title: Thallium(III) complexes of the metalloligands [Pt₂(μ-S)₂(PPh₃)₄] and [Pt₂(μ-Se)₂(PPh₃)₄]

authors: Rose, Sarah L.

subjects: Platinum complexes

abstract: Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with the diarylthallium(III) bromides Ar₂TlBr [Ar = Ph and p-ClC₆H₄] in methanol gave good yields of the thallium(III) adducts [Pt₂(μ-S)₂(PPh₃)4TlAr₂]⁺, isolated as their BPh₄⁻ salts. The corresponding selenide complex [Pt₂(μ-Se)₂(PPh₃)₄TlPh₂]BPh₄ was similarly synthesised from [Pt₂(μ-Se)₂(PPh₃)₄], Ph₂TlBr and NaBPh₄. The reaction of [Pt₂(μ-S)₂(PPh₃)₄] with PhTlBr₂ gave [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]⁺, while reaction with TlBr₃ gave the dibromothallium(III) adduct [Pt₂(μ-S)₂(PPh₃)₄TlBr₂]⁺[TlBr₄]⁻. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt₂(μ-S)₂(PPh₃)₄TlPh₂]BPh₄, [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]BPh₄ and [Pt₂(μ-S)₂(PPh₃)₄TlBr₂][TlBr₄] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl-S and Pt...Tl distances, and an increasing S-Tl-S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported.

text: Thallium(III) complexes of the metalloligands [Pt₂(μ-S)₂(PPh₃)₄] and [Pt₂(μ-Se)₂(PPh₃)₄] Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with the diarylthallium(III) bromides Ar₂TlBr [Ar = Ph and p-ClC₆H₄] in methanol gave good yields of the thallium(III) adducts [Pt₂(μ-S)₂(PPh₃)4TlAr₂]⁺, isolated as their BPh₄⁻ salts. The corresponding selenide complex [Pt₂(μ-Se)₂(PPh₃)₄TlPh₂]BPh₄ was similarly synthesised from [Pt₂(μ-Se)₂(PPh₃)₄], Ph₂TlBr and NaBPh₄. The reaction of [Pt₂(μ-S)₂(PPh₃)₄] with PhTlBr₂ gave [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]⁺, while reaction with TlBr₃ gave the dibromothallium(III) adduct [Pt₂(μ-S)₂(PPh₃)₄TlBr₂]⁺[TlBr₄]⁻. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt₂(μ-S)₂(PPh₃)₄TlPh₂]BPh₄, [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]BPh₄ and [Pt₂(μ-S)₂(PPh₃)₄TlBr₂][TlBr₄] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl-S and Pt...Tl distances, and an increasing S-Tl-S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported.

year: 2009

title: New ensemble methods for evolving data streams

authors: Bifet, Albert

subjects: computer science

abstract: Advanced analysis of data streams is quickly becoming a key area of data mining research as the number of applications demanding such processing increases. Online mining when such data streams evolve over time, that is when concepts drift or change completely, is becoming one of the core issues. When tackling non-stationary concepts, ensembles of classifiers have several advantages over single classifier methods: they are easy to scale and parallelize, they can adapt to change quickly by pruning under-performing parts of the ensemble, and they therefore usually also generate more accurate concept descriptions. This paper proposes a new experimental data stream framework for studying concept drift, and two new variants of Bagging: ADWIN Bagging and Adaptive-Size Hoeffding Tree (ASHT) Bagging. Using the new experimental framework, an evaluation study on synthetic and real-world datasets comprising up to ten million examples shows that the new ensemble methods perform very well compared to several known methods.

text: New ensemble methods for evolving data streams Advanced analysis of data streams is quickly becoming a key area of data mining research as the number of applications demanding such processing increases. Online mining when such data streams evolve over time, that is when concepts drift or change completely, is becoming one of the core issues. When tackling non-stationary concepts, ensembles of classifiers have several advantages over single classifier methods: they are easy to scale and parallelize, they can adapt to change quickly by pruning under-performing parts of the ensemble, and they therefore usually also generate more accurate concept descriptions. This paper proposes a new experimental data stream framework for studying concept drift, and two new variants of Bagging: ADWIN Bagging and Adaptive-Size Hoeffding Tree (ASHT) Bagging. Using the new experimental framework, an evaluation study on synthetic and real-world datasets comprising up to ten million examples shows that the new ensemble methods perform very well compared to several known methods.

year: 2009

title: Listening and Learning from Rangatahi Māori: the Voices of Māori Youth

authors: Berryman, Mere

subjects: student self-determination

abstract: This paper presents three stories-over-time of the secondary schooling experiences of New Zealand’s rangatahi Māori–or Māori youth. The stories span fifteen years of New Zealand schooling and are told from three perspectives: the experiences of the students as told in their own words; the voices of youth within the prevailing political contexts of government policy; and, the reframing and repositioning of researchers listening to the experiences of rangatahi Māori who believe they have succeeded as Māori. In reality, the stories are interwoven, however, in an effort to make sense of the various methodological dilemmas, risks, and entanglements across the three points of learning, we have endeavored to disentangle these different threads from the whole and follow these independent of each other. We then weave these threads together again, as we sense-make across this complexity to identify implications for other educators, policy makers and researchers.

text: Listening and Learning from Rangatahi Māori: the Voices of Māori Youth This paper presents three stories-over-time of the secondary schooling experiences of New Zealand’s rangatahi Māori–or Māori youth. The stories span fifteen years of New Zealand schooling and are told from three perspectives: the experiences of the students as told in their own words; the voices of youth within the prevailing political contexts of government policy; and, the reframing and repositioning of researchers listening to the experiences of rangatahi Māori who believe they have succeeded as Māori. In reality, the stories are interwoven, however, in an effort to make sense of the various methodological dilemmas, risks, and entanglements across the three points of learning, we have endeavored to disentangle these different threads from the whole and follow these independent of each other. We then weave these threads together again, as we sense-make across this complexity to identify implications for other educators, policy makers and researchers.

year: 2017