title: Extraction of amaranth starch from an aqueous medium using microfiltration: Membrane characterisation

authors: Middlewood, Paul Gregory

subjects: amaranth starch

abstract: The research reported here investigated microfiltration as an alternative to density-based processes for separating amaranth starch-milk produced by the pilot-scale Al-Hakkak process into a starch-rich concentrate and an aqueous stream containing the soluble proteins and carbohydrates. A Millipore ProFlux M12 Tangential Filtration System, fitted with a 1000 kDa regenerated cellulose membrane, was used as the experimental apparatus. The selected membrane retained all the starch granules, but also retained more protein than desired (protein retention was 67% and the starch-rich concentrate had a dry-basis protein content of 12%). Analysis of the feed liquor, and diafiltered concentrate, revealed the presence of some non-starch insoluble material. This material, which may have been protein-based, was present in the starch-milk produced using the pilot-scale method but not the laboratory-scale method, and its presence determined the final protein content of the diafiltered concentrate. The optimal transmembrane pressure was approximately 100–150 kPa, above which flux increased non-linearly with pressure. However, the flux–pressure relationship was weak, suggesting that higher operating pressures may be sustainable.

text: Extraction of amaranth starch from an aqueous medium using microfiltration: Membrane characterisation The research reported here investigated microfiltration as an alternative to density-based processes for separating amaranth starch-milk produced by the pilot-scale Al-Hakkak process into a starch-rich concentrate and an aqueous stream containing the soluble proteins and carbohydrates. A Millipore ProFlux M12 Tangential Filtration System, fitted with a 1000 kDa regenerated cellulose membrane, was used as the experimental apparatus. The selected membrane retained all the starch granules, but also retained more protein than desired (protein retention was 67% and the starch-rich concentrate had a dry-basis protein content of 12%). Analysis of the feed liquor, and diafiltered concentrate, revealed the presence of some non-starch insoluble material. This material, which may have been protein-based, was present in the starch-milk produced using the pilot-scale method but not the laboratory-scale method, and its presence determined the final protein content of the diafiltered concentrate. The optimal transmembrane pressure was approximately 100–150 kPa, above which flux increased non-linearly with pressure. However, the flux–pressure relationship was weak, suggesting that higher operating pressures may be sustainable.

year: 2012

title: Fitness consequences of population bottlenecks in an invasive blowfly

authors: Croft, Lillian

subjects: biological invasion

abstract: Invasive species often undergo demographic bottlenecks that cause a decrease in genetic diversity and associated reductions in population fitness. Despite this, they manage to thrive in novel environments. Investigating the effects of inbreeding and genetic bottlenecks on population fitness for invasive species is, therefore, key to understanding how they may survive in new environments. We used the blowfly Calliphora vicina (Sciences, Mathématiques et Physique, 1830, 2, 1), which is native to Europe and was introduced to Australia and New Zealand, to examine the effects of genetic diversity on population fitness. We first collected 59 samples from 15 populations across New Zealand and one in Australia, and used 20,501 biallelic SNPs to investigate population genomic diversity, structure and admixture. We then explored the impacts of repeated experimental bottlenecks on population fitness by creating inbred and outbred lines of C. vicina and measuring a variety of fitness traits. In wild-caught samples, we found low overall genetic diversity, signals of genetic admixture and limited (<3%) genetic differentiation between North and South Island populations, with genetic links between the South Island and Australia. Following experimental bottlenecks, we found significant reductions in fitness for inbred lines. However, fitness effects were not felt equally across all phenotypic traits. Moreover, they were not enough to cause population collapse in any experimental line, suggesting that C. vicina (when under relaxed selection, as in laboratory settings) may be able to compensate for population bottlenecks even when highly inbred. Our results demonstrate the value of a tractable experimental system for investigating processes that may facilitate or hamper biological invasion.

text: Fitness consequences of population bottlenecks in an invasive blowfly Invasive species often undergo demographic bottlenecks that cause a decrease in genetic diversity and associated reductions in population fitness. Despite this, they manage to thrive in novel environments. Investigating the effects of inbreeding and genetic bottlenecks on population fitness for invasive species is, therefore, key to understanding how they may survive in new environments. We used the blowfly Calliphora vicina (Sciences, Mathématiques et Physique, 1830, 2, 1), which is native to Europe and was introduced to Australia and New Zealand, to examine the effects of genetic diversity on population fitness. We first collected 59 samples from 15 populations across New Zealand and one in Australia, and used 20,501 biallelic SNPs to investigate population genomic diversity, structure and admixture. We then explored the impacts of repeated experimental bottlenecks on population fitness by creating inbred and outbred lines of C. vicina and measuring a variety of fitness traits. In wild-caught samples, we found low overall genetic diversity, signals of genetic admixture and limited (<3%) genetic differentiation between North and South Island populations, with genetic links between the South Island and Australia. Following experimental bottlenecks, we found significant reductions in fitness for inbred lines. However, fitness effects were not felt equally across all phenotypic traits. Moreover, they were not enough to cause population collapse in any experimental line, suggesting that C. vicina (when under relaxed selection, as in laboratory settings) may be able to compensate for population bottlenecks even when highly inbred. Our results demonstrate the value of a tractable experimental system for investigating processes that may facilitate or hamper biological invasion.

year: 2024

title: Contextualizing street homelessness in New Zealand: A case study approach

authors: Groot, Shiloh Ann Maree

subjects: homelessness

abstract: Homelessness is commonly associated with large urban settings. For people who sleep on the streets it encompasses experiences of stigma, regulation and displacement, marginalization, violence, loneliness, and bodily decline. This thesis addresses the lack of research into the everyday practices of homeless people in New Zealand through a detailed exploration of the experiences of four homeless people. Through critically engaging with relevant scholarly literature this study documents the importance of human fortitude, agency, and meaningful social engagements in the lives of homeless people. Attention is given to how four homeless people (Brett, Daniel, Joshua and Ariā) construct place-based identities and the relational, spatial and material dimensions of homelessness, which are central to participants’ everyday lives. Participants were recruited through experienced community workers at the Auckland City Mission. A case-based ethnographic approach was used to engage with participants through volunteer work, direct observations, biographical interviews, photo-production projects, and photo-elicitation interviews. Workshops with staff on each case study were conducted to bridge the divide between critical scholars and community groups through advocacy and joint action. The analysis considers each case in turn. Brett differentiates himself from other homeless people and works to find space for himself to gain respite and solitude. Daniel engages in domestic practices on the streets that are commonly associated with home-making, such as decorating a physical space with personal objects and cultivating a sense of place, routine, comfort, and familiarity. Joshua immerses himself in a street family and forms close relationships with other homeless people that provide him with a sense of belonging, purpose, connection, support and responsibility. Ariā exemplifies how Māori cultural practices can enrich and mould a person’s efforts to retain a positive sense of self while homeless. Māori cultural concepts relating to caring, leadership, unity, relationships, spirituality, history and place are evoked to ground understandings of Ariā’s everyday life. Strategies for making a life on the streets involves Brett, Daniel, Joshua and Ariā working to maintain a sense of self and place in the face of adversity. A core finding from this research relates to the resilience of these participants, which spans personal and relational dimensions and extends to the social and physical environment.

text: Contextualizing street homelessness in New Zealand: A case study approach Homelessness is commonly associated with large urban settings. For people who sleep on the streets it encompasses experiences of stigma, regulation and displacement, marginalization, violence, loneliness, and bodily decline. This thesis addresses the lack of research into the everyday practices of homeless people in New Zealand through a detailed exploration of the experiences of four homeless people. Through critically engaging with relevant scholarly literature this study documents the importance of human fortitude, agency, and meaningful social engagements in the lives of homeless people. Attention is given to how four homeless people (Brett, Daniel, Joshua and Ariā) construct place-based identities and the relational, spatial and material dimensions of homelessness, which are central to participants’ everyday lives. Participants were recruited through experienced community workers at the Auckland City Mission. A case-based ethnographic approach was used to engage with participants through volunteer work, direct observations, biographical interviews, photo-production projects, and photo-elicitation interviews. Workshops with staff on each case study were conducted to bridge the divide between critical scholars and community groups through advocacy and joint action. The analysis considers each case in turn. Brett differentiates himself from other homeless people and works to find space for himself to gain respite and solitude. Daniel engages in domestic practices on the streets that are commonly associated with home-making, such as decorating a physical space with personal objects and cultivating a sense of place, routine, comfort, and familiarity. Joshua immerses himself in a street family and forms close relationships with other homeless people that provide him with a sense of belonging, purpose, connection, support and responsibility. Ariā exemplifies how Māori cultural practices can enrich and mould a person’s efforts to retain a positive sense of self while homeless. Māori cultural concepts relating to caring, leadership, unity, relationships, spirituality, history and place are evoked to ground understandings of Ariā’s everyday life. Strategies for making a life on the streets involves Brett, Daniel, Joshua and Ariā working to maintain a sense of self and place in the face of adversity. A core finding from this research relates to the resilience of these participants, which spans personal and relational dimensions and extends to the social and physical environment.

year: 2010