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: A multifaceted approach to understanding unexpected sound change. The bilabial trills of Vanuatu’s Malekula Island

authors: Rangelov, T

subjects: Austronesian

abstract: This paper demonstrates that unexpected sound changes are best explained by an approach that accounts for different motivations: phonetic, structural and social. Here, we focus on a multifaceted investigation of the crosslinguistically uncommon bilabial trills to show the complex interaction between different drivers of sound change. In this paper, we highlight and examine the prenasalized voiced bilabial trill mʙ and plain voiceless bilabial trill P [ʙ̥] found in a number of Oceanic languages spoken on Malekula Island in Vanuatu. We offer a comparative-historical analysis, and we identify the various forces that have led to the emergence and persistence of mʙ and P in Malekula languages: the historical articulatory environments, the particular make-up of the consonant inventories of these languages, complementary sound changes and phonological processes, contact with non-Austronesian languages, and in-group identity attachment. Furthermore, we offer a hypothesis for the relative timing of these factors on the historical pathway of Malekula’s bilabial trills.

text: A multifaceted approach to understanding unexpected sound change. The bilabial trills of Vanuatu’s Malekula Island This paper demonstrates that unexpected sound changes are best explained by an approach that accounts for different motivations: phonetic, structural and social. Here, we focus on a multifaceted investigation of the crosslinguistically uncommon bilabial trills to show the complex interaction between different drivers of sound change. In this paper, we highlight and examine the prenasalized voiced bilabial trill mʙ and plain voiceless bilabial trill P [ʙ̥] found in a number of Oceanic languages spoken on Malekula Island in Vanuatu. We offer a comparative-historical analysis, and we identify the various forces that have led to the emergence and persistence of mʙ and P in Malekula languages: the historical articulatory environments, the particular make-up of the consonant inventories of these languages, complementary sound changes and phonological processes, contact with non-Austronesian languages, and in-group identity attachment. Furthermore, we offer a hypothesis for the relative timing of these factors on the historical pathway of Malekula’s bilabial trills.

year: 2023-02-07

title: Opening Address to the National Māori Graduates of Psychology Symposium 2002: Making a difference

authors: Nikora, Linda Waimarie

subjects: Maori

abstract: The opening address to the National Māori Graduates of Psychology Symposium 2002.  This address introduces the themes of the conference: Kia matāra - negotiating the challenges in Māori development, kia mau – recruitment and retention, Tuhia mai, whiua atu – research and methodology, tinia mai – intervantions and treatment, taitaia i te ahi manuka – pride upon the skin.

text: Opening Address to the National Māori Graduates of Psychology Symposium 2002: Making a difference The opening address to the National Māori Graduates of Psychology Symposium 2002.  This address introduces the themes of the conference: Kia matāra - negotiating the challenges in Māori development, kia mau – recruitment and retention, Tuhia mai, whiua atu – research and methodology, tinia mai – intervantions and treatment, taitaia i te ahi manuka – pride upon the skin.

year: 2003