title: A combined SNIFTIRS and XANES study of electrically polarised copper electrodes in DMSO and DMF solutions of cyanate (NCO⁻), thiocyanate (NCS⁻) and selenocyanate (NCSe⁻) ions

authors: Alwis, L. K. H. K.

abstract: A SNIFTIRS (subtractively normalized interfacial Fourier transform infrared spectroscopy) and X-ray absorption spectroscopy (XAS) study of electrically polarized copper electrodes in six polar aprotic solvent-based systems is presented. In the systems investigated, i.e. dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) solutions containing pseudohalide species of cyanate (NCO⁻), thiocyanate (NCS⁻) and selenocyanate (NCSe⁻) codissolved with tetrabutylammonium perchlorate (TBAP), Cu was found to dissolve over a wide range of potentials to produce the corresponding Cu(I) pseudohalide and/or Cu(II) pseudohalide complex ion species. Insoluble deposited films were also observed at higher anodic applied potentials, thought to be CuSCN in the Cu/NCS⁻/DMSO or DMF systems, and solid K(SeCN)₃ in the Cu/NCSe⁻/DMSO or DMF systems respectively. The presence of the Cu(II) and/or Cu(I) oxidation states in complexes formed by polarization in Cu/pseudohalide ion systems in DMSO was clearly proven using XAS of cell solutions sampled after SNIFTIRS/electrical polarization experiments. In addition, Fourier transform infrared (FTIR) and X-ray absorption near edge spectroscopy (XANES) data obtained from model solutions prepared from mixing Cu(I) and/or Cu(II) salts with the respective pseudohalide ions in DMF and DMSO confirmed the speciation observed in the electrochemical experiments.

text: A combined SNIFTIRS and XANES study of electrically polarised copper electrodes in DMSO and DMF solutions of cyanate (NCO⁻), thiocyanate (NCS⁻) and selenocyanate (NCSe⁻) ions A SNIFTIRS (subtractively normalized interfacial Fourier transform infrared spectroscopy) and X-ray absorption spectroscopy (XAS) study of electrically polarized copper electrodes in six polar aprotic solvent-based systems is presented. In the systems investigated, i.e. dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) solutions containing pseudohalide species of cyanate (NCO⁻), thiocyanate (NCS⁻) and selenocyanate (NCSe⁻) codissolved with tetrabutylammonium perchlorate (TBAP), Cu was found to dissolve over a wide range of potentials to produce the corresponding Cu(I) pseudohalide and/or Cu(II) pseudohalide complex ion species. Insoluble deposited films were also observed at higher anodic applied potentials, thought to be CuSCN in the Cu/NCS⁻/DMSO or DMF systems, and solid K(SeCN)₃ in the Cu/NCSe⁻/DMSO or DMF systems respectively. The presence of the Cu(II) and/or Cu(I) oxidation states in complexes formed by polarization in Cu/pseudohalide ion systems in DMSO was clearly proven using XAS of cell solutions sampled after SNIFTIRS/electrical polarization experiments. In addition, Fourier transform infrared (FTIR) and X-ray absorption near edge spectroscopy (XANES) data obtained from model solutions prepared from mixing Cu(I) and/or Cu(II) salts with the respective pseudohalide ions in DMF and DMSO confirmed the speciation observed in the electrochemical experiments.

year: 2015

title: Thermographic inspection to provide quality assurance for reinforced 3D printer filaments

authors: Huang, Ding Yi Monique

subjects: Thermography inspection natural fibre reinforced filaments

abstract: This research demonstrates the feasibility of active thermography in inspecting 3D printing filaments. Examine the potential of pulsed phase thermography in quality assurance of short and natural fibre reinforced polymer composites. Signal analysis scripts were built in Matlab to process the raw data recordings collected. These scripts included were; Single Pixel Analysis (SPA) that consisted of 2D wavelet denoising and single pixel plotted through time; Thermal Signal Reconstruction (TSR); and Pulsed
Phase Thermography (PPT) that implemented the inbuilt with Fast Fourier Transform (FFT). 3D printed natural fibre composites offer sustainable and cost-effective solutions to material challenges. When considering combining natural fibres and 3D printing there are several manufacturing challenges that must be overcome. The focus of this research is to ascertain if active thermography is a suitable tool for online inspection of fibre reinforced filaments used for 3D printing composites. The aim of the inspection is to
identify fibre rich and fibre poor regions along the filament, where uniformly distributed fibres and heating along the filament are preferred. Regions with a locally high weight percent of fibres, known as a fibre bunch, can cause problems when used to print a part resulting in a waste of materials and failed print jobs. The paper presents a feasibility study showing the potential of using pulsed thermography to identify fibre bunching. An external heating stimulus is applied to the sample and an infrared detector is used to monitor the thermal decay. The thermal contrast produced by fibre bunches compared to regions of uniformly distributed fibres is used to identify potential problem areas and provide a means of quality control. Investigation includes variation of the heating stimulus, data collection and data processing routines. Flat bottom holes (FBH) and notches of the samples were easiest to detect, filaments mixed with fibres and salt were more challenging and difficult to detect, which will require further investigations.

text: Thermographic inspection to provide quality assurance for reinforced 3D printer filaments This research demonstrates the feasibility of active thermography in inspecting 3D printing filaments. Examine the potential of pulsed phase thermography in quality assurance of short and natural fibre reinforced polymer composites. Signal analysis scripts were built in Matlab to process the raw data recordings collected. These scripts included were; Single Pixel Analysis (SPA) that consisted of 2D wavelet denoising and single pixel plotted through time; Thermal Signal Reconstruction (TSR); and Pulsed
Phase Thermography (PPT) that implemented the inbuilt with Fast Fourier Transform (FFT). 3D printed natural fibre composites offer sustainable and cost-effective solutions to material challenges. When considering combining natural fibres and 3D printing there are several manufacturing challenges that must be overcome. The focus of this research is to ascertain if active thermography is a suitable tool for online inspection of fibre reinforced filaments used for 3D printing composites. The aim of the inspection is to
identify fibre rich and fibre poor regions along the filament, where uniformly distributed fibres and heating along the filament are preferred. Regions with a locally high weight percent of fibres, known as a fibre bunch, can cause problems when used to print a part resulting in a waste of materials and failed print jobs. The paper presents a feasibility study showing the potential of using pulsed thermography to identify fibre bunching. An external heating stimulus is applied to the sample and an infrared detector is used to monitor the thermal decay. The thermal contrast produced by fibre bunches compared to regions of uniformly distributed fibres is used to identify potential problem areas and provide a means of quality control. Investigation includes variation of the heating stimulus, data collection and data processing routines. Flat bottom holes (FBH) and notches of the samples were easiest to detect, filaments mixed with fibres and salt were more challenging and difficult to detect, which will require further investigations.

year: 2020

title: Explaining Maori under-achievement in standardised reading tests: The role of social and individual characteristics

authors: Lock, Kelly J.

subjects: education

abstract: In New Zealand, Maori students have lower educational attainment levels than their Pakeha counterparts, which is a major contributor to the earnings inequality between these two groups. This study attempts to identify determinants of the gap in educational attainment using data on reading test scores for a sample of 3031 15‐year‐old Maori and Pakeha students. Using a decomposition method that is commonly applied to income inequality analyses, the determinants of the reading literacy test score gap between Maori and Pakeha students are identified. The main contributors to this gap are family factors, student's opinions, and school factors (including decile). An understanding of the determinants of the test score gap provides insights into how effective policy makers can be at reducing this inequality.

text: Explaining Maori under-achievement in standardised reading tests: The role of social and individual characteristics In New Zealand, Maori students have lower educational attainment levels than their Pakeha counterparts, which is a major contributor to the earnings inequality between these two groups. This study attempts to identify determinants of the gap in educational attainment using data on reading test scores for a sample of 3031 15‐year‐old Maori and Pakeha students. Using a decomposition method that is commonly applied to income inequality analyses, the determinants of the reading literacy test score gap between Maori and Pakeha students are identified. The main contributors to this gap are family factors, student's opinions, and school factors (including decile). An understanding of the determinants of the test score gap provides insights into how effective policy makers can be at reducing this inequality.

year: 2008