title: Effect of Nb addition on the phase stability microstructure, and mechanical properties of powder metallurgy Ti-5Fe-xNb alloys

authors: Manogar, Balakrishnan

abstract: Ti alloys contemplating the simultaneous addition of Fe and Nb are available in the literature as Fe enhances the strength and Nb improves the biological behaviour of Ti. Nevertheless, casting has been the main manufacturing process, the Nb content is normally ≥10 wt.%, and no tensile properties are available. In this study, Ti-5Fe-xNb alloys (x = 2, 6, and 9 wt.%) were produced via powder metallurgy, which is more energy efficient than casting, with the aim of understanding the relationship between the mechanical behaviour and the microstructural changes brought about by the progressive addition of a greater amount of Nb. This study shows that the increment of the Nb content reduces the densification of the alloys, as the relative density decreases from 98.2% to 95.0%, but remarkably increases the volume fraction of the stabilised β phase (14→36%). Accordingly, the Ti-5Fe-xNb alloys are characterised by Widmanstätten microstructures, which become finer for higher Nb contents, and progressively higher mechanical properties including yield stress (725–949 MPa), ultimate tensile strength (828–995 MPa), and hardness (66.5–67.6 HRA), but lower elongation to fracture (4.0–5.1%). It is found that the ductility is much more influenced by the presence of the residual pores, whereas the strength greatly depends on the microstructural changes brought about by the addition of the alloying elements.

text: Effect of Nb addition on the phase stability microstructure, and mechanical properties of powder metallurgy Ti-5Fe-xNb alloys Ti alloys contemplating the simultaneous addition of Fe and Nb are available in the literature as Fe enhances the strength and Nb improves the biological behaviour of Ti. Nevertheless, casting has been the main manufacturing process, the Nb content is normally ≥10 wt.%, and no tensile properties are available. In this study, Ti-5Fe-xNb alloys (x = 2, 6, and 9 wt.%) were produced via powder metallurgy, which is more energy efficient than casting, with the aim of understanding the relationship between the mechanical behaviour and the microstructural changes brought about by the progressive addition of a greater amount of Nb. This study shows that the increment of the Nb content reduces the densification of the alloys, as the relative density decreases from 98.2% to 95.0%, but remarkably increases the volume fraction of the stabilised β phase (14→36%). Accordingly, the Ti-5Fe-xNb alloys are characterised by Widmanstätten microstructures, which become finer for higher Nb contents, and progressively higher mechanical properties including yield stress (725–949 MPa), ultimate tensile strength (828–995 MPa), and hardness (66.5–67.6 HRA), but lower elongation to fracture (4.0–5.1%). It is found that the ductility is much more influenced by the presence of the residual pores, whereas the strength greatly depends on the microstructural changes brought about by the addition of the alloying elements.

year: 2022-09-15

title: Application of flow cytometry for examining phytoplankton succession in two eutrophic lakes

authors: Dennis, Marie

subjects: Cyanophyta

abstract: Flow cytometry has potential as a rapid assessment technique to evaluate phytoplankton biomass and species composition. It facilitates for multi-parameter analysis of individual cells on the basis of light scattering effects induced from cellular constituents, as well as auto-fluorescence. Fluorescence emission characteristics may be especially useful in classifying cyanobacteria as they contain phycoerythrin which emits light predominantly in the 550–600 nm waveband, chlorophyll-a (650–700 nm emission) and allophycocyanin (660 nm emission). The objective of our study was to assess the utility of flow cytometry for the rapid identification and sorting of freshwater algae and cyanobacteria species. Using a selection of laboratory-cultured freshwater algae and cyanobacteria species, this study demonstrated unique light scatter and fluorescent characteristics for each species examined, allowing for rapid species identification and sorting of mixed populations of laboratory cultures and samples from two lakes in the Rotorua region (New Zealand). Analysis of lake water samples collected over seven months demonstrated changes in abundance and community composition of phytoplankton in the two lakes and demonstrates that flow cytometry may be a useful technique for examining seasonal changes in phytoplankton composition.

text: Application of flow cytometry for examining phytoplankton succession in two eutrophic lakes Flow cytometry has potential as a rapid assessment technique to evaluate phytoplankton biomass and species composition. It facilitates for multi-parameter analysis of individual cells on the basis of light scattering effects induced from cellular constituents, as well as auto-fluorescence. Fluorescence emission characteristics may be especially useful in classifying cyanobacteria as they contain phycoerythrin which emits light predominantly in the 550–600 nm waveband, chlorophyll-a (650–700 nm emission) and allophycocyanin (660 nm emission). The objective of our study was to assess the utility of flow cytometry for the rapid identification and sorting of freshwater algae and cyanobacteria species. Using a selection of laboratory-cultured freshwater algae and cyanobacteria species, this study demonstrated unique light scatter and fluorescent characteristics for each species examined, allowing for rapid species identification and sorting of mixed populations of laboratory cultures and samples from two lakes in the Rotorua region (New Zealand). Analysis of lake water samples collected over seven months demonstrated changes in abundance and community composition of phytoplankton in the two lakes and demonstrates that flow cytometry may be a useful technique for examining seasonal changes in phytoplankton composition.

year: 2011

title: Genealogical Violence: Mormon (Mis)Appropriation of Māori Cultural Memory through Falsification of Whakapapa

authors: Simon, Hemopereki

subjects: whakapapa

abstract: The study examines how members of the historically white possessive and supremacist Church of Jesus Christ of Latter-day Saints in the United States (mis)appropriated Māori genealogy, known as whakapapa. The Mormon use of whakapapa to promote Mormon cultural memory and narratives perpetuates settler/invader colonialism and white supremacy, as this paper shows. The research discusses Church racism against Native Americans and Pacific Peoples. This paper uses Anthropologist Thomas Murphy’s scholarship to demonstrate how problematic the Book of Mormon’s religio-colonial identity of Lamanites is for these groups. Application of Aileen Moreton-Robinson’s white possessive doctrine and Hemopereki Simon’s adaptation to cover Church-Indigenous relations and the salvation contract is discussed. We explore collective and cultural memory and discuss key Māori concepts like Mana, Taonga, Tapu, and Whakapapa. A brief review of LDS scholar Louis C. Midgley’s views on Church culture, including Herewini Jones’s whakapapa wānanga, is followed by a discussion of Māori cultural considerations and issues. The paper concludes that the alteration perpetuates settler/invader colonialism and Pacific peoples’ racialization and white supremacy. Genetics science and human migration studies contradict Mormon identity narratives and suggest the BOM is spiritual rather than historical. Finally, the paper suggests promoting intercultural engagement on Mormon (mis)appropriation of taonga Māori.

text: Genealogical Violence: Mormon (Mis)Appropriation of Māori Cultural Memory through Falsification of Whakapapa The study examines how members of the historically white possessive and supremacist Church of Jesus Christ of Latter-day Saints in the United States (mis)appropriated Māori genealogy, known as whakapapa. The Mormon use of whakapapa to promote Mormon cultural memory and narratives perpetuates settler/invader colonialism and white supremacy, as this paper shows. The research discusses Church racism against Native Americans and Pacific Peoples. This paper uses Anthropologist Thomas Murphy’s scholarship to demonstrate how problematic the Book of Mormon’s religio-colonial identity of Lamanites is for these groups. Application of Aileen Moreton-Robinson’s white possessive doctrine and Hemopereki Simon’s adaptation to cover Church-Indigenous relations and the salvation contract is discussed. We explore collective and cultural memory and discuss key Māori concepts like Mana, Taonga, Tapu, and Whakapapa. A brief review of LDS scholar Louis C. Midgley’s views on Church culture, including Herewini Jones’s whakapapa wānanga, is followed by a discussion of Māori cultural considerations and issues. The paper concludes that the alteration perpetuates settler/invader colonialism and Pacific peoples’ racialization and white supremacy. Genetics science and human migration studies contradict Mormon identity narratives and suggest the BOM is spiritual rather than historical. Finally, the paper suggests promoting intercultural engagement on Mormon (mis)appropriation of taonga Māori.

year: 2024