title: Moisture sensitivity and compressive performance of 3D-printed cellulose-biopolyester foam lattices

authors: McDonald-Wharry, John

subjects: Science & Technology

abstract: Biobased, foam-like polyester composite materials were 3D-printed from a thermoset paste formulation. This paste formulation was composed of sebacic acid, glycerol, citric acid, and cellulose nanocrystals in water and ethanol with potassium chloride as a salt porogen. Thin walls and lattices were 3D-printed with geometry selected to facilitate post-printing processes such as water removal during polyester curing and the post-curing removal of the salt porogen. The compressive performance of these moisture-sensitive lattice structures was investigated after conditioning at different humidity levels and by water immersion. Finite element analysis was used to simulate the compressive performance of these porous lattice structures using a crushable foam material model. Addition of plant triglyceride oils from sunflower and coconut were trialled to modify the compressive performance and moisture sensitivity. Addition of 5 wt% coconut oil to the formulation prior to 3D-printing was found to lower the cured material’s stiffness under dry conditions while increasing the compressive plateau strength of the lattice structures after water immersion.

text: Moisture sensitivity and compressive performance of 3D-printed cellulose-biopolyester foam lattices Biobased, foam-like polyester composite materials were 3D-printed from a thermoset paste formulation. This paste formulation was composed of sebacic acid, glycerol, citric acid, and cellulose nanocrystals in water and ethanol with potassium chloride as a salt porogen. Thin walls and lattices were 3D-printed with geometry selected to facilitate post-printing processes such as water removal during polyester curing and the post-curing removal of the salt porogen. The compressive performance of these moisture-sensitive lattice structures was investigated after conditioning at different humidity levels and by water immersion. Finite element analysis was used to simulate the compressive performance of these porous lattice structures using a crushable foam material model. Addition of plant triglyceride oils from sunflower and coconut were trialled to modify the compressive performance and moisture sensitivity. Addition of 5 wt% coconut oil to the formulation prior to 3D-printing was found to lower the cured material’s stiffness under dry conditions while increasing the compressive plateau strength of the lattice structures after water immersion.

year: 2021

title: Willingness-to-pay for renewable energy: Primary and discretionary choice of British households' for micro-generation technologies

authors: Scarpa, Riccardo

subjects: renewable energy

abstract: This paper documents the policy context of renewable energy production in the European Union. The research adopts a choice experiment approach to investigate households' WTP for these renewable energy technologies in the UK. The micro-generation technologies comprise solar photovoltaic, micro-wind, solar thermal, heat pumps, and biomass boilers and pellet stoves. The study compares the results from conditional and mixed logit models, which estimate the distribution of utility coefficients and then derives WTP values as a ratio of the attribute coefficient to the price coefficient, with a model in which the WTP distribution is estimated directly from utility in the money space. The results suggest that whilst renewable energy adoption is significantly valued by households, this value is not sufficiently large, for the vast majority of households, to cover the higher capital costs of micro-generation energy technologies.

text: Willingness-to-pay for renewable energy: Primary and discretionary choice of British households' for micro-generation technologies This paper documents the policy context of renewable energy production in the European Union. The research adopts a choice experiment approach to investigate households' WTP for these renewable energy technologies in the UK. The micro-generation technologies comprise solar photovoltaic, micro-wind, solar thermal, heat pumps, and biomass boilers and pellet stoves. The study compares the results from conditional and mixed logit models, which estimate the distribution of utility coefficients and then derives WTP values as a ratio of the attribute coefficient to the price coefficient, with a model in which the WTP distribution is estimated directly from utility in the money space. The results suggest that whilst renewable energy adoption is significantly valued by households, this value is not sufficiently large, for the vast majority of households, to cover the higher capital costs of micro-generation energy technologies.

year: 2010

title: Low copper levels measured in the aortic wall of New Zealand patients with non-syndromic ascending thoracic aortic aneurysm

authors: El-Gamel, Adam

subjects: Ascending aortic aneurysm

abstract: OBJECTIVES: Studies in animals have shown causal relationships between copper (Cu) deficiency and the development of thoracic aortic aneurysms (TAAs) [1, 2]. Cu deficiency is widespread in New Zealand (NZ) soils; the high soil pH from the use of lime fertilizers reduces the bioavailability of Cu for grazing animals and growing plants; this, in turn, reduces Cu availability in the NZ human food chain. Our study is a pilot study to explore associations between Cu and TAA. We measured Cu levels in aneurysmal aortic tissues in patients undergoing Bentall procedures and non-aneurysmal aortic tissue from coronary artery bypass graft patients. METHODS: Aortic samples were collected from 2 groups of patients during elective open-heart surgery over 4 months between November 2017 and February 2018. The groups were a TAA group, patients with non-syndromic aortic aneurysm and without the bicuspid aortic valve or known infectious or inflammatory condition (ANEURYSM; n = 13), and a control coronary artery bypass graft group (CONTROL; n = 44). Standardized digested dry tissue weighed samples were analysed from both groups. Tissue extraction of trace elements was carried out using HCl-H2O2 digestion and a highly sensitive analytical technique, inductively coupled plasma mass spectrometry-used to measure elemental concentrations. RESULTS: Cu concentration (mean ± SD) was significantly lower in ANEURYSM (3.34 ± 0.16 µg/g) when compared to the CONTROL group tissues (4.33 ± 0.20 µg/g) (dry weight; mean ± SD; Student's t-test, P < 0.05). Over 46% of the Aneurysm patients were Maori and live in a geographically Cu-deficient NZ territory. CONCLUSIONS: Cu deficiency may play a role in the development or progression of non-syndromic ascending aortic aneurysms in NZ. Maori patients are more at risk as they commonly live in rural NZ, dependent on locally grown nutritional sources. Further studies are required to confirm this exciting finding and to establish cause and effect relationship.

text: Low copper levels measured in the aortic wall of New Zealand patients with non-syndromic ascending thoracic aortic aneurysm OBJECTIVES: Studies in animals have shown causal relationships between copper (Cu) deficiency and the development of thoracic aortic aneurysms (TAAs) [1, 2]. Cu deficiency is widespread in New Zealand (NZ) soils; the high soil pH from the use of lime fertilizers reduces the bioavailability of Cu for grazing animals and growing plants; this, in turn, reduces Cu availability in the NZ human food chain. Our study is a pilot study to explore associations between Cu and TAA. We measured Cu levels in aneurysmal aortic tissues in patients undergoing Bentall procedures and non-aneurysmal aortic tissue from coronary artery bypass graft patients. METHODS: Aortic samples were collected from 2 groups of patients during elective open-heart surgery over 4 months between November 2017 and February 2018. The groups were a TAA group, patients with non-syndromic aortic aneurysm and without the bicuspid aortic valve or known infectious or inflammatory condition (ANEURYSM; n = 13), and a control coronary artery bypass graft group (CONTROL; n = 44). Standardized digested dry tissue weighed samples were analysed from both groups. Tissue extraction of trace elements was carried out using HCl-H2O2 digestion and a highly sensitive analytical technique, inductively coupled plasma mass spectrometry-used to measure elemental concentrations. RESULTS: Cu concentration (mean ± SD) was significantly lower in ANEURYSM (3.34 ± 0.16 µg/g) when compared to the CONTROL group tissues (4.33 ± 0.20 µg/g) (dry weight; mean ± SD; Student's t-test, P < 0.05). Over 46% of the Aneurysm patients were Maori and live in a geographically Cu-deficient NZ territory. CONCLUSIONS: Cu deficiency may play a role in the development or progression of non-syndromic ascending aortic aneurysms in NZ. Maori patients are more at risk as they commonly live in rural NZ, dependent on locally grown nutritional sources. Further studies are required to confirm this exciting finding and to establish cause and effect relationship.

year: 2022-09-09