title: Peptide synthesis with a proteinase from the extremely thermophilic organism Thermus Rt41A

authors: Wilson, Shelley-Ann

subjects: peptide synthesis

abstract: A proteinase isolated from Thermus RT41a was immobilized to controlled pore glass beads and was used in the free and immobilized forms for peptide synthesis. The observed maximum yield was the same in both cases. a number of dipeptides were produced from amino acid esters and amides. The best acyl components, from those tested, were found to be Ac-Phe-OEt and Bz-Ala-OMe. Tur-NH2, Trp-NH2, Leu-pNA, and Val-pNA were all reactive nucleophiles.The kinetically controlled synthesis of Bz-ala-Tyr-NH2 was optimized by studying the effect of pH, temperature, solvent concentration, ionic strength, and nucleophile and acyl donor concentration, ionic strength, and nucleophile and acyl donor concentration on the maximum yield. The initial conditions used were 25 mM Bz–ala-OMe, 25 mM Tyr-NH2, 70°C, pH 8.0, and 10% v/v dimethylformamide (DMF). The optimum conditions were 90% v/v DMF using 80 mM bz-Ala-OMe and 615 mM Tyr-NH2 at 40°C and pH 10. These conditions increased the maximum conversion from 0.75% to 26% (of the original ester concentration). In a number of other cosolvents, the best peptide yields were observed with acetonitrile and ethyl acetate. In 90% acetonitrile similar yields were observed to those in 90% DMF under optimized conditions except that the acyl donor and nucleophile concentrations could be reduced to 25 mM and 100mM, respectively. The effect of the blocking group on the nucleophile was also investigated; -βNA and -pNA as blocking groups improved the yields markedly. The blocking and leaving groups of the acyldonor had no effect on the dipeptide yield.

text: Peptide synthesis with a proteinase from the extremely thermophilic organism Thermus Rt41A A proteinase isolated from Thermus RT41a was immobilized to controlled pore glass beads and was used in the free and immobilized forms for peptide synthesis. The observed maximum yield was the same in both cases. a number of dipeptides were produced from amino acid esters and amides. The best acyl components, from those tested, were found to be Ac-Phe-OEt and Bz-Ala-OMe. Tur-NH2, Trp-NH2, Leu-pNA, and Val-pNA were all reactive nucleophiles.The kinetically controlled synthesis of Bz-ala-Tyr-NH2 was optimized by studying the effect of pH, temperature, solvent concentration, ionic strength, and nucleophile and acyl donor concentration, ionic strength, and nucleophile and acyl donor concentration on the maximum yield. The initial conditions used were 25 mM Bz–ala-OMe, 25 mM Tyr-NH2, 70°C, pH 8.0, and 10% v/v dimethylformamide (DMF). The optimum conditions were 90% v/v DMF using 80 mM bz-Ala-OMe and 615 mM Tyr-NH2 at 40°C and pH 10. These conditions increased the maximum conversion from 0.75% to 26% (of the original ester concentration). In a number of other cosolvents, the best peptide yields were observed with acetonitrile and ethyl acetate. In 90% acetonitrile similar yields were observed to those in 90% DMF under optimized conditions except that the acyl donor and nucleophile concentrations could be reduced to 25 mM and 100mM, respectively. The effect of the blocking group on the nucleophile was also investigated; -βNA and -pNA as blocking groups improved the yields markedly. The blocking and leaving groups of the acyldonor had no effect on the dipeptide yield.

year: 1994

title: Microstructure and mechanical properties of large size as-cast Ti-43Al-9V-0.2Y (at.%) alloy ingot from brim to centre

authors: Kong, Fantao

subjects: Intermetallics

abstract: A Ti-43Al-9V-0.2Y (at.%) alloy ingot with the size of Ф160×400mm was prepared by vacuum arc remelting (VAR). The microstructure of the as-cast Ti-43Al-9V-0.2Y alloy was composed of B2/α₂/γ lamellar colonies and massive B2 and γ phases which were distributed along the boundaries of these lamellar colonies in the form of equiaxed grains. Based on the grain size variation along the radius direction of the ingot, the ingot could be divided into four ring regions from brim to centre. It has been understood that the grain size variation between these four regions was due to the interplay of the effects of the cooling rate and the yttrium content on solidified microstructures in these regions. Mechanical testing of the samples cut from these four regions showed that there existed a clear correlation between the yield strength and the average grain sizes of the four ring regions, which approximately conformed to a Hall-Petch relationship.

text: Microstructure and mechanical properties of large size as-cast Ti-43Al-9V-0.2Y (at.%) alloy ingot from brim to centre A Ti-43Al-9V-0.2Y (at.%) alloy ingot with the size of Ф160×400mm was prepared by vacuum arc remelting (VAR). The microstructure of the as-cast Ti-43Al-9V-0.2Y alloy was composed of B2/α₂/γ lamellar colonies and massive B2 and γ phases which were distributed along the boundaries of these lamellar colonies in the form of equiaxed grains. Based on the grain size variation along the radius direction of the ingot, the ingot could be divided into four ring regions from brim to centre. It has been understood that the grain size variation between these four regions was due to the interplay of the effects of the cooling rate and the yttrium content on solidified microstructures in these regions. Mechanical testing of the samples cut from these four regions showed that there existed a clear correlation between the yield strength and the average grain sizes of the four ring regions, which approximately conformed to a Hall-Petch relationship.

year: 2011

title: He raraunga inamata, he toronga ānamata, he huanga āke tonu atu: A multifaceted approach to improving quality of life for upper limb amputees

authors: August, Luke

subjects: Prosthesis

abstract: This thesis investigates innovative approaches to enhance the quality of life for upper limb amputees, integrating advanced prosthetic design, neurocontrol systems, and Māori knowledge systems. With the prevalence of prosthetic rejection and limitations in current designs affecting amputees' daily functionality and psychological well-being, a multifaceted strategy is essential. This research aims to address these challenges by improving prosthetic functionality, user control mechanisms, and incorporating cultural perspectives into prosthetic development.
The study first focuses on the design, development, and evaluation of four low-cost prosthetic hands. Assessing their Degrees of Freedom (DoF), Range of Motion (RoM), and Kapandji scores. The research proposes a novel hybrid coupled-tendon system. This system aims to combine the adaptability of underactuated designs with the precision control of coupled mechanisms, enhancing the prosthetic hands' functionality and grasp versatility.
In exploring control mechanisms, an EEG-based control system was developed to improve the intuitiveness of prosthetic control. Through comparative analysis of motor execution and action observation training regimes, facilitated by a digital twin, the study evaluates the efficacy of these methods in enhancing users' control over the prosthetics. The research identifies limitations in the classification of multiple active grasps and suggests potential improvements through augmented and virtual reality training environments. 
This thesis incorporates Māori perspectives by examining how mātauranga Māori can inform and enrich prosthetic design and usage. Through the analysis of pūrākau Māori, this work highlights the importance of considering the mauri, whakapapa of materials in prosthetic manufacturing and the implications of tapu on control systems. This inclusion aims to create culturally resonant devices that acknowledge and integrate the spiritual and cultural dimensions of the user's identity, offering a holistic approach to prosthetic development.
This interdisciplinary research contributes to the field by proposing a comprehensive framework that not only advances prosthetic technology but also aligns with cultural values and practices. By addressing the technical, psychological, and cultural needs of upper limb amputees, the project underscores the potential of combining engineering innovation with cultural wisdom to significantly improve amputees' autonomy and well-being. The findings advocate for a more inclusive and holistic approach to prosthetic development, emphasizing the importance of user-centric design and cultural competency in enhancing the quality of life for individuals with limb loss.

text: He raraunga inamata, he toronga ānamata, he huanga āke tonu atu: A multifaceted approach to improving quality of life for upper limb amputees This thesis investigates innovative approaches to enhance the quality of life for upper limb amputees, integrating advanced prosthetic design, neurocontrol systems, and Māori knowledge systems. With the prevalence of prosthetic rejection and limitations in current designs affecting amputees' daily functionality and psychological well-being, a multifaceted strategy is essential. This research aims to address these challenges by improving prosthetic functionality, user control mechanisms, and incorporating cultural perspectives into prosthetic development.
The study first focuses on the design, development, and evaluation of four low-cost prosthetic hands. Assessing their Degrees of Freedom (DoF), Range of Motion (RoM), and Kapandji scores. The research proposes a novel hybrid coupled-tendon system. This system aims to combine the adaptability of underactuated designs with the precision control of coupled mechanisms, enhancing the prosthetic hands' functionality and grasp versatility.
In exploring control mechanisms, an EEG-based control system was developed to improve the intuitiveness of prosthetic control. Through comparative analysis of motor execution and action observation training regimes, facilitated by a digital twin, the study evaluates the efficacy of these methods in enhancing users' control over the prosthetics. The research identifies limitations in the classification of multiple active grasps and suggests potential improvements through augmented and virtual reality training environments. 
This thesis incorporates Māori perspectives by examining how mātauranga Māori can inform and enrich prosthetic design and usage. Through the analysis of pūrākau Māori, this work highlights the importance of considering the mauri, whakapapa of materials in prosthetic manufacturing and the implications of tapu on control systems. This inclusion aims to create culturally resonant devices that acknowledge and integrate the spiritual and cultural dimensions of the user's identity, offering a holistic approach to prosthetic development.
This interdisciplinary research contributes to the field by proposing a comprehensive framework that not only advances prosthetic technology but also aligns with cultural values and practices. By addressing the technical, psychological, and cultural needs of upper limb amputees, the project underscores the potential of combining engineering innovation with cultural wisdom to significantly improve amputees' autonomy and well-being. The findings advocate for a more inclusive and holistic approach to prosthetic development, emphasizing the importance of user-centric design and cultural competency in enhancing the quality of life for individuals with limb loss.

year: 2024