title: Optimization of Sol–Gel-Formed ZnO:Al Processing Parameters by Observation of Dopant Ion Location Using Solid-State ²⁷Al NMR Spectrometry

authors: Kemmitt, Tim

subjects: chemistry

abstract: We report the discrimination of Al doping sites in sol–gel-formed ZnO powders by solid-state 27Al nuclear magnetic resonance (NMR) spectrometry. A degree of control of dopant placement is demonstrated by modifying sol precursors and processing parameters. ZnO powders containing 1–8 at. % aluminum ions were prepared from aqueous citrate-amino-alcohol-based gels calcined at 500 °C. The powders were characterized using ²⁷Al NMR spectrometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Solid-state ²⁷Al NMR spectrometry clearly distinguished between different Al environments and was effective in determining the relative amounts of incorporation of Al dopant ions into the Zn lattice sites in the zincite structure. This allowed a synthesis protocol to be developed to optimize the doping effectiveness. Relatively minor variations in processing conditions could influence the degree and mode of Al incorporation. Optimal conditions were found to include a 90 °C drying step, followed by placement in a preheated (500 °C) furnace for 1 h. An ethanolamine-containing precursor was shown to perform much better than precursors containing alternative amino alcohols.

text: Optimization of Sol–Gel-Formed ZnO:Al Processing Parameters by Observation of Dopant Ion Location Using Solid-State ²⁷Al NMR Spectrometry We report the discrimination of Al doping sites in sol–gel-formed ZnO powders by solid-state 27Al nuclear magnetic resonance (NMR) spectrometry. A degree of control of dopant placement is demonstrated by modifying sol precursors and processing parameters. ZnO powders containing 1–8 at. % aluminum ions were prepared from aqueous citrate-amino-alcohol-based gels calcined at 500 °C. The powders were characterized using ²⁷Al NMR spectrometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Solid-state ²⁷Al NMR spectrometry clearly distinguished between different Al environments and was effective in determining the relative amounts of incorporation of Al dopant ions into the Zn lattice sites in the zincite structure. This allowed a synthesis protocol to be developed to optimize the doping effectiveness. Relatively minor variations in processing conditions could influence the degree and mode of Al incorporation. Optimal conditions were found to include a 90 °C drying step, followed by placement in a preheated (500 °C) furnace for 1 h. An ethanolamine-containing precursor was shown to perform much better than precursors containing alternative amino alcohols.

year: 2011

title: Cost-effective mitigation of greenhouse gas emissions from different dairy systems in the Waikato region of New Zealand

authors: Adler, Alfredo A.

subjects: dairy production

abstract: The New Zealand dairy industry produces approximately 17% of this country's total greenhouse gas emissions (GHG-e) and it is also this nation's largest export industry. The industry needs to reduce GHG-e under proposed policy directives and for ongoing market security. Given these pressures, there is the need to identify cost-effective management strategies to reduce on-farm GHG-e. The objective of this study was to investigate how the management of dairy farms in the Waikato region of New Zealand could change to minimise the abatement costs associated with GHG-e mitigation. Three typical farm systems importing low (less than 10%), medium (10–20%), and high (more than 20%) amounts of supplement are modelled using a non-linear optimisation model.

A reduction in nitrogen fertiliser application was the production factor that changed the most to achieve the cap in all of the simulated systems, followed by a reduction in stocking rate. With the prices used in this study, decreasing farming intensity by reducing nitrogen fertiliser by 21–42% and stocking rate by 8–10% represented a cost of $68–$119/ha and a production reduction of 54–117 kg MS/ha for the three systems studied. Improving reproductive performance proved to be effective in reducing GHG-e, allowing for fewer replacement cows to be supported. However, it did not have a significant effect on profit when emissions were unconstrained. Nitrification inhibitors and stand-off pads were not identified as useful mitigation options, given their high cost relative to de-intensification.

text: Cost-effective mitigation of greenhouse gas emissions from different dairy systems in the Waikato region of New Zealand The New Zealand dairy industry produces approximately 17% of this country's total greenhouse gas emissions (GHG-e) and it is also this nation's largest export industry. The industry needs to reduce GHG-e under proposed policy directives and for ongoing market security. Given these pressures, there is the need to identify cost-effective management strategies to reduce on-farm GHG-e. The objective of this study was to investigate how the management of dairy farms in the Waikato region of New Zealand could change to minimise the abatement costs associated with GHG-e mitigation. Three typical farm systems importing low (less than 10%), medium (10–20%), and high (more than 20%) amounts of supplement are modelled using a non-linear optimisation model.

A reduction in nitrogen fertiliser application was the production factor that changed the most to achieve the cap in all of the simulated systems, followed by a reduction in stocking rate. With the prices used in this study, decreasing farming intensity by reducing nitrogen fertiliser by 21–42% and stocking rate by 8–10% represented a cost of $68–$119/ha and a production reduction of 54–117 kg MS/ha for the three systems studied. Improving reproductive performance proved to be effective in reducing GHG-e, allowing for fewer replacement cows to be supported. However, it did not have a significant effect on profit when emissions were unconstrained. Nitrification inhibitors and stand-off pads were not identified as useful mitigation options, given their high cost relative to de-intensification.

year: 2013

title: Te Kāhui a Kiwa—Advancing Indigenous self determination and wellbeing through trade and can the CPTPP help

authors: Mika, Jason

abstract: This report provides an interim account of a conference held in Hamilton on 28-29 June 2023 called Te Kāhui a Kiwa—Advancing Indigenous self-determination and wellbeing through trade and can the CPTPP help. The conference was hosted by the University of Waikato, working collaboratively with Ngā Toki Whakarururanga, with funding from the Ministry of Foreign Affairs and Trade (Manatū Aorere). University kaumātua (elder) Koro Taki Turner gifted the conference its name. Kāhui refers to an assembly of stars or in this case, people, while Kiwa is short for Te Moana nui a Kiwa—the great ocean of Kiwa, the Pacific Ocean.

text: Te Kāhui a Kiwa—Advancing Indigenous self determination and wellbeing through trade and can the CPTPP help This report provides an interim account of a conference held in Hamilton on 28-29 June 2023 called Te Kāhui a Kiwa—Advancing Indigenous self-determination and wellbeing through trade and can the CPTPP help. The conference was hosted by the University of Waikato, working collaboratively with Ngā Toki Whakarururanga, with funding from the Ministry of Foreign Affairs and Trade (Manatū Aorere). University kaumātua (elder) Koro Taki Turner gifted the conference its name. Kāhui refers to an assembly of stars or in this case, people, while Kiwa is short for Te Moana nui a Kiwa—the great ocean of Kiwa, the Pacific Ocean.

year: 2023-07-13