title: Additive manufacturing of hygromorphic structures using regenerated cellulose/PLA biocomposites

authors: Gauss, Christian

abstract: Three-dimensional printing technologies are at the forefront of the current industrial revolution, enabling the production of complex shapes using a wide range of materials without relying on large production facilities. Increasing it further, 4D printing is a new concept in which printed objects respond to environmental stimuli and change shape or other characteristics with time in a controlled and predicted manner. However, the development of bio-based material alternatives that can be integrated into a circular economy is limited if compared with other non-renewable polymers traditionally used for these applications. Bioderived and/or biodegradable thermoplastics reinforced with bioderived fibres have compelling attributes in this context; they can be recycled, can be used in smart materials (4D printing), and, if necessary, can biodegrade at the end of their life cycle, leaving no harmful waste in the environment. In this work, we demonstrate the potential of PLA-based biocomposites with high content of regenerated cellulose fibres (lyocell) for 3D printed structures produced by fused deposition modelling (FDM) that change shape in response to moisture (hygromorphic). The main mechanism involved in this behaviour is related to the anisotropic swelling of the cellulose fibres that are preferentially aligned in the composite during printing. Using a bi-layered architecture of passive and active layers, we developed different prototypes with 2D to 3D transformation capability triggered by moisture with a high degree of shape change.

text: Additive manufacturing of hygromorphic structures using regenerated cellulose/PLA biocomposites Three-dimensional printing technologies are at the forefront of the current industrial revolution, enabling the production of complex shapes using a wide range of materials without relying on large production facilities. Increasing it further, 4D printing is a new concept in which printed objects respond to environmental stimuli and change shape or other characteristics with time in a controlled and predicted manner. However, the development of bio-based material alternatives that can be integrated into a circular economy is limited if compared with other non-renewable polymers traditionally used for these applications. Bioderived and/or biodegradable thermoplastics reinforced with bioderived fibres have compelling attributes in this context; they can be recycled, can be used in smart materials (4D printing), and, if necessary, can biodegrade at the end of their life cycle, leaving no harmful waste in the environment. In this work, we demonstrate the potential of PLA-based biocomposites with high content of regenerated cellulose fibres (lyocell) for 3D printed structures produced by fused deposition modelling (FDM) that change shape in response to moisture (hygromorphic). The main mechanism involved in this behaviour is related to the anisotropic swelling of the cellulose fibres that are preferentially aligned in the composite during printing. Using a bi-layered architecture of passive and active layers, we developed different prototypes with 2D to 3D transformation capability triggered by moisture with a high degree of shape change.

year: 2022

title: Local and regional influences over soil microbial metacommunities in the Transantarctic Mountains

authors: Sokol, Eric R.

subjects: Science & Technology

abstract: The metacommunity concept provides a useful framework to assess the influence of local and regional controls over diversity patterns. Culture‐independent studies of soil microbial communities in the McMurdo Dry Valleys of East Antarctica (77° S) have shown that bacterial diversity is related to soil geochemical gradients, while studies targeting edaphic cyanobacteria have linked local diversity patterns to dispersal‐based processes. In this study, we increased the spatial extent of observed soil microbial communities to cover the Beardmore Glacier region in the central Transantarctic Mountains (84° S). We used community profiling techniques to characterize diversity patterns for bacteria and the cyanobacterial subcomponent of the microbial community. Diversity partitioning was used to calculate beta diversity and estimate among‐site dissimilarity in the metacommunity. We then used variation partitioning to assess the relationship between beta diversity and environmental and spatial gradients. We found that dominant groups in the soil bacterial metacommunity were influenced by gradients in pH and soil moisture at the Transantarctic scale (800 km). Conversely, beta diversity for the cyanobacterial component of the edaphic microbial metacommunity was decoupled from these environmental gradients, and was more related to spatial filters, suggesting that wind‐driven dispersal dynamics created cyanobacterial biogeography at a local scale (<3 km).

text: Local and regional influences over soil microbial metacommunities in the Transantarctic Mountains The metacommunity concept provides a useful framework to assess the influence of local and regional controls over diversity patterns. Culture‐independent studies of soil microbial communities in the McMurdo Dry Valleys of East Antarctica (77° S) have shown that bacterial diversity is related to soil geochemical gradients, while studies targeting edaphic cyanobacteria have linked local diversity patterns to dispersal‐based processes. In this study, we increased the spatial extent of observed soil microbial communities to cover the Beardmore Glacier region in the central Transantarctic Mountains (84° S). We used community profiling techniques to characterize diversity patterns for bacteria and the cyanobacterial subcomponent of the microbial community. Diversity partitioning was used to calculate beta diversity and estimate among‐site dissimilarity in the metacommunity. We then used variation partitioning to assess the relationship between beta diversity and environmental and spatial gradients. We found that dominant groups in the soil bacterial metacommunity were influenced by gradients in pH and soil moisture at the Transantarctic scale (800 km). Conversely, beta diversity for the cyanobacterial component of the edaphic microbial metacommunity was decoupled from these environmental gradients, and was more related to spatial filters, suggesting that wind‐driven dispersal dynamics created cyanobacterial biogeography at a local scale (<3 km).

year: 2013

title: Kaupapa Maori research: An indigenous approach to creating knowledge

authors: Bishop, Russell

subjects: Maori

abstract: This paper seeks to identify how issues of epistemological racism are addressed in practice
within an indigenous Kaupapa (philosophy) Maori approach to research, and how such
considerations may impact on the Western trained and positioned researcher. One fundamental
understanding to a Kaupapa Maori approach to research is that it is the discursive practice
that is Kaupapa Maori that positions researchers in such a way as to operationalise selfdetermination
(agentic positioning and behaviour) for research participants. This is because the
cultural aspirations, understandings and practices of Maori people implement and organise the
research process. Further, the research issues of power; initiation, benefits, representation,
legitimation, and accountability are addressed and understood in practice by practitioners of
Kaupapa Maori research through the development of a participatory mode of consciousness.

text: Kaupapa Maori research: An indigenous approach to creating knowledge This paper seeks to identify how issues of epistemological racism are addressed in practice
within an indigenous Kaupapa (philosophy) Maori approach to research, and how such
considerations may impact on the Western trained and positioned researcher. One fundamental
understanding to a Kaupapa Maori approach to research is that it is the discursive practice
that is Kaupapa Maori that positions researchers in such a way as to operationalise selfdetermination
(agentic positioning and behaviour) for research participants. This is because the
cultural aspirations, understandings and practices of Maori people implement and organise the
research process. Further, the research issues of power; initiation, benefits, representation,
legitimation, and accountability are addressed and understood in practice by practitioners of
Kaupapa Maori research through the development of a participatory mode of consciousness.

year: 1999