title: Development of sustainable composites from treated harakeke (New Zealand flax) fibre and poly(lactic) acid

authors: Akindoyo, John O.

abstract: The building and construction sector consumes large volume of materials, it generates enormous amounts of solid wastes, and it is responsible for about 40% of annual global CO2 emissions. So, sustainable biodegradable, recyclable or renewable materials such as polymer-based materials are seen as potential substitutes to their non-renewable, non-environmentally friendly counterparts. Poly (lactic acid) (PLA) is a polymer produced from renewable sources, thereby supporting sustainability. The use of PLA is sometimes limited by its inherent brittleness, and insufficient mechanical strength when used alone. The brittleness of PLA may be reduced by toughening it with rubbery additives, while its strength can be improved through reinforcement with materials such as natural fibres.  

In this thesis, fibres extracted from harakeke (Phormium tenax), otherwise called New Zealand flax is used as reinforcement in PLA composites. The fibre properties were modified to facilitate processability, improve its compatibility with PLA, and to enhance its reinforcing ability by removing components such as lignin and hemicellulose which are detrimental to the mechanical and thermal performance of the composite. Different methods such as chemical treatment with alkali solutions, mechanical processing, and enzymatic treatment were explored to modify the harakeke fibre. In addition, polybutylene succinate (PBS) was blended with PLA, followed by reactive compatibilization of the reinforced PLA/PBS blend with dicumyl peroxide (DCP), with the aim of improving the toughness of the composite. 

The results show that harakeke fibre is a good reinforcement for PLA, as it increased the composite strength from 62±1.02 MPa to 82±0.98 MPa. In addition, it was found that PLA/PBS blends can be reactively compatibilized and reinforced concurrently, thereby supporting the production of composites with improved mechanical, thermal, and thermomechanical performance. Generally, the results show that enzymatic treatment could serve as a more sustainable environmentally friendly route to fibre treatment as it obviates a chemical processing route and supports recyclability and reusability. Likewise, the combination of mechanical processing with enzymatic treatment has great potential for producing large scale environmentally friendly and good quality fibres, suitable for composites.

text: Development of sustainable composites from treated harakeke (New Zealand flax) fibre and poly(lactic) acid The building and construction sector consumes large volume of materials, it generates enormous amounts of solid wastes, and it is responsible for about 40% of annual global CO2 emissions. So, sustainable biodegradable, recyclable or renewable materials such as polymer-based materials are seen as potential substitutes to their non-renewable, non-environmentally friendly counterparts. Poly (lactic acid) (PLA) is a polymer produced from renewable sources, thereby supporting sustainability. The use of PLA is sometimes limited by its inherent brittleness, and insufficient mechanical strength when used alone. The brittleness of PLA may be reduced by toughening it with rubbery additives, while its strength can be improved through reinforcement with materials such as natural fibres.  

In this thesis, fibres extracted from harakeke (Phormium tenax), otherwise called New Zealand flax is used as reinforcement in PLA composites. The fibre properties were modified to facilitate processability, improve its compatibility with PLA, and to enhance its reinforcing ability by removing components such as lignin and hemicellulose which are detrimental to the mechanical and thermal performance of the composite. Different methods such as chemical treatment with alkali solutions, mechanical processing, and enzymatic treatment were explored to modify the harakeke fibre. In addition, polybutylene succinate (PBS) was blended with PLA, followed by reactive compatibilization of the reinforced PLA/PBS blend with dicumyl peroxide (DCP), with the aim of improving the toughness of the composite. 

The results show that harakeke fibre is a good reinforcement for PLA, as it increased the composite strength from 62±1.02 MPa to 82±0.98 MPa. In addition, it was found that PLA/PBS blends can be reactively compatibilized and reinforced concurrently, thereby supporting the production of composites with improved mechanical, thermal, and thermomechanical performance. Generally, the results show that enzymatic treatment could serve as a more sustainable environmentally friendly route to fibre treatment as it obviates a chemical processing route and supports recyclability and reusability. Likewise, the combination of mechanical processing with enzymatic treatment has great potential for producing large scale environmentally friendly and good quality fibres, suitable for composites.

year: 2025

title: Determining and testing the optimal pure-tone frequency for use in acoustic conditioning of free-ranging common carp (Cyprinus carpio)

authors: Mahoney, Brennan Andrew

subjects: carp

abstract: Pure-tone frequencies of 400, 700, and 1000 Hz were tested to determine which achieved the strongest response when used in conditioning experiments on captive common carp (Cyprinus carpio) for the purpose of determining the most effective frequency to use in conditioning experiments on free-ranging common carp. Captive common carp were shown to have the strongest response to the 400 Hz frequency after training that associated sound with food. Response was quantified as moving into a feeding arena when the sound was broadcast, and all frequencies achieved conditioning within five days. Secondly, the attenuation of the three frequencies were compared in a Waikato lake (Lake Kaituna) containing common carp. The ability to maintain signal strength over distance is necessary for frequencies used in the acoustic conditioning of free-ranging common carp due to the potentially large distances involved. Attenuation of the 400 Hz and 700 Hz pure tone frequencies were not significantly different but were both lower than that of the 1000 Hz frequency. The 400 Hz pure tone frequency was used in subsequent experiments on the acoustic conditioning of free-ranging common carp in Lake Kaituna because of superior performance in acoustic conditioning of captive common carp and low attenuation in a natural water body containing free-ranging common carp,. Thirdly, the 400 Hz pure tone was evaluated for its ability to be associated with food by free-ranging common carp. Capture rates at treatment sites where 400 Hz pure tone was broadcast compared to control sites where no sound was broadcast following a five-day training phase and 24 h of no sound or food, were 2.1 times greater during a three-day capture phase. This study demonstrates the trainability of common carp, a trait that can be used to improve control of wild common carp populations.

text: Determining and testing the optimal pure-tone frequency for use in acoustic conditioning of free-ranging common carp (Cyprinus carpio) Pure-tone frequencies of 400, 700, and 1000 Hz were tested to determine which achieved the strongest response when used in conditioning experiments on captive common carp (Cyprinus carpio) for the purpose of determining the most effective frequency to use in conditioning experiments on free-ranging common carp. Captive common carp were shown to have the strongest response to the 400 Hz frequency after training that associated sound with food. Response was quantified as moving into a feeding arena when the sound was broadcast, and all frequencies achieved conditioning within five days. Secondly, the attenuation of the three frequencies were compared in a Waikato lake (Lake Kaituna) containing common carp. The ability to maintain signal strength over distance is necessary for frequencies used in the acoustic conditioning of free-ranging common carp due to the potentially large distances involved. Attenuation of the 400 Hz and 700 Hz pure tone frequencies were not significantly different but were both lower than that of the 1000 Hz frequency. The 400 Hz pure tone frequency was used in subsequent experiments on the acoustic conditioning of free-ranging common carp in Lake Kaituna because of superior performance in acoustic conditioning of captive common carp and low attenuation in a natural water body containing free-ranging common carp,. Thirdly, the 400 Hz pure tone was evaluated for its ability to be associated with food by free-ranging common carp. Capture rates at treatment sites where 400 Hz pure tone was broadcast compared to control sites where no sound was broadcast following a five-day training phase and 24 h of no sound or food, were 2.1 times greater during a three-day capture phase. This study demonstrates the trainability of common carp, a trait that can be used to improve control of wild common carp populations.

year: 2012

title: Te ahi tawhito, te ahi tipua, te ahi nā Mahuika: Re-igniting native women’s ceremony

authors: Murphy, Ngahuia Aroha Grace

subjects: Native women's ceremony

abstract: This research examines the multiple ways in which Māori, and Hawai’ian and Native American women, are re-activating feminine ceremonial forms and recovering sacred relationships with customary feminine deities. Attention is focused on the creation of personal ritual practices that respond to contemporary decolonising and ecological contexts.
A mana wahine theoretical and methodological framework motivated by emancipatory agendas that seek to facilitate transformation is used. Key to mana wahine projects is the creation of space for Native women to define themselves and their own stories and knowledges. This is important because Native women’s voices, knowledge and ritual histories continue to be marginalised. Furthermore, debased colonial renditions of femininity, which have been reproduced, perpetuate patriarchal and colonial politics that engender discord in Native communities today.  
The study used a suite of complimentary methods to engage 45 Native women and men. Interviews and kōrero (discussion), ceremony, mana wahine wānanga (women’s sacred learning space), Native sacred site visits, solicited journals, collaboration in ritual theatre productions, and analysis of mana wahine artworks as discursive texts were employed to gather stories of spiritual continuation that are unique and largely unchartered in academia. 
The empirical material is organised around four themes in four different chapters. The first of these empirical chapters re-interprets colonial ethnographic material alongside karakia (incantations), mōteatea (songs), cosmological and tribal stories, to reveal bold examples of Māori female ritual leadership. The second empirical chapter comprises an analysis of key colonial processes that have attempted to erase Native women’s ritual ontologies and the strident expressions of Native women’s resistance to colonial imperatives. The third empirical chapter investigates the multiple channels through which Native women are restoring their ceremonial lives. The fourth chapter investigates rerenga atua (menstruation) rituals that celebrate the Native feminine body as a cosmological site of communion with feminine deities. 
The rich weave of Native women’s stories of ceremony, old and new, threads into decolonising Indigenous scholarship around the world that also seeks to recover the sacred feminine as a key site of Native sovereignty. These discussions reveal a self-renewing Native belief system based on vibrant and evolving rituals that respond directly to current socio-political, spiritual and ecological realities.

text: Te ahi tawhito, te ahi tipua, te ahi nā Mahuika: Re-igniting native women’s ceremony This research examines the multiple ways in which Māori, and Hawai’ian and Native American women, are re-activating feminine ceremonial forms and recovering sacred relationships with customary feminine deities. Attention is focused on the creation of personal ritual practices that respond to contemporary decolonising and ecological contexts.
A mana wahine theoretical and methodological framework motivated by emancipatory agendas that seek to facilitate transformation is used. Key to mana wahine projects is the creation of space for Native women to define themselves and their own stories and knowledges. This is important because Native women’s voices, knowledge and ritual histories continue to be marginalised. Furthermore, debased colonial renditions of femininity, which have been reproduced, perpetuate patriarchal and colonial politics that engender discord in Native communities today.  
The study used a suite of complimentary methods to engage 45 Native women and men. Interviews and kōrero (discussion), ceremony, mana wahine wānanga (women’s sacred learning space), Native sacred site visits, solicited journals, collaboration in ritual theatre productions, and analysis of mana wahine artworks as discursive texts were employed to gather stories of spiritual continuation that are unique and largely unchartered in academia. 
The empirical material is organised around four themes in four different chapters. The first of these empirical chapters re-interprets colonial ethnographic material alongside karakia (incantations), mōteatea (songs), cosmological and tribal stories, to reveal bold examples of Māori female ritual leadership. The second empirical chapter comprises an analysis of key colonial processes that have attempted to erase Native women’s ritual ontologies and the strident expressions of Native women’s resistance to colonial imperatives. The third empirical chapter investigates the multiple channels through which Native women are restoring their ceremonial lives. The fourth chapter investigates rerenga atua (menstruation) rituals that celebrate the Native feminine body as a cosmological site of communion with feminine deities. 
The rich weave of Native women’s stories of ceremony, old and new, threads into decolonising Indigenous scholarship around the world that also seeks to recover the sacred feminine as a key site of Native sovereignty. These discussions reveal a self-renewing Native belief system based on vibrant and evolving rituals that respond directly to current socio-political, spiritual and ecological realities.

year: 2019