title: Native grain refinement of magnesium alloys

authors: Cao, Peng

subjects: Magnesium

abstract: High purity Mg–Al type alloys have a naturally fine grain size compared to commercial purity alloys with the same basic composition. This is referred to as native grain refinement. It is shown that native grain refinement occurs only in magnesium alloys containing aluminium. The mechanism is attributed to the Al4C3 particles existing in these alloys.

text: Native grain refinement of magnesium alloys High purity Mg–Al type alloys have a naturally fine grain size compared to commercial purity alloys with the same basic composition. This is referred to as native grain refinement. It is shown that native grain refinement occurs only in magnesium alloys containing aluminium. The mechanism is attributed to the Al4C3 particles existing in these alloys.

year: 2005-10

title: The functionalisation of wool by tris(hydroxymethyl)phosphine for metal ion recovery

authors: Addison, Simon James

subjects: THP

abstract: Tris(hydroxymethyl)phosphine (THP) was prepared by the addition of a stoichiometric amount of base to tetrakis(hydroxymethyl)phosphonium chloride (THPC).  Freshly prepared THP was successfully immobilised onto wool through a Mannich-type condensation reaction between a hydroxymethyl group and an amine on the wool surface, forming stable gt;P-CH2-Nlt; coupling links.  The immobilisation of THP to wool stabilised the THP, which resulted in the decreased oxidation of THP to tris(hydroxymethyl)phosphine oxide (THPO).  

The presence of immobilised phosphine groups was determined colorimetrically by reaction with Ni2+ ions, which produced a bright orange nickel-phosphine complex, as well as quantitatively, by measuring nickel uptake using ICP-MS.  Immobilised THP-wool showed proportional binding for varying concentrations of metal solution.  Decreasing or increasing the concentration of the metal solution resulted in a corresponding proportional response of metal binding.  Following immobilisation onto wool, oxidation of the system by 6% H2O2 resulted in a reduced binding of 24% for Cu, 25% for Co, 27% for Ni, and 93% for Cd relative to unoxidised THP immobilised onto wool.

Additional modification of the THP-wool systems via reaction with amino acids and other related compounds overall did not appear to enhance the metal binding capacity relative to the unmodified THP-wool system.  The only modified THP-wool system that showed either retention or an increase in metal binding capacity for all metals analysed was that of 2-aminopyridine, followed by oxidation with H₂O₂.

text: The functionalisation of wool by tris(hydroxymethyl)phosphine for metal ion recovery Tris(hydroxymethyl)phosphine (THP) was prepared by the addition of a stoichiometric amount of base to tetrakis(hydroxymethyl)phosphonium chloride (THPC).  Freshly prepared THP was successfully immobilised onto wool through a Mannich-type condensation reaction between a hydroxymethyl group and an amine on the wool surface, forming stable gt;P-CH2-Nlt; coupling links.  The immobilisation of THP to wool stabilised the THP, which resulted in the decreased oxidation of THP to tris(hydroxymethyl)phosphine oxide (THPO).  

The presence of immobilised phosphine groups was determined colorimetrically by reaction with Ni2+ ions, which produced a bright orange nickel-phosphine complex, as well as quantitatively, by measuring nickel uptake using ICP-MS.  Immobilised THP-wool showed proportional binding for varying concentrations of metal solution.  Decreasing or increasing the concentration of the metal solution resulted in a corresponding proportional response of metal binding.  Following immobilisation onto wool, oxidation of the system by 6% H2O2 resulted in a reduced binding of 24% for Cu, 25% for Co, 27% for Ni, and 93% for Cd relative to unoxidised THP immobilised onto wool.

Additional modification of the THP-wool systems via reaction with amino acids and other related compounds overall did not appear to enhance the metal binding capacity relative to the unmodified THP-wool system.  The only modified THP-wool system that showed either retention or an increase in metal binding capacity for all metals analysed was that of 2-aminopyridine, followed by oxidation with H₂O₂.

year: 2009

title: Unpacking media narratives: Racism and problematic reasonings

authors: Tan, Kyle K. H.

abstract: In this research brief, we present summaries of four case studies of racism in mainstream and social media in Aotearoa. Through a series of carefully selected datasets sourced from TV episodes (Police TEN 7), print media such as news articles (including Northland checkpoints), and tweets (Three Waters reform), we outline how Māori are represented across these mediums. With an expert in language modelling on our team, we analysed large datasets that give us sufficient statistical power to infer specific Māori discourses on respective platforms. Further, we examined key themes that characterise how Māori are represented in the media and signal the scale of anti-Māori attacks. For instance, we found that the predominant discussion on Three Waters reform on Twitter focused on ‘conflict’ (distrust towards government; 33%) and ‘capability’ (questioning the credibility of the reform; 23%) rather than its core intention of promoting water ‘safety’ (7%). The modelling analysis was supplemented by in-depth qualitative analysis that integrates anti-Māori themes (Moewaka-Barnes et al., 2012) and problematic reasoning tactics (Sturgill, 2021) to elucidate how false, deficit-based rhetoric about Māori is deployed to fuel racism and disinformation. In summary, our findings reinforce Kupu Taea’s call for new media sectors to integrate Te Tiriti o Waitangi into their practices to safeguard Māori and other minoritised groups who are likely to be at the fore of racist attacks.

text: Unpacking media narratives: Racism and problematic reasonings In this research brief, we present summaries of four case studies of racism in mainstream and social media in Aotearoa. Through a series of carefully selected datasets sourced from TV episodes (Police TEN 7), print media such as news articles (including Northland checkpoints), and tweets (Three Waters reform), we outline how Māori are represented across these mediums. With an expert in language modelling on our team, we analysed large datasets that give us sufficient statistical power to infer specific Māori discourses on respective platforms. Further, we examined key themes that characterise how Māori are represented in the media and signal the scale of anti-Māori attacks. For instance, we found that the predominant discussion on Three Waters reform on Twitter focused on ‘conflict’ (distrust towards government; 33%) and ‘capability’ (questioning the credibility of the reform; 23%) rather than its core intention of promoting water ‘safety’ (7%). The modelling analysis was supplemented by in-depth qualitative analysis that integrates anti-Māori themes (Moewaka-Barnes et al., 2012) and problematic reasoning tactics (Sturgill, 2021) to elucidate how false, deficit-based rhetoric about Māori is deployed to fuel racism and disinformation. In summary, our findings reinforce Kupu Taea’s call for new media sectors to integrate Te Tiriti o Waitangi into their practices to safeguard Māori and other minoritised groups who are likely to be at the fore of racist attacks.

year: 2025