title: Structural changes as a result of processing in thermoplastic bloodmeal

authors: Verbeek, Casparus Johan R.

subjects: extrusion

abstract: Bloodmeal (BM) can be thermoplastically processed resulting in a material with good mechanical properties by using a correct combination of additives. In this article, combinations of water, sodium sulfite (SS), sodium dodecyl sulfate (SDS), and urea were compounded with BM, and water absorption, solubility, thermal stability, and protein secondary structure were assessed. Thermal stability of processed plastics was reduced when using 2 or 3 pphbm (parts per hundred parts BM) SS and 20 pphbm urea, mostly indicative of a reduction in covalent crosslinking. SS was required for chain mobility during processing, however, without sufficient plasticization degradation will occur instead of melt formation. SDS further improved processability and consolidation leading to increased water absorption and solubility, indicative of a reduction in chain interactions. It was found that BM proteins are highly denatured and thermoplastic processing reduced ordered structures further. Additional minor structural changes occurred as a result of reduced covalent and noncovalent interactions after processing. It was concluded that the increase in water absorption and solubility was due to changes in intermolecular and intramolecular interactions, rather than substantial structural changes.

text: Structural changes as a result of processing in thermoplastic bloodmeal Bloodmeal (BM) can be thermoplastically processed resulting in a material with good mechanical properties by using a correct combination of additives. In this article, combinations of water, sodium sulfite (SS), sodium dodecyl sulfate (SDS), and urea were compounded with BM, and water absorption, solubility, thermal stability, and protein secondary structure were assessed. Thermal stability of processed plastics was reduced when using 2 or 3 pphbm (parts per hundred parts BM) SS and 20 pphbm urea, mostly indicative of a reduction in covalent crosslinking. SS was required for chain mobility during processing, however, without sufficient plasticization degradation will occur instead of melt formation. SDS further improved processability and consolidation leading to increased water absorption and solubility, indicative of a reduction in chain interactions. It was found that BM proteins are highly denatured and thermoplastic processing reduced ordered structures further. Additional minor structural changes occurred as a result of reduced covalent and noncovalent interactions after processing. It was concluded that the increase in water absorption and solubility was due to changes in intermolecular and intramolecular interactions, rather than substantial structural changes.

year: 2012

title: Semi-mechanistic modelling in nonlinear regression: a case study

authors: Domijan, Katarina

subjects: statistics

abstract: This paper discusses the use of highly parameterized semi-mechanistic nonlinear models with particular reference to the PARJIB crop response model of Reid (2002)[Yield response to nutrient supply across a wide range of conditions 1. Model derivation. Field Crops Research77, 161–171]. Compared to empirical linear approaches, such models promise improved generality of application but present considerable challenges for estimation. Some success has been achieved with a fitting approach that uses a Levenberg–Marquardt algorithm starting from initial values determined by a genetic algorithm. Attention must be paid, however, to correlations between parameter estimates and an approach is described to identify these based on large simulated datasets. This work illustrates the value for the scientist in exploring the correlation structure in mechanistic or semi-mechanistic models. Such information might be used to reappraise the structure of the model itself, especially if the experimental evidence is not strong enough to allow estimation of a parameter free of assumptions about the values of others. Thus statistical modelling and analysis can complement mechanistic studies, making more explicit what is known and what is not known about the processes being modelled and guiding further research.

text: Semi-mechanistic modelling in nonlinear regression: a case study This paper discusses the use of highly parameterized semi-mechanistic nonlinear models with particular reference to the PARJIB crop response model of Reid (2002)[Yield response to nutrient supply across a wide range of conditions 1. Model derivation. Field Crops Research77, 161–171]. Compared to empirical linear approaches, such models promise improved generality of application but present considerable challenges for estimation. Some success has been achieved with a fitting approach that uses a Levenberg–Marquardt algorithm starting from initial values determined by a genetic algorithm. Attention must be paid, however, to correlations between parameter estimates and an approach is described to identify these based on large simulated datasets. This work illustrates the value for the scientist in exploring the correlation structure in mechanistic or semi-mechanistic models. Such information might be used to reappraise the structure of the model itself, especially if the experimental evidence is not strong enough to allow estimation of a parameter free of assumptions about the values of others. Thus statistical modelling and analysis can complement mechanistic studies, making more explicit what is known and what is not known about the processes being modelled and guiding further research.

year: 2006

title: Using the stars to indigenize the public sphere: Matariki over New Zealand

authors: Hardy, Anna

subjects: Arts & Humanities

abstract: As the rate of affiliation to Christian identity continues to decline in Aotearoa New Zealand (only 49 percent of the population said they were Christian in the last census), public space has become more receptive to other forms of religiosity. In particular, community rituals around the winter movements of the Matariki (Pleiades) constellation have gained support since the year 2000. For instance, the capital city, Wellington, has replaced a centuries’ old British fireworks festival, Guy Fawkes, with an enlarged version of its Matariki celebrations: an action seen as a tipping point in the incorporation of Māori spiritual values into public life. Interactions between European colonisers and Māori have been characterised for more than 250 years by tensions between the relational thinking of Māori who see human beings as both participating in and constrained by an environment resonant with divine energies, and the quantitative, hierarchical, ‘Great Chain of Being’ model that had long been dominant among Europeans. Now, when the natural environment worldwide is under strain from population and economic pressures, it seems to some both appropriate and vital to look to epistemological and spiritual models that are intimately responsive to the specificities of location.

text: Using the stars to indigenize the public sphere: Matariki over New Zealand As the rate of affiliation to Christian identity continues to decline in Aotearoa New Zealand (only 49 percent of the population said they were Christian in the last census), public space has become more receptive to other forms of religiosity. In particular, community rituals around the winter movements of the Matariki (Pleiades) constellation have gained support since the year 2000. For instance, the capital city, Wellington, has replaced a centuries’ old British fireworks festival, Guy Fawkes, with an enlarged version of its Matariki celebrations: an action seen as a tipping point in the incorporation of Māori spiritual values into public life. Interactions between European colonisers and Māori have been characterised for more than 250 years by tensions between the relational thinking of Māori who see human beings as both participating in and constrained by an environment resonant with divine energies, and the quantitative, hierarchical, ‘Great Chain of Being’ model that had long been dominant among Europeans. Now, when the natural environment worldwide is under strain from population and economic pressures, it seems to some both appropriate and vital to look to epistemological and spiritual models that are intimately responsive to the specificities of location.

year: 2019