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

authors: Gauss, Christian

subjects: 4D printing

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. Evolving from these, 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. Bioderived and/or biodegradable thermoplastics reinforced with bioderived fibres have compelling attributes for 3D printing applications; they can be recycled, used in smart materials (4D printing) and if necessary, can biodegrade at the end of their life cycle. In this work, we demonstrate the potential use of biocomposites based on poly(lactic acid) (PLA) with a high content of regenerated cellulose fibres (lyocell) in hygromorphic structures, 3D printed using fused deposition modelling (FDM). The shape-change potential was assessed by 3D printing bi-material strips with passive and active layers composed of neat PLA and the composite, respectively and by measuring and modelling the change in curvature with the increase in water absorption. 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 this mechanism and a bi-material layout, prototypes of different sizes with 2D to 3D transformation triggered by moisture were 3D printed.

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. Evolving from these, 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. Bioderived and/or biodegradable thermoplastics reinforced with bioderived fibres have compelling attributes for 3D printing applications; they can be recycled, used in smart materials (4D printing) and if necessary, can biodegrade at the end of their life cycle. In this work, we demonstrate the potential use of biocomposites based on poly(lactic acid) (PLA) with a high content of regenerated cellulose fibres (lyocell) in hygromorphic structures, 3D printed using fused deposition modelling (FDM). The shape-change potential was assessed by 3D printing bi-material strips with passive and active layers composed of neat PLA and the composite, respectively and by measuring and modelling the change in curvature with the increase in water absorption. 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 this mechanism and a bi-material layout, prototypes of different sizes with 2D to 3D transformation triggered by moisture were 3D printed.

year: 2023

title: Path dependence or convergence? The evolution of corporate ownership around the world

authors: Yeh, Andrew Jia-Yuh

subjects: ownership dispersion

abstract: We offer a model that sheds light on the debate over whether corporate ownership concentration converges to the Berle-Means image. Our model takes into account the importance of both legal rules and firm-specific arrangements. Our analytical result is that share ownership concentration either persists or falls depending on the relative importance of these protective arrangements. In particular, our model predicts: (a) diffuse corporate ownership in nations that impose legal limits on blockholders’ clout to expropriate minority shareholder rights, and (b) concentrated corporate ownership in nations that rely on asset specificity as a form of investor protection. 
Our empirical work suggests partial convergence toward Berle-Means diffuse share ownership. It is thereby reasonable to infer the existence of path dependent forces on ownership concentration. But this result does not preclude the possibility of functional convergence or convergence to the diffuse form of share ownership via cross-listings on the major U.S. stock exchanges that impose stringent disclosure and listing requirements. In essence, these results suggest a case for the co-existence of the preexisting path-dependency and functional-convergence stories.

text: Path dependence or convergence? The evolution of corporate ownership around the world We offer a model that sheds light on the debate over whether corporate ownership concentration converges to the Berle-Means image. Our model takes into account the importance of both legal rules and firm-specific arrangements. Our analytical result is that share ownership concentration either persists or falls depending on the relative importance of these protective arrangements. In particular, our model predicts: (a) diffuse corporate ownership in nations that impose legal limits on blockholders’ clout to expropriate minority shareholder rights, and (b) concentrated corporate ownership in nations that rely on asset specificity as a form of investor protection. 
Our empirical work suggests partial convergence toward Berle-Means diffuse share ownership. It is thereby reasonable to infer the existence of path dependent forces on ownership concentration. But this result does not preclude the possibility of functional convergence or convergence to the diffuse form of share ownership via cross-listings on the major U.S. stock exchanges that impose stringent disclosure and listing requirements. In essence, these results suggest a case for the co-existence of the preexisting path-dependency and functional-convergence stories.

year: 2007-12

title: Explaining Maori under-achievement in standardised reading tests: The role of social and individual characteristics

authors: Lock, Kelly J.

subjects: education

abstract: In New Zealand, Maori students have lower educational attainment levels than their Pakeha counterparts, which is a major contributor to the earnings inequality between these two groups. This study attempts to identify determinants of the gap in educational attainment using data on reading test scores for a sample of 3031 15‐year‐old Maori and Pakeha students. Using a decomposition method that is commonly applied to income inequality analyses, the determinants of the reading literacy test score gap between Maori and Pakeha students are identified. The main contributors to this gap are family factors, student's opinions, and school factors (including decile). An understanding of the determinants of the test score gap provides insights into how effective policy makers can be at reducing this inequality.

text: Explaining Maori under-achievement in standardised reading tests: The role of social and individual characteristics In New Zealand, Maori students have lower educational attainment levels than their Pakeha counterparts, which is a major contributor to the earnings inequality between these two groups. This study attempts to identify determinants of the gap in educational attainment using data on reading test scores for a sample of 3031 15‐year‐old Maori and Pakeha students. Using a decomposition method that is commonly applied to income inequality analyses, the determinants of the reading literacy test score gap between Maori and Pakeha students are identified. The main contributors to this gap are family factors, student's opinions, and school factors (including decile). An understanding of the determinants of the test score gap provides insights into how effective policy makers can be at reducing this inequality.

year: 2008