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: Insights on the environmental impacts associated with visible disturbance of ice-free ground in Antarctica

authors: Brooks, Shaun T.

subjects: Science & Technology

abstract: The small ice-free areas of Antarctica provide an essential habitat for most evident terrestrial biodiversity, as well as being disproportionately targeted by human activity. Visual detection of disturbance within these environments has become a useful tool for measuring areas affected by human impact, but questions remain as to what environmental consequences such disturbance actually has. To answer such questions, several factors must be considered, including the climate and biotic and abiotic characteristics. Although a body of research has established the consequences of disturbance at given locations, this paper was conceived in order to assess whether their findings could be generalized as a statement across the Antarctic continent. From a review of 31 studies within the Maritime Antarctic, Continental Antarctic and McMurdo Dry Valleys regions, we found that 83% confirmed impacts in areas of visible disturbance. Disturbance was found to modify the physical environment, consequently reducing habitat suitability as well as directly damaging biota. Visible disturbance was also associated with hydrocarbon and heavy metal contamination and non-native species establishment, reflecting the pressures from human activity in these sites. The results add significance to existing footprint measurements based on visual analysis, should aid on-the-ground appreciation of probable impacts in sites of disturbance and benefit environmental assessment processes.

text: Insights on the environmental impacts associated with visible disturbance of ice-free ground in Antarctica The small ice-free areas of Antarctica provide an essential habitat for most evident terrestrial biodiversity, as well as being disproportionately targeted by human activity. Visual detection of disturbance within these environments has become a useful tool for measuring areas affected by human impact, but questions remain as to what environmental consequences such disturbance actually has. To answer such questions, several factors must be considered, including the climate and biotic and abiotic characteristics. Although a body of research has established the consequences of disturbance at given locations, this paper was conceived in order to assess whether their findings could be generalized as a statement across the Antarctic continent. From a review of 31 studies within the Maritime Antarctic, Continental Antarctic and McMurdo Dry Valleys regions, we found that 83% confirmed impacts in areas of visible disturbance. Disturbance was found to modify the physical environment, consequently reducing habitat suitability as well as directly damaging biota. Visible disturbance was also associated with hydrocarbon and heavy metal contamination and non-native species establishment, reflecting the pressures from human activity in these sites. The results add significance to existing footprint measurements based on visual analysis, should aid on-the-ground appreciation of probable impacts in sites of disturbance and benefit environmental assessment processes.

year: 2019

title: Pākehā counsellors consider their positioning: Towards postcolonial praxis

authors: Crocket, Alastair Robert

subjects: Counselling

abstract: The challenges of achieving the potential, which the Treaty of Waitangi offers for a postcolonial present and future, have shaped life in Aotearoa New Zealand over the last four decades. This thesis draws on this history and challenge to consider the practice possibilities for Pākehā counsellors when they work with clients and colleagues of other cultures. It is strongly influenced by the Treaty of Waitangi but seeks not to be limited to a Māori/Pākehā binary. It has been undertaken in the hopes of informing developments in the practice of students seeking to qualify to work as counsellors and more experienced practitioners. The first theoretical foundation for this study is poststructuralism which is considered as a braided stream of theorizing where braids divide and unite. A Foucauldian social constructionism underlies this project, which extends to a consideration of subjectification, agency and positioning theory. This study is also intentionally postcolonial drawing on Said’s seminal works, Orientalism (1979) and Culture and Imperialism (1993) and North American and European writing about identity politics and intersectionality. It views the centring of the Treaty of Waitangi in this land as postcolonial work. These two emphases, poststructuralism and postcolonialism, provide the theoretical base for an exploration of the context of professional counselling practice in Aotearoa New Zealand. Five experienced counsellors constituted a research group who firstly discussed practising as a Pākehā counsellor and then acknowledged their hopes and fears for their practice with clients of other cultures. In later stages of the data generation the participants were invited to join in processes of discourse analysis and deconstruction which produced shifts in practice and practice identity. This study identifies two forms of praxis that might inform a counselling practice which seeks to achieve a postcolonial purpose: these are named as critical discursive praxis and critical Pākehā praxis.

text: Pākehā counsellors consider their positioning: Towards postcolonial praxis The challenges of achieving the potential, which the Treaty of Waitangi offers for a postcolonial present and future, have shaped life in Aotearoa New Zealand over the last four decades. This thesis draws on this history and challenge to consider the practice possibilities for Pākehā counsellors when they work with clients and colleagues of other cultures. It is strongly influenced by the Treaty of Waitangi but seeks not to be limited to a Māori/Pākehā binary. It has been undertaken in the hopes of informing developments in the practice of students seeking to qualify to work as counsellors and more experienced practitioners. The first theoretical foundation for this study is poststructuralism which is considered as a braided stream of theorizing where braids divide and unite. A Foucauldian social constructionism underlies this project, which extends to a consideration of subjectification, agency and positioning theory. This study is also intentionally postcolonial drawing on Said’s seminal works, Orientalism (1979) and Culture and Imperialism (1993) and North American and European writing about identity politics and intersectionality. It views the centring of the Treaty of Waitangi in this land as postcolonial work. These two emphases, poststructuralism and postcolonialism, provide the theoretical base for an exploration of the context of professional counselling practice in Aotearoa New Zealand. Five experienced counsellors constituted a research group who firstly discussed practising as a Pākehā counsellor and then acknowledged their hopes and fears for their practice with clients of other cultures. In later stages of the data generation the participants were invited to join in processes of discourse analysis and deconstruction which produced shifts in practice and practice identity. This study identifies two forms of praxis that might inform a counselling practice which seeks to achieve a postcolonial purpose: these are named as critical discursive praxis and critical Pākehā praxis.

year: 2010