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High pressure polymer science : routes to drug delivery
Get PDFThe area of high pressure is receiving great attention and being used to study a range of materials including metals, minerals, energetic materials and pharmaceuticals. Polymers are being increasingly used in pharmaceutical and biomedical applications. The main reason behind this is their physico-chemical characteristics that can be tuned to suit different applications. These characteristics can differ in different forms of the same compound. These forms can be obtained by different techniques including high pressure (Chapter 1).;The work presented in this thesis has used high pressure techniques, including diamond anvil cells (DACs) and large volume press cell, to investigate pharmaceutical polymers and a model active pharmaceutical ingredient (ibuprofen). The change of materials under pressure was studied by in-situ Raman spectroscopy (Chapter 2). The first challenge faced in this project was fluorescence, which hinders Raman spectroscopy.;Surface enhanced Raman spectroscopy (SERS) technique was adopted to improve the signal and overcome fluorescence. This was achieved successfully on weak Raman scattering amino acids and fluorescent polymers (Chapter 3). A range of commonly used polymers were studied under high pressure in DAC. Poly glycolic acid (PGA) and poly lactic acid (PLA) exhibited a similar phenomenon of moving from crystalline or semi-crystalline into a less ordered form between 4-5 GPa. Ethylcellulose (EC) and hydroxypropyl methylcellulose (HPMC) demonstrated a similar change at about 2-3 GPa (Chapter 4).;Both EC and HPMC were used as a platform for sustained release dosage forms in different ratios with ibuprofen. These formulations were mixed using resonant acoustic mixing technique and subjected to high pressure (0.8 GPa) before being tested for drug release. The change in release patterns was mainly caused by the pressure transmitting medium (PTM) rather than the application of pressure (Chapter 5). Individual formulation components were used as received powders, treated by PTM at ambient pressure and subjected to 0.8 GPa before exploring their flowability.;The PTM treatment and pressure has increased the flow function of polymers but not ibuprofen. The formulation blends were tested for flowability in powder and ambient pressure forms. Unlike individual components, the treated blends exhibited a decrease in flow function and increase in cohesion (Chapter 6).;Overall, this thesis demonstrates that the application of pressure, using DACs, on commonly used polymers in pharmaceutical applications does help in inducing phase transitions at different pressures. Adapting SERS technique has been successful in overcoming fluorescence in polymers and improving Raman signal in weakly scattering amino acids. The application of pressure, using large volume press, did not have a significant effect on release pattern of APIs from the tested formulations.;The change was mainly due to the pressure transmitting medium. The effect of pressure was tested on powder flowability and found to increase polymers flowability but not ibuprofen.The area of high pressure is receiving great attention and being used to study a range of materials including metals, minerals, energetic materials and pharmaceuticals. Polymers are being increasingly used in pharmaceutical and biomedical applications. The main reason behind this is their physico-chemical characteristics that can be tuned to suit different applications. These characteristics can differ in different forms of the same compound. These forms can be obtained by different techniques including high pressure (Chapter 1).;The work presented in this thesis has used high pressure techniques, including diamond anvil cells (DACs) and large volume press cell, to investigate pharmaceutical polymers and a model active pharmaceutical ingredient (ibuprofen). The change of materials under pressure was studied by in-situ Raman spectroscopy (Chapter 2). The first challenge faced in this project was fluorescence, which hinders Raman spectroscopy.;Surface enhanced Raman spectroscopy (SERS) technique was adopted to improve the signal and overcome fluorescence. This was achieved successfully on weak Raman scattering amino acids and fluorescent polymers (Chapter 3). A range of commonly used polymers were studied under high pressure in DAC. Poly glycolic acid (PGA) and poly lactic acid (PLA) exhibited a similar phenomenon of moving from crystalline or semi-crystalline into a less ordered form between 4-5 GPa. Ethylcellulose (EC) and hydroxypropyl methylcellulose (HPMC) demonstrated a similar change at about 2-3 GPa (Chapter 4).;Both EC and HPMC were used as a platform for sustained release dosage forms in different ratios with ibuprofen. These formulations were mixed using resonant acoustic mixing technique and subjected to high pressure (0.8 GPa) before being tested for drug release. The change in release patterns was mainly caused by the pressure transmitting medium (PTM) rather than the application of pressure (Chapter 5). Individual formulation components were used as received powders, treated by PTM at ambient pressure and subjected to 0.8 GPa before exploring their flowability.;The PTM treatment and pressure has increased the flow function of polymers but not ibuprofen. The formulation blends were tested for flowability in powder and ambient pressure forms. Unlike individual components, the treated blends exhibited a decrease in flow function and increase in cohesion (Chapter 6).;Overall, this thesis demonstrates that the application of pressure, using DACs, on commonly used polymers in pharmaceutical applications does help in inducing phase transitions at different pressures. Adapting SERS technique has been successful in overcoming fluorescence in polymers and improving Raman signal in weakly scattering amino acids. The application of pressure, using large volume press, did not have a significant effect on release pattern of APIs from the tested formulations.;The change was mainly due to the pressure transmitting medium. The effect of pressure was tested on powder flowability and found to increase polymers flowability but not ibuprofen
Mitigating the erosion of transient stability margins in Great Britain through novel wind farm control techniques
Get PDFThe predominant North-to-South active power flow across the border between Scotland and England has historically been limited by system stability considerations. As the penetration of variable-speed wind power plants in Great Britain grows (reducing the generation share of traditional synchronous generation), it is imperative that stability limits, operational flexibility, efficiency and system security are not unduly eroded as a result. The studies reported in this thesis illustrate the impacts on critical fault clearing times and active power transfer limits through this North-South corridor, known as the B6 boundary, in the presence of increasing penetrations of wind power generation on the GB transmission system. By focussing on the transient behaviour of a representative reduced test system following a three-phase short-circuit fault occurring on one of the two double-circuits constituting the B6 boundary, the impacts on the transient stability margins are qualitatively identified. There is a pressing necessity for new wind farms to be able to mitigate, as much as possible, their own negative impacts on system stability margins. The transient stability improvement achieved by tailoring the low voltage ride-through reactive power control response of wind farms is first investigated, and a novel control technique is then presented which can significantly mitigate the erosion of the transient stability performance of power systems, in the presence of in-creasing amounts of wind power, by tailoring the immediate post-fault active power recovery ramp-rates of the wind power plants around the system. The impacts of these control techniques on critical fault clearing times and power transfer limits are investigated. In particular, it has been found that the use of slower active power recovery from wind farms located in exporting regions when a short circuit fault occurs on the export corridor will provide significant benefits for both of these metrics, while a faster active power recovery in importing regions will provide a similar transient stability benefit. However, it is also shown that there are potential detrimental effects for system frequency stability. In addition, important impacts of wind farm settings in respect of low voltage ride through are revealed whereby the LVRT controls can act to erode stability margins if careful consideration of their settings is not taken. Assuming a future power system with high levels of centralised observability and controllability (or decentralised co-operative control systems), it may be possible to continually “dispatch” the reactive power gains and active power recovery ramp rates discussed in this thesis to match the current system setpoint and to seek an optimal transient response to a range of credible contingencies.The predominant North-to-South active power flow across the border between Scotland and England has historically been limited by system stability considerations. As the penetration of variable-speed wind power plants in Great Britain grows (reducing the generation share of traditional synchronous generation), it is imperative that stability limits, operational flexibility, efficiency and system security are not unduly eroded as a result. The studies reported in this thesis illustrate the impacts on critical fault clearing times and active power transfer limits through this North-South corridor, known as the B6 boundary, in the presence of increasing penetrations of wind power generation on the GB transmission system. By focussing on the transient behaviour of a representative reduced test system following a three-phase short-circuit fault occurring on one of the two double-circuits constituting the B6 boundary, the impacts on the transient stability margins are qualitatively identified. There is a pressing necessity for new wind farms to be able to mitigate, as much as possible, their own negative impacts on system stability margins. The transient stability improvement achieved by tailoring the low voltage ride-through reactive power control response of wind farms is first investigated, and a novel control technique is then presented which can significantly mitigate the erosion of the transient stability performance of power systems, in the presence of in-creasing amounts of wind power, by tailoring the immediate post-fault active power recovery ramp-rates of the wind power plants around the system. The impacts of these control techniques on critical fault clearing times and power transfer limits are investigated. In particular, it has been found that the use of slower active power recovery from wind farms located in exporting regions when a short circuit fault occurs on the export corridor will provide significant benefits for both of these metrics, while a faster active power recovery in importing regions will provide a similar transient stability benefit. However, it is also shown that there are potential detrimental effects for system frequency stability. In addition, important impacts of wind farm settings in respect of low voltage ride through are revealed whereby the LVRT controls can act to erode stability margins if careful consideration of their settings is not taken. Assuming a future power system with high levels of centralised observability and controllability (or decentralised co-operative control systems), it may be possible to continually “dispatch” the reactive power gains and active power recovery ramp rates discussed in this thesis to match the current system setpoint and to seek an optimal transient response to a range of credible contingencies
Evaluation of a custom made anatomical guide for orthognathic surgery
Get PDFOrthognathic surgery is a routinely used surgical technique for the correction of dento-facial deformities. During a Le Fort I orthognathic procedure the maxilla is surgically separated from the skull and the surgical positioning wafer is placed between the occlusal surfaces of the upper and lower dentition. However, the physiological response to general aesthesia results in loss of muscle tone in the mandible, which has a profound influence on the correct amount of maxillary advancement required. The expertise and visual judgement of the surgeon is relied upon to foresee and eliminate this potential source of error. However, this may not be possible to achieve in all cases, therefore there is a need for a device to guide the surgical position of the maxilla independent of the mandibular dentition. The aim of this study was to design and validate a custom made anatomical repositioning surgical framework for accurately repositioning the maxilla independently of the mandible during a Le Fort I osteotomy. A single plastic anatomical skull was scanned using a helical Computed Tomography (CT) scanner. Utilising 3D manipulation software, forty-three Le Fort I orthognathic surgery movements were planned. A custom made anatomical repositioning guide was designed and 3D printed for all movements. Each guide was used to reposition the maxilla of the physical skull and then laser scanned using a GOM blue light scanner. GOMinspect software was used to compare the planned and physical position of the repositioned maxilla. The results of the experiment were statistically evaluated.Orthognathic surgery is a routinely used surgical technique for the correction of dento-facial deformities. During a Le Fort I orthognathic procedure the maxilla is surgically separated from the skull and the surgical positioning wafer is placed between the occlusal surfaces of the upper and lower dentition. However, the physiological response to general aesthesia results in loss of muscle tone in the mandible, which has a profound influence on the correct amount of maxillary advancement required. The expertise and visual judgement of the surgeon is relied upon to foresee and eliminate this potential source of error. However, this may not be possible to achieve in all cases, therefore there is a need for a device to guide the surgical position of the maxilla independent of the mandibular dentition. The aim of this study was to design and validate a custom made anatomical repositioning surgical framework for accurately repositioning the maxilla independently of the mandible during a Le Fort I osteotomy. A single plastic anatomical skull was scanned using a helical Computed Tomography (CT) scanner. Utilising 3D manipulation software, forty-three Le Fort I orthognathic surgery movements were planned. A custom made anatomical repositioning guide was designed and 3D printed for all movements. Each guide was used to reposition the maxilla of the physical skull and then laser scanned using a GOM blue light scanner. GOMinspect software was used to compare the planned and physical position of the repositioned maxilla. The results of the experiment were statistically evaluated
Partial discharge denoising for power cables
Get PDFPartial discharge (PD) diagnostics is considered a major and effective tool for the monitoring of insulating conditions of power cables. As such, a large amount of off-line or online PD measurements have been deployed in power cables during the past decades. However, challenges still exist in PD diagnostics for power cables. Noise is one of the challenges involved in PD measurement. This thesis develops new algorithms based on the characteristics of both PD signals and noise to improve the effectiveness of wavelet-based PD denoising. In the meantime, it presents new findings in the application of empirical mode decomposition (EMD) in PD denoising. Wavelet-based technique has received high attention in the area of PD denoising, it still faces challenges, however, in wavelet selection, decomposition scale determination, and noise estimation. It is therefore the first area of interest in this thesis to improve the effectiveness of existing wavelet-based technique in PD detection by incorporating proposed algorithms. These new algorithms were developed based on the difference of entropy between transformed PD signals and noise, and the sparsity of transformed PD signals corrupted by noise. One concern commonly expressed by critics of wavelet-based technique is a pre-defined wavelet is applied in wavelet-based technique. EMD is an algorithm that can decompose a signal based on the signal itself. Thus, the second area of interest in this thesis is to further investigate the application of EMD in PD denoising; a technique that does not require the selection of a pre-defined signal to represent the "unknown" signal of interest. A new method for relative mode selection (RMS) was proposed based on the entropy of each intrinsic mode function (IMF). Although this new method cannot outperform the existing ones, it reveals that RMS is not as important as claimed in the application of EMD in signal denoising. Also, PD signals, especially those with lower magnitudes, can receive serious distortion through EMD-based denoising. Finally, comparisons between wavelet-based and EMD-based denoising were implemented in the following aspects, i.e., executing time, distortion, effectiveness, adaptivity and robustness. Results unveil that improved wavelet-based technique is more preferable as it can present better performance in PD denoising.Partial discharge (PD) diagnostics is considered a major and effective tool for the monitoring of insulating conditions of power cables. As such, a large amount of off-line or online PD measurements have been deployed in power cables during the past decades. However, challenges still exist in PD diagnostics for power cables. Noise is one of the challenges involved in PD measurement. This thesis develops new algorithms based on the characteristics of both PD signals and noise to improve the effectiveness of wavelet-based PD denoising. In the meantime, it presents new findings in the application of empirical mode decomposition (EMD) in PD denoising. Wavelet-based technique has received high attention in the area of PD denoising, it still faces challenges, however, in wavelet selection, decomposition scale determination, and noise estimation. It is therefore the first area of interest in this thesis to improve the effectiveness of existing wavelet-based technique in PD detection by incorporating proposed algorithms. These new algorithms were developed based on the difference of entropy between transformed PD signals and noise, and the sparsity of transformed PD signals corrupted by noise. One concern commonly expressed by critics of wavelet-based technique is a pre-defined wavelet is applied in wavelet-based technique. EMD is an algorithm that can decompose a signal based on the signal itself. Thus, the second area of interest in this thesis is to further investigate the application of EMD in PD denoising; a technique that does not require the selection of a pre-defined signal to represent the "unknown" signal of interest. A new method for relative mode selection (RMS) was proposed based on the entropy of each intrinsic mode function (IMF). Although this new method cannot outperform the existing ones, it reveals that RMS is not as important as claimed in the application of EMD in signal denoising. Also, PD signals, especially those with lower magnitudes, can receive serious distortion through EMD-based denoising. Finally, comparisons between wavelet-based and EMD-based denoising were implemented in the following aspects, i.e., executing time, distortion, effectiveness, adaptivity and robustness. Results unveil that improved wavelet-based technique is more preferable as it can present better performance in PD denoising
Adoption of preassembled building services components in Saudi Arabia: consultants' and contractors' influence
Get PDFThis thesis was previously held under moratorium from 20th August 2019 until 20th August 2024.In general, the applications of preassembled building services components (PBSC) are limited. These applications provide several advantages for stakeholders, including project delivery. Project delivery has been highlighted as a difficulty in project construction within several contexts, including that of Saudi Arabia. Such PBSC are deemed new technologies that require consideration by practitioners and users; therefore, the theory of planned behaviour (TPB) is employed in this research. This study explores consultant and contractor influence on using PBSC in complex office developments within Saudi Arabia. Methodologically, an exploratory mixed-methods approach is employed as a research design. By applying the TPB, this research explores consultant and contractor perceptions, stakeholder influence on the decision (subjective norms (SN)), and the external contextual control on the decision (perceived behavioural control (PBC)). This exploration predicts the behaviour of consultants and contractors regarding using PBSC in complex office developments. Semi-structured interviews (N=15) were developed based on the TPB to explore the context. Then, the transcriptions of these interviews were analysed using grounded theory to build propositions that assisted in constructing a questionnaire instrument. A self-administered survey questionnaire was developed as a primary research method, including a sample of 338 consultants and 323 contractors who were randomly selected (response rate ≈ 38%). Descriptive analysis, ordinal regression, and t-Tests were used for the quantitative data analysis. The results reveal that respondents have a significant intention to use PBSC in complex office development. The majority of these applications include prefabricated vertical and horizontal distribution and terminal unit preassembly. Three case studies were site-visited to confirm the validity of the final adopted model of this research. Consequently, the results reveal that the top three benefits identified are as follows: the quality of the products, the speed of the project, and the reduction in the construction cost. It is worth noting that PBSC applications include certain challenges, such as the reduction of design flexibility, the limitation of making changes onsite, and the need for extra preparatory work. The stakeholder influence on decisions includes those of the client, consultants, and regulators. Moreover, the external contextual behaviour that controls decision-making includes financial support, government regulations, and manufacturing capacity. The reasons that prevent non-practitioners from using PBSC include the increase of the overall project cost, the increase in risk, and the limitation of design flexibility. Consequently, several recommendations are proposed, including the need for further research to assess strategies to promote the adoption of PBSC in complex office developments, as well as the enhancement of the role of subcontractors through these strategies to professionally assist the PBSC marketplace. This study provides client guidance to help practitioners to better understand the key factors that affect consultant and contractor use of PBSC in complex office developments.In general, the applications of preassembled building services components (PBSC) are limited. These applications provide several advantages for stakeholders, including project delivery. Project delivery has been highlighted as a difficulty in project construction within several contexts, including that of Saudi Arabia. Such PBSC are deemed new technologies that require consideration by practitioners and users; therefore, the theory of planned behaviour (TPB) is employed in this research. This study explores consultant and contractor influence on using PBSC in complex office developments within Saudi Arabia. Methodologically, an exploratory mixed-methods approach is employed as a research design. By applying the TPB, this research explores consultant and contractor perceptions, stakeholder influence on the decision (subjective norms (SN)), and the external contextual control on the decision (perceived behavioural control (PBC)). This exploration predicts the behaviour of consultants and contractors regarding using PBSC in complex office developments. Semi-structured interviews (N=15) were developed based on the TPB to explore the context. Then, the transcriptions of these interviews were analysed using grounded theory to build propositions that assisted in constructing a questionnaire instrument. A self-administered survey questionnaire was developed as a primary research method, including a sample of 338 consultants and 323 contractors who were randomly selected (response rate ≈ 38%). Descriptive analysis, ordinal regression, and t-Tests were used for the quantitative data analysis. The results reveal that respondents have a significant intention to use PBSC in complex office development. The majority of these applications include prefabricated vertical and horizontal distribution and terminal unit preassembly. Three case studies were site-visited to confirm the validity of the final adopted model of this research. Consequently, the results reveal that the top three benefits identified are as follows: the quality of the products, the speed of the project, and the reduction in the construction cost. It is worth noting that PBSC applications include certain challenges, such as the reduction of design flexibility, the limitation of making changes onsite, and the need for extra preparatory work. The stakeholder influence on decisions includes those of the client, consultants, and regulators. Moreover, the external contextual behaviour that controls decision-making includes financial support, government regulations, and manufacturing capacity. The reasons that prevent non-practitioners from using PBSC include the increase of the overall project cost, the increase in risk, and the limitation of design flexibility. Consequently, several recommendations are proposed, including the need for further research to assess strategies to promote the adoption of PBSC in complex office developments, as well as the enhancement of the role of subcontractors through these strategies to professionally assist the PBSC marketplace. This study provides client guidance to help practitioners to better understand the key factors that affect consultant and contractor use of PBSC in complex office developments
Understanding working class orientations towards higher education - a qualitative study of education decision making practice
Get PDFThis thesis investigates the experiences of a group of working-class pupils as they experience educational-decision making in post-compulsory education. It focuses on a cohort of 28 pupils, identified as being the highest-attaining within a school with historically low-progression rates to Higher Education. The study presents the findings of an in-depth sociological study which investigates the ways in which these young people orientate and navigate towards post-school destinations. Based on emerging ideas from social practice theory, this study adopts a methodological approach which considers the multi-sited nature of post-16 choices.;The study explores how senior management responded to both policy to increase academic performance, and to localised and contextualised practice at the site in which temporal and historic community understandings of schooling and employment persist. Within these arrangements, the study focuses on the experiences of a close friendship group of ten pupils as they explore possibilities to study at university.;Using methods of interviews, group discussions, participant observation and forms of actionable research (St John, 2013), the study identifies senior management strategies to support academic progress and considers pupil alignment towards academic engagement. It shows the extent to which activities need to be brokered at the site in order for pupils to access a more privileged existence in Higher Education. It also shows the extent to which this involves a collective negotiation of practice by pupils and their close networks as they participate in activities to support successful applications.;The thesis suggests that in the neglect of adequate explorations of working-class pupil experiences, current policy and interventions to address this issue maintain a focus on the individual, and fail to grasp effectively the more complex reproductive and transformative processes within peer groups, schools and community cultures. The thesis concludes by outlining several suggestions for future research and policy in this area.This thesis investigates the experiences of a group of working-class pupils as they experience educational-decision making in post-compulsory education. It focuses on a cohort of 28 pupils, identified as being the highest-attaining within a school with historically low-progression rates to Higher Education. The study presents the findings of an in-depth sociological study which investigates the ways in which these young people orientate and navigate towards post-school destinations. Based on emerging ideas from social practice theory, this study adopts a methodological approach which considers the multi-sited nature of post-16 choices.;The study explores how senior management responded to both policy to increase academic performance, and to localised and contextualised practice at the site in which temporal and historic community understandings of schooling and employment persist. Within these arrangements, the study focuses on the experiences of a close friendship group of ten pupils as they explore possibilities to study at university.;Using methods of interviews, group discussions, participant observation and forms of actionable research (St John, 2013), the study identifies senior management strategies to support academic progress and considers pupil alignment towards academic engagement. It shows the extent to which activities need to be brokered at the site in order for pupils to access a more privileged existence in Higher Education. It also shows the extent to which this involves a collective negotiation of practice by pupils and their close networks as they participate in activities to support successful applications.;The thesis suggests that in the neglect of adequate explorations of working-class pupil experiences, current policy and interventions to address this issue maintain a focus on the individual, and fail to grasp effectively the more complex reproductive and transformative processes within peer groups, schools and community cultures. The thesis concludes by outlining several suggestions for future research and policy in this area
Contextualising social enterprise : hybrid entrepreneuring in the creative industries
Get PDFThe electronic version of this thesis was previously held under moratorium between 15 May 2020 and 27 January 2022.Social enterprise provides a foundation for community-based organisations that aim to address local and societal issues through mission-centred and income-generating activities. Theoretical interest in social enterprise continues to grow across many fields of academic inquiry, including within entrepreneurship. In practice, social enterprise has also emerged, with some abundance, within bordering economic sectors, such as the creative industries. However, despite this intersectoral rise, there is a gap in knowledge around the emergence of a creative social enterprise (CSE) phenomenon. The thesis explores the hybrid space between social enterprise and the creative industries in the Scottish landscape and focuses on the emergence of hybrid entrepreneuring within the creative industries, as experienced by creative practitioners building creative social enterprises. This study seeks to explore the landscape of Scotland's creative social enterprises and investigate how they utilise hybridity to navigate the marginal position between the two institutional and economic fields. The research aims involve exploring the impact of creative social enterprise on those practitioners who create them; identifying how CSEs develop strategies;understanding how CSEs engage in their broader networks and environments;investigating the institutional environments affecting the emergence of creative socialenterprises; and discovering the experiences of creative practitioners and their processes of engagement with their hybrid contexts. The creative industries and social enterprise sectors are essential to the growth of Scotland's economy (CreativeScotland, 2016a; Scottish Government, 2016b; Skills Development Scotland, 2015; Social Value Lab, 2017; The Scottish Government, 2015), though, conventionally, they are considered as separate sectors. The thesis draws from sociological studies of entrepreneurship (Granovetter, 1985; Thornton, 1999) to develop the theoretical and contextual landscape of the study around a hybrid institutional context. The context also builds on prior studies of hybridity (Battilana and Dorado, 2010; Doherty et al., 2014; Rushton, 2014; Santos et al., 2015) as a critical domain for exploring the phenomenon of CSEs. An embedded, social constructionist approach is employed for understanding the phenomenological experiences of creative practitioners developing social enterprises. The approach involves the use of a reflexive methodology, which embraces the embedded nature of the research journey and encourages a co-creative research process between researcher and participants. Key findings position hybrid entrepreneurial practice as a viable way for creative practitioners to build their social enterprises at the margins of institutional contexts and identify hybrid entrepreneuring as a primary resource in navigating behaviours to generate an interflow of hybrid value-actors within a hybrid organisation. The research study provides value to the field of entrepreneurship by elucidating the experiences of alternative types of entrepreneurial activity within a hybrid institutional context, which has implications for how industry practitioners understand their organisational processes and how institutional stakeholders may engage in the development of new organisational structures.Social enterprise provides a foundation for community-based organisations that aim to address local and societal issues through mission-centred and income-generating activities. Theoretical interest in social enterprise continues to grow across many fields of academic inquiry, including within entrepreneurship. In practice, social enterprise has also emerged, with some abundance, within bordering economic sectors, such as the creative industries. However, despite this intersectoral rise, there is a gap in knowledge around the emergence of a creative social enterprise (CSE) phenomenon. The thesis explores the hybrid space between social enterprise and the creative industries in the Scottish landscape and focuses on the emergence of hybrid entrepreneuring within the creative industries, as experienced by creative practitioners building creative social enterprises. This study seeks to explore the landscape of Scotland's creative social enterprises and investigate how they utilise hybridity to navigate the marginal position between the two institutional and economic fields. The research aims involve exploring the impact of creative social enterprise on those practitioners who create them; identifying how CSEs develop strategies;understanding how CSEs engage in their broader networks and environments;investigating the institutional environments affecting the emergence of creative socialenterprises; and discovering the experiences of creative practitioners and their processes of engagement with their hybrid contexts. The creative industries and social enterprise sectors are essential to the growth of Scotland's economy (CreativeScotland, 2016a; Scottish Government, 2016b; Skills Development Scotland, 2015; Social Value Lab, 2017; The Scottish Government, 2015), though, conventionally, they are considered as separate sectors. The thesis draws from sociological studies of entrepreneurship (Granovetter, 1985; Thornton, 1999) to develop the theoretical and contextual landscape of the study around a hybrid institutional context. The context also builds on prior studies of hybridity (Battilana and Dorado, 2010; Doherty et al., 2014; Rushton, 2014; Santos et al., 2015) as a critical domain for exploring the phenomenon of CSEs. An embedded, social constructionist approach is employed for understanding the phenomenological experiences of creative practitioners developing social enterprises. The approach involves the use of a reflexive methodology, which embraces the embedded nature of the research journey and encourages a co-creative research process between researcher and participants. Key findings position hybrid entrepreneurial practice as a viable way for creative practitioners to build their social enterprises at the margins of institutional contexts and identify hybrid entrepreneuring as a primary resource in navigating behaviours to generate an interflow of hybrid value-actors within a hybrid organisation. The research study provides value to the field of entrepreneurship by elucidating the experiences of alternative types of entrepreneurial activity within a hybrid institutional context, which has implications for how industry practitioners understand their organisational processes and how institutional stakeholders may engage in the development of new organisational structures
Phytochemical and biological investigation of Lathyrus linofilius as a possible treatment in diabesity
Get PDFPreviously held under moratorium from 10 February 2020 until 10 February 2022Diabetes is a world-wide issue which can affect people at any age. It is ranked as oneof the top 10 diseases responsible for death worldwide. According to the InternationalDiabetes Federation, 424.9 million people worldwide were estimated to have diabetesin 2017 (90% with type 2 diabetes) and this number is projected to reach 629 millionpatients by 2045. The current treatments for managing diabetes are linked with anumber of side effects including severe hypoglycaemia, permanent neurologicaldeficit, stomach-ache, headache, lactic acidosis, liver damage, dizziness and death insome cases. Therefore, there is a need for improved anti-diabetic drugs with fewer sideeffects to enhance patient compliance and to control blood glucose levels more tightly.Natural products and plants in particular, offer an alternative to syntheticdrugs. Lathyrus linifolius is a plant whose tubers have historically been used as anappetite suppressant during medieval times in times when food was scarce. Due to theclose link between appetite suppressants and the treatment of diabetes/obesity, theplant’s leaves and tubers were examined for their potential anti-diabetic and antiobesity activity.This project aimed to: 1) produce Lathyrus linifolius extracts using Soxhlet apparatusextraction from which bioactive compounds could be isolated by columnchromatography and characterised by nuclear magnetic resonance (NMR); 2) assessthe anti-diabetic and anti-obesity activity of the extracts and compounds; 3) investigatethe anti-inflammatory and anti-oxidant activity of the extracts and compounds in invitro assays; 4) identify the effects of the tuber treatment on the gene expression ofappropriate diabesity components in normal rat pancreatic tissues obtained from aprevious study in which rats were fed with tubers; and 5) re-assess Lathyrus linifoliuseffects on obese Zucker rats and monitor the effects on body weight, food intake, waterintake and blood glucose levels.1) Four compounds were isolated for the first time from the ethyl acetate extract of thetubers; these were betulinic acid, lupeol, stigmasterol and β-sitosterol. The isolatedcompounds are known for their beneficial effects on hyperglycaemia and obesity tosome extent. Betulinic acid was the major component in the tubers and leaves.2) In biological assays, the ethyl acetate extract and betulinic acid from the tubers werepotent α-glucosidase inhibitors (P<0.05) with IC50 of 9.5 µg/ml and 5.5 µM,respectively. Moreover, the leaf ethyl acetate and methanol extracts were also stronginhibitors of α-glucosidase (P<0.05) with IC50 of 0.58 µg/ml and 4.3 µg/ml,respectively. In an anti-obesity assay, based on pancreatic lipase, the ethyl acetatetuber extract at 30 µg/ml and betulinic acid at 30 µM showed 50% enzymeinhibition (P<0.05); and the hexane extract from the leaves showed 30% inhibition. InHepG2 cells, leaf hexane extract showed a significant increase in glucose uptake whichwas comparable to that of insulin. These findings showed promising results for theplant to be used as an anti-diabetic and anti-obesity agent. Inflammation and oxidativestress are implicated in diabesity and determined the subsequent investigation.3) Moreover, all the plant extracts and isolated compounds at 30 µg/ml or 30 µMshowed a greater than 70% protection (P<0.05) in L929 cells (mouse fibroblastscommonly used for anti-inflammatory studies) from the cytotoxic effects of tumournecrosis factor alpha (10 µM). This was followed by investigating the ability ofLathyrus linifolius to inhibit nuclear factor kappa-light-chain-enhancer of activated Bcells (NF-ƙB) in the NCTC cell line (human skin cells transfected with a NF-ƙBluciferase reporter vector, used in anti-inflammatory studies). Betulinic acid, ethylacetate extract of the tubers, hexane and ethyl acetate extracts of the leaves inhibitedNF-ƙB which gave a NF-ƙB % inhibition of 70, 40, 30 and 30, respectively. Abetulinic acid inhibition curve was performed and found to inhibit NF-ƙB expressionwith an IC50 of 22.8 µM. Oxidative stress was then investigated following the positivefindings in the anti-inflammatory assays. Lathyrus linifolius extracts and isolatedcompounds were not reactive oxygen species-generators and significantly (P<0.05)protected cells from reactive oxygen species generated by tert-butyl hydroperoxide inSH-SY5Y (neuronal), HepG2 (hepatic) and Panc1 (pancreatic) cells, except lupeol inHepG2 cells. In HepG2 cells, glutathione levels were significantly (P<0.05) increasedby ethyl acetate extract of the tubers which confirmed the potential anti-oxidantactivity of Lathyrus linifolius.4) It was considered pertinent to carry out a retrospective investigation into any genechanges using RNA-Sequencing and real-time quantitative polymerase chain reaction(RT-qPCR) on RNA isolated from rat pancreatic tissues in a feeding study withLathyrus linifolius tubers carried out by Woods (2017). It was found that theadiponectin gene (Adipoq) was highly up-regulated (P<0.05) whereas genes thatcontribute to pancreatic β-cells damage for example Il1β and Tnfrsf19 were downregulated (P<0.05).5) Then, the biological effects of Lathyrus linifolius on an animal model for diabesitywere followed up. Dried, powdered Lathyrus linifolius tubers (100-200 mg/kg BW)were dissolved in deionised water, mixed with Farley’s rusks and given to obeseZucker rats daily for 16 days. However, the results showed that there were no effectson the body weight, food intake, water intake or blood glucose of Zucker rats and thismay have occurred due to the low Lathyrus linifolius dosage used and the shortduration of the study. It was decided not to carry out any further investigation (such asRNA- Sequencing) after this as there was no significant difference in results betweenthe obese Zucker rats and normal rats as observed in the previous feed study.These findings suggest that compounds from Lathyrus linifolius could possibly be usedas anti-diabetic and anti-obesity agents in the future, based on the positive resultsobtained from the in vitro and ex vivo assays in this study. This study should befollowed by assessing the effects of Lathyrus linifolius on body weight, food intake,water intake and blood glucose in humans.Diabetes is a world-wide issue which can affect people at any age. It is ranked as oneof the top 10 diseases responsible for death worldwide. According to the InternationalDiabetes Federation, 424.9 million people worldwide were estimated to have diabetesin 2017 (90% with type 2 diabetes) and this number is projected to reach 629 millionpatients by 2045. The current treatments for managing diabetes are linked with anumber of side effects including severe hypoglycaemia, permanent neurologicaldeficit, stomach-ache, headache, lactic acidosis, liver damage, dizziness and death insome cases. Therefore, there is a need for improved anti-diabetic drugs with fewer sideeffects to enhance patient compliance and to control blood glucose levels more tightly.Natural products and plants in particular, offer an alternative to syntheticdrugs. Lathyrus linifolius is a plant whose tubers have historically been used as anappetite suppressant during medieval times in times when food was scarce. Due to theclose link between appetite suppressants and the treatment of diabetes/obesity, theplant’s leaves and tubers were examined for their potential anti-diabetic and antiobesity activity.This project aimed to: 1) produce Lathyrus linifolius extracts using Soxhlet apparatusextraction from which bioactive compounds could be isolated by columnchromatography and characterised by nuclear magnetic resonance (NMR); 2) assessthe anti-diabetic and anti-obesity activity of the extracts and compounds; 3) investigatethe anti-inflammatory and anti-oxidant activity of the extracts and compounds in invitro assays; 4) identify the effects of the tuber treatment on the gene expression ofappropriate diabesity components in normal rat pancreatic tissues obtained from aprevious study in which rats were fed with tubers; and 5) re-assess Lathyrus linifoliuseffects on obese Zucker rats and monitor the effects on body weight, food intake, waterintake and blood glucose levels.1) Four compounds were isolated for the first time from the ethyl acetate extract of thetubers; these were betulinic acid, lupeol, stigmasterol and β-sitosterol. The isolatedcompounds are known for their beneficial effects on hyperglycaemia and obesity tosome extent. Betulinic acid was the major component in the tubers and leaves.2) In biological assays, the ethyl acetate extract and betulinic acid from the tubers werepotent α-glucosidase inhibitors (P<0.05) with IC50 of 9.5 µg/ml and 5.5 µM,respectively. Moreover, the leaf ethyl acetate and methanol extracts were also stronginhibitors of α-glucosidase (P<0.05) with IC50 of 0.58 µg/ml and 4.3 µg/ml,respectively. In an anti-obesity assay, based on pancreatic lipase, the ethyl acetatetuber extract at 30 µg/ml and betulinic acid at 30 µM showed 50% enzymeinhibition (P<0.05); and the hexane extract from the leaves showed 30% inhibition. InHepG2 cells, leaf hexane extract showed a significant increase in glucose uptake whichwas comparable to that of insulin. These findings showed promising results for theplant to be used as an anti-diabetic and anti-obesity agent. Inflammation and oxidativestress are implicated in diabesity and determined the subsequent investigation.3) Moreover, all the plant extracts and isolated compounds at 30 µg/ml or 30 µMshowed a greater than 70% protection (P<0.05) in L929 cells (mouse fibroblastscommonly used for anti-inflammatory studies) from the cytotoxic effects of tumournecrosis factor alpha (10 µM). This was followed by investigating the ability ofLathyrus linifolius to inhibit nuclear factor kappa-light-chain-enhancer of activated Bcells (NF-ƙB) in the NCTC cell line (human skin cells transfected with a NF-ƙBluciferase reporter vector, used in anti-inflammatory studies). Betulinic acid, ethylacetate extract of the tubers, hexane and ethyl acetate extracts of the leaves inhibitedNF-ƙB which gave a NF-ƙB % inhibition of 70, 40, 30 and 30, respectively. Abetulinic acid inhibition curve was performed and found to inhibit NF-ƙB expressionwith an IC50 of 22.8 µM. Oxidative stress was then investigated following the positivefindings in the anti-inflammatory assays. Lathyrus linifolius extracts and isolatedcompounds were not reactive oxygen species-generators and significantly (P<0.05)protected cells from reactive oxygen species generated by tert-butyl hydroperoxide inSH-SY5Y (neuronal), HepG2 (hepatic) and Panc1 (pancreatic) cells, except lupeol inHepG2 cells. In HepG2 cells, glutathione levels were significantly (P<0.05) increasedby ethyl acetate extract of the tubers which confirmed the potential anti-oxidantactivity of Lathyrus linifolius.4) It was considered pertinent to carry out a retrospective investigation into any genechanges using RNA-Sequencing and real-time quantitative polymerase chain reaction(RT-qPCR) on RNA isolated from rat pancreatic tissues in a feeding study withLathyrus linifolius tubers carried out by Woods (2017). It was found that theadiponectin gene (Adipoq) was highly up-regulated (P<0.05) whereas genes thatcontribute to pancreatic β-cells damage for example Il1β and Tnfrsf19 were downregulated (P<0.05).5) Then, the biological effects of Lathyrus linifolius on an animal model for diabesitywere followed up. Dried, powdered Lathyrus linifolius tubers (100-200 mg/kg BW)were dissolved in deionised water, mixed with Farley’s rusks and given to obeseZucker rats daily for 16 days. However, the results showed that there were no effectson the body weight, food intake, water intake or blood glucose of Zucker rats and thismay have occurred due to the low Lathyrus linifolius dosage used and the shortduration of the study. It was decided not to carry out any further investigation (such asRNA- Sequencing) after this as there was no significant difference in results betweenthe obese Zucker rats and normal rats as observed in the previous feed study.These findings suggest that compounds from Lathyrus linifolius could possibly be usedas anti-diabetic and anti-obesity agents in the future, based on the positive resultsobtained from the in vitro and ex vivo assays in this study. This study should befollowed by assessing the effects of Lathyrus linifolius on body weight, food intake,water intake and blood glucose in humans
Cost of energy optimisation of offshore wind turbine pmg drive trains based on uncertainty
Get PDFOffshore wind is a constantly evolving industry as the demand for clean renewable sources of energy continues to grow globally. The cost of energy (COE) is measure of the cost per unit of energy supplied by a provider over the lifetime of a project. Methods in which to reduce this cost are always a priority for parties involved in the design, installation and operation of a wind farm. This thesis explores the contribution of wind turbine drive train design and optimisation in the reduction of COE whilst providing a review of the most sensitive design parameters.Chapters 1 and 2 provide the background to the COE calculation for offshore wind turbines and introduces some of the key issues with current models and challenges for creating reliable designs. Chapter 3 outlines the COE model methodology and introduces base case results for 4 different drive trains with permanent magnet generators (three geared designs and one direct drive topology without a gearbox). Chapter 4 provides an optimisation process based on a genetic algorithm to allow the design to be improved whilst considering several constraints. Chapter 5 looks at the optimised designs under different price input conditions to assess the impact on the COE. Chapter 6 introduces the concepts of robust optimisation and optimisation under uncertainty to account for price variability associated with material used in the drive train.This thesis provides a novel approach to drive train optimisation whilst accounting for price uncertainty. The study highlights the key vulnerabilities for a design under material price fluctuations and presents design processes which include uncertainty and provide robust solutions for various drive train topologies.The effect of drive train design and optimisation suggests that direct drive topologies (that do not have a gearbox) can offer the lowest COE solutions. This is primarily due to the increase in reliability achieved by eradicating the failures associated with wind turbine gearboxes. This result supports current trends observed in large offshore wind turbines where many of the installed >6MW machines are direct drive permanent magnet generators. Additionally, a well-designed drive train has the potential to reduce the COE by up to 15% as discussed in this thesis.Offshore wind is a constantly evolving industry as the demand for clean renewable sources of energy continues to grow globally. The cost of energy (COE) is measure of the cost per unit of energy supplied by a provider over the lifetime of a project. Methods in which to reduce this cost are always a priority for parties involved in the design, installation and operation of a wind farm. This thesis explores the contribution of wind turbine drive train design and optimisation in the reduction of COE whilst providing a review of the most sensitive design parameters.Chapters 1 and 2 provide the background to the COE calculation for offshore wind turbines and introduces some of the key issues with current models and challenges for creating reliable designs. Chapter 3 outlines the COE model methodology and introduces base case results for 4 different drive trains with permanent magnet generators (three geared designs and one direct drive topology without a gearbox). Chapter 4 provides an optimisation process based on a genetic algorithm to allow the design to be improved whilst considering several constraints. Chapter 5 looks at the optimised designs under different price input conditions to assess the impact on the COE. Chapter 6 introduces the concepts of robust optimisation and optimisation under uncertainty to account for price variability associated with material used in the drive train.This thesis provides a novel approach to drive train optimisation whilst accounting for price uncertainty. The study highlights the key vulnerabilities for a design under material price fluctuations and presents design processes which include uncertainty and provide robust solutions for various drive train topologies.The effect of drive train design and optimisation suggests that direct drive topologies (that do not have a gearbox) can offer the lowest COE solutions. This is primarily due to the increase in reliability achieved by eradicating the failures associated with wind turbine gearboxes. This result supports current trends observed in large offshore wind turbines where many of the installed >6MW machines are direct drive permanent magnet generators. Additionally, a well-designed drive train has the potential to reduce the COE by up to 15% as discussed in this thesis
The transnational chains of super-exploitation in the 21st century : the experiences of Haitian workers in Brazil
Get PDFPreviously held under moratorium from 9th November 2019 until 26th August 2024.This thesis discusses the super-exploitation of Haitian workers in Brazil. It refers to the emerging patterns of south-south migration and the incorporation of international migrant labour into the strategies for economic development in the Global South. The study makes an innovative contribution to the conceptualisation of super-exploitation in contemporary capitalism, particularly in relation to the field of social reproduction.
The concept of super-exploitation has been a theoretical alternative to northern centric conceptual frameworks of employment relations and its relationship with strategies for economic development in the Global South. The conventional definition is that super-exploitation drives the wages of workers below the amount necessary for their social reproduction. While this argument is technically correct, the literature has under-theorized the way in which super-exploitation has occurred in Southern countries and how international migration represents a new chapter in the expansion of super-exploitation. This thesis argues that the definition of super-exploitation can be refined by a better understanding of the social composition of the workforce in these countries, in other words, by understanding the specific historical and contextual conditions which shape the social reproduction of super-exploited workers.
This thesis, therefore, aims to re-conceptualise super-exploitation by exploring the multidimensional dynamics and the patterns of social reproduction it assumes in the experiences of a particular group of workers, migrants from Haiti in Brazil. Forty-two semi-structured interviews were collected with Haitian migrants in Brazil and analysed alongside immigration and labour market statistics. Three key themes emerged from those interviews and were organised into three chapters: citizenship, transnational network relations and employment. Findings showed that Haitians are super-exploited in Brazil because their social reproduction is over-determined by a constellation of political-citizenship and community/networking relationships which, although crucial for the survival of Haitians, contribute to their subordination to super-exploitation. Therefore, super-exploitation can be defined more accurately as a combination of economic and non-economic forces that entangle productive-reproductive-exploitative relationships, thereby shaping the dependence of workers on wages below the value necessary for their social reproduction. In showing these entanglements, this study offers a better understanding of how south-south migration relates to the emerging forms of labour exploitation in the 21st century in Latin America.This thesis discusses the super-exploitation of Haitian workers in Brazil. It refers to the emerging patterns of south-south migration and the incorporation of international migrant labour into the strategies for economic development in the Global South. The study makes an innovative contribution to the conceptualisation of super-exploitation in contemporary capitalism, particularly in relation to the field of social reproduction.
The concept of super-exploitation has been a theoretical alternative to northern centric conceptual frameworks of employment relations and its relationship with strategies for economic development in the Global South. The conventional definition is that super-exploitation drives the wages of workers below the amount necessary for their social reproduction. While this argument is technically correct, the literature has under-theorized the way in which super-exploitation has occurred in Southern countries and how international migration represents a new chapter in the expansion of super-exploitation. This thesis argues that the definition of super-exploitation can be refined by a better understanding of the social composition of the workforce in these countries, in other words, by understanding the specific historical and contextual conditions which shape the social reproduction of super-exploited workers.
This thesis, therefore, aims to re-conceptualise super-exploitation by exploring the multidimensional dynamics and the patterns of social reproduction it assumes in the experiences of a particular group of workers, migrants from Haiti in Brazil. Forty-two semi-structured interviews were collected with Haitian migrants in Brazil and analysed alongside immigration and labour market statistics. Three key themes emerged from those interviews and were organised into three chapters: citizenship, transnational network relations and employment. Findings showed that Haitians are super-exploited in Brazil because their social reproduction is over-determined by a constellation of political-citizenship and community/networking relationships which, although crucial for the survival of Haitians, contribute to their subordination to super-exploitation. Therefore, super-exploitation can be defined more accurately as a combination of economic and non-economic forces that entangle productive-reproductive-exploitative relationships, thereby shaping the dependence of workers on wages below the value necessary for their social reproduction. In showing these entanglements, this study offers a better understanding of how south-south migration relates to the emerging forms of labour exploitation in the 21st century in Latin America
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