title: Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

authors: Bolzoni, Leandro

abstract: The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles.

text: Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles.

year: 2016

title: Feasibility of water quality monitoring by remote sensing in the Waikato Region

authors: Lehmann, Moritz K.

subjects: Remote sensing

abstract: The Waikato Regional Council (WRC) has statutory environmental monitoring requirements, including commitments arising from the National Policy Statement for Freshwater Management and State of the Environment reporting. Lakes, large rivers and estuaries pose a challenge for water quality monitoring programs due to their size, number and accessibility. To meet the increasing demand for more comprehensive monitoring to facilitate evidence-based regional policy making, cost-effective monitoring tools capable of capturing multiple attributes at various temporal and spatial scales are desirable.

text: Feasibility of water quality monitoring by remote sensing in the Waikato Region The Waikato Regional Council (WRC) has statutory environmental monitoring requirements, including commitments arising from the National Policy Statement for Freshwater Management and State of the Environment reporting. Lakes, large rivers and estuaries pose a challenge for water quality monitoring programs due to their size, number and accessibility. To meet the increasing demand for more comprehensive monitoring to facilitate evidence-based regional policy making, cost-effective monitoring tools capable of capturing multiple attributes at various temporal and spatial scales are desirable.

year: 2017

title: Adolescent Māori mothers experiences with social support during pregnancy, birth and motherhood and their participation in education

authors: Rawiri, Casey

subjects: social support

abstract: The purpose of this research was to investigate the role of social support in helping
adolescent Māori mothers cope with pregnancy, birth and motherhood, with a
particular emphasis on its role in enabling them to continue at school. The aim of this
research is to understand and make sense of these experiences and to perhaps identify
gaps within an individual's social network. The analysis and methodology of the
research was underpinned by a community psychology framework.
Nine interviews were conducted with young Māori women who had become pregnant
and continued with their pregnancy, all before the age of 20. The in depth interviews
included questions focusing on the young women learning of pregnancy, the
pregnancy, birth, caring for their child and their experiences with education and future
plans.
Negative experiences were usually those which involved unsupportive people.
Positive interactions were those where support, of all types, was offered and useful to
my participants and their children. Education was highlighted as the most effective
way of providing a better life for adolescent mothers and their children.
The research highlights the importance of social support and the continuation of
education. Combining the efforts of positive social networks and social support
services can improve the lives of adolescent Māori mothers and their children.

text: Adolescent Māori mothers experiences with social support during pregnancy, birth and motherhood and their participation in education The purpose of this research was to investigate the role of social support in helping
adolescent Māori mothers cope with pregnancy, birth and motherhood, with a
particular emphasis on its role in enabling them to continue at school. The aim of this
research is to understand and make sense of these experiences and to perhaps identify
gaps within an individual's social network. The analysis and methodology of the
research was underpinned by a community psychology framework.
Nine interviews were conducted with young Māori women who had become pregnant
and continued with their pregnancy, all before the age of 20. The in depth interviews
included questions focusing on the young women learning of pregnancy, the
pregnancy, birth, caring for their child and their experiences with education and future
plans.
Negative experiences were usually those which involved unsupportive people.
Positive interactions were those where support, of all types, was offered and useful to
my participants and their children. Education was highlighted as the most effective
way of providing a better life for adolescent mothers and their children.
The research highlights the importance of social support and the continuation of
education. Combining the efforts of positive social networks and social support
services can improve the lives of adolescent Māori mothers and their children.

year: 2007