title: The metabolism of parts of seeds during early germination

authors: Collins, Desmond Michael

abstract: There have been few studies of the metabolism of germinating seeds during the first minutes and hours of imbibition. This is partly because most biochemical techniques are unsuitable for studying these biological systems. One technique that has been developed for studying such systems involves using tritiated water as a tracer. In this technique the biological material is placed in tritiated water for a known time and then extracted. The extracts are chromatographed on paper and the tritium labelled compounds are detected by scintillation radioautography. The technique has already been successfully applied to the study of intact seeds of two species of dicotyledons. In this present work the technique was used to study the metabolic development during the first six hours of imbibition of the different parts of seeds from four species: a monocotyledon (barley), two dicotyledons (Phaseolus vulgaris and castor oil), and a gymnosperm (Pinus radiata). The seeds of these species are representative of the majority of seeds in the plant world. The results show that performing experiments on excised parts of seeds provides additional information to that obtained from using intact seeds. The most important conclusion of this work is that the axes and embryos of all seeds develop the same basic metabolic pathways during the first hours of imbibition and that these pathways develop in a similar order. Amino acid metabolism begins during the first few minutes of imbibition, followed by the metabolism of Krebs cycle acids and, after two hours, sucrose metabolism. Ten different labelled compounds were identified and labelled groups of compounds described as lipids and sugar phosphates were also present. Detailed conclusions are made about the metabolism based on the tritium labelled compounds formed, together with any other relevant information available. A number of additional experiments, including ¹⁴C tracer experiments, were performed on parts of two of the seeds. These experiments enabled more definite conclusions to be made about the metabolism of sucrose and 4-aminobutyrate, two of the compounds labelled in the tritiated water experiments. Most and in some cases all the labelled compounds formed in the axes and embryos were also found in the storage organs. However, the rate of metabolic development of the storage organs was slower than that of their corresponding axes or embryos, and a comparison of water absorption to metabolism indicated that initially this may have been due to their slower water absorption. The metabolic development was not as uniform among the storage organs as it was among the embryos and axes. In particular, the barley endosperm appeared to have a much simpler metabolism than the castor oil endosperm and it was shown that its metabolism occurred entirely in the aleurone layer of cells on its surface. It is concluded that the metabolic development of seed storage organs depends more on their morphology and function than on their embryological origin.

text: The metabolism of parts of seeds during early germination There have been few studies of the metabolism of germinating seeds during the first minutes and hours of imbibition. This is partly because most biochemical techniques are unsuitable for studying these biological systems. One technique that has been developed for studying such systems involves using tritiated water as a tracer. In this technique the biological material is placed in tritiated water for a known time and then extracted. The extracts are chromatographed on paper and the tritium labelled compounds are detected by scintillation radioautography. The technique has already been successfully applied to the study of intact seeds of two species of dicotyledons. In this present work the technique was used to study the metabolic development during the first six hours of imbibition of the different parts of seeds from four species: a monocotyledon (barley), two dicotyledons (Phaseolus vulgaris and castor oil), and a gymnosperm (Pinus radiata). The seeds of these species are representative of the majority of seeds in the plant world. The results show that performing experiments on excised parts of seeds provides additional information to that obtained from using intact seeds. The most important conclusion of this work is that the axes and embryos of all seeds develop the same basic metabolic pathways during the first hours of imbibition and that these pathways develop in a similar order. Amino acid metabolism begins during the first few minutes of imbibition, followed by the metabolism of Krebs cycle acids and, after two hours, sucrose metabolism. Ten different labelled compounds were identified and labelled groups of compounds described as lipids and sugar phosphates were also present. Detailed conclusions are made about the metabolism based on the tritium labelled compounds formed, together with any other relevant information available. A number of additional experiments, including ¹⁴C tracer experiments, were performed on parts of two of the seeds. These experiments enabled more definite conclusions to be made about the metabolism of sucrose and 4-aminobutyrate, two of the compounds labelled in the tritiated water experiments. Most and in some cases all the labelled compounds formed in the axes and embryos were also found in the storage organs. However, the rate of metabolic development of the storage organs was slower than that of their corresponding axes or embryos, and a comparison of water absorption to metabolism indicated that initially this may have been due to their slower water absorption. The metabolic development was not as uniform among the storage organs as it was among the embryos and axes. In particular, the barley endosperm appeared to have a much simpler metabolism than the castor oil endosperm and it was shown that its metabolism occurred entirely in the aleurone layer of cells on its surface. It is concluded that the metabolic development of seed storage organs depends more on their morphology and function than on their embryological origin.

year: 1973

title: Engineering the heterogeneous nuclei in Al-Si alloys for solidification control

authors: Bolzoni, Leandro

subjects: Aluminium alloys

abstract: Aluminium alloys are particularly advantageous for transportation industries to reduce the weight of the vehicles and thus pollution. The optimisation of the performances of Al alloys can be achieved by engineering and enhancing the heterogeneous nucleation of the melt. In this work, we demonstrate how the inoculation of commercial Al-Si alloys by Nb-based phases permits to improve and control the solidification process. We show that NbB2/Al3Nb are potent heterogeneous nucleation substrates for Al-Si alloys. The improved nucleation makes the material structure less dependent on the processing conditions such as solidification time and chemistry of the alloy (i.e. Si content). This permits to design and fabricate lighter structural components with improved and more isotropic performances.

text: Engineering the heterogeneous nuclei in Al-Si alloys for solidification control Aluminium alloys are particularly advantageous for transportation industries to reduce the weight of the vehicles and thus pollution. The optimisation of the performances of Al alloys can be achieved by engineering and enhancing the heterogeneous nucleation of the melt. In this work, we demonstrate how the inoculation of commercial Al-Si alloys by Nb-based phases permits to improve and control the solidification process. We show that NbB2/Al3Nb are potent heterogeneous nucleation substrates for Al-Si alloys. The improved nucleation makes the material structure less dependent on the processing conditions such as solidification time and chemistry of the alloy (i.e. Si content). This permits to design and fabricate lighter structural components with improved and more isotropic performances.

year: 2016-12

title: Cultural Theory Made Critical: Towards a Theory of the Indigenous Intellectual

authors: Hireme, Hemi Te Rere

abstract: Despite the fact that Western critical theory has provided us with theories of the power relations that operate within our lives, I argue that the indigenous element is nonetheless understated within these theories. To this end, my thesis is precisely that we must make the "cultural" critical. I argue that various theories of cognitive and moral submissiveness must be supplemented with a theory of submissiveness at the indigenous level in order for issues of latent power to be addressed. This thesis is therefore about developing a theory that for tangata whenua seeks to overcome one of the most debilitating effects of colonial domination - a loss of critical consciousness. I advocate the need for a new type of intellectual - the indigenous intellectual. 
I present my thesis in two parts. Part One examines Western critical theory to understand the processes that contribute to colonial domination. Here, I identify relations and processes of power that have contributed to a continuing assault on tangata whenua cultural continuity and well-being. Of particular significance are Foucault's study of governmentalisation and normalisation and Gramsci's notion of hegemony and the traditional and organic intellectuals. 
Part Two records not only how this understanding is put into action by way of the introduction of a "critical theory" component in programmes at Te Whare Wananga 0 Awanuiarangi over a number of years, but also offers a critical cultural theory in the form of the indigenous intellectual. While it acknowledges the extreme value of Western critical theory in allowing tangata whenua to understand the relations of power and the effects of colonial domination, the programme also identifies the many voids and spaces within Western critical theory that leave unanswered the oppressiveness and hegemony of cultural and ideological colonisation. I conclude my thesis by arguing that, whilst many in leadership positions claim allegiance to Gramsci' s concept of the organic intellectual, their ideological stance is anything but organic. By examining why they do not represent indigenous interests "organically", I argue that a new concept is needed to expose the sham of much of our contemporary "inorganic" politics: that our cultural needs are better served by a concept of the "indigenous" intellectual.

text: Cultural Theory Made Critical: Towards a Theory of the Indigenous Intellectual Despite the fact that Western critical theory has provided us with theories of the power relations that operate within our lives, I argue that the indigenous element is nonetheless understated within these theories. To this end, my thesis is precisely that we must make the "cultural" critical. I argue that various theories of cognitive and moral submissiveness must be supplemented with a theory of submissiveness at the indigenous level in order for issues of latent power to be addressed. This thesis is therefore about developing a theory that for tangata whenua seeks to overcome one of the most debilitating effects of colonial domination - a loss of critical consciousness. I advocate the need for a new type of intellectual - the indigenous intellectual. 
I present my thesis in two parts. Part One examines Western critical theory to understand the processes that contribute to colonial domination. Here, I identify relations and processes of power that have contributed to a continuing assault on tangata whenua cultural continuity and well-being. Of particular significance are Foucault's study of governmentalisation and normalisation and Gramsci's notion of hegemony and the traditional and organic intellectuals. 
Part Two records not only how this understanding is put into action by way of the introduction of a "critical theory" component in programmes at Te Whare Wananga 0 Awanuiarangi over a number of years, but also offers a critical cultural theory in the form of the indigenous intellectual. While it acknowledges the extreme value of Western critical theory in allowing tangata whenua to understand the relations of power and the effects of colonial domination, the programme also identifies the many voids and spaces within Western critical theory that leave unanswered the oppressiveness and hegemony of cultural and ideological colonisation. I conclude my thesis by arguing that, whilst many in leadership positions claim allegiance to Gramsci' s concept of the organic intellectual, their ideological stance is anything but organic. By examining why they do not represent indigenous interests "organically", I argue that a new concept is needed to expose the sham of much of our contemporary "inorganic" politics: that our cultural needs are better served by a concept of the "indigenous" intellectual.

year: 2002