title: The influence of warming on phosphorus burial in continental margin sediments

authors: Zhao, M

subjects: climate

abstract: The marine phosphorus cycle plays a critical role in regulating rates of primary productivity and thus the size of the marine biosphere. Yet, the cumulative effects of temperature change—and warming, in particular—on marine phosphorus burial remain poorly understood. Here, we explore a benthic biogeochemical model that accounts for the compounded effect of temperature on the kinetics of key diagenetic reaction pathways, diffusion coefficients, seawater pH, dissolved O2 concentration and bioturbation, in order to provide a new predictive framework for understanding the temperature response associated with P burial in continental margin settings. We find that temperature has a direct and positive impact on marine phosphorus burial, as it directly increases the formation rate of key mineral P-removal pathways—foremost carbonate fluorapatite (CFA). The increase in authigenic P burial during climate warming is likely to partially counter the effects of increased water-column P regeneration rate during climate warming events, and thus influence the extent of oceanic anoxia and organic matter burial, a factor that should be considered when assessing the response of the P cycle in the face of warming.

text: The influence of warming on phosphorus burial in continental margin sediments The marine phosphorus cycle plays a critical role in regulating rates of primary productivity and thus the size of the marine biosphere. Yet, the cumulative effects of temperature change—and warming, in particular—on marine phosphorus burial remain poorly understood. Here, we explore a benthic biogeochemical model that accounts for the compounded effect of temperature on the kinetics of key diagenetic reaction pathways, diffusion coefficients, seawater pH, dissolved O2 concentration and bioturbation, in order to provide a new predictive framework for understanding the temperature response associated with P burial in continental margin settings. We find that temperature has a direct and positive impact on marine phosphorus burial, as it directly increases the formation rate of key mineral P-removal pathways—foremost carbonate fluorapatite (CFA). The increase in authigenic P burial during climate warming is likely to partially counter the effects of increased water-column P regeneration rate during climate warming events, and thus influence the extent of oceanic anoxia and organic matter burial, a factor that should be considered when assessing the response of the P cycle in the face of warming.

year: 2023

title: Mechanical behaviour of Titanium, Ti-6Al-4V (wt %) alloy and Ti-47Al-2Cr (at %) alloy produced using powder compact forging

authors: Nadakuduru, Vijay Navaratna

subjects: mechanical behaviour

abstract: Powder compact forging was used to produce bulk consolidated titanium and Ti-6Al-4V (wt %) and Ti-47Al-2Cr (at%) alloy disks from hydrogenated and dehydrogenated (HDH) and gas atomised powders (GA) powders (in the case of titanium and Ti-6Al-4V) and a mechanically milled powder (in the case of Ti-47Al-2Cr alloy). The bulk titanium and Ti-6Al-4V (wt %) alloy have been produced by forging of the powder compacts. The Ti-47Al-2Cr (at %) alloy was produced using canned powder compact forging of a Ti/Al/Cr composite powder. The purpose of the present study is to investigate the deformation and fracture behaviour of the bulk consolidated as-forged materials, by conducting tensile testing at room temperature (RT) and examination of the fractured specimens which had near-α, α + β and γ phase structures, respectively. It was found that as-forged bulk titanium disk produced using HDH powder showed a yield point with a yield strength of ~700 MPa and with a considerable amount of ductility. While the as-forged Ti-6Al-4V (wt %) alloy produced using HDH powder, fractured prematurely without any yielding. On the other hand yielding was observed in the as-forged Ti-6Al-4V (wt %) alloy produced using GA powder, showing a yield strength of ~970 MPa and a considerable amount of plastic strain to fracture. The bulk consolidated Ti-47Al-2Cr (at %) alloy also fractured prematurely with fracture strength of ~125 MPa. The mechanical behaviour of the as-forged bulk materials was found to be dependent on several factors such as initial powders used, green density of the powder compact, forging parameters used during forging. It was expected that the entrapped gas in green compacts, absorbed oxygen, porosity and inter-particle bonding play an important role on the quality of the as-forged material, which in turn affected the mechanical behaviour of the bulk material.

text: Mechanical behaviour of Titanium, Ti-6Al-4V (wt %) alloy and Ti-47Al-2Cr (at %) alloy produced using powder compact forging Powder compact forging was used to produce bulk consolidated titanium and Ti-6Al-4V (wt %) and Ti-47Al-2Cr (at%) alloy disks from hydrogenated and dehydrogenated (HDH) and gas atomised powders (GA) powders (in the case of titanium and Ti-6Al-4V) and a mechanically milled powder (in the case of Ti-47Al-2Cr alloy). The bulk titanium and Ti-6Al-4V (wt %) alloy have been produced by forging of the powder compacts. The Ti-47Al-2Cr (at %) alloy was produced using canned powder compact forging of a Ti/Al/Cr composite powder. The purpose of the present study is to investigate the deformation and fracture behaviour of the bulk consolidated as-forged materials, by conducting tensile testing at room temperature (RT) and examination of the fractured specimens which had near-α, α + β and γ phase structures, respectively. It was found that as-forged bulk titanium disk produced using HDH powder showed a yield point with a yield strength of ~700 MPa and with a considerable amount of ductility. While the as-forged Ti-6Al-4V (wt %) alloy produced using HDH powder, fractured prematurely without any yielding. On the other hand yielding was observed in the as-forged Ti-6Al-4V (wt %) alloy produced using GA powder, showing a yield strength of ~970 MPa and a considerable amount of plastic strain to fracture. The bulk consolidated Ti-47Al-2Cr (at %) alloy also fractured prematurely with fracture strength of ~125 MPa. The mechanical behaviour of the as-forged bulk materials was found to be dependent on several factors such as initial powders used, green density of the powder compact, forging parameters used during forging. It was expected that the entrapped gas in green compacts, absorbed oxygen, porosity and inter-particle bonding play an important role on the quality of the as-forged material, which in turn affected the mechanical behaviour of the bulk material.

year: 2011

title: Tito Waiata-Tito Pūoro: extending the Kīngitanga music tradition.

authors: Rollo, Te Manaaroha Pirihira

subjects: Kīngitanga

abstract: Since 1858, music has always been an integral part of the Kīngitanga movement in New Zealand. As this music tradition evolves with the introduction of new musical idioms, genres and digital technology, so too do the practices of composing new works. 

The objective of this research was to construct a model for combining waiata, taonga pūoro and New Zealand electroacoustic music, in order to create new works that enhance the Kīngitanga music tradition.  Developing a model for composing and integrating these idioms within a Māori context presented problems, as traditional Māori music conflict with contemporary Western forms. 

To generate a framework and practical model for composing hybrid music, an examination of selected New Zealand works was first carried out through: a) the collection of 50 traditional and contemporary waiata relating to the Kīngitanga b) the collection of 10 New Zealand taonga pūoro works and c) a collection of 10 New Zealand electroacoustic music. An analysis of the music and compositional processes of each idiom implementing the ‘de-construct in order to re-construct’ approach to understand how they work musically and compositionally was accomplished. 

To demonstrate the outcome of my models, six original compositions were presented exploring different aspects of musical composition. These models focused on sound architecture and explored a) communicative relationships between composer, performer, and audience b) Holistic Co-hear-ence, implementing the horizontal and vertical layering model, and c) technical approaches using digital technology. To comply with Māori principles of composition and performance, each model and new work demonstrated Kaupapa Māori , Wairua  and Te Mana - Te Ihi - Te Wehi - Te Tapu . 

The findings and original contributions of this research provide a model that combines two musical traditions and three music idioms, and in turn, may guide contemporary composers in creating new works that extend the Kīngitanga music tradition.

text: Tito Waiata-Tito Pūoro: extending the Kīngitanga music tradition. Since 1858, music has always been an integral part of the Kīngitanga movement in New Zealand. As this music tradition evolves with the introduction of new musical idioms, genres and digital technology, so too do the practices of composing new works. 

The objective of this research was to construct a model for combining waiata, taonga pūoro and New Zealand electroacoustic music, in order to create new works that enhance the Kīngitanga music tradition.  Developing a model for composing and integrating these idioms within a Māori context presented problems, as traditional Māori music conflict with contemporary Western forms. 

To generate a framework and practical model for composing hybrid music, an examination of selected New Zealand works was first carried out through: a) the collection of 50 traditional and contemporary waiata relating to the Kīngitanga b) the collection of 10 New Zealand taonga pūoro works and c) a collection of 10 New Zealand electroacoustic music. An analysis of the music and compositional processes of each idiom implementing the ‘de-construct in order to re-construct’ approach to understand how they work musically and compositionally was accomplished. 

To demonstrate the outcome of my models, six original compositions were presented exploring different aspects of musical composition. These models focused on sound architecture and explored a) communicative relationships between composer, performer, and audience b) Holistic Co-hear-ence, implementing the horizontal and vertical layering model, and c) technical approaches using digital technology. To comply with Māori principles of composition and performance, each model and new work demonstrated Kaupapa Māori , Wairua  and Te Mana - Te Ihi - Te Wehi - Te Tapu . 

The findings and original contributions of this research provide a model that combines two musical traditions and three music idioms, and in turn, may guide contemporary composers in creating new works that extend the Kīngitanga music tradition.

year: 2014