title: Experimental investigation of timber-to-steel connection using self-drilling wing screws

authors: Mohanswamy, Gowrava

abstract: Self-drilling wing screws are well-suited for hardwood and pressed material boards and are explored as an alternative connector to traditional bolts for connecting thick hot-rolled steel with timber. The wing avoids force-feeding of the screw into the timber which prevents the timber from cracking. However, limited studies were found on the timber-to-steel connection using self-drilling wing screws under shear loading. This paper investigates the shear behaviour and capacity of self-drilling winged screw connections between radiata pine timber and hot rolled steel plate through the experimental test. In addition, tensile coupon tests, screw bending tests, moisture content tests, screw pullout tests, and screw bearing tests were performed to determine the material properties of the steel, timber, and screws. A total of 70 experimental tests were conducted on the timber to steel connection connections with different steel thicknesses (8mm-20mm), timber thickness (15mm-45mm), numbers of screws (1-3), and screw axis angle (45°-90°). The failure mode is theoretically analyzed using Johansen yield theory. The resulting data from Eurocode 5 [24] was compared with experimental results as current AS/NZ standards lack adequate guidance in addressing timber-to-steel connections. From the above comparison, it was found that the Eurocode 5 [24] was under-conservative by 90%. Based on the experimental results, new design equations for calculating the shear capacity of self-drilling winged screws are proposed.

text: Experimental investigation of timber-to-steel connection using self-drilling wing screws Self-drilling wing screws are well-suited for hardwood and pressed material boards and are explored as an alternative connector to traditional bolts for connecting thick hot-rolled steel with timber. The wing avoids force-feeding of the screw into the timber which prevents the timber from cracking. However, limited studies were found on the timber-to-steel connection using self-drilling wing screws under shear loading. This paper investigates the shear behaviour and capacity of self-drilling winged screw connections between radiata pine timber and hot rolled steel plate through the experimental test. In addition, tensile coupon tests, screw bending tests, moisture content tests, screw pullout tests, and screw bearing tests were performed to determine the material properties of the steel, timber, and screws. A total of 70 experimental tests were conducted on the timber to steel connection connections with different steel thicknesses (8mm-20mm), timber thickness (15mm-45mm), numbers of screws (1-3), and screw axis angle (45°-90°). The failure mode is theoretically analyzed using Johansen yield theory. The resulting data from Eurocode 5 [24] was compared with experimental results as current AS/NZ standards lack adequate guidance in addressing timber-to-steel connections. From the above comparison, it was found that the Eurocode 5 [24] was under-conservative by 90%. Based on the experimental results, new design equations for calculating the shear capacity of self-drilling winged screws are proposed.

year: 2024

title: The molecular basis of the effect of temperature on enzyme activity

authors: Daniel, Roy M.

subjects: adaptation

abstract: Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the twostate (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme’s catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

text: The molecular basis of the effect of temperature on enzyme activity Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the twostate (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme’s catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

year: 2010

title: Weaving Mātauranga Māori into climate change education with primary school students in New Zealand

authors: Jackson, Ryan

abstract: This thesis explores the integration of Indigenous knowledge, specifically mātauranga Māori, into climate change education for primary school children in Aotearoa (New Zealand). It engages with pūrākau (verbal narratives that encode knowledge) gifted by the local hapū (Rangitāne sub-tribe) to a kura (school). The study contributes to the growing body of research that addresses a gap in research and teaching practice, which, despite global calls for action, remains inconsistent in teaching at this age level or lacks direct curriculum guidance in Aotearoa.

The main question for this study was: In what ways can Rangitāne pūrākau engage and further the understanding of Year five and six ākonga (learners) in learning about climate change within a kura in the lower North Island of Aotearoa?

This research used a mix of different research methods to explore this question. A learning intervention wove a pūrākau, climate change concepts and kai (food) together to create a ten-week learning programme. This learning intervention was then implemented by a kaiako (teacher) with a group of 21 Year five and six ākonga. Data were collected using pre- and post-tests to assess what students learned during the learning intervention, a group interview with the ākonga to hear their voices in the study, and an interview with their kaiako to gain insights into how engaged the ākonga were, their opinion on their understandings, and how aspects of the intervention went.

Analysis of the findings shows that the use of pūrākau and other forms of mātauranga Māori helped ākonga connect deeply with the material, which contributed positively to their engagement and to them gaining a sound understanding of complex climate change concepts. The research suggests that presenting scientific information through a familiar cultural lens contributed to making the topic less confusing and easier for the ākonga to grasp. This approach not only helped to improve their understanding but also enhanced the mana of ākonga Māori and their connection to the whenua (the land).

This research has several main implications. The findings provide evidence that incorporating Indigenous knowledge has wider educational benefits in climate change education, supporting the body of research that states what works well for ākonga Māori works well for all learners. The research also highlighted the importance of the concept of ako, literally meaning ‘to teach and learn,’ as the kaiako showed strength in being able to learn alongside ākonga. The thesis supports the use of Indigenous knowledge systems such as pūrākau alongside Western knowledge systems to develop holistic learning experiences. A recommendation from this thesis is to further explore the development of a climate change education model, relevant to the context of Aotearoa, which would centralise Indigenous knowledge. This could be modelled in the form of a waka hourua (double hulled ocean voyaging canoe) with the tohunga (knowledge holder and expert) on board signifying the use of Indigenous knowledge systems, with narratives such as pūrākau, playing a part in climate change education.

text: Weaving Mātauranga Māori into climate change education with primary school students in New Zealand This thesis explores the integration of Indigenous knowledge, specifically mātauranga Māori, into climate change education for primary school children in Aotearoa (New Zealand). It engages with pūrākau (verbal narratives that encode knowledge) gifted by the local hapū (Rangitāne sub-tribe) to a kura (school). The study contributes to the growing body of research that addresses a gap in research and teaching practice, which, despite global calls for action, remains inconsistent in teaching at this age level or lacks direct curriculum guidance in Aotearoa.

The main question for this study was: In what ways can Rangitāne pūrākau engage and further the understanding of Year five and six ākonga (learners) in learning about climate change within a kura in the lower North Island of Aotearoa?

This research used a mix of different research methods to explore this question. A learning intervention wove a pūrākau, climate change concepts and kai (food) together to create a ten-week learning programme. This learning intervention was then implemented by a kaiako (teacher) with a group of 21 Year five and six ākonga. Data were collected using pre- and post-tests to assess what students learned during the learning intervention, a group interview with the ākonga to hear their voices in the study, and an interview with their kaiako to gain insights into how engaged the ākonga were, their opinion on their understandings, and how aspects of the intervention went.

Analysis of the findings shows that the use of pūrākau and other forms of mātauranga Māori helped ākonga connect deeply with the material, which contributed positively to their engagement and to them gaining a sound understanding of complex climate change concepts. The research suggests that presenting scientific information through a familiar cultural lens contributed to making the topic less confusing and easier for the ākonga to grasp. This approach not only helped to improve their understanding but also enhanced the mana of ākonga Māori and their connection to the whenua (the land).

This research has several main implications. The findings provide evidence that incorporating Indigenous knowledge has wider educational benefits in climate change education, supporting the body of research that states what works well for ākonga Māori works well for all learners. The research also highlighted the importance of the concept of ako, literally meaning ‘to teach and learn,’ as the kaiako showed strength in being able to learn alongside ākonga. The thesis supports the use of Indigenous knowledge systems such as pūrākau alongside Western knowledge systems to develop holistic learning experiences. A recommendation from this thesis is to further explore the development of a climate change education model, relevant to the context of Aotearoa, which would centralise Indigenous knowledge. This could be modelled in the form of a waka hourua (double hulled ocean voyaging canoe) with the tohunga (knowledge holder and expert) on board signifying the use of Indigenous knowledge systems, with narratives such as pūrākau, playing a part in climate change education.

year: 2025