title: The Viscometric determination of somatic cell levels in cows' milk

authors: Milne, John Ross

abstract: The California Mastitis Test (CMT) is a test used for estimating the number of somatic cells in a milk sample. A reagent (secondary alkyl sulphate) is added to the milk and the number of somatic cells estimated from the resultant viscosity of the mixture. 
The Ruakura rolling ball viscometer has been developed to measure the viscosity of the CMT gel. It consists of a tube mounted horizontally so that the milk-reagent mixture can be introduced into it. After a holding time of 26 seconds the tube tips through an angle of 25° allowing a stainless steel ball to roll through the mixture for a standard time before returning to the horizontal. The distance the ball has rolled is inversely related to the viscosity developed. The physical function of the viscometer follows Stokes' Law. 
The range of the instrument is suited to reading the viscosity developed by the CMT reaction in New Zealand herd milks. 
The viscous reaction in milk is caused by somatic cell nuclei forming a fibrillar network. The reaction intensity is related to the DNA content of the milk sample. Proteins can modify the viscosity developed. Bacterial DNA does not enter the reaction. The network is fragile and rheomalaxic in nature. The reaction intensity in milk varies with time. An approximate 25 second holding time is required before determining the viscosity. After this holding time the reaction intensity progressively decreases. Milk to be tested should be under 24 hours old although refrigeration or boric acid preservative can extend this time. Different operators can rank milk samples by somatic cell count in a similar order with the Ruakura rolling ball viscometer. 
There is a significant correlation (r = 0.92***) between Ruakura rolling ball viscometer and somatic cell count of herd milk samples.

text: The Viscometric determination of somatic cell levels in cows' milk The California Mastitis Test (CMT) is a test used for estimating the number of somatic cells in a milk sample. A reagent (secondary alkyl sulphate) is added to the milk and the number of somatic cells estimated from the resultant viscosity of the mixture. 
The Ruakura rolling ball viscometer has been developed to measure the viscosity of the CMT gel. It consists of a tube mounted horizontally so that the milk-reagent mixture can be introduced into it. After a holding time of 26 seconds the tube tips through an angle of 25° allowing a stainless steel ball to roll through the mixture for a standard time before returning to the horizontal. The distance the ball has rolled is inversely related to the viscosity developed. The physical function of the viscometer follows Stokes' Law. 
The range of the instrument is suited to reading the viscosity developed by the CMT reaction in New Zealand herd milks. 
The viscous reaction in milk is caused by somatic cell nuclei forming a fibrillar network. The reaction intensity is related to the DNA content of the milk sample. Proteins can modify the viscosity developed. Bacterial DNA does not enter the reaction. The network is fragile and rheomalaxic in nature. The reaction intensity in milk varies with time. An approximate 25 second holding time is required before determining the viscosity. After this holding time the reaction intensity progressively decreases. Milk to be tested should be under 24 hours old although refrigeration or boric acid preservative can extend this time. Different operators can rank milk samples by somatic cell count in a similar order with the Ruakura rolling ball viscometer. 
There is a significant correlation (r = 0.92***) between Ruakura rolling ball viscometer and somatic cell count of herd milk samples.

year: 1973

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: Rototuna, 2024

authors: Apiata, Hāwea

abstract: Bilingual poetry in response to the public sculpture 'Te Ohomauri o Matariki' by Dion Hitchens in collaboration with James Ormsby.

text: Rototuna, 2024 Bilingual poetry in response to the public sculpture 'Te Ohomauri o Matariki' by Dion Hitchens in collaboration with James Ormsby.

year: 2024-03-29