title: Iron(III) complexes of the metalloligand [Pt2(μ-S)2(PPh3)4]

authors: Henderson, William

subjects: Crystal structure

abstract: Reaction of [Pt₂(μ-S)₂(PPh₃) ₄] with (NH₄)₂SO₄•FeSO ₄•6H₂O and 2 mol equivalents of picolinic acid (HPic) or 8-hydroxyquinoline (HQ) and trimethylamine base gives iron(III) adducts [Pt₂(μ-S)₂(PPh₃) ₄FePic2]+ and [Pt₂(μ-S) ₂(PPh₃)₄FeQ₂]+, isolated as hexafluorophosphate salts; these complexes are the first isolated iron(III) derivatives of [Pt₂(μ-S)₂(PPh₃) ₄]. The X-ray structure of [Pt₂(μ-S) ₂(PPh₃)₄FePic2]PF6 shows the presence of a rare distorted trigonal prismatic coordination geometry while magnetic measurements confirm the presence of high-spin iron(III) centres in the complexes.

text: Iron(III) complexes of the metalloligand [Pt2(μ-S)2(PPh3)4] Reaction of [Pt₂(μ-S)₂(PPh₃) ₄] with (NH₄)₂SO₄•FeSO ₄•6H₂O and 2 mol equivalents of picolinic acid (HPic) or 8-hydroxyquinoline (HQ) and trimethylamine base gives iron(III) adducts [Pt₂(μ-S)₂(PPh₃) ₄FePic2]+ and [Pt₂(μ-S) ₂(PPh₃)₄FeQ₂]+, isolated as hexafluorophosphate salts; these complexes are the first isolated iron(III) derivatives of [Pt₂(μ-S)₂(PPh₃) ₄]. The X-ray structure of [Pt₂(μ-S) ₂(PPh₃)₄FePic2]PF6 shows the presence of a rare distorted trigonal prismatic coordination geometry while magnetic measurements confirm the presence of high-spin iron(III) centres in the complexes.

year: 2013

title: Evaluation of two Compton camera models for scintimammography

authors: Uche, Chibueze Zimuzo

subjects: Compton camera

abstract: We study the performance of a Si/LaBr3:Ce Compton camera model for scintimammography, and compare it with a Si/NaI(Tl) model of similar geometry. The GEANT4 simulation toolkit was used to study the behaviour of the cameras at 511 keV. Certain simulation steps, such as the modelling of radionuclide decay times, scintillation photon transport and interactions with photomultipliers, as well as detector dead time corrections were included to make the modelling of the cameras more realistic than previous studies. The Si/LaBr3:Ce Compton camera shows superior efficiency of 2.0×10⁻³ and resolution of 5.3 mm over the Si/NaI(Tl) Compton camera model which has the efficiency of 1.6×10⁻³ and resolution of 6.9 mm at a source-to-scatterer distance of interest, 2.5 cm. A similar result sequence is obtained for two breast tumours of 5 mm diameter embedded in the medial region of an average-size breast phantom of thickness 5 cm. Notably, the signal-to-noise ratios (SNR) obtained for the Si/LaBr3:Ce camera are 9.7 and 3.4 for tumour/background radiation uptakes of 10:1 and 6:1, whereas 6.8 and 2.4 were obtained for the Si/NaI(Tl) camera model for the same tumour/background radiation uptakes respectively. It is therefore envisioned that with lower cost, LaBr3:Ce could replace NaI(Tl) as the Compton camera absorber.

text: Evaluation of two Compton camera models for scintimammography We study the performance of a Si/LaBr3:Ce Compton camera model for scintimammography, and compare it with a Si/NaI(Tl) model of similar geometry. The GEANT4 simulation toolkit was used to study the behaviour of the cameras at 511 keV. Certain simulation steps, such as the modelling of radionuclide decay times, scintillation photon transport and interactions with photomultipliers, as well as detector dead time corrections were included to make the modelling of the cameras more realistic than previous studies. The Si/LaBr3:Ce Compton camera shows superior efficiency of 2.0×10⁻³ and resolution of 5.3 mm over the Si/NaI(Tl) Compton camera model which has the efficiency of 1.6×10⁻³ and resolution of 6.9 mm at a source-to-scatterer distance of interest, 2.5 cm. A similar result sequence is obtained for two breast tumours of 5 mm diameter embedded in the medial region of an average-size breast phantom of thickness 5 cm. Notably, the signal-to-noise ratios (SNR) obtained for the Si/LaBr3:Ce camera are 9.7 and 3.4 for tumour/background radiation uptakes of 10:1 and 6:1, whereas 6.8 and 2.4 were obtained for the Si/NaI(Tl) camera model for the same tumour/background radiation uptakes respectively. It is therefore envisioned that with lower cost, LaBr3:Ce could replace NaI(Tl) as the Compton camera absorber.

year: 2011

title: Kuta (Eleocharis sphacelata, Cyperaceae), a locally important and highly valued weaving plant

authors: Wehi, Priscilla M.

subjects: Northland (N.Z.)

abstract: This article introduces and discusses kuta (Eleocharis sphacelata, Cyperaceae), a tall spikerush found on the margins of shallow lakes in New Zealand, which, although often overlooked, is considered in Northland to be a valuable weaving resource.

text: Kuta (Eleocharis sphacelata, Cyperaceae), a locally important and highly valued weaving plant This article introduces and discusses kuta (Eleocharis sphacelata, Cyperaceae), a tall spikerush found on the margins of shallow lakes in New Zealand, which, although often overlooked, is considered in Northland to be a valuable weaving resource.

year: 2006