title: Achieving reliable and repeatable electrochemical impedance spectroscopy of rechargeable batteries at extra-low frequencies

authors: Dunn, Christopher

abstract: There is a need for techniques for efficient and accurate measurement of the impedance of rechargeable batteries at extra-low frequencies (ELFs, of the order of microhertz), as these reflect real usage and cycling patterns, and their importance in fractional battery circuit modeling is becoming increasingly apparent. Major impediments include the time required to perform such measurements and “drift” in impedance values when measurements are taken from the same battery at different times. Moreover, commercial impedance analyzers are generally unable to measure at these frequencies. We describe here our use of programmable two-quadrant power supplies to deliver multiple small-signal measurement tones in the presence of large-signal “working” currents, and our use of these data to generate impedance measurements with good precision and in reasonable time. The improvement in the quality of electrochemical impedance spectroscopy (EIS) data is verified through root-mean-square error (RMSE) when fitting equivalent-circuit models (ECMs).

text: Achieving reliable and repeatable electrochemical impedance spectroscopy of rechargeable batteries at extra-low frequencies There is a need for techniques for efficient and accurate measurement of the impedance of rechargeable batteries at extra-low frequencies (ELFs, of the order of microhertz), as these reflect real usage and cycling patterns, and their importance in fractional battery circuit modeling is becoming increasingly apparent. Major impediments include the time required to perform such measurements and “drift” in impedance values when measurements are taken from the same battery at different times. Moreover, commercial impedance analyzers are generally unable to measure at these frequencies. We describe here our use of programmable two-quadrant power supplies to deliver multiple small-signal measurement tones in the presence of large-signal “working” currents, and our use of these data to generate impedance measurements with good precision and in reasonable time. The improvement in the quality of electrochemical impedance spectroscopy (EIS) data is verified through root-mean-square error (RMSE) when fitting equivalent-circuit models (ECMs).

year: 2022

title: The Innovative Learning Environment in New Zealand: Supporting Teacher Transition

authors: Jensen, Rochelle Jane

subjects: ILE

abstract: The surge of teachers transitioning to innovative learning environments (ILEs), together with the knowledge that teachers have a large impact on student achievement, has prompted this study. Shifts to ILEs are supported by the Ministry of Education (2014b) building policy and aspirations for 21st Century learners (Ministry of Education, 2007; Partnership for 21st Century Learning, 2016). However, very little guidance exists to aid successful transition. Thus, this study adopts an interpretive, case study approach and uses mixed methods to examine the key question of how teachers can be supported to transition from single-cell classrooms to ILEs.
The experiences of six New Zealand-based intermediate teachers are examined in detail. They see a need for transition processes to include all staff, regardless of the physical environment in which they teach. Feedback suggests transitions should be based on a whole-school vision that aligns with the principles of modern learning practice (MLP). A need for school management to lead the process and ensure systems are aligned to enable desired pedagogy is also emphasised. Well-planned professional learning development (PLD) grounded in dialogic sense-making can be personalised and can include a focus on interpersonal skills, MLP and developing student agency. The careful selection of teaching teams, and the implementation of evaluation systems to monitor the impacts of MLP and the physical environment, are also key to successful transition. When transition includes ILE design, architects and practitioners must work closely together to create a well-designed physical space that fosters desired practice. Findings from this study can be used to inform transition processes for policy makers, school leaders and practitioners.

text: The Innovative Learning Environment in New Zealand: Supporting Teacher Transition The surge of teachers transitioning to innovative learning environments (ILEs), together with the knowledge that teachers have a large impact on student achievement, has prompted this study. Shifts to ILEs are supported by the Ministry of Education (2014b) building policy and aspirations for 21st Century learners (Ministry of Education, 2007; Partnership for 21st Century Learning, 2016). However, very little guidance exists to aid successful transition. Thus, this study adopts an interpretive, case study approach and uses mixed methods to examine the key question of how teachers can be supported to transition from single-cell classrooms to ILEs.
The experiences of six New Zealand-based intermediate teachers are examined in detail. They see a need for transition processes to include all staff, regardless of the physical environment in which they teach. Feedback suggests transitions should be based on a whole-school vision that aligns with the principles of modern learning practice (MLP). A need for school management to lead the process and ensure systems are aligned to enable desired pedagogy is also emphasised. Well-planned professional learning development (PLD) grounded in dialogic sense-making can be personalised and can include a focus on interpersonal skills, MLP and developing student agency. The careful selection of teaching teams, and the implementation of evaluation systems to monitor the impacts of MLP and the physical environment, are also key to successful transition. When transition includes ILE design, architects and practitioners must work closely together to create a well-designed physical space that fosters desired practice. Findings from this study can be used to inform transition processes for policy makers, school leaders and practitioners.

year: 2019

title: The role of mānuka (Leptospermum scoparium) riparian plantings in the mitigation of diffuse agricultural nitrogen

authors: Adamson, Olivia María

subjects: Manuka

abstract: The disruption of nutrient cycles in agricultural settings, particularly pastoral farming, is responsible for up to 70% of the nitrogen (N) loads entering streams in New Zealand (NZ) — resulting in the widespread degradation of freshwater ecosystems. Riparian plantings are one strategy to mitigate the losses of N from land to water, removing N by denitrification and plant uptake. Some types of vegetation are more effective than others at intercepting N, due to their ecology, impact on soil quality and root exudates. Mānuka (Leptospermum scoparium) is a plant native to NZ, and the species could be a good candidate to mitigate N losses due its ability to tolerate high N loads and co-benefits such as farm diversification through apiculture or essential oil production. Previous work also suggests that L. scoparium could be a biological nitrification inhibitor (BNI), limiting nitrate (NO₃⁻) production in soil.

The aim of this study was to investigate the potential of mānuka to intercept and remove N in an experimental riparian buffer in Lake Waikare. Currently, the lake is eutrophic due to high nutrient and sediment inputs. Significant restoration efforts have been made in recent years, led by many hapuu around the lake. All are very passionate and determined to recover the mauri of this ecosystem and reconnect the people to the lake, as well as provide economic opportunities. The riparian band had been established for four years and was set up as a series of experimental plots with different vegetation types, including plots solely in mānuka, and grassed controls. The plots are on a Perch- Gley Ultic Soil underlain by a slowly permeable clay layer— the Hamilton Ash. Further, the study sought to explore the relationship between soil physical properties and N cycling, and to identify influences expected by the local hydrology— as there was evidence of perching and lateral flow in the site. A series of suction-cup lysimeters were installed and pore water was sampled seven times between May and July 2021. Samples were analysed for total N (TN), total Kjeldahl N (TKN), NO₃⁻ and ammonium (NH₄⁺).

The results show that the riparian buffer is effectively removing N from subsurface flows, with TN declining from an average of 9.32 mg/l at 1 m into the buffer to 2.03 mg/l at 7 m. Although N concentrations were higher under mānuka, the total amount of N extracted from those plots was 21% less due to high rainfall interception by the canopy (63.9%), limiting the transport of the solute. Indicators of soil physical quality, bulk density (ρb) and macroporosity (MP), were investigated as potential causes for differences in the movement of N. There was a 17% improvement in ρb, and 38% improvement in MP relative to 2017 measurements, before the riparian band was established. No appreciable differences in soil physical properties were found between vegetation types at this early stage in the inception of the riparian buffer, although changes are likely to occur as the mānuka trees mature and the impact of roots is more developed. Shallow wells were deployed to monitor the dynamics of the water table, as there was evidence of winter perching. Dip wells demonstrated the existence of a short- lived perched water table, resulting in lateral flow, and likely impacting the degree of soil gleying in different parts of the riparian band. Water and contaminants are likely to move laterally over the Hamilton Ash towards the drain, supported by the accumulation of NO₃⁻ at the boundary with the clay layer.
Future work should be devoted to better quantifying NO₃⁻ leaching from the riparian plot by incorporating a drainage model, as well as further investigating the relative importance of N removal pathways at this site (i.e. denitrification and plant uptake)— including the potential for the lower part of the riparian band, closest to the drain, to become a hotspot for nitrous oxide (N₂O) emissions. It would also be of value to revisit this study in 4-10 years to explore how the buffer impacts soil quality and N dynamics in the subsurface as it matures.

text: The role of mānuka (Leptospermum scoparium) riparian plantings in the mitigation of diffuse agricultural nitrogen The disruption of nutrient cycles in agricultural settings, particularly pastoral farming, is responsible for up to 70% of the nitrogen (N) loads entering streams in New Zealand (NZ) — resulting in the widespread degradation of freshwater ecosystems. Riparian plantings are one strategy to mitigate the losses of N from land to water, removing N by denitrification and plant uptake. Some types of vegetation are more effective than others at intercepting N, due to their ecology, impact on soil quality and root exudates. Mānuka (Leptospermum scoparium) is a plant native to NZ, and the species could be a good candidate to mitigate N losses due its ability to tolerate high N loads and co-benefits such as farm diversification through apiculture or essential oil production. Previous work also suggests that L. scoparium could be a biological nitrification inhibitor (BNI), limiting nitrate (NO₃⁻) production in soil.

The aim of this study was to investigate the potential of mānuka to intercept and remove N in an experimental riparian buffer in Lake Waikare. Currently, the lake is eutrophic due to high nutrient and sediment inputs. Significant restoration efforts have been made in recent years, led by many hapuu around the lake. All are very passionate and determined to recover the mauri of this ecosystem and reconnect the people to the lake, as well as provide economic opportunities. The riparian band had been established for four years and was set up as a series of experimental plots with different vegetation types, including plots solely in mānuka, and grassed controls. The plots are on a Perch- Gley Ultic Soil underlain by a slowly permeable clay layer— the Hamilton Ash. Further, the study sought to explore the relationship between soil physical properties and N cycling, and to identify influences expected by the local hydrology— as there was evidence of perching and lateral flow in the site. A series of suction-cup lysimeters were installed and pore water was sampled seven times between May and July 2021. Samples were analysed for total N (TN), total Kjeldahl N (TKN), NO₃⁻ and ammonium (NH₄⁺).

The results show that the riparian buffer is effectively removing N from subsurface flows, with TN declining from an average of 9.32 mg/l at 1 m into the buffer to 2.03 mg/l at 7 m. Although N concentrations were higher under mānuka, the total amount of N extracted from those plots was 21% less due to high rainfall interception by the canopy (63.9%), limiting the transport of the solute. Indicators of soil physical quality, bulk density (ρb) and macroporosity (MP), were investigated as potential causes for differences in the movement of N. There was a 17% improvement in ρb, and 38% improvement in MP relative to 2017 measurements, before the riparian band was established. No appreciable differences in soil physical properties were found between vegetation types at this early stage in the inception of the riparian buffer, although changes are likely to occur as the mānuka trees mature and the impact of roots is more developed. Shallow wells were deployed to monitor the dynamics of the water table, as there was evidence of winter perching. Dip wells demonstrated the existence of a short- lived perched water table, resulting in lateral flow, and likely impacting the degree of soil gleying in different parts of the riparian band. Water and contaminants are likely to move laterally over the Hamilton Ash towards the drain, supported by the accumulation of NO₃⁻ at the boundary with the clay layer.
Future work should be devoted to better quantifying NO₃⁻ leaching from the riparian plot by incorporating a drainage model, as well as further investigating the relative importance of N removal pathways at this site (i.e. denitrification and plant uptake)— including the potential for the lower part of the riparian band, closest to the drain, to become a hotspot for nitrous oxide (N₂O) emissions. It would also be of value to revisit this study in 4-10 years to explore how the buffer impacts soil quality and N dynamics in the subsurface as it matures.

year: 2021