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: Myostatin signals through Pax7 to regulate satellite cell self-renewal

authors: McFarlane, Craig Desmond

subjects: Myostatin

abstract: Myostatin, a Transforming Growth Factor-beta (TGF-β) super-family member, has previously been shown to negatively regulate satellite cell activation and self-renewal. However, to date the mechanism behind Myostatin function in satellite cell biology is not known. Here we show that Myostatin signals via a Pax7-dependent mechanism to regulate satellite cell self-renewal. While excess Myostatin inhibited Pax7 expression via ERK1/2 signaling, an increase in Pax7 expression was observed following both genetic inactivation and functional antagonism of Myostatin. As a result, we show that either blocking or inactivating Myostatin enhances the partitioning of the fusion-incompetent self-renewed satellite cell lineage (high Pax7 expression, low MyoD expression) from the pool of actively proliferating myogenic precursor cells. Consistent with this result, over-expression of Pax7 in C2C12 myogenic cells resulted in increased self-renewal through a mechanism which slowed both myogenic proliferation and differentiation. Taken together, these results suggest that increased expression of Pax7 promotes satellite cell self-renewal, and furthermore Myostatin may control the process of satellite cell self-renewal through regulation of Pax7. Thus we speculate that, in addition to the intrinsic factors (such as Pax7), extrinsic factors both positive and negative in nature, will play a major role in determining the stemness of skeletal muscle satellite cells.

text: Myostatin signals through Pax7 to regulate satellite cell self-renewal Myostatin, a Transforming Growth Factor-beta (TGF-β) super-family member, has previously been shown to negatively regulate satellite cell activation and self-renewal. However, to date the mechanism behind Myostatin function in satellite cell biology is not known. Here we show that Myostatin signals via a Pax7-dependent mechanism to regulate satellite cell self-renewal. While excess Myostatin inhibited Pax7 expression via ERK1/2 signaling, an increase in Pax7 expression was observed following both genetic inactivation and functional antagonism of Myostatin. As a result, we show that either blocking or inactivating Myostatin enhances the partitioning of the fusion-incompetent self-renewed satellite cell lineage (high Pax7 expression, low MyoD expression) from the pool of actively proliferating myogenic precursor cells. Consistent with this result, over-expression of Pax7 in C2C12 myogenic cells resulted in increased self-renewal through a mechanism which slowed both myogenic proliferation and differentiation. Taken together, these results suggest that increased expression of Pax7 promotes satellite cell self-renewal, and furthermore Myostatin may control the process of satellite cell self-renewal through regulation of Pax7. Thus we speculate that, in addition to the intrinsic factors (such as Pax7), extrinsic factors both positive and negative in nature, will play a major role in determining the stemness of skeletal muscle satellite cells.

year: 2008

title: Evaluation of the Whānau Ora Wellbeing Service of Te Whakaruruhau: Final report

authors: Robertson, Neville

subjects: whānau ora

abstract: Domestic violence and child abuse represent significant threats to whānau ora. Conversely, the weakening or loss of whānau ties can increase the vulnerability of whānau members to domestic violence and child abuse. Thus enhancing whānau ora in the context of domestic violence and child abuse is both a high priority and a significant challenge.

Te Whakaruruhau Māori Women’s Refuge has been providing safe housing, support and advocacy to women and children for over two decades and has become a key agency in family violence networks in Kirikiriroa. The development of the Whānau Ora Wellbeing Service, the focus of this evaluation, was a logical extension of Refuge services.

The Māori and Psychology Research Unit was commissioned in mid‐2011 to conduct this evaluation. It is based on ten case studies of clients in the programme, interviews with Te Whakaruruhau staff and key informants in allied agencies, and participant‐observation of Refuge activities. The case studies provide insights into the lived experience of women dealing with violence, their attempts to protect themselves and their children, and their experiences of – and reflections upon – the Whānau Ora Wellbeing programme.

text: Evaluation of the Whānau Ora Wellbeing Service of Te Whakaruruhau: Final report Domestic violence and child abuse represent significant threats to whānau ora. Conversely, the weakening or loss of whānau ties can increase the vulnerability of whānau members to domestic violence and child abuse. Thus enhancing whānau ora in the context of domestic violence and child abuse is both a high priority and a significant challenge.

Te Whakaruruhau Māori Women’s Refuge has been providing safe housing, support and advocacy to women and children for over two decades and has become a key agency in family violence networks in Kirikiriroa. The development of the Whānau Ora Wellbeing Service, the focus of this evaluation, was a logical extension of Refuge services.

The Māori and Psychology Research Unit was commissioned in mid‐2011 to conduct this evaluation. It is based on ten case studies of clients in the programme, interviews with Te Whakaruruhau staff and key informants in allied agencies, and participant‐observation of Refuge activities. The case studies provide insights into the lived experience of women dealing with violence, their attempts to protect themselves and their children, and their experiences of – and reflections upon – the Whānau Ora Wellbeing programme.

year: 2013-07-20