title: X-ray diffraction for phase identification in Ti-based alloys: Benefits and limitations

authors: Bolzoni, Leandro

abstract: X-ray diffraction (XRD) is routinely used to characterise Ti alloys, as it provides insight on structure-related aspects. However, there are no dedicated reports on its accuracy are available. To fill this gap, this work aims at examining the benefits and limitations of XRD analysis for phase identification in Ti-based alloys. It is worth mentioning that this study analyses both standard and experimental Ti alloys but the scope is primarily on alloys slow cooled from high temperature, thus characterised by equilibrium microstructures. To be comprehensive, this study considers the all spectrum of Ti alloys, ranging from alpha to beta Ti alloys. It is found that successful identification and quantification of the phases is achieved in the majority of the different type of Ti-based alloys. However, in some instances like for near-alpha alloys, the output of XRD analysis needs to be complemented with other characterisation techniques such as microscopy to be able to fully characterise the material. The correlation between the results of XRD analysis and the molybdenum equivalent parameter (MoE), which is widely used to design Ti alloys, was also investigated using structural-analytical models. The parallel model is found to be the best to estimate the amount of β-Ti phase as a function of the MoE parameter.

text: X-ray diffraction for phase identification in Ti-based alloys: Benefits and limitations X-ray diffraction (XRD) is routinely used to characterise Ti alloys, as it provides insight on structure-related aspects. However, there are no dedicated reports on its accuracy are available. To fill this gap, this work aims at examining the benefits and limitations of XRD analysis for phase identification in Ti-based alloys. It is worth mentioning that this study analyses both standard and experimental Ti alloys but the scope is primarily on alloys slow cooled from high temperature, thus characterised by equilibrium microstructures. To be comprehensive, this study considers the all spectrum of Ti alloys, ranging from alpha to beta Ti alloys. It is found that successful identification and quantification of the phases is achieved in the majority of the different type of Ti-based alloys. However, in some instances like for near-alpha alloys, the output of XRD analysis needs to be complemented with other characterisation techniques such as microscopy to be able to fully characterise the material. The correlation between the results of XRD analysis and the molybdenum equivalent parameter (MoE), which is widely used to design Ti alloys, was also investigated using structural-analytical models. The parallel model is found to be the best to estimate the amount of β-Ti phase as a function of the MoE parameter.

year: 2024

title: The Effect of Cell Immobilization by Calcium Alginate on Bacterially Induced Calcium Carbonate Precipitation

authors: Seifan, Mostafa

subjects: bacteria

abstract: Microbially induced mineral precipitation is recognized as a widespread phenomenon in nature. A diverse range of minerals including carbonate, sulphides, silicates, and phosphates can be produced through biomineralization. Calcium carbonate (CaCO₃) is one of the most common substances used in various industries and is mostly extracted by mining. In recent years, production of CaCO₃ by bacteria has drawn much attention because it is an environmentally- and health-friendly pathway. Although CaCO₃ can be produced by some genera of bacteria through autotrophic and heterotrophic pathways, the possibility of producing CaCO₃ in different environmental conditions has remained a challenge to determine. In this study, calcium alginate was proposed as a protective carrier to increase the bacterial tolerance to extreme environmental conditions. The model showed that the highest concentration of CaCO₃ is achieved when the bacterial cells are immobilized in the calcium alginate beads fabricated using 1.38% w/v Na-alginate and 0.13 M CaCl₂.

text: The Effect of Cell Immobilization by Calcium Alginate on Bacterially Induced Calcium Carbonate Precipitation Microbially induced mineral precipitation is recognized as a widespread phenomenon in nature. A diverse range of minerals including carbonate, sulphides, silicates, and phosphates can be produced through biomineralization. Calcium carbonate (CaCO₃) is one of the most common substances used in various industries and is mostly extracted by mining. In recent years, production of CaCO₃ by bacteria has drawn much attention because it is an environmentally- and health-friendly pathway. Although CaCO₃ can be produced by some genera of bacteria through autotrophic and heterotrophic pathways, the possibility of producing CaCO₃ in different environmental conditions has remained a challenge to determine. In this study, calcium alginate was proposed as a protective carrier to increase the bacterial tolerance to extreme environmental conditions. The model showed that the highest concentration of CaCO₃ is achieved when the bacterial cells are immobilized in the calcium alginate beads fabricated using 1.38% w/v Na-alginate and 0.13 M CaCl₂.

year: 2017

title: Te Ira Atua: The spiritual spark of the child

authors: Rameka, Lesley Kay

abstract: “E ai ki tā te Māori he atua tonu kei roto i te mokopuna ina whānau mai ana ia ki tēnei ao” (Ministry of Education, 1996, p. 35). This quote is from the New Zealand Ministry of Education’s early childhood curriculum policy statement, Te Whāriki: He Whāriki Matauranga mo ngā Mokopuna o Aotearoa/Early Childhood Curriculum (Ministry of Education, 1996). It speaks of the godliness or spiritual essence each child inherits from their ancestors when they are born (Early Childhood Development, 1999; Reedy, 2003). From a traditional Māori perspective, not only is the child endowed with spiritual potential or a divine spirit, but the world the child is born into is also endowed with spiritual influences.

text: Te Ira Atua: The spiritual spark of the child “E ai ki tā te Māori he atua tonu kei roto i te mokopuna ina whānau mai ana ia ki tēnei ao” (Ministry of Education, 1996, p. 35). This quote is from the New Zealand Ministry of Education’s early childhood curriculum policy statement, Te Whāriki: He Whāriki Matauranga mo ngā Mokopuna o Aotearoa/Early Childhood Curriculum (Ministry of Education, 1996). It speaks of the godliness or spiritual essence each child inherits from their ancestors when they are born (Early Childhood Development, 1999; Reedy, 2003). From a traditional Māori perspective, not only is the child endowed with spiritual potential or a divine spirit, but the world the child is born into is also endowed with spiritual influences.

year: 2015