title: Foaming Novatein Thermoplastic Protein

authors: Gavin, Chanelle Anne Rose

abstract: Most plastics are produced from non-renewable and/or non-biodegradable polymers. The negative environmental impact of these has been a strong driver for bioplastic development. Proteins are naturally occurring biopolymers which can be denatured and plasticised to produce thermoplastic materials. Novatein Thermoplastic Protein (NTP) is a patented blend of blood meal (a highly aggregated protein) and processing additives which: reduce hydrogen bonding, break cross links between cysteine residues, disrupt hydrophobic interactions, and facilitate protein unfolding. Water and triethylene glycol (TEG) are added as plasticisers to produce a powder which can be extruded, and subsequently injection moulded.
As Novatein is both bio-derived and biodegradable there is the opportunity for using it as an alternative loose fill packing material. This work aimed to develop an appropriate foaming method and the principles governing it. 
Foaming was initially investigated through extrusion which was unsuccessful due to the low speed and pressure drop. However, by using high speed and pressure, Novatein was successfully foamed in an injection moulder under free expansion. Foaming achieved densities between 0.2-0.5 g/cm3, at temperatures between 160-165°C. The mechanical properties varied with density but compressive strengths between 200 and 600 kPa and elastic moduli between 2.2 and 8 MPa were typical. Increasing temperature further did not improve expansion as the material degraded. The narrow processing window is characteristic of the material’s semi-crystalline nature which arises from residual protein secondary structure (α-helices and β-sheets). Although Novatein softens at high temperature, it does not form a typical melt.
Processing depends upon the interactions between protein, additives, and plasticisers. Highly plasticised Novatein phase separates into protein rich, protein-plasticiser, and plasticiser rich regions. This results in variable morphology characterised by: unfoamed regions, variable cell sizes and both open and closed cells. 

Varying water, urea and TEG impacted the foaming ability; adding urea lowered the extensional viscosity improving foaming while also acting as a blowing agent. Water and TEG reduced the shear viscosity and softening point respectively reducing expansion. Water was expected to improve expansion by acting as a blowing agent, however increasing water and TEG both increased cell size, but delayed stabilisation decreasing expansion.
Following nucleation a bubble grows by diffusion of gas molecules from the surrounding polymer. As these molecules leave, the viscosity increases, controlling bubble growth. Simultaneously, growth causes chain alignment within the surrounding polymer. Through FT-IR, bubbles were shown to appear in regions high in β-sheets. Two mechanisms were proposed; either a bubble nucleates near a β-sheet and grows until it encounters other β-sheet structures or that chain alignment enables hydrogen bonding between the chains, forming these structures. FT-IR also showed a high concentration of TEG at the bubble surface suggesting that nucleation occurred in regions high in water and TEG. The accumulation of TEG at a bubble surface occurs as water (steam) diffuses into the bubble causing expansion, pushing TEG into the surroundings.
Bubble stabilisation is achieved through either a loss plasticiser molecules or a decrease in temperature. In over plasticised blends, water keeps the viscosity in the surrounding polymer low, while increasing TEG reduced the softening point, both allowing more time for gases to diffuse out.
This work developed a suitable foaming method and an understanding of the role of protein secondary structure and rheology for Novatein, which can be foamed despite its high β-sheet content.

text: Foaming Novatein Thermoplastic Protein Most plastics are produced from non-renewable and/or non-biodegradable polymers. The negative environmental impact of these has been a strong driver for bioplastic development. Proteins are naturally occurring biopolymers which can be denatured and plasticised to produce thermoplastic materials. Novatein Thermoplastic Protein (NTP) is a patented blend of blood meal (a highly aggregated protein) and processing additives which: reduce hydrogen bonding, break cross links between cysteine residues, disrupt hydrophobic interactions, and facilitate protein unfolding. Water and triethylene glycol (TEG) are added as plasticisers to produce a powder which can be extruded, and subsequently injection moulded.
As Novatein is both bio-derived and biodegradable there is the opportunity for using it as an alternative loose fill packing material. This work aimed to develop an appropriate foaming method and the principles governing it. 
Foaming was initially investigated through extrusion which was unsuccessful due to the low speed and pressure drop. However, by using high speed and pressure, Novatein was successfully foamed in an injection moulder under free expansion. Foaming achieved densities between 0.2-0.5 g/cm3, at temperatures between 160-165°C. The mechanical properties varied with density but compressive strengths between 200 and 600 kPa and elastic moduli between 2.2 and 8 MPa were typical. Increasing temperature further did not improve expansion as the material degraded. The narrow processing window is characteristic of the material’s semi-crystalline nature which arises from residual protein secondary structure (α-helices and β-sheets). Although Novatein softens at high temperature, it does not form a typical melt.
Processing depends upon the interactions between protein, additives, and plasticisers. Highly plasticised Novatein phase separates into protein rich, protein-plasticiser, and plasticiser rich regions. This results in variable morphology characterised by: unfoamed regions, variable cell sizes and both open and closed cells. 

Varying water, urea and TEG impacted the foaming ability; adding urea lowered the extensional viscosity improving foaming while also acting as a blowing agent. Water and TEG reduced the shear viscosity and softening point respectively reducing expansion. Water was expected to improve expansion by acting as a blowing agent, however increasing water and TEG both increased cell size, but delayed stabilisation decreasing expansion.
Following nucleation a bubble grows by diffusion of gas molecules from the surrounding polymer. As these molecules leave, the viscosity increases, controlling bubble growth. Simultaneously, growth causes chain alignment within the surrounding polymer. Through FT-IR, bubbles were shown to appear in regions high in β-sheets. Two mechanisms were proposed; either a bubble nucleates near a β-sheet and grows until it encounters other β-sheet structures or that chain alignment enables hydrogen bonding between the chains, forming these structures. FT-IR also showed a high concentration of TEG at the bubble surface suggesting that nucleation occurred in regions high in water and TEG. The accumulation of TEG at a bubble surface occurs as water (steam) diffuses into the bubble causing expansion, pushing TEG into the surroundings.
Bubble stabilisation is achieved through either a loss plasticiser molecules or a decrease in temperature. In over plasticised blends, water keeps the viscosity in the surrounding polymer low, while increasing TEG reduced the softening point, both allowing more time for gases to diffuse out.
This work developed a suitable foaming method and an understanding of the role of protein secondary structure and rheology for Novatein, which can be foamed despite its high β-sheet content.

year: 2019

title: Adversarial risk analysis for first-price sealed-bid auctions

authors: Ejaz, Muhammad

subjects: Adversarial risk analysis

abstract: First-price sealed-bid (FPSB) auctions have mostly been modelled in auction theory using the decision-theoretic and Bayesian game-theoretic approaches. From a practical point of view, each approach has its limitations. To overcome those limitations, Rios Insua et al. (2009) introduced an approach, called adversarial risk analysis (ARA) that provides an optimal solution for one of the intervening agents, based on a decision making problem in hand and treating the intelligent adversaries' decisions as uncertainties. ARA solutions for FPSB auctions have previously been found but only under strong assumptions which make the model somewhat unrealistic.
In this thesis, we use ARA methodology and model bidders' behaviours in FPSB auctions using more realistic assumptions. First, we model bidders' behaviours by defining a new utility function that considers bidders' wealth which is assumed to be different for each bidder. We consider bidders' wealth since it is a significant determinant of their bidding behaviour in these auctions. Also, we define new risk behaviour parameters that change with the relative change in circumstances of bidders' wealth. In our modelling, we assume that the auctioned item is normal and has a reserve price which is known in advance to each bidder. We find ARA solutions not only for risk-neutral but also for risk-averse as well as risk-seeking bidders. We model these auctions by ARA framework using non-strategic play, level-k thinking, mirror equilibrium (ME) and Bayes Nash equilibrium (BNE) solution concepts. Finding ARA solutions using non-strategic play and level-k thinking, ME and BNE (asymmetric case) solution concepts, we assume two bidders. Whereas, we assume n bidders while finding ARA solutions using BNE symmetric case.
Second, we use ARA methodology and model bidders' behaviours using the utility function that takes into account bidders' winning and losing regret for the auctioned item. We define new winning and losing regret parameters and a modified utility function in order to take into account the effect of bidders' wealth on their bidding behaviours. Using the modified utility function, we find ARA solutions using non-strategic play and level-k thinking solution concepts assuming n bidders participating in these auctions. 
We give numerical examples to illustrate our methodology.

text: Adversarial risk analysis for first-price sealed-bid auctions First-price sealed-bid (FPSB) auctions have mostly been modelled in auction theory using the decision-theoretic and Bayesian game-theoretic approaches. From a practical point of view, each approach has its limitations. To overcome those limitations, Rios Insua et al. (2009) introduced an approach, called adversarial risk analysis (ARA) that provides an optimal solution for one of the intervening agents, based on a decision making problem in hand and treating the intelligent adversaries' decisions as uncertainties. ARA solutions for FPSB auctions have previously been found but only under strong assumptions which make the model somewhat unrealistic.
In this thesis, we use ARA methodology and model bidders' behaviours in FPSB auctions using more realistic assumptions. First, we model bidders' behaviours by defining a new utility function that considers bidders' wealth which is assumed to be different for each bidder. We consider bidders' wealth since it is a significant determinant of their bidding behaviour in these auctions. Also, we define new risk behaviour parameters that change with the relative change in circumstances of bidders' wealth. In our modelling, we assume that the auctioned item is normal and has a reserve price which is known in advance to each bidder. We find ARA solutions not only for risk-neutral but also for risk-averse as well as risk-seeking bidders. We model these auctions by ARA framework using non-strategic play, level-k thinking, mirror equilibrium (ME) and Bayes Nash equilibrium (BNE) solution concepts. Finding ARA solutions using non-strategic play and level-k thinking, ME and BNE (asymmetric case) solution concepts, we assume two bidders. Whereas, we assume n bidders while finding ARA solutions using BNE symmetric case.
Second, we use ARA methodology and model bidders' behaviours using the utility function that takes into account bidders' winning and losing regret for the auctioned item. We define new winning and losing regret parameters and a modified utility function in order to take into account the effect of bidders' wealth on their bidding behaviours. Using the modified utility function, we find ARA solutions using non-strategic play and level-k thinking solution concepts assuming n bidders participating in these auctions. 
We give numerical examples to illustrate our methodology.

year: 2021

title: Toi Tuku Iho: An exploration of oranga and mana motuhake through toi

authors: Waititi, Kahurangi Rora

subjects: Toi tuku iho

abstract: This research examines how mahi toi as process, theory, and output can contribute to oranga and mana motuhake for whānau, hapū, and iwi which is explored through the tribal storytelling practices of Te Whānau a Apanui. In this thesis, I argue that kōrero tuku iho is the umbilical link to our ancestors that sustains us with teachings; cultivating a richness and depth of self and connection through story. I demonstrate that the vehicles of sharing are as varied as the stories themselves and are known as “toi” or our creative expressions of kōrero tuku iho. 
The key focus of this thesis is to reveal how toi can be used to decolonise and re-indigenise research methodologies and facilitate transformation through praxis. Iwi storytellers were interviewed, sharing that within our toi practices lie a myriad of ways to challenge colonial structures and ideologies, ground us in tīpuna knowledge systems, and provide a space to innovate solutions to the challenges of te ao hurihuri (a changing world). The kaikōrero provided a collective and relational lens that fostered the development of a Toi Tuku Iho methodology. This was processed through a creative output that I created of a digital story that was filmed to reveal how knowledge through stories can become taonga tuku iho. A Toi Tuku Iho methodology is proffered to understand the complex processes of iwi storytelling and reveal the relationality between innovation and what this thesis refers to as the tipuna continuum.
Themes explored in the thesis are an ecosystem of learning through people, place, story, whakapapa and time; how iwi oranga is viewed and contributed to by toi; and how mana motuhake is embraced and enacted through kōrero tuku iho. Furthermore, the application of kaupapa Māori creative practices to this research expands the academic confines of knowledge production to include Indigenous stories and toi. The thesis demonstrates that the research process, potential products, and outcomes, are transformed by using these practices.  Storyscapes, timescapes, landscapes and generations past and future merge together, in this research, to facilitate dreams and aspirations for future generations. The collapsing of timescapes is explored through audio-visual digital storytelling, a medium known to manoeuvre time to enhance a story. I seek to amplify the power of tribal storytelling through toi to transform the spaces we occupy both within and outside of our iwi. Mahi toi ignites our creative selves to dream and can activate a belief to explore beyond what we know. I argue that Toi Tuku Iho has the potential to engage communities, on their own terms, in their own ways and for their own means.

text: Toi Tuku Iho: An exploration of oranga and mana motuhake through toi This research examines how mahi toi as process, theory, and output can contribute to oranga and mana motuhake for whānau, hapū, and iwi which is explored through the tribal storytelling practices of Te Whānau a Apanui. In this thesis, I argue that kōrero tuku iho is the umbilical link to our ancestors that sustains us with teachings; cultivating a richness and depth of self and connection through story. I demonstrate that the vehicles of sharing are as varied as the stories themselves and are known as “toi” or our creative expressions of kōrero tuku iho. 
The key focus of this thesis is to reveal how toi can be used to decolonise and re-indigenise research methodologies and facilitate transformation through praxis. Iwi storytellers were interviewed, sharing that within our toi practices lie a myriad of ways to challenge colonial structures and ideologies, ground us in tīpuna knowledge systems, and provide a space to innovate solutions to the challenges of te ao hurihuri (a changing world). The kaikōrero provided a collective and relational lens that fostered the development of a Toi Tuku Iho methodology. This was processed through a creative output that I created of a digital story that was filmed to reveal how knowledge through stories can become taonga tuku iho. A Toi Tuku Iho methodology is proffered to understand the complex processes of iwi storytelling and reveal the relationality between innovation and what this thesis refers to as the tipuna continuum.
Themes explored in the thesis are an ecosystem of learning through people, place, story, whakapapa and time; how iwi oranga is viewed and contributed to by toi; and how mana motuhake is embraced and enacted through kōrero tuku iho. Furthermore, the application of kaupapa Māori creative practices to this research expands the academic confines of knowledge production to include Indigenous stories and toi. The thesis demonstrates that the research process, potential products, and outcomes, are transformed by using these practices.  Storyscapes, timescapes, landscapes and generations past and future merge together, in this research, to facilitate dreams and aspirations for future generations. The collapsing of timescapes is explored through audio-visual digital storytelling, a medium known to manoeuvre time to enhance a story. I seek to amplify the power of tribal storytelling through toi to transform the spaces we occupy both within and outside of our iwi. Mahi toi ignites our creative selves to dream and can activate a belief to explore beyond what we know. I argue that Toi Tuku Iho has the potential to engage communities, on their own terms, in their own ways and for their own means.

year: 2023