title: Interactive solar panel simulation tool - from GHI to PV output

authors: Suppers, Joris

subjects: computer science

abstract: The production and integration of solar panels is steadily growing in New Zealand and worldwide. The most common way to install solar panels in New Zealand is flat on top of the most north-facing roof. This method is used as it is space efficient, reduces mounting costs and will capture most of the sun’s movement throughout the day. New Zealand homes typically have a small roof pitch. This means an installed solar panel will have a low tilt, allowing for best input in summer. However, this may not be the best result for individuals, as they may want a different outcome such as: maximum energy output in winter, maximum yearly output or a balanced output throughout each month. This paper describes a solar panel tool, which has been developed to enable users to explore interactively the impact on electricity production based on the orientation of the panels.

text: Interactive solar panel simulation tool - from GHI to PV output The production and integration of solar panels is steadily growing in New Zealand and worldwide. The most common way to install solar panels in New Zealand is flat on top of the most north-facing roof. This method is used as it is space efficient, reduces mounting costs and will capture most of the sun’s movement throughout the day. New Zealand homes typically have a small roof pitch. This means an installed solar panel will have a low tilt, allowing for best input in summer. However, this may not be the best result for individuals, as they may want a different outcome such as: maximum energy output in winter, maximum yearly output or a balanced output throughout each month. This paper describes a solar panel tool, which has been developed to enable users to explore interactively the impact on electricity production based on the orientation of the panels.

year: 2017

title: Novel polymeric microcapsules for targeted drug delivery

authors: Lin, Yuewen

subjects: polymer

abstract: Microencapsulation is a technology in which small particles or droplets are entrapped by a coating to give the particles with many useful properties. Microcapsules have been used to protect the encapsulated material from the environmental conditions or to release the active agent in a sustained and controlled manner into the surrounding medium. This thesis investigated how to develop a post-ruminal delivery system based on polymeric microencapsulation. A major criterion was to develop microcapsules with reversible switching in response to changes of pH in the in vivo environment so contents could be released. The microcapsules must have a thin shell strong enough to withstand harsh physical conditions and a large hollow centre, which will maximise drug-carrying capacity. Two processes were developed to manufacture pH-responsive microcapsules - conventional interfacial polymerisation with plasma-induced grafting and a novel phase-inversion technique with chemical grafting. This research demonstrated that microcapsules with a porous shell could be manufactured by interfacial polymerisation. Carboxyl groups introduced onto the pores in the microcapsule by plasma-induced graft polymerisation of acrylic acid allowed pore openings to be controlled by the pH change of the environment. Polyamide microcapsules made by interfacial polymerisation had a hollow core and a porous shell with smooth external and rough internal surfaces. Their average diameter of 28 µm decreased with increased stirring rate during polymerisation. Shell porosity could be changed by adjusting the ratio of amine monomers used to form the microcapsule shell. An argon plasma treatment was developed to graft acrylic acid onto the microcapsule surface. Plasma treatment with 90 seconds produced 0.56 mmol/g of grafting extent. The effect of pH on releasing contents from poly(acrylic acid)-grafted microcapsules was investigated using two different sized molecules (vitamin B12 and cytochrome c) to simulate model drugs. Release rate was not significantly affected by molecular size; contents were retained when pH was between 7 and 5.5 and released when pH was between 5 and 3.5. Full release occurred at pH below 3. Further studies showed that micron-sized microcapsules with a hollow core and a thick matrix wall could be made from polycaprolactone, polysulfone and polystyrene. A modified solvent evaporation process reduced shell thickness but the microcapsules still had a non-porous skin. Process parameters such as polymer concentration, temperature, surfactant, solvent composition, stirring speed, processing pressure, and co-polymer additives influenced structure and internal morphology of the microcapsules. Morphological characteristics of the microcapsules strongly depended on the way the coating polymer is precipitated, particularly the non solvent–polymer–solvent interactions. Chemical grafting was not successful for grafting acrylic acid onto the polycaprolactone and polysulfone microcapsules. Polystyrene microcapsules with a hollow core and porous micro-channel shell structure were successfully produced using a novel formulation in a phase-inversion process. The outer skin could be removed by re-dissolving the formed microcapsules in a suitable solvent. Open pores with inter-connected micro-channels on the microcapsule surface can be produced by carefully controlling the time the microcapsules are in the solvent. The microcapsule was functionalised using free radical polymerisation to graft acrylic acid onto its surface. However, these microcapsules did not completely retain their contents at pH 7 and had a slow release profile when pH was decreased. Recommendations are given on how to improve and optimise the process. Polystyrene microcapsules made with a simple and inexpensive phase-inversion technique have potential as a targeted drug delivery system. They could be re-usable, compared to most other systems that degrade or disintegrate, and may have other applications as a carrier to immobilise desired molecules onto the microcapsules. Further investigations to optimise manufacturing polystyrene microcapsules should include: larger scale trials; further investigations, using orthogonal tests with multi-variation analysis to optimise factors affection microcapsule porosity and extent of grafting; identifying an alternative, faster way to analyse pore size; and developing a mathematical model for the release rate.

text: Novel polymeric microcapsules for targeted drug delivery Microencapsulation is a technology in which small particles or droplets are entrapped by a coating to give the particles with many useful properties. Microcapsules have been used to protect the encapsulated material from the environmental conditions or to release the active agent in a sustained and controlled manner into the surrounding medium. This thesis investigated how to develop a post-ruminal delivery system based on polymeric microencapsulation. A major criterion was to develop microcapsules with reversible switching in response to changes of pH in the in vivo environment so contents could be released. The microcapsules must have a thin shell strong enough to withstand harsh physical conditions and a large hollow centre, which will maximise drug-carrying capacity. Two processes were developed to manufacture pH-responsive microcapsules - conventional interfacial polymerisation with plasma-induced grafting and a novel phase-inversion technique with chemical grafting. This research demonstrated that microcapsules with a porous shell could be manufactured by interfacial polymerisation. Carboxyl groups introduced onto the pores in the microcapsule by plasma-induced graft polymerisation of acrylic acid allowed pore openings to be controlled by the pH change of the environment. Polyamide microcapsules made by interfacial polymerisation had a hollow core and a porous shell with smooth external and rough internal surfaces. Their average diameter of 28 µm decreased with increased stirring rate during polymerisation. Shell porosity could be changed by adjusting the ratio of amine monomers used to form the microcapsule shell. An argon plasma treatment was developed to graft acrylic acid onto the microcapsule surface. Plasma treatment with 90 seconds produced 0.56 mmol/g of grafting extent. The effect of pH on releasing contents from poly(acrylic acid)-grafted microcapsules was investigated using two different sized molecules (vitamin B12 and cytochrome c) to simulate model drugs. Release rate was not significantly affected by molecular size; contents were retained when pH was between 7 and 5.5 and released when pH was between 5 and 3.5. Full release occurred at pH below 3. Further studies showed that micron-sized microcapsules with a hollow core and a thick matrix wall could be made from polycaprolactone, polysulfone and polystyrene. A modified solvent evaporation process reduced shell thickness but the microcapsules still had a non-porous skin. Process parameters such as polymer concentration, temperature, surfactant, solvent composition, stirring speed, processing pressure, and co-polymer additives influenced structure and internal morphology of the microcapsules. Morphological characteristics of the microcapsules strongly depended on the way the coating polymer is precipitated, particularly the non solvent–polymer–solvent interactions. Chemical grafting was not successful for grafting acrylic acid onto the polycaprolactone and polysulfone microcapsules. Polystyrene microcapsules with a hollow core and porous micro-channel shell structure were successfully produced using a novel formulation in a phase-inversion process. The outer skin could be removed by re-dissolving the formed microcapsules in a suitable solvent. Open pores with inter-connected micro-channels on the microcapsule surface can be produced by carefully controlling the time the microcapsules are in the solvent. The microcapsule was functionalised using free radical polymerisation to graft acrylic acid onto its surface. However, these microcapsules did not completely retain their contents at pH 7 and had a slow release profile when pH was decreased. Recommendations are given on how to improve and optimise the process. Polystyrene microcapsules made with a simple and inexpensive phase-inversion technique have potential as a targeted drug delivery system. They could be re-usable, compared to most other systems that degrade or disintegrate, and may have other applications as a carrier to immobilise desired molecules onto the microcapsules. Further investigations to optimise manufacturing polystyrene microcapsules should include: larger scale trials; further investigations, using orthogonal tests with multi-variation analysis to optimise factors affection microcapsule porosity and extent of grafting; identifying an alternative, faster way to analyse pore size; and developing a mathematical model for the release rate.

year: 2009

title: Reha Aperahama: a Ngati Rahiri rangatira

authors: Hart, Philip

abstract: Reha Aperahama had an illustrious whakapapa and was affiliated to several hapu. His father was notable as one of the most loyal rangatira (from the Crown’s perspective) in Hauraki, and Reha followed his lead, probably in part because of the financial rewards he received from selling land to settlers. He tried to maximize his income from this source, spending several years pleading for permission to sell his Te Kawana block (near Te Aroha). After opposing Ngati Haua ambitions to acquire the Aroha block, by 1878 he was willing to encourage road building. 
Reha was regularly before the courts because of his inability or reluctance to pay his debts, occasionally perjuring himself to avoid liability. In his later years he had little money. Despite occasionally being drunk and even violent, he was an important figure in Maori society, with a leadership role in his hapu and in the Mormon church. He was also notable for his marital complications.

text: Reha Aperahama: a Ngati Rahiri rangatira Reha Aperahama had an illustrious whakapapa and was affiliated to several hapu. His father was notable as one of the most loyal rangatira (from the Crown’s perspective) in Hauraki, and Reha followed his lead, probably in part because of the financial rewards he received from selling land to settlers. He tried to maximize his income from this source, spending several years pleading for permission to sell his Te Kawana block (near Te Aroha). After opposing Ngati Haua ambitions to acquire the Aroha block, by 1878 he was willing to encourage road building. 
Reha was regularly before the courts because of his inability or reluctance to pay his debts, occasionally perjuring himself to avoid liability. In his later years he had little money. Despite occasionally being drunk and even violent, he was an important figure in Maori society, with a leadership role in his hapu and in the Mormon church. He was also notable for his marital complications.

year: 2016