title: Engineering and evaluation of hemp fibre reinforced polypropylene composites: Fibre treatment and matrix modification

authors: Beckermann, Gareth

subjects: B. Interface/interphase

abstract: Hemp fibres were alkali treated to improve their suitability for use as reinforcements in composite materials. Improvements in tensile strength, Young’s modulus, fibre separation, crystallinity index, lignin reduction and thermal stability were observed for hemp fibres treated with a solution of 5 wt% NaOH/2 wt% Na₂SO₃. A range of hemp fibre reinforced polypropylene composites were produced by extrusion and injection moulding, and the effect of fibre treatments and MAPP content on the tensile strength and Young’s modulus of composites were investigated. The optimum composite, consisting of polypropylene, 40 wt% NaOH/Na₂SO₃ treated hemp fibre and 4 wt% MAPP, was found to have a tensile strength of 50.5 MPa and a Young’s modulus of 5.31 GPa.

text: Engineering and evaluation of hemp fibre reinforced polypropylene composites: Fibre treatment and matrix modification Hemp fibres were alkali treated to improve their suitability for use as reinforcements in composite materials. Improvements in tensile strength, Young’s modulus, fibre separation, crystallinity index, lignin reduction and thermal stability were observed for hemp fibres treated with a solution of 5 wt% NaOH/2 wt% Na₂SO₃. A range of hemp fibre reinforced polypropylene composites were produced by extrusion and injection moulding, and the effect of fibre treatments and MAPP content on the tensile strength and Young’s modulus of composites were investigated. The optimum composite, consisting of polypropylene, 40 wt% NaOH/Na₂SO₃ treated hemp fibre and 4 wt% MAPP, was found to have a tensile strength of 50.5 MPa and a Young’s modulus of 5.31 GPa.

year: 2008

title: Dogs' scent detection performance with rapidly changing targets

authors: Chia, Maria Shue Ying

abstract: Scent detection dogs trained to detect one target scent are sometimes needed to detect a different target. Recent studies have demonstrated that scent detection animals can be trained to detect multiple scents simultaneously. However, in some cases, it may be problematic if the dogs indicate on previous targets. Therefore, it would be useful to know how quickly they can learn to detect new target scents, and not to indicate on previously trained target scents. The aim of this study was to evaluate dogs’ ability to learn to detect new target scents while simultaneously rejecting all previously trained target scents. Firstly, five pet dogs were trained to detect a training scent (amyl acetate) using an automated apparatus. The dogs were then required to detect a four new target scents within four phases. Target scents were treated as non-target scents in all subsequent phases; indications on previously trained target scents were not reinforced. Non-target scents in each phase consisted of three randomly selected chemicals that were presented in a randomised rotation. The dogs were required to complete a phase with one target and meet the criteria of more than 80% for correct indication and correct rejection responses, without performing an indication response more than once on the previous target scent for four out of five sessions. The results of the experiment demonstrated that (1) the dogs were able to successfully discriminate between the specified target scent and all non-target scents within each phase; (2) the persistence of indication behaviour on previously trained target scents decreased more rapidly with each phase; and (3) there was a re-emergence of indication responses when each previously trained target scent was presented after extinction conditions. In summary, the present study demonstrates that dogs can be retrained to indicate on new targets and reject previous targets. The learning processes associated with the dogs learning to indicate on new targets, and learning not to indicate on previous target scents must both be considered. These results have significant practical implications and it is hoped that the they will improve our ability to employ individual scent-detection animals to find multiple targets.

text: Dogs' scent detection performance with rapidly changing targets Scent detection dogs trained to detect one target scent are sometimes needed to detect a different target. Recent studies have demonstrated that scent detection animals can be trained to detect multiple scents simultaneously. However, in some cases, it may be problematic if the dogs indicate on previous targets. Therefore, it would be useful to know how quickly they can learn to detect new target scents, and not to indicate on previously trained target scents. The aim of this study was to evaluate dogs’ ability to learn to detect new target scents while simultaneously rejecting all previously trained target scents. Firstly, five pet dogs were trained to detect a training scent (amyl acetate) using an automated apparatus. The dogs were then required to detect a four new target scents within four phases. Target scents were treated as non-target scents in all subsequent phases; indications on previously trained target scents were not reinforced. Non-target scents in each phase consisted of three randomly selected chemicals that were presented in a randomised rotation. The dogs were required to complete a phase with one target and meet the criteria of more than 80% for correct indication and correct rejection responses, without performing an indication response more than once on the previous target scent for four out of five sessions. The results of the experiment demonstrated that (1) the dogs were able to successfully discriminate between the specified target scent and all non-target scents within each phase; (2) the persistence of indication behaviour on previously trained target scents decreased more rapidly with each phase; and (3) there was a re-emergence of indication responses when each previously trained target scent was presented after extinction conditions. In summary, the present study demonstrates that dogs can be retrained to indicate on new targets and reject previous targets. The learning processes associated with the dogs learning to indicate on new targets, and learning not to indicate on previous target scents must both be considered. These results have significant practical implications and it is hoped that the they will improve our ability to employ individual scent-detection animals to find multiple targets.

year: 2020

title: What are Bicultural Psychological Services?

authors: Thomas, David R.

subjects: Maori students

abstract: The present paper is intended to stimulate discussion on the development of bicultural psychological services in Aotearoa/New Zealand, focusing primarily on services provided by psychologists trained in tertiary educational institutions. Patterns of biculturalism emerging among human services in New Zealand are briefly described, then topics relevant to the provision of bicultural psychological services, that are appropriate for both Maori and Pakeha, in Aotearoa are discussed.

text: What are Bicultural Psychological Services? The present paper is intended to stimulate discussion on the development of bicultural psychological services in Aotearoa/New Zealand, focusing primarily on services provided by psychologists trained in tertiary educational institutions. Patterns of biculturalism emerging among human services in New Zealand are briefly described, then topics relevant to the provision of bicultural psychological services, that are appropriate for both Maori and Pakeha, in Aotearoa are discussed.

year: 1993