These results confirm post-concussion symptoms persist long-term, and may not improve beyond the levels reported at 12-months post-injury. Further research is needed to explore the impact that treatment of mood symptoms early post- injury may have on recovery.

text: Subjective cognitive complaints 8-Years after mild traumatic brain injury Mild traumatic brain injury (TBI) is common and can result in symptoms that persist for years after the initial injury. The symptoms following TBI are dynamic, and can result in cognitive, emotional, behavioural and physical symptoms, often collectively referred to as post-concussion symptoms. Persistent post-concussion symptoms impact education, employment, relationships and quality of life. The first aim of this study was to evaluate the long-term symptoms of adults eight- years after a mild TBI compared to a TBI-free group. The second aim of this study was to compare the prevalence and severity of post-concussion symptoms that were reported at 1-month post-injury, 12-months post-injury, and the symptoms reported now, at 8 years post-injury. Finally, the factors contributing to subjective cognitive complaints at 8-years post-injury were explored.
A population-based sample of 151 adults who sustained a mild TBI (mTBI) between 2010 and 2011 participated in this study. Additionally, 213 participants with no history of head injury took part. Both groups answered questions about current post-concussion symptoms using the Rivermead Post-Concussion Symptom Questionnaire (RPQ). The results of this study revealed the prevalence and severity of post- concussion symptoms was significantly greater in participants with mTBI at 8- years post-injury. Differences in cognitive symptoms were most prominent between groups, with the mTBI participants reporting significantly more cognitive complaints. When evaluating symptom-severity over time, we found no significant change in post-concussion symptoms from 12-months post-injury to 8-years. Older age at injury and increased symptoms of depression were associated with increased cognitive complaints at 8-years post-injury. These results confirm post-concussion symptoms persist long-term, and may not improve beyond the levels reported at 12-months post-injury. Further research is needed to explore the impact that treatment of mood symptoms early post- injury may have on recovery.

year: 2019

title: The Digital Divide in New Zealand: The position of Māori and Pacific peoples

authors: Gibson, John

subjects: Māori digital access

abstract: Information and communication technology plays an ever-growing role in economic, political and social life and those who are unable to access such technologies are increasingly disadvantaged. Hence, what has come to be known as the ‘digital divide’ is of considerable significance. Here, indicators of that divide as it affects Māori and Pacific Islands peoples in Aotearoa/New Zealand are presented and discussed.

text: The Digital Divide in New Zealand: The position of Māori and Pacific peoples Information and communication technology plays an ever-growing role in economic, political and social life and those who are unable to access such technologies are increasingly disadvantaged. Hence, what has come to be known as the ‘digital divide’ is of considerable significance. Here, indicators of that divide as it affects Māori and Pacific Islands peoples in Aotearoa/New Zealand are presented and discussed.

year: 2002-09