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Characterization of inducible antibiotic production by streptomycetes isolated from hyper-arid environments
No full textAntimicrobial resistance is a major threat to the future of human society with 10 million deaths projected in 2050. However, the search for new antimicrobials faces a setback in the rediscovery of the already known antibiotics. One strategy to mitigate this problem is the study of isolates from extreme environments, e.g. the Atacama Desert in Chile, adapted to those conditions and potentially encoding new specialised metabolites. Another method is to employ a multi-approach strategy for the discovery and elucidation of new metabolites combining genomics and metabolomics.;This research project employed bioactivity assays, whole-genome analysis and metabolomics to determine the antibiotic potential from bioassays, identification of potential biosynthetic gene clusters and the elucidation of the compounds(s) responsible for the activity. Fourteen strains, closely related to Streptomyces phaeoluteigriseus by 16S rRNA, were isolated from two locations 30 km apart with similar altitude from the Atacama Desert. Further to taxonomic similarity the isolates showed also observable similarities, e.g. soluble pigment, despite inhabiting different locations.;However, differential growth inhibition of several indicator strains, e.g. Staphylococcus aureus and Enterococcus faecalis was observed between isolates of both locations. Furthermore, phenotypic analysis and hyper-spectral imaging revealed hidden diversity of the isolates. Whole-genome analysis contradicted the phylogenetic relationship observed using 16S rRNA. Unique inter and intraspecific variations between isolates emerged with two distinct clades forming, revealing the possibility of soil 7 isolates to be a new species.;Additionally, highly diverse plasmid profiles were observed instead of phages suggesting that the observed unique variations could result from horizontal gene transfer. Antibacterial activity was observed in solid and liquid cultures, especially in isolates from soil 7. Mass spectrometry analysis helped identify cinerubin B and unknown congeners of actinomycin (MW 1307.552). The latter were produced in large quantity by PH2 8 and further scale-up fermentation allowed the purification of an anti-E. faecalis metabolite.;Actinomycin Y1 was its main constituent however further purification is required due to its low purity. In this study, the potential of the Atacama Desert to promote genetic and metabolomic diversification of closely evolutionary strains by niche specific pressures leading to production of known and, most importantly, bioactive metabolite production was demonstrated.Antimicrobial resistance is a major threat to the future of human society with 10 million deaths projected in 2050. However, the search for new antimicrobials faces a setback in the rediscovery of the already known antibiotics. One strategy to mitigate this problem is the study of isolates from extreme environments, e.g. the Atacama Desert in Chile, adapted to those conditions and potentially encoding new specialised metabolites. Another method is to employ a multi-approach strategy for the discovery and elucidation of new metabolites combining genomics and metabolomics.;This research project employed bioactivity assays, whole-genome analysis and metabolomics to determine the antibiotic potential from bioassays, identification of potential biosynthetic gene clusters and the elucidation of the compounds(s) responsible for the activity. Fourteen strains, closely related to Streptomyces phaeoluteigriseus by 16S rRNA, were isolated from two locations 30 km apart with similar altitude from the Atacama Desert. Further to taxonomic similarity the isolates showed also observable similarities, e.g. soluble pigment, despite inhabiting different locations.;However, differential growth inhibition of several indicator strains, e.g. Staphylococcus aureus and Enterococcus faecalis was observed between isolates of both locations. Furthermore, phenotypic analysis and hyper-spectral imaging revealed hidden diversity of the isolates. Whole-genome analysis contradicted the phylogenetic relationship observed using 16S rRNA. Unique inter and intraspecific variations between isolates emerged with two distinct clades forming, revealing the possibility of soil 7 isolates to be a new species.;Additionally, highly diverse plasmid profiles were observed instead of phages suggesting that the observed unique variations could result from horizontal gene transfer. Antibacterial activity was observed in solid and liquid cultures, especially in isolates from soil 7. Mass spectrometry analysis helped identify cinerubin B and unknown congeners of actinomycin (MW 1307.552). The latter were produced in large quantity by PH2 8 and further scale-up fermentation allowed the purification of an anti-E. faecalis metabolite.;Actinomycin Y1 was its main constituent however further purification is required due to its low purity. In this study, the potential of the Atacama Desert to promote genetic and metabolomic diversification of closely evolutionary strains by niche specific pressures leading to production of known and, most importantly, bioactive metabolite production was demonstrated
Modelling of MMC-HVDC system for EMT study
Get PDFThe modular multilevel converter (MMC) technology has been a subject of increasing importance for high voltage direct current (HVDC) systems due to its technical advantages in terms of scalability, performance and efficiency. There are already several MMC-HVDC projects in construction and operation worldwide. Offline and real-time simulations of MMC-HVDC systems prior to project construction are important for both power system operators and electrical equipment suppliers. In electromagnetic-transients (EMT) simulations, significant simulation challenges are brought by MMC-HVDC systems since a large number of sub-modules (SMs) in each MMC have to be simulated individually. Therefore, a detailed investigation on MMC-HVDC modelling methods is of great theoretical and engineering values.;In this thesis, the half-bridge (HB) MMC offline (PSCAD) and real-time (RSCAD) models with adjustable number of SMs per arm with generic and customized control functions are developed using different MMC modelling methods, namely, detailed switching, switching function, Thevenin equivalent and averaged models. The developed models are validated against benchmark models from PSCAD software libraries for accuracy during steady-steady operation, and AC and DC short circuit faults. Simulation efficiencies of different HB-MMC models are compared for offline PSCAD simulation. The comprehensive comparison of the offline simulation waveforms proves that the averaged and switching function HB-MMC models produce largely identical results as those from the Thevenin equivalent MMC model in the PSCAD MMC library, but with much greater simulation efficiency.;In this thesis, interoperability of different MMC topologies, namely, the HB, full-bridge (FB) and hybrid MMCs are assessed quantitatively. Based on the aforementioned modelling methods, FB and hybrid MMC simulation models are developed and validated. Offline and real-time three-terminal DC grid models closely resembling the Caithness-Morey-Shetland HVDC system are developed to investigate DC grid power flow control during steady-state and AC faults. Interoperability of different MMC topologies in the DC grid is assessed quantitatively using offline PSCAD and real-time RSCAD simulations.;Furthermore, a frequency-domain small-signal impedance measurement tool in RSCAD is presented to extract the impedances of MMC and connected AC networks for stability assessment. The scenario of a simplified GB AC network connected to an MMC is provided in RSCAD for real-time simulation use. Focusing on grid-connected converter system, the effect of AC cables and MMC time-domain modelling methods on their impedance are investigated. Through impedance measurement and comparison, it has been found that the different time-domain modelling methods of MMC have no significant effect on the impedance of the MMC. Since most frequency-domain analysis for MMC is based on the averaged model, this conclusion provides a theoretical basis for the frequency-domain MMC modelling research.The modular multilevel converter (MMC) technology has been a subject of increasing importance for high voltage direct current (HVDC) systems due to its technical advantages in terms of scalability, performance and efficiency. There are already several MMC-HVDC projects in construction and operation worldwide. Offline and real-time simulations of MMC-HVDC systems prior to project construction are important for both power system operators and electrical equipment suppliers. In electromagnetic-transients (EMT) simulations, significant simulation challenges are brought by MMC-HVDC systems since a large number of sub-modules (SMs) in each MMC have to be simulated individually. Therefore, a detailed investigation on MMC-HVDC modelling methods is of great theoretical and engineering values.;In this thesis, the half-bridge (HB) MMC offline (PSCAD) and real-time (RSCAD) models with adjustable number of SMs per arm with generic and customized control functions are developed using different MMC modelling methods, namely, detailed switching, switching function, Thevenin equivalent and averaged models. The developed models are validated against benchmark models from PSCAD software libraries for accuracy during steady-steady operation, and AC and DC short circuit faults. Simulation efficiencies of different HB-MMC models are compared for offline PSCAD simulation. The comprehensive comparison of the offline simulation waveforms proves that the averaged and switching function HB-MMC models produce largely identical results as those from the Thevenin equivalent MMC model in the PSCAD MMC library, but with much greater simulation efficiency.;In this thesis, interoperability of different MMC topologies, namely, the HB, full-bridge (FB) and hybrid MMCs are assessed quantitatively. Based on the aforementioned modelling methods, FB and hybrid MMC simulation models are developed and validated. Offline and real-time three-terminal DC grid models closely resembling the Caithness-Morey-Shetland HVDC system are developed to investigate DC grid power flow control during steady-state and AC faults. Interoperability of different MMC topologies in the DC grid is assessed quantitatively using offline PSCAD and real-time RSCAD simulations.;Furthermore, a frequency-domain small-signal impedance measurement tool in RSCAD is presented to extract the impedances of MMC and connected AC networks for stability assessment. The scenario of a simplified GB AC network connected to an MMC is provided in RSCAD for real-time simulation use. Focusing on grid-connected converter system, the effect of AC cables and MMC time-domain modelling methods on their impedance are investigated. Through impedance measurement and comparison, it has been found that the different time-domain modelling methods of MMC have no significant effect on the impedance of the MMC. Since most frequency-domain analysis for MMC is based on the averaged model, this conclusion provides a theoretical basis for the frequency-domain MMC modelling research
A qualitative multi-method study to explore the relevance of Benner's 'novice to expert' nursing theory in contemporary post-registration wound care higher education
Get PDFAIM: The aim of this thesis is to explore the relevance of Benner's 1984 five-stage 'novice to expert' nursing theory of skills acquisition and development in post-registration wound care nursing higher education in one institute in south west Scotland.;BACKGROUND: Since 1984, the fundamental assertions and learning and teaching strategies associated with each stage of Benner's theory have continued to inform pre- and post-registration wound care nursing education. However, in the last four decades, numerous influential governmental, political, economic, regulatory and practice policy developments have taken place and indications suggest that Benner's theory may now no longer best serve the unique needs of wound care education and that use of this approach to curriculum development would benefit from review.;METHOD: Through the prism of advocacy-participatory research, a qualitative sequential multi-method research design was used to review Benner's theory in three distinct phases. First, a critical analysis of the effects of policy discourse on education and practice was undertaken, followed by a directed investigation to identify particular characteristics of regular everyday wound care practices able to enlighten curriculum design. Finally, the thesis moves to understand how incorporating the informed and deliberated views of students themselves in theory development itself might benefit future provision.;FINDINGS: The findings challenge many of Benner's original assertions and uncover deficiencies in contemporary approaches to curriculum design thought to contribute to the extensive unacceptable levels of variation and inequitable standards in patient wound care. Ambiguity is inherent in wound care and, although undesirable and thought to compromise professional accountability, it is an intrinsic and essential feature for practitioners to manage the extremely unpredictable nature of such care. As an adjunct to the learning and teaching strategies associated with Benner's theory and an alternative to standardising and loading the curriculum, it should be accepted that, in wound care, there are never enough resources and information that is available to direct practice is often inconclusive or incomplete. Learning should therefore instead develop particular cognitive, meta-cognitive and attitudinal skills for practitioners to arrive at the 'best answer' possible by adapting Wood's 'build-bridge-extend' (BBE) approach to the wound care context.;CONCLUSIONS: Benner's theory no longer adequately characterises wound care education provision and should be developed to represent the influences of policy, practice and student voices.AIM: The aim of this thesis is to explore the relevance of Benner's 1984 five-stage 'novice to expert' nursing theory of skills acquisition and development in post-registration wound care nursing higher education in one institute in south west Scotland.;BACKGROUND: Since 1984, the fundamental assertions and learning and teaching strategies associated with each stage of Benner's theory have continued to inform pre- and post-registration wound care nursing education. However, in the last four decades, numerous influential governmental, political, economic, regulatory and practice policy developments have taken place and indications suggest that Benner's theory may now no longer best serve the unique needs of wound care education and that use of this approach to curriculum development would benefit from review.;METHOD: Through the prism of advocacy-participatory research, a qualitative sequential multi-method research design was used to review Benner's theory in three distinct phases. First, a critical analysis of the effects of policy discourse on education and practice was undertaken, followed by a directed investigation to identify particular characteristics of regular everyday wound care practices able to enlighten curriculum design. Finally, the thesis moves to understand how incorporating the informed and deliberated views of students themselves in theory development itself might benefit future provision.;FINDINGS: The findings challenge many of Benner's original assertions and uncover deficiencies in contemporary approaches to curriculum design thought to contribute to the extensive unacceptable levels of variation and inequitable standards in patient wound care. Ambiguity is inherent in wound care and, although undesirable and thought to compromise professional accountability, it is an intrinsic and essential feature for practitioners to manage the extremely unpredictable nature of such care. As an adjunct to the learning and teaching strategies associated with Benner's theory and an alternative to standardising and loading the curriculum, it should be accepted that, in wound care, there are never enough resources and information that is available to direct practice is often inconclusive or incomplete. Learning should therefore instead develop particular cognitive, meta-cognitive and attitudinal skills for practitioners to arrive at the 'best answer' possible by adapting Wood's 'build-bridge-extend' (BBE) approach to the wound care context.;CONCLUSIONS: Benner's theory no longer adequately characterises wound care education provision and should be developed to represent the influences of policy, practice and student voices
Development of atomic magnetometry towards unshielded sensors
Get PDFThis thesis describes experiments in double-resonance magnetometry with aview to the development of future portable magnetic sensors. Two experimental setups - shielded and unshielded - are described, as well as design choicesthat facilitate scalability to compact, portable sensors. This work includes several techniques to mitigate noise or otherwise improve sensitivity. Maintaining the sensitivity of the device has been prioritised while incorporating miniaturised components, and a sensitivity of 2 pT/√ Hz has been achieved in the unshielded environment. Additionally, the bandwidth of the sensor has been found to be 520 Hz. An iterative optimisation routine for the improvement of field homogeneity produced by static field coils is presented, aswell as procedures for the characterisation of microfabricated atomic vapour cells. A technique to address periodic noise has been developed and has successfully suppressed noise arising from the 50 Hz mains AC line, with 22 dB noise suppression achieved between 45 and 55 Hz. Two magnetic gradiometry configurations are also discussed, and preliminary results presented, with an outlook to further development.This thesis describes experiments in double-resonance magnetometry with aview to the development of future portable magnetic sensors. Two experimental setups - shielded and unshielded - are described, as well as design choicesthat facilitate scalability to compact, portable sensors. This work includes several techniques to mitigate noise or otherwise improve sensitivity. Maintaining the sensitivity of the device has been prioritised while incorporating miniaturised components, and a sensitivity of 2 pT/√ Hz has been achieved in the unshielded environment. Additionally, the bandwidth of the sensor has been found to be 520 Hz. An iterative optimisation routine for the improvement of field homogeneity produced by static field coils is presented, aswell as procedures for the characterisation of microfabricated atomic vapour cells. A technique to address periodic noise has been developed and has successfully suppressed noise arising from the 50 Hz mains AC line, with 22 dB noise suppression achieved between 45 and 55 Hz. Two magnetic gradiometry configurations are also discussed, and preliminary results presented, with an outlook to further development
Responsive temperature and pressure sensor design for in-situ prosthesis monitoring applications based on the piezoelectric and pyroelectric effects in lead zirconate titanate
Get PDFThis thesis presents the development of a sensor based on the pyroelectric and piezoelectric effects that can be used to measure both temperature and/or axial stress for specific use within a prosthetic socket, and more generally as a responsive temperature sensor capable of detecting high frequency skin temperature oscillations in medical diagnostic applications. Knowledge of an amputees' residual limb skin temperature is considered to be of particular importance as an indicator of tissue health. With this in mind, a prototype wearable sensor for real-time temperature measurement at the skin/prosthetic socket/liner interface was developed and measurements that provide a proof of concept are presented. The sensor exploits the large pyroelectric effect present in ferroelectric lead zirconate titanate {cedil}{9D}{91}{83}{cedil}{9D}{91}{8F}{cedil}{9D}{91}{joiner}{cedil}{9D}{91}{9F}{cedil}{9D}{91}{AElig}({cedil}{9D}{91}{87}{cedil}{9D}{91}{96}(1{acute}{88}{92}{cedil}{9D}{91}{AElig}){cedil}{9D}{91}{82}3) (PZT) and has several inherent advantages over other methods of temperature sensing. The sensor element chosen is a low cost commercially available diaphragm PZT-5H element with a brass substrate. While the development of the sensor concentrates on the specific application of surface temperature measurement, the mathematical models developed also describe the sensor response to an applied axial stress that can be used as a measure of the pressure applied to the residual limb by the confinement of a prosthetic socket. Using the mathematical models, substrate clamping was found to significantly increase the effective pyroelectric coefficient. A subsequent experimentally obtained value for the effective pyroelectric coefficient was found to be very close to the value predicted by the mathematical models, confirming the effect of substrate clamping. Immittance models are developed to investigate the temperature dependence of the sensor element immittance, mechanical and constant strain electrical capacitances over the temperature range 20{phono}{mllhring}C to 40{phono}{mllhring}C. Both capacitances were found to be significantly temperature dependent and therefore charge-mode signal conditioning was chosen to mitigate temperature effects on the signal-conditioning response. Subsequent response measurements were found to yield a linear response over the temperature range of interest. Bipolar and unipolar charge amplifier designs are developed and built to provide signal-conditioning for use in sensor response measurements. The unipolar type is a single supply 5V prototype with low power consumption and is also designed for use with an e-Health platform in a wearable sensor configuration. In addition, a single supply enhanced open loop gain design that mitigates the effect of reduced dielectric resistance in the sensor element is presented.;Using the developed mathematical models, the sensor is predicted to be capable of measuring frequencies from DC up to 6.8rads{acute}{88}{92}1 with a rise time to the 98% peak of 0.12s and 0.18s for a DC and 6.8rads{acute}{88}{92}1 step, respectively. However, the use of a polymer liner between the sensor element and measurement surface is found to severely limit the usable frequency response of the sensor due to severe amplitude and phase distortion, precluding direct use of the sensor to measure skin surface temperature. Being relevant to the safety of remote e-Health monitoring, the challenges ICT networks must face to maintain quality of service are discussed and it is shown that an increasing amount of traffic, increasing power consumption and electronic bottlenecks are three main challenges that require a solution. The ability of ICT networks to satisfy the growing global demand for data is under threat due to the speed limitations of current CMOS based electronic technologies, leading to electronic bottlenecks and threats to the sustainability of the quality of service critically required for e-Health monitoring.This thesis presents the development of a sensor based on the pyroelectric and piezoelectric effects that can be used to measure both temperature and/or axial stress for specific use within a prosthetic socket, and more generally as a responsive temperature sensor capable of detecting high frequency skin temperature oscillations in medical diagnostic applications. Knowledge of an amputees' residual limb skin temperature is considered to be of particular importance as an indicator of tissue health. With this in mind, a prototype wearable sensor for real-time temperature measurement at the skin/prosthetic socket/liner interface was developed and measurements that provide a proof of concept are presented. The sensor exploits the large pyroelectric effect present in ferroelectric lead zirconate titanate {cedil}{9D}{91}{83}{cedil}{9D}{91}{8F}{cedil}{9D}{91}{joiner}{cedil}{9D}{91}{9F}{cedil}{9D}{91}{AElig}({cedil}{9D}{91}{87}{cedil}{9D}{91}{96}(1{acute}{88}{92}{cedil}{9D}{91}{AElig}){cedil}{9D}{91}{82}3) (PZT) and has several inherent advantages over other methods of temperature sensing. The sensor element chosen is a low cost commercially available diaphragm PZT-5H element with a brass substrate. While the development of the sensor concentrates on the specific application of surface temperature measurement, the mathematical models developed also describe the sensor response to an applied axial stress that can be used as a measure of the pressure applied to the residual limb by the confinement of a prosthetic socket. Using the mathematical models, substrate clamping was found to significantly increase the effective pyroelectric coefficient. A subsequent experimentally obtained value for the effective pyroelectric coefficient was found to be very close to the value predicted by the mathematical models, confirming the effect of substrate clamping. Immittance models are developed to investigate the temperature dependence of the sensor element immittance, mechanical and constant strain electrical capacitances over the temperature range 20{phono}{mllhring}C to 40{phono}{mllhring}C. Both capacitances were found to be significantly temperature dependent and therefore charge-mode signal conditioning was chosen to mitigate temperature effects on the signal-conditioning response. Subsequent response measurements were found to yield a linear response over the temperature range of interest. Bipolar and unipolar charge amplifier designs are developed and built to provide signal-conditioning for use in sensor response measurements. The unipolar type is a single supply 5V prototype with low power consumption and is also designed for use with an e-Health platform in a wearable sensor configuration. In addition, a single supply enhanced open loop gain design that mitigates the effect of reduced dielectric resistance in the sensor element is presented.;Using the developed mathematical models, the sensor is predicted to be capable of measuring frequencies from DC up to 6.8rads{acute}{88}{92}1 with a rise time to the 98% peak of 0.12s and 0.18s for a DC and 6.8rads{acute}{88}{92}1 step, respectively. However, the use of a polymer liner between the sensor element and measurement surface is found to severely limit the usable frequency response of the sensor due to severe amplitude and phase distortion, precluding direct use of the sensor to measure skin surface temperature. Being relevant to the safety of remote e-Health monitoring, the challenges ICT networks must face to maintain quality of service are discussed and it is shown that an increasing amount of traffic, increasing power consumption and electronic bottlenecks are three main challenges that require a solution. The ability of ICT networks to satisfy the growing global demand for data is under threat due to the speed limitations of current CMOS based electronic technologies, leading to electronic bottlenecks and threats to the sustainability of the quality of service critically required for e-Health monitoring
Design and implementation of IoT enabled generic platform for precision livestock farming and applications
Get PDFThis thesis focuses on precision agriculture of livestock farming. Precision Livestock Farming is a modern farming development that emphasises on deploying advanced information and communication technology in physical farms to optimise the contributions of individual animals. Relevant techniques such as the Internet of Things (IoT), machine learning and 5G communication are all needed for improving the level of automation, intelligence and efficiency towards smart farming.;With the support of more powerful computing resources, we are capable of handling massive volumes of data, where highly automated processes can be applied for data capturing, analysis and improved decision making. In addition to the economic benefits, Precision Livestock Farming also meets several social goals, such as high-quality and safe food products, efficient and sustainable livestock farming, better animal welfare and low footprint to the environment.;Manual observation of animals is a tedious job, especially over a long time, and it can often be affected by the observer's bias. As a result, IoT enabled AI machine learning-based automatic monitoring and management of livestock with image processing and analysis can offer massive potential for producing the unbiased status report in a more efficient and effective way. By utilizing the real-time monitoring technology, and the corresponding management system can boost productivity whilst reducing the cost and environmental emissions in livestock farms.;To tackle this emerging issue and needs, a Precision Livestock Farming platform has been designed and implemented in this thesis, with the support of various sensors and corresponding analytics technologies. By continuously recording and analysing live data, it can not only recognise the welfare and health status of the animals but also for evidence-based smart decision-making with the support of the massive volumes of data. For implementing the proposed system, various techniques have been introduced to address the challenging issues, especially real-time multi-camera video streaming and transmission in an on-demand manner for improving the efficiency and efficacy in mobile/cloud-based environments.;As a case study, the developed generic platform has been applied for tracking and behaviour recognition of pigs. These include background detection, object detection, object classification and target selection, followed by object tracking and behaviour recognition. The successful application has not only validated the efficacy of the proposed system but also demonstrated the flexibility and great potential of the proposed system in a wide range of application areas.;Finally, some future directions are also provided after the summary of the contribution points, which are expected to benefit the further development of the corresponding fields and the automation and intelligence of the livestock farming.This thesis focuses on precision agriculture of livestock farming. Precision Livestock Farming is a modern farming development that emphasises on deploying advanced information and communication technology in physical farms to optimise the contributions of individual animals. Relevant techniques such as the Internet of Things (IoT), machine learning and 5G communication are all needed for improving the level of automation, intelligence and efficiency towards smart farming.;With the support of more powerful computing resources, we are capable of handling massive volumes of data, where highly automated processes can be applied for data capturing, analysis and improved decision making. In addition to the economic benefits, Precision Livestock Farming also meets several social goals, such as high-quality and safe food products, efficient and sustainable livestock farming, better animal welfare and low footprint to the environment.;Manual observation of animals is a tedious job, especially over a long time, and it can often be affected by the observer's bias. As a result, IoT enabled AI machine learning-based automatic monitoring and management of livestock with image processing and analysis can offer massive potential for producing the unbiased status report in a more efficient and effective way. By utilizing the real-time monitoring technology, and the corresponding management system can boost productivity whilst reducing the cost and environmental emissions in livestock farms.;To tackle this emerging issue and needs, a Precision Livestock Farming platform has been designed and implemented in this thesis, with the support of various sensors and corresponding analytics technologies. By continuously recording and analysing live data, it can not only recognise the welfare and health status of the animals but also for evidence-based smart decision-making with the support of the massive volumes of data. For implementing the proposed system, various techniques have been introduced to address the challenging issues, especially real-time multi-camera video streaming and transmission in an on-demand manner for improving the efficiency and efficacy in mobile/cloud-based environments.;As a case study, the developed generic platform has been applied for tracking and behaviour recognition of pigs. These include background detection, object detection, object classification and target selection, followed by object tracking and behaviour recognition. The successful application has not only validated the efficacy of the proposed system but also demonstrated the flexibility and great potential of the proposed system in a wide range of application areas.;Finally, some future directions are also provided after the summary of the contribution points, which are expected to benefit the further development of the corresponding fields and the automation and intelligence of the livestock farming
Modelling high peak-power solid-state lasers
Get PDFThis thesis aims to improve existing design processes, increasing efficiency and reducing development costs through the use of numerical modelling techniques. This is achieved through leverage of existing modelling software, MATLAB and Zemax, and development of custom integrations, greatly enhancing their current capabilities.;This thesis is comprised of three distinct research projects the first of which details the development of a tool that enables automated analysis and interrogation of optical modelling systems. This tool was used to make recommendations in the design stages for a laser product developed at Thales UK Ltd., the sponsor company for this thesis.;The second major project concerned the modelling of a non-line-of-sight Light Detection and Ranging (LIDAR) system, using ray-tracing techniques to simulate time-of-flight responses from obstructed scenes. These models were used to analyse and understand some of the underlying relationships that governed this novel technology, and the author of this thesis presented these results at the conference Advanced Optics for Defense Applications:UV through LWIR - Baltimore, United States in 2016 [1].;The final research chapter details the development of a temporal and spatially discrete, numerical model, for investigating the evolution of gain within an active medium, during the pumping period. Amplified Spontaneous Emission (ASE) limits the energy available for useful gain and can severely impact the performance of highpower lasers, especially Q-switched systems.;This model confrimed expectations around a novel rod geometry for suppression in high-power solid-state gain medium that could see benefits for Q-switched systems. These recommendations are the first steps to securing further investment to progress these designs into the physical domain and can be used to explore further, at significantly reduced costs.;This project has produced a number of tools to benefit those developing solid-state laser systems.This thesis aims to improve existing design processes, increasing efficiency and reducing development costs through the use of numerical modelling techniques. This is achieved through leverage of existing modelling software, MATLAB and Zemax, and development of custom integrations, greatly enhancing their current capabilities.;This thesis is comprised of three distinct research projects the first of which details the development of a tool that enables automated analysis and interrogation of optical modelling systems. This tool was used to make recommendations in the design stages for a laser product developed at Thales UK Ltd., the sponsor company for this thesis.;The second major project concerned the modelling of a non-line-of-sight Light Detection and Ranging (LIDAR) system, using ray-tracing techniques to simulate time-of-flight responses from obstructed scenes. These models were used to analyse and understand some of the underlying relationships that governed this novel technology, and the author of this thesis presented these results at the conference Advanced Optics for Defense Applications:UV through LWIR - Baltimore, United States in 2016 [1].;The final research chapter details the development of a temporal and spatially discrete, numerical model, for investigating the evolution of gain within an active medium, during the pumping period. Amplified Spontaneous Emission (ASE) limits the energy available for useful gain and can severely impact the performance of highpower lasers, especially Q-switched systems.;This model confrimed expectations around a novel rod geometry for suppression in high-power solid-state gain medium that could see benefits for Q-switched systems. These recommendations are the first steps to securing further investment to progress these designs into the physical domain and can be used to explore further, at significantly reduced costs.;This project has produced a number of tools to benefit those developing solid-state laser systems
Numerical analysis and material selection of functionally graded pipes based on metals and ceramics for deep offshore oil and gas operations in Gulf of Guinea
Get PDFThe environmentally challenged conditions of deep offshore oil and gas operations has necessitated the demand for unique materials that could withstand both the loading conditions of the operations and the corrosion resistance. The work presented herein has explored the use of Functionally Graded Material (FGM) to validate its ability to proffer solutions to deep offshore oil and gas operations and their components, particularly in the Gulf of Guinea.;FGM was specifically used in the present work due to its unique property exhibition that changes continuously throughout its thickness with no discontinuities within the material. This unique feature was utilized in this research to derive a combination of FGM's that could meet the required strength, fracture toughness, specific stiffness and corrosion rate for oil and gas operations in Gulf of Guinea.;An assessment of currently available material combinations was investigated to determine feasible FGM combinations (metal and ceramics) that could meet the unique operating requirements. In tandem, the Analytic Hierarchy Process (AHP) technique was further used to rank the materials identified and a sensitivity analysis was carried out on weight, price and density variations in the final ranking the material. The four (4) most highly ranked Metal/Ceramic combinations were used for all the finite element thermal and structural analyses undertaken in this work.;Four (4) distinct FGM pipe were modelled by finite element analysis (FEA) using the Abaqus Finite Element system based on the key Metal/Ceramics materials selected, to reasonably mimic the physical behaviour of a series of offshore piping systems configurations. In practice, three piping configurations were considered; Straight, Elbow and T- Piece pipe components, all these were modelled for a range of pressure and temperature conditions.. From the reviewed literature, only a few benchmarks were available to validate the computational models, this is as a result of the evolving nature of the usage of FGM for piping in oil and gas industry.;Using work by Ghannad et al. on '2D thermo-elastic model of an axisymmetric FGM hollow cylinder', the FGM parameters used for the validation were axial stress, circumferential stress and von-mises stress. The comparison of results obtained from Ghannad's Paper showed excellent agreement with deviations of most of the variables used for the within 5% with both the numerical and analytical results from the literature.;As an FGM cannot have a single yield point by definition, an equation for the determination of effective yield strength for FGM's was developed which depends on the yield strength of the FGM constituents and the non-homogeneity factor of the FGM. This equation was validated using the conventional averaging approach of the FGM yield strengths and it showed excellent agreement with less than 1% for FGM's with higher numbers of layers.;Further to the determination of an ideal approach to calculate the effective yield strength of the FGM's, the Finite Element Analysis (FEA) of the four FGM combinations were modelled using the approach in the validated model with the main intent of predicting the design limits for each of the FGM material combinations. This was repeated for the three piping components considered (Straight, Elbow and T-Piece Pipe configurations).;The normalized stress approach was used for the determination of the design limit, this approach compared the effective yield strength of the FGM to the effective Von-mises stress for each of the configurations to determine the FGM failure tendencies due to yielding. The FGM design limit was determined when any of the layer in the FGM normalized stress was closest to one (1), above this limit the material begins to yield (Fail). The design limit was determined using the normalized stress between the ranges of 0.99< normalized stress<1.01.;The FEA of the FGM's considered was limited to thermal and pressure loading, hence only thermal and pressure design limits were determined for all the FG''s considered in all the configurations and non-homogeneity factors.;From the typical oil and gas operating conditions considered in Gulf of Guinea, the design limit results for the Straight pipes reveals that all the 20 FGM's could be deployed for the operations being considered. The results from this study allowed straight FGM's to be ranked based on thermal and pressure loading conditions.;On the same note, the design limit results for the Elbow Pipes reveals that only 10 FG's from the 20 modelled FG's could be adequately deployed for the operations being considered. The results from this study allowed elbow FGM's to be ranked based on thermal and pressure loading conditions.;Furthermore, the design limit results for the T-Pieces Pipes reveals that all the FGM's modelled could be adequately deployed for the operations being considered. The results from this study allowed T-piece FGM's to be ranked based on thermal and pressure loading conditions.;Finally, it is worth noting that the work undertaken herein concludes the development of a matrix of internal pressure and thermal loading for Straight, Elbow and T-Piece FGM Pipe configurations that could serve as guide for FGM material selection for oil and gas service conditions similar to that in Gulf of Guinea.The environmentally challenged conditions of deep offshore oil and gas operations has necessitated the demand for unique materials that could withstand both the loading conditions of the operations and the corrosion resistance. The work presented herein has explored the use of Functionally Graded Material (FGM) to validate its ability to proffer solutions to deep offshore oil and gas operations and their components, particularly in the Gulf of Guinea.;FGM was specifically used in the present work due to its unique property exhibition that changes continuously throughout its thickness with no discontinuities within the material. This unique feature was utilized in this research to derive a combination of FGM's that could meet the required strength, fracture toughness, specific stiffness and corrosion rate for oil and gas operations in Gulf of Guinea.;An assessment of currently available material combinations was investigated to determine feasible FGM combinations (metal and ceramics) that could meet the unique operating requirements. In tandem, the Analytic Hierarchy Process (AHP) technique was further used to rank the materials identified and a sensitivity analysis was carried out on weight, price and density variations in the final ranking the material. The four (4) most highly ranked Metal/Ceramic combinations were used for all the finite element thermal and structural analyses undertaken in this work.;Four (4) distinct FGM pipe were modelled by finite element analysis (FEA) using the Abaqus Finite Element system based on the key Metal/Ceramics materials selected, to reasonably mimic the physical behaviour of a series of offshore piping systems configurations. In practice, three piping configurations were considered; Straight, Elbow and T- Piece pipe components, all these were modelled for a range of pressure and temperature conditions.. From the reviewed literature, only a few benchmarks were available to validate the computational models, this is as a result of the evolving nature of the usage of FGM for piping in oil and gas industry.;Using work by Ghannad et al. on '2D thermo-elastic model of an axisymmetric FGM hollow cylinder', the FGM parameters used for the validation were axial stress, circumferential stress and von-mises stress. The comparison of results obtained from Ghannad's Paper showed excellent agreement with deviations of most of the variables used for the within 5% with both the numerical and analytical results from the literature.;As an FGM cannot have a single yield point by definition, an equation for the determination of effective yield strength for FGM's was developed which depends on the yield strength of the FGM constituents and the non-homogeneity factor of the FGM. This equation was validated using the conventional averaging approach of the FGM yield strengths and it showed excellent agreement with less than 1% for FGM's with higher numbers of layers.;Further to the determination of an ideal approach to calculate the effective yield strength of the FGM's, the Finite Element Analysis (FEA) of the four FGM combinations were modelled using the approach in the validated model with the main intent of predicting the design limits for each of the FGM material combinations. This was repeated for the three piping components considered (Straight, Elbow and T-Piece Pipe configurations).;The normalized stress approach was used for the determination of the design limit, this approach compared the effective yield strength of the FGM to the effective Von-mises stress for each of the configurations to determine the FGM failure tendencies due to yielding. The FGM design limit was determined when any of the layer in the FGM normalized stress was closest to one (1), above this limit the material begins to yield (Fail). The design limit was determined using the normalized stress between the ranges of 0.99< normalized stress<1.01.;The FEA of the FGM's considered was limited to thermal and pressure loading, hence only thermal and pressure design limits were determined for all the FG''s considered in all the configurations and non-homogeneity factors.;From the typical oil and gas operating conditions considered in Gulf of Guinea, the design limit results for the Straight pipes reveals that all the 20 FGM's could be deployed for the operations being considered. The results from this study allowed straight FGM's to be ranked based on thermal and pressure loading conditions.;On the same note, the design limit results for the Elbow Pipes reveals that only 10 FG's from the 20 modelled FG's could be adequately deployed for the operations being considered. The results from this study allowed elbow FGM's to be ranked based on thermal and pressure loading conditions.;Furthermore, the design limit results for the T-Pieces Pipes reveals that all the FGM's modelled could be adequately deployed for the operations being considered. The results from this study allowed T-piece FGM's to be ranked based on thermal and pressure loading conditions.;Finally, it is worth noting that the work undertaken herein concludes the development of a matrix of internal pressure and thermal loading for Straight, Elbow and T-Piece FGM Pipe configurations that could serve as guide for FGM material selection for oil and gas service conditions similar to that in Gulf of Guinea
Integrating polarisation effects into non-polarisable models to better model the self-assembly of mesoporous silica nanomaterials
Get PDFMesoporous silica nanomaterials are a class of materials of rapidly growing importance. Despite this, many details of their synthesis are still poorly understood. For this reason, computational studies have been widely used to further our understanding of the processes involved at the molecular level. Unfortunately, many of these models are either too generic or specialised for general use and neglect phenomena that play an important role in the synthesis process, such as polarisation.;For this reason, this thesis had two main goals: 1) to develop new methodologies to integrate polarisation effects into fixed-charge force fields; 2) to employ these new insights into a generic, transferable force field for organosilica molecules. In this work, we demonstrated that the current modelling paradigm for water, the solvent in which mesoporous silica synthesis takes place, is fundamentally flawed when it comes to accounting for the cost of polarisation in the free energy.;We have therefore proposed a new, more detailed analytical correction that can obviate this current failing of classical non-polarisable force fields. Subsequently, we carried out a detailed analysis of different methodologies for obtainingpoint charges suitable for the liquid phase from quantum-mechanical calculations. Finally, we employed quantum-mechanical calculations, molecular dynamics simulations and polarisation corrections to parametrise models for organosilica molecules.;This was then used to propose a molecular model for silicic acid, the principal precursor in the synthesis of mesoporous silica, via transferability. In future, we plan to expand our proposed transferable force field to a wider range of organosilica molecules, thereby facilitating the simulation of the silica synthesis with a much wider range of organosilica precursors. This would be advantageous for the discovery of new, in situ functionalised mesoporous silica nanomaterials.Mesoporous silica nanomaterials are a class of materials of rapidly growing importance. Despite this, many details of their synthesis are still poorly understood. For this reason, computational studies have been widely used to further our understanding of the processes involved at the molecular level. Unfortunately, many of these models are either too generic or specialised for general use and neglect phenomena that play an important role in the synthesis process, such as polarisation.;For this reason, this thesis had two main goals: 1) to develop new methodologies to integrate polarisation effects into fixed-charge force fields; 2) to employ these new insights into a generic, transferable force field for organosilica molecules. In this work, we demonstrated that the current modelling paradigm for water, the solvent in which mesoporous silica synthesis takes place, is fundamentally flawed when it comes to accounting for the cost of polarisation in the free energy.;We have therefore proposed a new, more detailed analytical correction that can obviate this current failing of classical non-polarisable force fields. Subsequently, we carried out a detailed analysis of different methodologies for obtainingpoint charges suitable for the liquid phase from quantum-mechanical calculations. Finally, we employed quantum-mechanical calculations, molecular dynamics simulations and polarisation corrections to parametrise models for organosilica molecules.;This was then used to propose a molecular model for silicic acid, the principal precursor in the synthesis of mesoporous silica, via transferability. In future, we plan to expand our proposed transferable force field to a wider range of organosilica molecules, thereby facilitating the simulation of the silica synthesis with a much wider range of organosilica precursors. This would be advantageous for the discovery of new, in situ functionalised mesoporous silica nanomaterials
Investigation towards the role of LmxOSM3.1 phosphorylation and the identification of its interaction partners using an improved method of proximity labelling
No full textLeishmaniasis is a parasitic infection provoked by vector-borne protozoan Leishmania, of the family Trypanosomatidae, transmitted by female hematophagous sand flies. It is endemic to tropical/subtropical regions. However, its geographical distribution is anticipated to diversify, due to climate change, urbanisation, and deforestation. Therefore, the global figure of those affected (12 million) is likely to increase. Examples of current leishmanias is therapeutics include pentavalent antimonials, amphotericin B, miltefosine, paromomycin, and pentamidine. Unfortunately, they do not come without limitations, hence, more effective treatments are needed. Kinases and kinesins have been shown to be promising drug targets.;LmxOSM3.1 is expected to be a plus end-directed 170kDa, homodimeric N-kinesin, whose function is to mediate anterograde transport (IFT) in the flagellum. CeOSM3 p802 null mutants provoke a complete loss in the (sensory) ciliary distal domain of C. elegans and a 37.5% to 50% decrease in cilium length. Thus, LmxOSM3.1 is anticipated to be fundamental for flagellar length regulation in L. mexicana. The kinase domain of LmxMPK13 exhibits a high degree of homologyto the H. sapiens MOK and C. reinhardtii LF4, whereby down regulation of either protein promotesciliary elongation. As both LmxOSM3.1 and LmxMPK13 are implicated in flagellar regulation, it is hypothesised that LmxOSM3.1 functions as a substrate of LmxMPK13 and together they coordinate flagellum length.;In 2C-mTID, a proximity-based assay to define potential protein-protein interactions (PPIs), miniTurbo (mTID) and LmxOSM3.1 (PoI) are fused to FKBP and FRB (of the FRB-FKBPmammalian oligomerisation system), respectively. A cell line expressing the CRISPR-Cas9 machinery and mTID fused to FKPB was generated but not yet assessed on a molecular level. Likewise, LmxOSM3.1 and LmxMPK13 tagged with FRB still require to be integrated into the genome of this cell line using CRISPR to prove LmxOSM3.1 as a substrate of LmxMPK13. To investigate the importance of phosphorylation of LmxOSM3.1 in vivo, LmxOSM3.1 is replaced with LmxOSM3.1GFP encoding C-terminally GFP-tagged wild type, S477A, and S477DLmxOSM3.1 mutants using CRISPR. Three A1OSM3SDGFP promastigote transfectants were generated (A5, C6, and E7) appearing immobile and aflagellated, which may be due to the Cterminal GFP disrupting IFT cargo binding, LmxOSM3.1 inactivation by phosphorylation mimicked by D477, or the mutation generally interfering with LmxOSM3.1 activity, e.g. by restricting flagellar access or promoting kinesin degradation.;However, some A1OSM3SDGFP promastigote transfectants (A6, B2, B4, C3, and C10) appeared normal. Therefore, the latter Leishmania are presumed to have a single allele replacement of LmxOSM3.1 maintaining a fully functional wild type allele. So far, no A1OSM3SAGFP promastigote transfectants could be generated. To conclude, further research is required to corroborate LmxOSM3.1 as a substrate of LmxMPK13 with phosphorylation on Ser477, LmxOSM3.2 as a PPI of LmxOSM3.1, and GFP or Ser477Asp as the causative factor for a flagellated LmxOSM3.1SD.Leishmaniasis is a parasitic infection provoked by vector-borne protozoan Leishmania, of the family Trypanosomatidae, transmitted by female hematophagous sand flies. It is endemic to tropical/subtropical regions. However, its geographical distribution is anticipated to diversify, due to climate change, urbanisation, and deforestation. Therefore, the global figure of those affected (12 million) is likely to increase. Examples of current leishmanias is therapeutics include pentavalent antimonials, amphotericin B, miltefosine, paromomycin, and pentamidine. Unfortunately, they do not come without limitations, hence, more effective treatments are needed. Kinases and kinesins have been shown to be promising drug targets.;LmxOSM3.1 is expected to be a plus end-directed 170kDa, homodimeric N-kinesin, whose function is to mediate anterograde transport (IFT) in the flagellum. CeOSM3 p802 null mutants provoke a complete loss in the (sensory) ciliary distal domain of C. elegans and a 37.5% to 50% decrease in cilium length. Thus, LmxOSM3.1 is anticipated to be fundamental for flagellar length regulation in L. mexicana. The kinase domain of LmxMPK13 exhibits a high degree of homologyto the H. sapiens MOK and C. reinhardtii LF4, whereby down regulation of either protein promotesciliary elongation. As both LmxOSM3.1 and LmxMPK13 are implicated in flagellar regulation, it is hypothesised that LmxOSM3.1 functions as a substrate of LmxMPK13 and together they coordinate flagellum length.;In 2C-mTID, a proximity-based assay to define potential protein-protein interactions (PPIs), miniTurbo (mTID) and LmxOSM3.1 (PoI) are fused to FKBP and FRB (of the FRB-FKBPmammalian oligomerisation system), respectively. A cell line expressing the CRISPR-Cas9 machinery and mTID fused to FKPB was generated but not yet assessed on a molecular level. Likewise, LmxOSM3.1 and LmxMPK13 tagged with FRB still require to be integrated into the genome of this cell line using CRISPR to prove LmxOSM3.1 as a substrate of LmxMPK13. To investigate the importance of phosphorylation of LmxOSM3.1 in vivo, LmxOSM3.1 is replaced with LmxOSM3.1GFP encoding C-terminally GFP-tagged wild type, S477A, and S477DLmxOSM3.1 mutants using CRISPR. Three A1OSM3SDGFP promastigote transfectants were generated (A5, C6, and E7) appearing immobile and aflagellated, which may be due to the Cterminal GFP disrupting IFT cargo binding, LmxOSM3.1 inactivation by phosphorylation mimicked by D477, or the mutation generally interfering with LmxOSM3.1 activity, e.g. by restricting flagellar access or promoting kinesin degradation.;However, some A1OSM3SDGFP promastigote transfectants (A6, B2, B4, C3, and C10) appeared normal. Therefore, the latter Leishmania are presumed to have a single allele replacement of LmxOSM3.1 maintaining a fully functional wild type allele. So far, no A1OSM3SAGFP promastigote transfectants could be generated. To conclude, further research is required to corroborate LmxOSM3.1 as a substrate of LmxMPK13 with phosphorylation on Ser477, LmxOSM3.2 as a PPI of LmxOSM3.1, and GFP or Ser477Asp as the causative factor for a flagellated LmxOSM3.1SD
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