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: Structural analysis of the GH43 enzyme Xsa43E from Butyrivibrio proteoclasticus

authors: Till, Marisa

subjects: Butyrivibrio proteoclasticus

abstract: The rumen of dairy cattle can be thought of as a large, stable fermentation vat and as such it houses a large and diverse community of microorganisms. The bacterium Butyrivibrio proteoclasticus is a representative of a significant component of this microbial community. It is a xylan-degrading organism whose genome encodes a large number of open reading frames annotated as fibre-degrading enzymes. This suite of enzymes is essential for the organism to utilize the plant material within the rumen as a fuel source, facilitating its survival in this competitive environment. Xsa43E, a GH43 enzyme from B. proteoclasticus, has been structurally and functionally characterized. Here, the structure of selenomethionine-derived Xsa43E determined to 1.3 Å resolution using single-wavelength anomalous diffraction is reported. Xsa43E possesses the characteristic five-bladed β-propeller domain seen in all GH43 enzymes. GH43 enzymes can have a range of functions, and the functional characterization of Xsa43E shows it to be an arabinofuranosidase capable of cleaving arabinose side chains from short segments of xylan. Full functional and structural characterization of xylan-degrading enzymes will aid in creating an enzyme cocktail that can be used to completely degrade plant material into simple sugars. These molecules have a range of applications as starting materials for many industrial processes, including renewable alternatives to fossil fuels.

text: Structural analysis of the GH43 enzyme Xsa43E from Butyrivibrio proteoclasticus The rumen of dairy cattle can be thought of as a large, stable fermentation vat and as such it houses a large and diverse community of microorganisms. The bacterium Butyrivibrio proteoclasticus is a representative of a significant component of this microbial community. It is a xylan-degrading organism whose genome encodes a large number of open reading frames annotated as fibre-degrading enzymes. This suite of enzymes is essential for the organism to utilize the plant material within the rumen as a fuel source, facilitating its survival in this competitive environment. Xsa43E, a GH43 enzyme from B. proteoclasticus, has been structurally and functionally characterized. Here, the structure of selenomethionine-derived Xsa43E determined to 1.3 Å resolution using single-wavelength anomalous diffraction is reported. Xsa43E possesses the characteristic five-bladed β-propeller domain seen in all GH43 enzymes. GH43 enzymes can have a range of functions, and the functional characterization of Xsa43E shows it to be an arabinofuranosidase capable of cleaving arabinose side chains from short segments of xylan. Full functional and structural characterization of xylan-degrading enzymes will aid in creating an enzyme cocktail that can be used to completely degrade plant material into simple sugars. These molecules have a range of applications as starting materials for many industrial processes, including renewable alternatives to fossil fuels.

year: 2014-08-29

title: Monitoring first year Maori students enrolled in selected Faculty of Arts and Social Sciences courses: A report prepared for the Dean of the Faculty of Arts and Social Sciences

authors: Levy, Michelle Patricia

subjects: maori students

abstract: Monitoring first year Maori Students Enrolled in Selected Faculty of Arts andSocial Sciences Courses. The total number of Maori students targeted by this project was 182, representing 93% of the total number of Maori students enrolled in Semester B level one courses. The majority of students participating in this initiative were first year students, although a small number of students taking 100 level courses were second, third or graduate year students. 11 Student views on the monitoring and support initiative Students were provided with the opportunity to comment on the monitoring and support initiative. All students contacted (49) recommended that this intervention continue for future first year Maori students enrolled in FASS.

text: Monitoring first year Maori students enrolled in selected Faculty of Arts and Social Sciences courses: A report prepared for the Dean of the Faculty of Arts and Social Sciences Monitoring first year Maori Students Enrolled in Selected Faculty of Arts andSocial Sciences Courses. The total number of Maori students targeted by this project was 182, representing 93% of the total number of Maori students enrolled in Semester B level one courses. The majority of students participating in this initiative were first year students, although a small number of students taking 100 level courses were second, third or graduate year students. 11 Student views on the monitoring and support initiative Students were provided with the opportunity to comment on the monitoring and support initiative. All students contacted (49) recommended that this intervention continue for future first year Maori students enrolled in FASS.

year: 2003-03-01