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A CFD study of fluid-structure interaction problems for floating offshore wind turbines
Get PDFAs one of the fastest growing renewable energy sources, wind energy is playing an increasingly important part in addressing the climate change and energy crisis issues the world is currently facing. The abundance of wind resource in offshore areas makes them a popular choice for turbine installation. In the past few years, several floating wind projects have emerged where wind turbines are installed far offshore in deepwater sites on moored platforms. Compared to land-based or offshore fixed-bottom wind turbines, an FOWT is a fully coupled system where the wind turbine with flexible blades and the floating platform with its mooring system interact with each other in wind and waves, which makes old design tools inadequate.;This work aims to develop a fully coupled high-fidelity aero-hydro-mooring-elastic analysis tool, and to better understand the sophisticated fluid-structure interactions for FOWTs.;The numerical tool developed in this work takes advantage of the open source CFD toolbox OpenFOAM to accurately solve wind turbine aerodynamics and floating platform hydrodynamics, and utilises the open source MBD code MBDyn for structural dynamics within a multibody framework while modelling flexible bodies based on a nonlinear beam theory. Coupling of these two solvers is achieved by establishing an interface library to exchange data with the help of the TCP/IP protocol.;Additionally, to tackle the complex mesh movement in FOWT simulations, a mesh motion solver is developed in OpenFOAM by combining the sliding mesh technique and the dynamic mesh morphing method. A mooring system analysis module comprising a quasi-static method and a lumped-mass based dynamic approach is also implemented to simulate mooring lines in an FOWT system.;A series of test cases is firstly studied to validate the various features of the tool, including basic fluid flow solving, modelling of wind turbine aerodynamics, hydrodynamic analysis of a floating structure with its mooring system, dynamic analysis of a riser or mooring line and coupled analysis of flow induced vibration of a flexible beam. The developed tool is then applied to analyse FSI problems of FOWTs under three different scenarios.;Firstly, a coupled aero-hydro-mooring analysis is carried out for the OC4 semisubmersible FOWT under regular waves and uniform wind speed. Blade flexibility is ignored, and mooring lines are solved using the quasi-static method. Interactions between the moored platform and the wind turbine are investigated, focusing on of platform motion on the aerodynamic performance of the wind turbine and the impacts of wind turbine aerodynamics on the responses of the floating platform and its mooring system.;Subsequently, an aeroelastic analysis is conducted for the NREL 5-MW offshore wind turbine with flexible blades under uniform wind speed. Effects of blade flexibility on wind turbine aerodynamics and structural responses are studied using the developed CFD-MBD tool. The floating platform supporting the turbine is not directly modelled for simplicity and the influence of platform motion responses on the turbine are analysed via imposing a prescribed surge motion to the turbine base.;Fully coupled aero-hydro-mooring-elastic analysis is lastly carried out for the OC4 semi-submersible FOWT under a combined wind/wave condition to demonstrate the capabilities of the developed CFD-MBD tool. Responses of the floating system are investigated in terms of platform hydrodynamics, mooring system dynamics, wind turbine aerodynamics and blade structural dynamics. Interactions between the FOWT and fluid flow are analysed by visualising results obtained via the CFD approach.As one of the fastest growing renewable energy sources, wind energy is playing an increasingly important part in addressing the climate change and energy crisis issues the world is currently facing. The abundance of wind resource in offshore areas makes them a popular choice for turbine installation. In the past few years, several floating wind projects have emerged where wind turbines are installed far offshore in deepwater sites on moored platforms. Compared to land-based or offshore fixed-bottom wind turbines, an FOWT is a fully coupled system where the wind turbine with flexible blades and the floating platform with its mooring system interact with each other in wind and waves, which makes old design tools inadequate.;This work aims to develop a fully coupled high-fidelity aero-hydro-mooring-elastic analysis tool, and to better understand the sophisticated fluid-structure interactions for FOWTs.;The numerical tool developed in this work takes advantage of the open source CFD toolbox OpenFOAM to accurately solve wind turbine aerodynamics and floating platform hydrodynamics, and utilises the open source MBD code MBDyn for structural dynamics within a multibody framework while modelling flexible bodies based on a nonlinear beam theory. Coupling of these two solvers is achieved by establishing an interface library to exchange data with the help of the TCP/IP protocol.;Additionally, to tackle the complex mesh movement in FOWT simulations, a mesh motion solver is developed in OpenFOAM by combining the sliding mesh technique and the dynamic mesh morphing method. A mooring system analysis module comprising a quasi-static method and a lumped-mass based dynamic approach is also implemented to simulate mooring lines in an FOWT system.;A series of test cases is firstly studied to validate the various features of the tool, including basic fluid flow solving, modelling of wind turbine aerodynamics, hydrodynamic analysis of a floating structure with its mooring system, dynamic analysis of a riser or mooring line and coupled analysis of flow induced vibration of a flexible beam. The developed tool is then applied to analyse FSI problems of FOWTs under three different scenarios.;Firstly, a coupled aero-hydro-mooring analysis is carried out for the OC4 semisubmersible FOWT under regular waves and uniform wind speed. Blade flexibility is ignored, and mooring lines are solved using the quasi-static method. Interactions between the moored platform and the wind turbine are investigated, focusing on of platform motion on the aerodynamic performance of the wind turbine and the impacts of wind turbine aerodynamics on the responses of the floating platform and its mooring system.;Subsequently, an aeroelastic analysis is conducted for the NREL 5-MW offshore wind turbine with flexible blades under uniform wind speed. Effects of blade flexibility on wind turbine aerodynamics and structural responses are studied using the developed CFD-MBD tool. The floating platform supporting the turbine is not directly modelled for simplicity and the influence of platform motion responses on the turbine are analysed via imposing a prescribed surge motion to the turbine base.;Fully coupled aero-hydro-mooring-elastic analysis is lastly carried out for the OC4 semi-submersible FOWT under a combined wind/wave condition to demonstrate the capabilities of the developed CFD-MBD tool. Responses of the floating system are investigated in terms of platform hydrodynamics, mooring system dynamics, wind turbine aerodynamics and blade structural dynamics. Interactions between the FOWT and fluid flow are analysed by visualising results obtained via the CFD approach
Game theoretical offshore container port competition
Get PDFContainer ports are indispensable parts of the container transport operations. In terms of container transport operations even better port services are desired to provide viability of reliable liner shipping service. Therefore, port competition to supply better port services is one of the natural consequences of the container transport evolution in the globalisation era. This thesis offers a port competition analysis as total transportation time and cost based between the container ports which serve to collided hinterlands with the integration of offshore container port system (OCPS) and ultra large container vessels (ULCV). An OCPS adaptation is assumed to create offshore container port related an inter-port container competition with other conventional container ports which can handle ULCVs. This OCPS is going to complicate competition game and conditions even much more between ports. The methodological approach of this study aims to develop a hybrid port competition analysis model to analyse port competition in terms of commercial and operational aspects. The model is divided to two different methodological stages. First proposed method is to apply total transportation time and cost based door-to-door container network analysis in order to determine the competitiveness of the given port alternatives. In this approach, according to total time and cost values, the weights of each competitive port are determined to define the position of ports in the competition in order to attract interest of the industrial customers. Operating costs, voyage costs, cargo handling costs and hinterland transportation cost, and also port construction costs are considered as main criteria to clarify the ports' position in the competition. Second method is to develop a game theoretical strategy concept to apply on the port competition regarding to lucrativeness and investment opportunity expectations of the port authorities. Integration and comparison of the both methodological approaches is going to provide valuable findings to analyse competitiveness level of container ports more accurately. Outcomes of this research may help for future business development strategies of port authorities, port operators, shipping liners and private and public port investors. This study is expected to provide a clear holistic comprehending about the underlying dynamics of the port competition for all counterparties involved in container transport operations.Container ports are indispensable parts of the container transport operations. In terms of container transport operations even better port services are desired to provide viability of reliable liner shipping service. Therefore, port competition to supply better port services is one of the natural consequences of the container transport evolution in the globalisation era. This thesis offers a port competition analysis as total transportation time and cost based between the container ports which serve to collided hinterlands with the integration of offshore container port system (OCPS) and ultra large container vessels (ULCV). An OCPS adaptation is assumed to create offshore container port related an inter-port container competition with other conventional container ports which can handle ULCVs. This OCPS is going to complicate competition game and conditions even much more between ports. The methodological approach of this study aims to develop a hybrid port competition analysis model to analyse port competition in terms of commercial and operational aspects. The model is divided to two different methodological stages. First proposed method is to apply total transportation time and cost based door-to-door container network analysis in order to determine the competitiveness of the given port alternatives. In this approach, according to total time and cost values, the weights of each competitive port are determined to define the position of ports in the competition in order to attract interest of the industrial customers. Operating costs, voyage costs, cargo handling costs and hinterland transportation cost, and also port construction costs are considered as main criteria to clarify the ports' position in the competition. Second method is to develop a game theoretical strategy concept to apply on the port competition regarding to lucrativeness and investment opportunity expectations of the port authorities. Integration and comparison of the both methodological approaches is going to provide valuable findings to analyse competitiveness level of container ports more accurately. Outcomes of this research may help for future business development strategies of port authorities, port operators, shipping liners and private and public port investors. This study is expected to provide a clear holistic comprehending about the underlying dynamics of the port competition for all counterparties involved in container transport operations
Non-thermal plasma technology for nitric oxide removal
Get PDFNon-thermal plasma, as a potential nitric oxide (NO) removal technology, has been researched for more than one decade. The advantage of direct non-thermal plasma treatment is that it is able to generate reactive species from the existing components in the flue gas without additional catalyst, oxidant or reductant, so any NO removal system based upon this technology is simple and easy to operate. However, the energy efficiency of non-thermal plasma technology is lower than the most commonly used selective catalytic reduction system for NO removal. In order to understand the possible reasons, it is important to investigate the mechanism of NO removal by direct non-thermal plasma treatment. Two of the most commonly used non-thermal plasma sources, dielectric barrier discharge (DBD) and corona discharge, are investigated. The most important reactive species include oxygen atom (O), ozone (O3) and hydroxyl radical (OH). Different reactive species lead to different chemical reaction pathways for NO removal. Under different NO concentration and discharge configurations, the dominant reactive species was found to change from one to another. For dielectric barrier discharge, when the initial NO concentration was higher than 420 ppm under dry condition, it was found that O was the dominant reactive species for NO oxidation and NO oxidation was independent on O2 concentration. When initial NO concentration was lower than 100 ppm under dry condition, it was found that O3 was the dominant reactive species and NO oxidation was dependent on O2 concentration. When NO concentration was in the range of 120 ppm to 190 ppm, there was a synergistic effect of O and O3 on NO oxidation. NO removal depended on the initial NO concentration. However, no matter what the initial NO concentration was, the NO removal energy efficiency was lower than 25g/kWh. When water vapour (H2O) was introduced into the gas mixture, reactive species OH was generated and provided an alternative chemical reaction pathway for NO removal. When initial NO concentration was 1000 ppm, NO removal was in the range of 150 ppm to 200 ppm, but the energy efficiency was in the range of 7 to 12 g/kWh. With an increase of temperature in DBD reactor, the effect of OH on NO removal was promoted. To further investigate the OH effect, a novel pin to water corona discharge configuration was used. The effect of discharge modes from Trichel pulse, pulseless and arc discharge was investigated. Under arc discharge mode, 200 ppm NO was generated at 6W discharge power. Under Trichel and pulseless discharge modes, NO removal increased with increasing discharge power. When initial NO concentration was 1000 ppm, the highest NO removal achieved was 715 ppm with 5.5 g/kWh energy efficiency.;In addition, it was found that the energy efficiency did not reduce with increasing discharge power. In order to increase the possibility of chemical reaction between NO and reactive species, higher initial NO concentration was used. To obtain higher NO concentration a process of NO absorption by activated carbon and thermal desorption was used. This increased the NO concentration from 1000 ppm up to 6%. It is found that at 6% level, NO could be partially oxidized by oxygen molecule (O2) and higher O2 concentration would obtain higher NO oxidation rate. Direct non-thermal plasma treatment can be used for NO removal but the energy efficiency (less than 30g/kWh) is too low to compete with the mature technologies including selective catalytic reduction (SCR) and low temperature oxidation (LoTOx) whose energy efficiencies are higher than 60 g/kWh. Although the energy efficiency is not improved in this research, the mechanism and chemical reaction pathways of NO removal are quantitatively analysed under different initial NO concentration levels by two different non-thermal plasma technologies (DBD and corona discharge). The dominant reactive species for NO removal can shift from O, O3 to OH. In addition, a novel technology which is a combination of non-thermal plasma, NO absorption and desorption processes is developed in this research. It offers a new mechanism for NO removal, because increasing the concentration of NO from ppm level to a few percentages creates a regime where NO removal can be effectively done by O2 rather than strong oxidants like O and O3. As the formation of O and O3 is more expensive than that of O2, this is a promising research direction for NO removal. However, based on the investigation in this research, some challenges are found. One is the poor selection between NO and H2O for activated carbon and the other one is high energy consumption for the desorption process.Non-thermal plasma, as a potential nitric oxide (NO) removal technology, has been researched for more than one decade. The advantage of direct non-thermal plasma treatment is that it is able to generate reactive species from the existing components in the flue gas without additional catalyst, oxidant or reductant, so any NO removal system based upon this technology is simple and easy to operate. However, the energy efficiency of non-thermal plasma technology is lower than the most commonly used selective catalytic reduction system for NO removal. In order to understand the possible reasons, it is important to investigate the mechanism of NO removal by direct non-thermal plasma treatment. Two of the most commonly used non-thermal plasma sources, dielectric barrier discharge (DBD) and corona discharge, are investigated. The most important reactive species include oxygen atom (O), ozone (O3) and hydroxyl radical (OH). Different reactive species lead to different chemical reaction pathways for NO removal. Under different NO concentration and discharge configurations, the dominant reactive species was found to change from one to another. For dielectric barrier discharge, when the initial NO concentration was higher than 420 ppm under dry condition, it was found that O was the dominant reactive species for NO oxidation and NO oxidation was independent on O2 concentration. When initial NO concentration was lower than 100 ppm under dry condition, it was found that O3 was the dominant reactive species and NO oxidation was dependent on O2 concentration. When NO concentration was in the range of 120 ppm to 190 ppm, there was a synergistic effect of O and O3 on NO oxidation. NO removal depended on the initial NO concentration. However, no matter what the initial NO concentration was, the NO removal energy efficiency was lower than 25g/kWh. When water vapour (H2O) was introduced into the gas mixture, reactive species OH was generated and provided an alternative chemical reaction pathway for NO removal. When initial NO concentration was 1000 ppm, NO removal was in the range of 150 ppm to 200 ppm, but the energy efficiency was in the range of 7 to 12 g/kWh. With an increase of temperature in DBD reactor, the effect of OH on NO removal was promoted. To further investigate the OH effect, a novel pin to water corona discharge configuration was used. The effect of discharge modes from Trichel pulse, pulseless and arc discharge was investigated. Under arc discharge mode, 200 ppm NO was generated at 6W discharge power. Under Trichel and pulseless discharge modes, NO removal increased with increasing discharge power. When initial NO concentration was 1000 ppm, the highest NO removal achieved was 715 ppm with 5.5 g/kWh energy efficiency.;In addition, it was found that the energy efficiency did not reduce with increasing discharge power. In order to increase the possibility of chemical reaction between NO and reactive species, higher initial NO concentration was used. To obtain higher NO concentration a process of NO absorption by activated carbon and thermal desorption was used. This increased the NO concentration from 1000 ppm up to 6%. It is found that at 6% level, NO could be partially oxidized by oxygen molecule (O2) and higher O2 concentration would obtain higher NO oxidation rate. Direct non-thermal plasma treatment can be used for NO removal but the energy efficiency (less than 30g/kWh) is too low to compete with the mature technologies including selective catalytic reduction (SCR) and low temperature oxidation (LoTOx) whose energy efficiencies are higher than 60 g/kWh. Although the energy efficiency is not improved in this research, the mechanism and chemical reaction pathways of NO removal are quantitatively analysed under different initial NO concentration levels by two different non-thermal plasma technologies (DBD and corona discharge). The dominant reactive species for NO removal can shift from O, O3 to OH. In addition, a novel technology which is a combination of non-thermal plasma, NO absorption and desorption processes is developed in this research. It offers a new mechanism for NO removal, because increasing the concentration of NO from ppm level to a few percentages creates a regime where NO removal can be effectively done by O2 rather than strong oxidants like O and O3. As the formation of O and O3 is more expensive than that of O2, this is a promising research direction for NO removal. However, based on the investigation in this research, some challenges are found. One is the poor selection between NO and H2O for activated carbon and the other one is high energy consumption for the desorption process
An edge processing solution development for vessel condition monitoring
Get PDFIn shipping, condition monitoring (CM) has the capacity for big data but also very high communications costs. Thus, the use of continuous condition monitoring in the shipping industry is not as prevalent as in others. It is found that trust in technology, data security/ownership, the capital cost of investment, cost of training, operational cost and direct benefit association are some of the most important inhibitors. To reduce the volume of data, edge processing is a new paradigm of computing. Its goal is to address the issues generated through the increasing flow of recorded data to central locations for big data analytics.;The existing solutions are adopted by 12% of the global fleet corresponding to the newbuilt ships, while sensors and monitoring infrastructure exists in the majority. Solutions targeting newbuilt ships have a requirement of extensive refitting and training overheads. Solutions for existing vessels are mostly hand-held equipment, do not support continuous monitoring and do not display the information in business relevantterms. A wireless ship CM reduces capital investment costs but has high operational costs due to the centralised data processing software.;The proposed novel system is edge processing wireless ship CM data under constrains. The system's traffic reduction is achieved through feature and event extraction on the data acquisition devices. Also a data management strategy is implemented along with decision support which provides direct benefit association with maintenance actions. The multi-constrain multi-parameter approach identifies the best maintenance action to be taken onboard the ship. Finally, minimal satellite data transmission provides visibility of condition to shore.;The system was successfully applied in case studies. According to the evaluation results, the system is reliable and suitable for the application, is able to identify and suggest appropriate maintenance actions and offers several benefits against other maintenance and condition monitoring approaches.In shipping, condition monitoring (CM) has the capacity for big data but also very high communications costs. Thus, the use of continuous condition monitoring in the shipping industry is not as prevalent as in others. It is found that trust in technology, data security/ownership, the capital cost of investment, cost of training, operational cost and direct benefit association are some of the most important inhibitors. To reduce the volume of data, edge processing is a new paradigm of computing. Its goal is to address the issues generated through the increasing flow of recorded data to central locations for big data analytics.;The existing solutions are adopted by 12% of the global fleet corresponding to the newbuilt ships, while sensors and monitoring infrastructure exists in the majority. Solutions targeting newbuilt ships have a requirement of extensive refitting and training overheads. Solutions for existing vessels are mostly hand-held equipment, do not support continuous monitoring and do not display the information in business relevantterms. A wireless ship CM reduces capital investment costs but has high operational costs due to the centralised data processing software.;The proposed novel system is edge processing wireless ship CM data under constrains. The system's traffic reduction is achieved through feature and event extraction on the data acquisition devices. Also a data management strategy is implemented along with decision support which provides direct benefit association with maintenance actions. The multi-constrain multi-parameter approach identifies the best maintenance action to be taken onboard the ship. Finally, minimal satellite data transmission provides visibility of condition to shore.;The system was successfully applied in case studies. According to the evaluation results, the system is reliable and suitable for the application, is able to identify and suggest appropriate maintenance actions and offers several benefits against other maintenance and condition monitoring approaches
Enhanced PV module efficiency to boost hybrid microgrid power and microgrid ancillary services market creation
Get PDFGusau, a city in Zamfara state, Nigeria, chosen as the research location is faced with a shortage of power supply as electricity supply from the national grid is unstable and inadequate, besides the majority of those in the remote area are isolated from the grid. The location has the potential for renewable resources. To end this challenge of power supply shortage, a hybrid electric power system, which employs the use of battery storage, solar and wind energy system with a diesel generator as a reserve to provide adequate power to 120 residential apartments in a settlement isolated from the grid is being designed. The result shows the total yearly electricity production is 168,545 kWh/yr, the yearly AC primary load consumption is 67160 kWh/yr, and the excess electricity is 88581 kWh/yr and the AC primary load was met.Solar energy is the most promising renewable energy in the location but the PV module, which converts solar energy into electricity is not efficient as the PV module power output reduces at the peak of sunlight. An experiment was conducted to improve the efficiency of the PV module using a multi-concept cooling technique at a derating factor of 80% and 95%. At a derating factor of 80%, an appreciable increase in the module output power was achieved with module + Al hint sink & water-cooling of the module surface temperature to 20°C. An output power increase of 20.96 W at 12:45 pm and an efficiency of over 3% were achieved. This increase in power output exceeds 250 watts with 0% losses. At a derating factor of 95%, an increase in power output from 250w to 262.4w was achieved.The MATLAB modelling of the hybrid PV/wind/diesel generator system shows the PV module contributes more power to the energy system at a temperature of 20°C than at 45°C.Hence, there is an increase in the PV power output to the hybrid energy system with increased module efficiency.My sponsors motivated this research, as they wanted me to work in this area.This thesis also contributes to the creation of microgrid ancillary services market, and the provision of voltage control ancillary services to low voltage distributed generation since it iscurrently applicable to large power networks.Gusau, a city in Zamfara state, Nigeria, chosen as the research location is faced with a shortage of power supply as electricity supply from the national grid is unstable and inadequate, besides the majority of those in the remote area are isolated from the grid. The location has the potential for renewable resources. To end this challenge of power supply shortage, a hybrid electric power system, which employs the use of battery storage, solar and wind energy system with a diesel generator as a reserve to provide adequate power to 120 residential apartments in a settlement isolated from the grid is being designed. The result shows the total yearly electricity production is 168,545 kWh/yr, the yearly AC primary load consumption is 67160 kWh/yr, and the excess electricity is 88581 kWh/yr and the AC primary load was met.Solar energy is the most promising renewable energy in the location but the PV module, which converts solar energy into electricity is not efficient as the PV module power output reduces at the peak of sunlight. An experiment was conducted to improve the efficiency of the PV module using a multi-concept cooling technique at a derating factor of 80% and 95%. At a derating factor of 80%, an appreciable increase in the module output power was achieved with module + Al hint sink & water-cooling of the module surface temperature to 20°C. An output power increase of 20.96 W at 12:45 pm and an efficiency of over 3% were achieved. This increase in power output exceeds 250 watts with 0% losses. At a derating factor of 95%, an increase in power output from 250w to 262.4w was achieved.The MATLAB modelling of the hybrid PV/wind/diesel generator system shows the PV module contributes more power to the energy system at a temperature of 20°C than at 45°C.Hence, there is an increase in the PV power output to the hybrid energy system with increased module efficiency.My sponsors motivated this research, as they wanted me to work in this area.This thesis also contributes to the creation of microgrid ancillary services market, and the provision of voltage control ancillary services to low voltage distributed generation since it iscurrently applicable to large power networks
Exploring the links between the ZDHHC9 gene and intellectual disability
Get PDFProtein palmitoylation (also known as S-acylation) is a widespread post-translational modification that regulates the trafficking and function of a diverse array of proteins. This modification is catalysed by a family of twenty-three zDHHC enzymes that exhibit both specific and overlapping substrate interactions. Mutations in the gene encoding zDHHC9 cause mild-to-moderate intellectual disability, seizures, speech and language impairment, hypoplasia of the corpus callosum and reduced volume of sub-cortical structures. In this thesis, behavioural phenotyping, magnetic resonance imaging (MRI), isolation of S- acylated proteins and metabolomics were conducted to investigate the effect of knock- out (KO) of the Zdhhc9 gene in mice in a C57BL/6 genetic background.;As a first step, end-point and quantitative Polymerase Chain reaction (PCR) were used to confirm KO of Zdhhc9 expression. Interestingly, although the mutant mice had ablated expression of mRNA encoding full-length zDHHC9, the mice did express reduced levels of a shorter Zdhhc9 transcript. However, immunoblotting analysis suggested that this shorter mRNA fragment did not lead to expression of a stable truncated form of zDHHC9 and further confirmed loss of zDHHC9 expression. Thus, the mouse line appears to be a true knock-out.;The Zdhhc9 KO male mice exhibit a range of abnormalities compared with their wild-type littermates: altered behaviour in the open-field test, elevated plus maze and acoustic startle test that is consistent with a reduced anxiety level; a reduced hang time in the hanging wire test that suggests underlying hypotonia but which may also be linked to reduced anxiety; deficits in the Morris water maze test of hippocampal-dependent spatial learning and memory; and a 36% reduction in corpus callosum volume revealed by MRI. Surprisingly, palmitoylation of several important pre- and post-synaptic proteins was not disrupted in either whole brain or hippocampus of Zdhhc9 KO mice, including H-Ras which has previously been proposed to be a key substrate of zDHHC9. This suggests that other unidentified substrates of zDHHC9 are linked to the observed changes.;Metabolomic profiling identified the pathways of tryptophan metabolism and of phenylalanine, tyrosine and tryptophan biosynthesis as significantly dysregulated in Zdhhc9 KO mice. Overall, this study highlights a key role for zDHHC9 in brain development and behaviour and supports the utility of the Zdhhc9 KO mouse line to investigate molecular and cellular changes linked to intellectual disability and other deficits in the human population.Protein palmitoylation (also known as S-acylation) is a widespread post-translational modification that regulates the trafficking and function of a diverse array of proteins. This modification is catalysed by a family of twenty-three zDHHC enzymes that exhibit both specific and overlapping substrate interactions. Mutations in the gene encoding zDHHC9 cause mild-to-moderate intellectual disability, seizures, speech and language impairment, hypoplasia of the corpus callosum and reduced volume of sub-cortical structures. In this thesis, behavioural phenotyping, magnetic resonance imaging (MRI), isolation of S- acylated proteins and metabolomics were conducted to investigate the effect of knock- out (KO) of the Zdhhc9 gene in mice in a C57BL/6 genetic background.;As a first step, end-point and quantitative Polymerase Chain reaction (PCR) were used to confirm KO of Zdhhc9 expression. Interestingly, although the mutant mice had ablated expression of mRNA encoding full-length zDHHC9, the mice did express reduced levels of a shorter Zdhhc9 transcript. However, immunoblotting analysis suggested that this shorter mRNA fragment did not lead to expression of a stable truncated form of zDHHC9 and further confirmed loss of zDHHC9 expression. Thus, the mouse line appears to be a true knock-out.;The Zdhhc9 KO male mice exhibit a range of abnormalities compared with their wild-type littermates: altered behaviour in the open-field test, elevated plus maze and acoustic startle test that is consistent with a reduced anxiety level; a reduced hang time in the hanging wire test that suggests underlying hypotonia but which may also be linked to reduced anxiety; deficits in the Morris water maze test of hippocampal-dependent spatial learning and memory; and a 36% reduction in corpus callosum volume revealed by MRI. Surprisingly, palmitoylation of several important pre- and post-synaptic proteins was not disrupted in either whole brain or hippocampus of Zdhhc9 KO mice, including H-Ras which has previously been proposed to be a key substrate of zDHHC9. This suggests that other unidentified substrates of zDHHC9 are linked to the observed changes.;Metabolomic profiling identified the pathways of tryptophan metabolism and of phenylalanine, tyrosine and tryptophan biosynthesis as significantly dysregulated in Zdhhc9 KO mice. Overall, this study highlights a key role for zDHHC9 in brain development and behaviour and supports the utility of the Zdhhc9 KO mouse line to investigate molecular and cellular changes linked to intellectual disability and other deficits in the human population
Investigating the use of mobile technology to promote active lifestyles and improved glycaemic control in individuals with type 2 diabetes
Get PDFThe purpose of this thesis was to examine the potential of using mobile technology to promote active lifestyles and improved glycaemic control in individuals with Type 2 diabetes. Chapter 1 introduced the research area, thesis rationale, and the design and structure of the thesis. Five studies were undertaken as part of this thesis. This first (Chapter 2) was a systematic and integrated literature review examining the effectiveness, acceptability and feasibility of using mobile technology to promote active living in adults with Type 2 Diabetes. The second (Chapter 3) presented the challenges and solutions of combining glucose and activity data sets measured continuously using mobile technology. The third (Chapter 4) examined the physical activity, sedentary behaviour and glucose patterns of adults with Type 2 diabetes in a free-living setting using mobile technology. The fourth (Chapter 5) examined the individual glycaemic response in adults with Type 2 Diabetes to interrupting prolonged sedentary behaviour in a controlled setting. Study five (Chapter 6) explored the experiences of, and attitudes towards, using mobile technologies to promote active living in adults with Type 2 diabetes. The final chapter (Chapter 7) discussed the findings of these studies in the wider context of the thesis and how the findings can be used to positively impact diabetes care and future research.The purpose of this thesis was to examine the potential of using mobile technology to promote active lifestyles and improved glycaemic control in individuals with Type 2 diabetes. Chapter 1 introduced the research area, thesis rationale, and the design and structure of the thesis. Five studies were undertaken as part of this thesis. This first (Chapter 2) was a systematic and integrated literature review examining the effectiveness, acceptability and feasibility of using mobile technology to promote active living in adults with Type 2 Diabetes. The second (Chapter 3) presented the challenges and solutions of combining glucose and activity data sets measured continuously using mobile technology. The third (Chapter 4) examined the physical activity, sedentary behaviour and glucose patterns of adults with Type 2 diabetes in a free-living setting using mobile technology. The fourth (Chapter 5) examined the individual glycaemic response in adults with Type 2 Diabetes to interrupting prolonged sedentary behaviour in a controlled setting. Study five (Chapter 6) explored the experiences of, and attitudes towards, using mobile technologies to promote active living in adults with Type 2 diabetes. The final chapter (Chapter 7) discussed the findings of these studies in the wider context of the thesis and how the findings can be used to positively impact diabetes care and future research
Biomineralised hydroxyapatite as a cement coating
Get PDFPreviously held under moratorium from 20th February 2019 until 20th February 2024.Ordinary Portland Cement (OPC) is the World’s most widely used building material. Cement is thusvulnerable to degradation through many processes. Bacteria are capable of generating minerals, ina process called biomineralisation. This may lead to the formation of many different minerals. Thereis precedent for applying biomineralisation processes to the repair and preservation of cements andconcretes.In this thesis, we observe and describe for the first time the bacterially-mediated deposition of ahydroxyapatite coating onto OPC, and describe the biochemical mechanisms underlying this process.The biogenic hydroxyapatite deposition takes place in a synergistic process with the cementsubstrate material; utilising a Pseudomonas fluorescens biofilm, phosphates from the growthmedium, and calcium from the cement substrate and pore solution.We additionally investigate the capacity of P. fluorescens to form biofilms under variedenvironmental conditions of temperature and carbon source availability, which is relevant to theapplication of the identified biogenic deposition system in the built environment. The investigationof P. fluorescens biofilms under these conditions is yet to be reported in the literature. We alsoestablish that varied P. fluorescens morphologies may emerge under different environmentalconditions, and carry out a novel structural characterisation and assay the fitness of these variedcolony morphologies.Developing upon these initial investigations, we characterise this biogenic hydroxyapatite in detailusing TEM, SEM-EDS, XRD, synchrotron-SAXS, and Mossbauer spectroscopy. We identify that thisbiogenic hydroxyapatite presents a less crystalline; plate like morphology, and reduced primaryparticle size in comparison to abiotic hydroxyapatite.The functional capacities of this biogenic hydroxyapatite as an OPC coating material are alsoinvestigated. We use focus-variation microscopy to characterise the surface topography of thecoating, nanoindentation to measure the hardness and elastic modulus of the biogenic and abiotichydroxyapatites, in combination with X-CT analysis to establish the completeness of the depositionprocess, and contact-angle measurements to investigate the hydrophobicity of the coating.Ordinary Portland Cement (OPC) is the World’s most widely used building material. Cement is thusvulnerable to degradation through many processes. Bacteria are capable of generating minerals, ina process called biomineralisation. This may lead to the formation of many different minerals. Thereis precedent for applying biomineralisation processes to the repair and preservation of cements andconcretes.In this thesis, we observe and describe for the first time the bacterially-mediated deposition of ahydroxyapatite coating onto OPC, and describe the biochemical mechanisms underlying this process.The biogenic hydroxyapatite deposition takes place in a synergistic process with the cementsubstrate material; utilising a Pseudomonas fluorescens biofilm, phosphates from the growthmedium, and calcium from the cement substrate and pore solution.We additionally investigate the capacity of P. fluorescens to form biofilms under variedenvironmental conditions of temperature and carbon source availability, which is relevant to theapplication of the identified biogenic deposition system in the built environment. The investigationof P. fluorescens biofilms under these conditions is yet to be reported in the literature. We alsoestablish that varied P. fluorescens morphologies may emerge under different environmentalconditions, and carry out a novel structural characterisation and assay the fitness of these variedcolony morphologies.Developing upon these initial investigations, we characterise this biogenic hydroxyapatite in detailusing TEM, SEM-EDS, XRD, synchrotron-SAXS, and Mossbauer spectroscopy. We identify that thisbiogenic hydroxyapatite presents a less crystalline; plate like morphology, and reduced primaryparticle size in comparison to abiotic hydroxyapatite.The functional capacities of this biogenic hydroxyapatite as an OPC coating material are alsoinvestigated. We use focus-variation microscopy to characterise the surface topography of thecoating, nanoindentation to measure the hardness and elastic modulus of the biogenic and abiotichydroxyapatites, in combination with X-CT analysis to establish the completeness of the depositionprocess, and contact-angle measurements to investigate the hydrophobicity of the coating
On the safety of LNG-fuelled ships
Get PDFWith an increasing pressure to use cleaner fuels in shipping, LNG has become a realistic marine fuel of choice by many ship-owners. Although it will undoubtedly contribute towards cleaner shipping, there is a general concern about the safety of its use. Such fears are based on the fact that an accidental release of this flammable mixture may lead to potential incidents, in particular, of fire and explosion. In this context, ensuring the safety is one of the most crucial tasks for the industry in adopting LNG as a marine fuel.;It is hardly surprising, therefore, that several rules, regulations, standards and guidelines have been produced at both international and local level. Nevertheless, due largely to the brevity of their history, the existing regulations and class rules appear to have some limitations and shortcomings, in particular, they lack explicit requirements in quantitative terms.;It is true that there are rules and guidance for design and operation of LNG process systems in chemical industry with a relatively long history, and they can to some extent be used to safeguard the use of LNG as a fuel, but the arrival of LNG-fuelled ships has made it essential and urgent that their safety should be investigated in detail.;In an effort to examine the existing regulations more intimately a conceptual design exercise to retrofit a 300,000 DWT very large ore carrier to use LNG as one of the marine fuels was carried out in accordance with current regulations. Although it was felt that the most hazardous areas of such a ship are with the fuel preparation room with high-pressure fuel supply system and the bunkering systems, the current regulations were not of much help during this process.;In order to obtain meaningful insights into their threats, the safety of these critical areas were systematically evaluated using quantitative risk assessment models that have been proven to be an effective and efficient tool for evaluating risks in oil/gas process systems.;It became obvious from the outset that an efficient computation tool is essential for the investigation. Consequently, the conventional quantitative risk assessment methods were modified and augmented to best suit the current problem and implemented in a computer program called Integrated Quantitative Risk Assessment (IQRA).;One of the main strengths of IQRA is that it can carry out the whole process of risk analysis from frequency calculation to evaluation of consequence in a seamless process, unlike existing software which require tedious post-processing to obtain the risk values. It has more than proven its worth during the course of this project.;LNG bunkering, at the two weakest ends (on-board LNG receiving point and LNG supplying point) were examined first. Usually such weak points are made relatively safe by imposing a 'safety exclusion zone' where non-essential personnel are not allowed entry during the process in question is in progress. However, there is no realistic regulation or guidance to help determining the extent of the zones. One of the few existing guidelines based on population-independent analysis requires an exclusion zone far too extensive and impossible to implement.;A realistic method of determining the exclusion zones based on statistical quantitative risk assessment was developed and demonstrated in this thesis. An interesting fact discovered through this study was the fact that short duration bunkering at large scale tends to require smaller exclusion zones than smaller scale bunker for longer duration.;The next area to examine was the fuel preparation room with a high-pressure fuel gas supply system. In this study, an event tree analysis was used to identify events that may cause vapour cloud explosion. General frequency data from various sources was used, and fault tree analysis was applied. Consequence was analysed in terms of the impact from explosion using a CFD and an FEA program. It was found that the structure of some sections of the fuel preparation room must be strengthened in addition to the scantling required by the classification rules.;Additionally, the safety of a medium-sized floating regasification unit was investigated by applying a hierarchical system modelling method newly put forward in this thesis. It demonstrated the excellence of the hierarchical system modelling in assessing the overall risk of complex process systems. The results were compared to the recommendations produced by a benchmark HAZOP study and selective quantitative risk assessment method.;This project established and demonstrated the way that the quantitative risk assessment techniques can be used to investigate the safety of a variety of novel marine LNG plants. A series of studies have proven that the framework and methodology developed in this thesis provides structured guidelines to conduct quantitative risk assessment associated with LNG-fuelled ships as well as LNG process systems regarding fire and explosion.;The facility for parametric and sensitivity analyses have also been shown to be an excellent tool in gaining insight into the nature and characteristics of risks that are inherent in oil/gas process systems while improving understanding of contributing factors to risks and methods of mitigating them as well as points to note during quantitative risk assessment. It is thought that such a tool will be a very useful aid in future rule development.;Last but not least, the safety of people and ships in using and/or processing LNG is paramount. If it is agreed that enhancing the current regulations is an urgent task, it is expected that the results of the studies carried out in this thesis can make a significant contribution to decision-making and further regulatory framework for port authorities and rule-makers.With an increasing pressure to use cleaner fuels in shipping, LNG has become a realistic marine fuel of choice by many ship-owners. Although it will undoubtedly contribute towards cleaner shipping, there is a general concern about the safety of its use. Such fears are based on the fact that an accidental release of this flammable mixture may lead to potential incidents, in particular, of fire and explosion. In this context, ensuring the safety is one of the most crucial tasks for the industry in adopting LNG as a marine fuel.;It is hardly surprising, therefore, that several rules, regulations, standards and guidelines have been produced at both international and local level. Nevertheless, due largely to the brevity of their history, the existing regulations and class rules appear to have some limitations and shortcomings, in particular, they lack explicit requirements in quantitative terms.;It is true that there are rules and guidance for design and operation of LNG process systems in chemical industry with a relatively long history, and they can to some extent be used to safeguard the use of LNG as a fuel, but the arrival of LNG-fuelled ships has made it essential and urgent that their safety should be investigated in detail.;In an effort to examine the existing regulations more intimately a conceptual design exercise to retrofit a 300,000 DWT very large ore carrier to use LNG as one of the marine fuels was carried out in accordance with current regulations. Although it was felt that the most hazardous areas of such a ship are with the fuel preparation room with high-pressure fuel supply system and the bunkering systems, the current regulations were not of much help during this process.;In order to obtain meaningful insights into their threats, the safety of these critical areas were systematically evaluated using quantitative risk assessment models that have been proven to be an effective and efficient tool for evaluating risks in oil/gas process systems.;It became obvious from the outset that an efficient computation tool is essential for the investigation. Consequently, the conventional quantitative risk assessment methods were modified and augmented to best suit the current problem and implemented in a computer program called Integrated Quantitative Risk Assessment (IQRA).;One of the main strengths of IQRA is that it can carry out the whole process of risk analysis from frequency calculation to evaluation of consequence in a seamless process, unlike existing software which require tedious post-processing to obtain the risk values. It has more than proven its worth during the course of this project.;LNG bunkering, at the two weakest ends (on-board LNG receiving point and LNG supplying point) were examined first. Usually such weak points are made relatively safe by imposing a 'safety exclusion zone' where non-essential personnel are not allowed entry during the process in question is in progress. However, there is no realistic regulation or guidance to help determining the extent of the zones. One of the few existing guidelines based on population-independent analysis requires an exclusion zone far too extensive and impossible to implement.;A realistic method of determining the exclusion zones based on statistical quantitative risk assessment was developed and demonstrated in this thesis. An interesting fact discovered through this study was the fact that short duration bunkering at large scale tends to require smaller exclusion zones than smaller scale bunker for longer duration.;The next area to examine was the fuel preparation room with a high-pressure fuel gas supply system. In this study, an event tree analysis was used to identify events that may cause vapour cloud explosion. General frequency data from various sources was used, and fault tree analysis was applied. Consequence was analysed in terms of the impact from explosion using a CFD and an FEA program. It was found that the structure of some sections of the fuel preparation room must be strengthened in addition to the scantling required by the classification rules.;Additionally, the safety of a medium-sized floating regasification unit was investigated by applying a hierarchical system modelling method newly put forward in this thesis. It demonstrated the excellence of the hierarchical system modelling in assessing the overall risk of complex process systems. The results were compared to the recommendations produced by a benchmark HAZOP study and selective quantitative risk assessment method.;This project established and demonstrated the way that the quantitative risk assessment techniques can be used to investigate the safety of a variety of novel marine LNG plants. A series of studies have proven that the framework and methodology developed in this thesis provides structured guidelines to conduct quantitative risk assessment associated with LNG-fuelled ships as well as LNG process systems regarding fire and explosion.;The facility for parametric and sensitivity analyses have also been shown to be an excellent tool in gaining insight into the nature and characteristics of risks that are inherent in oil/gas process systems while improving understanding of contributing factors to risks and methods of mitigating them as well as points to note during quantitative risk assessment. It is thought that such a tool will be a very useful aid in future rule development.;Last but not least, the safety of people and ships in using and/or processing LNG is paramount. If it is agreed that enhancing the current regulations is an urgent task, it is expected that the results of the studies carried out in this thesis can make a significant contribution to decision-making and further regulatory framework for port authorities and rule-makers
Implementing metabolomics tools in the search for new anti-proliferative agents from the plant-associated endophytes
Get PDFIn the search for new anticancer agents of natural origin against breast and lung cancer (ZR-75 and A549 cancer cell lines, respectively), plant-associated endophytes could be a good source for bioactive secondary metabolites. Twenty six endophytes were obtained from four different Jordanian plants; Anchusa strigosa, Anthemis palestina, Euphorbia peplus and Rumex cyprius. Internal transcribed spacer (ITS) gene sequencing was implemented to identify the obtained endophytes. Based on their biological activity and chemical profile, three endophytes namely Curvularia australiensis, Chaetomium subaffine and Fusarium acuminatum were chosen for the scale-up. These endophytes were cultured in liquid and rice media at different time periods to optimise their growth and production of compounds, employing both NMR and mass spectrometry-based metabolomics. The medium that afforded better yield, more chemical diverse extract and more potent biological activity was chosen for scaling-up purposes. Each of the scaled-up extracts was subjected to liquid-liquid partitioning followed by fractionation using a high-throughput flash-chromatography system. The fractions obtained from the first chromatography step were tested in-vitro against both breast and lung cancer (ZR-75 and A549 cell lines, respectively) and analysed using both proton nuclear magnetic resonance (NMR) and liquid chromatography-high resolution mass spectrometry (LC-HRMS). The HRMS data were processed with MZmine then subjected to Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA). The OPLS-DA results pinpointed the biologically active secondary metabolites. Metabolomics-guided isolation work targeted the bioactive secondary metabolites. As a result, five new compounds and ten known compounds were obtained from the three scaled-up endophytes. The isolated compounds were elucidated by employing 1D and 2D NMR then tested against ZR-75 and A549 cell lines. Twelve compounds were found active against ZR-75 cell line, which included five new compounds. Six compounds were found active against A549 cell line that included one of the new natural products isolated.In the search for new anticancer agents of natural origin against breast and lung cancer (ZR-75 and A549 cancer cell lines, respectively), plant-associated endophytes could be a good source for bioactive secondary metabolites. Twenty six endophytes were obtained from four different Jordanian plants; Anchusa strigosa, Anthemis palestina, Euphorbia peplus and Rumex cyprius. Internal transcribed spacer (ITS) gene sequencing was implemented to identify the obtained endophytes. Based on their biological activity and chemical profile, three endophytes namely Curvularia australiensis, Chaetomium subaffine and Fusarium acuminatum were chosen for the scale-up. These endophytes were cultured in liquid and rice media at different time periods to optimise their growth and production of compounds, employing both NMR and mass spectrometry-based metabolomics. The medium that afforded better yield, more chemical diverse extract and more potent biological activity was chosen for scaling-up purposes. Each of the scaled-up extracts was subjected to liquid-liquid partitioning followed by fractionation using a high-throughput flash-chromatography system. The fractions obtained from the first chromatography step were tested in-vitro against both breast and lung cancer (ZR-75 and A549 cell lines, respectively) and analysed using both proton nuclear magnetic resonance (NMR) and liquid chromatography-high resolution mass spectrometry (LC-HRMS). The HRMS data were processed with MZmine then subjected to Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA). The OPLS-DA results pinpointed the biologically active secondary metabolites. Metabolomics-guided isolation work targeted the bioactive secondary metabolites. As a result, five new compounds and ten known compounds were obtained from the three scaled-up endophytes. The isolated compounds were elucidated by employing 1D and 2D NMR then tested against ZR-75 and A549 cell lines. Twelve compounds were found active against ZR-75 cell line, which included five new compounds. Six compounds were found active against A549 cell line that included one of the new natural products isolated
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