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Marine microbial co-cultivation and the production of novel bioactive secondary metabolites for drug discovery
No full textThis thesis was previously held under moratorium from 13/10/17 until 01/11/19.Diminishing resources of terrestrial sourced compounds and the redundancy of synthetic chemistry based drugs has driven natural product research to probe the depths of the oceans for new secondary metabolites. In a project led by the University of Strathclyde in conjunction with the EU funded project Seabiotech, a metabolomic-based approach to drug discovery was utilised, to analyse and scale up the production of bioactive metabolites from marine microorganisms, using a cocultivation technique. Initially, a small scale study investigated three different strains of Streptomyces isolated from marine sediments near Oban, co-cultured with Rhodococcus sp. (SBT017) extracted from the sponge Sycon ciliatum, to increase the yield of novel secondary metabolites attained. SBT1625 (Streptomyces somaliensis) and SBT681 (Streptomyces sp.) cocultures were selected to scale-up the production of bioactive secondary metabolites for the treatment of metabolic diseases. Mass spectroscopy (MS) and 1D & 2D nuclear magnetic resonance (NMR) spectroscopy experiments in parallel with computer based metabolomic tools were adopted to chemically investigate the crude extracts, fractions and sub-fractions for bioactive metabolites with activity against the disease biomarkers; HDAC6, EL and PPARα. A total of 14 metabolites were isolated and structures were elucidated, seven of which are new metabolites not previously described, with six from bioactive fractions. A notable discovery was that of a novel proline-rich peptide SBT681/SBT017 co-culture that had exemplary inhibitory action (103.42%) for EL. Similarly, a fatty acid derivative isolated from the same co-culture had good bioactivity against a number of disease markers; principally the inhibition of HDAC6 (78.63%), but also of PPARα & PPARδ (36.49%). SBT1625/SBT017 co-culture also demonstrated the benefit of utilising cocultivation as a means to increase metabolite yields obtained. Marine derived natural product research offers an exciting and vastly untapped resource of novel secondary metabolites for the drug discovery pipeline.Diminishing resources of terrestrial sourced compounds and the redundancy of synthetic chemistry based drugs has driven natural product research to probe the depths of the oceans for new secondary metabolites. In a project led by the University of Strathclyde in conjunction with the EU funded project Seabiotech, a metabolomic-based approach to drug discovery was utilised, to analyse and scale up the production of bioactive metabolites from marine microorganisms, using a cocultivation technique. Initially, a small scale study investigated three different strains of Streptomyces isolated from marine sediments near Oban, co-cultured with Rhodococcus sp. (SBT017) extracted from the sponge Sycon ciliatum, to increase the yield of novel secondary metabolites attained. SBT1625 (Streptomyces somaliensis) and SBT681 (Streptomyces sp.) cocultures were selected to scale-up the production of bioactive secondary metabolites for the treatment of metabolic diseases. Mass spectroscopy (MS) and 1D & 2D nuclear magnetic resonance (NMR) spectroscopy experiments in parallel with computer based metabolomic tools were adopted to chemically investigate the crude extracts, fractions and sub-fractions for bioactive metabolites with activity against the disease biomarkers; HDAC6, EL and PPARα. A total of 14 metabolites were isolated and structures were elucidated, seven of which are new metabolites not previously described, with six from bioactive fractions. A notable discovery was that of a novel proline-rich peptide SBT681/SBT017 co-culture that had exemplary inhibitory action (103.42%) for EL. Similarly, a fatty acid derivative isolated from the same co-culture had good bioactivity against a number of disease markers; principally the inhibition of HDAC6 (78.63%), but also of PPARα & PPARδ (36.49%). SBT1625/SBT017 co-culture also demonstrated the benefit of utilising cocultivation as a means to increase metabolite yields obtained. Marine derived natural product research offers an exciting and vastly untapped resource of novel secondary metabolites for the drug discovery pipeline
Libyan Propolis : a comprehensive chemical, in vitro biological investigation and metabolomic profiling of antiprotozoal activity
Get PDFPropolis (bee-glue) is collected by bees from plants as a defensive substance in response to environmental pressures which include a range of microorganisms and parasites. These parasites are known to include the protozoal species Crithidia. Since it is collected by bees for the specific purpose of providing chemotherapeutic protection this increases the likelihood of finding active compounds in propolis compared with random screening of plants.;Twelve samples of Libyan propolis (P1-P12) were collected from different geographic zones of Libya. Ethanolic extracts of the twelve propolis samples were prepared and these were profiled initially by NMR which gave some general indication of the type of compounds which might be found in them providing signals typical of diterpene aldehydes and cycloartane triterpenoids depending on the origin of the sample.;There were limited signals in the aromatic region between 6 and 8 ppm in contrast to Northern European samples where many signals from flavonoid compounds would be expected. The extracts were profiled by high resolution LC-MS and the LC-MS data was extracted and modelled by SIMCA-P software using PCA with HCA, which separated the samples into five main groups based on their chemical composition.;The groups were according to Geographic origin which the samples from North East, North West, South East and Southwest Libya grouping together. The sample extracts were tested against a wide range of microorganisms including T. brucei, L. donovani, P. falciparum, C. fasiculata, M. marinum, S. aureus, K. pneumoniae and T. spiralis. In addition, cell based assays for cytotoxicity and anti-inflammatory activities were carried out.;Eighteen isolated compounds were isolated including: eight diterpenes (1) 13-epi-torulosal, (2) 13-O- acetyl epi-cupressic acid, (3) 13-epicupressic acid, (4) 13-epitorulosol, (15) acetylisocuppressic acid, (16) Agathadiol, (17) Isocupressic acid and, (18) isoagatholal, three lignans; (5) sesamin, (6) Demethylpiperitol, (7) 5', methoxy piperitol, (8) the flavonoid flavanone taxifolin-3-acetate-4'-methyl ether and five triterpenes of the cyclo artane type; (9) cycloartanol, (10) mangiferolic acid, (11) mangiferonic acid, (12) ambolic acid, (13) 27-hydroxymangeferonic acid and the resorcinol (14) cardol.;Both the crude extracts and isolated compounds exhibited activity against the range of microorganisms were tested such as T. brucei, L. donovani, P. falciparum, C. fasiculata, M. marinum, S. aureus, K. pneumoniae and T. spiralis.Propolis (bee-glue) is collected by bees from plants as a defensive substance in response to environmental pressures which include a range of microorganisms and parasites. These parasites are known to include the protozoal species Crithidia. Since it is collected by bees for the specific purpose of providing chemotherapeutic protection this increases the likelihood of finding active compounds in propolis compared with random screening of plants.;Twelve samples of Libyan propolis (P1-P12) were collected from different geographic zones of Libya. Ethanolic extracts of the twelve propolis samples were prepared and these were profiled initially by NMR which gave some general indication of the type of compounds which might be found in them providing signals typical of diterpene aldehydes and cycloartane triterpenoids depending on the origin of the sample.;There were limited signals in the aromatic region between 6 and 8 ppm in contrast to Northern European samples where many signals from flavonoid compounds would be expected. The extracts were profiled by high resolution LC-MS and the LC-MS data was extracted and modelled by SIMCA-P software using PCA with HCA, which separated the samples into five main groups based on their chemical composition.;The groups were according to Geographic origin which the samples from North East, North West, South East and Southwest Libya grouping together. The sample extracts were tested against a wide range of microorganisms including T. brucei, L. donovani, P. falciparum, C. fasiculata, M. marinum, S. aureus, K. pneumoniae and T. spiralis. In addition, cell based assays for cytotoxicity and anti-inflammatory activities were carried out.;Eighteen isolated compounds were isolated including: eight diterpenes (1) 13-epi-torulosal, (2) 13-O- acetyl epi-cupressic acid, (3) 13-epicupressic acid, (4) 13-epitorulosol, (15) acetylisocuppressic acid, (16) Agathadiol, (17) Isocupressic acid and, (18) isoagatholal, three lignans; (5) sesamin, (6) Demethylpiperitol, (7) 5', methoxy piperitol, (8) the flavonoid flavanone taxifolin-3-acetate-4'-methyl ether and five triterpenes of the cyclo artane type; (9) cycloartanol, (10) mangiferolic acid, (11) mangiferonic acid, (12) ambolic acid, (13) 27-hydroxymangeferonic acid and the resorcinol (14) cardol.;Both the crude extracts and isolated compounds exhibited activity against the range of microorganisms were tested such as T. brucei, L. donovani, P. falciparum, C. fasiculata, M. marinum, S. aureus, K. pneumoniae and T. spiralis
Regenerating the strength of thermally recycled glass fibres using chemical treatments
Get PDFThe processing and reuse of end-of-life composite products in an environmentally friendly manner is one of the most important challenges facing the industry and community. The development of an economically viable process for regenerating the properties of thermally recycled glass fibres (GFs) would have major technological, societal, economic and environmental impacts. The ultimate goal of this project is to enable cost-effective regeneration of the mechanical properties of GFs which have been produced from thermal recycling of end-of-life glass reinforced structural composites from automotive and wind energy applications. This work investigates the loss, and regeneration, of GF strength after thermal degradation at typical GRP recycling temperatures. The mechanical properties of APS sized and water sized (uncoated) Boron-free-E-glass fibres were first characterised using a conventional single fibre tension test. A substantial higher average strength was obtained from the APS sized fibres. Further investigation with GFs, coated with different silanes was carried out to determine any beneficial effect on GF mechanical properties. It was found that ɣ-Methacryloxypropyltrimethoxy Silane (MPS) and ɣ-Glycidoxypropyltrimethoxy Silane (GPS) prepared for 24 hours at RT and solution medium pH 5-5.5 in deionised water and ɣ-Aminopropyltriethoxy Silane prepared at 830C for 5 hours at solution medium natural pH (ET APS) in deionised water showed the higher increases in GF mechanical properties. Moreover, it was found that preparing the hydrolysed APS solution at elevated temperatures, had a beneficial effect on GF strength in comparison to a solution prepared at RT over 24 h (RT APS). Further investigation was carried out to identify any changes to the final products in solution and any structural differences between APS prepared at RT and at ET, that would lead to a conclusion about the difference in mechanical properties achieved. Using techniques such as Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infrared Spectroscopy (FTIR), several differences were identified. The results showed that ET APS contained less ethanol in solution after preparation, showing a relationship between the preparation temperature and the ethanol lost from the solution. On the other hand, the FTIR spectra indicated a higher polymerisation level of the ET APS, which suggested that a higher polymer may positively affect the mechanical performance of GFs. Hydrolysis at elevated temperature was found to be a novel and relatively easy way to prepare APS that improves the beneficial effect on GF strength. Thermal degradation of the APS sized Boron-free-E-glass fibres was also investigated across a wide range of temperatures. The results suggested that at temperatures around 3500C, the APS coating on the GFs surface starts to degrade and disappear, consequently reducing the protection provided by the APS layer. The effect of high temperature on GFs also creates cracks and flaws that may also contribute to the strength loss seen in these results which are consistent with the creation of defects for high temperature. Two other chemical treatments were investigated for their ability to regenerate the mechanical properties of the thermally conditioned GFs. An acidic treatment with hydrochloric acid (HCl) 37% v/v did produce a small increase of the average fibre strength, whilst a base treatment using concentrated sodium hydroxide (NaOH) solution at high temperature (950C) substantially improved the mechanical properties of thermal conditioned GFs, achieving up to 200% increase in fibre strength in comparison with the thermally degraded GFs. The optimum NaOH treatment conditions were further characterised in terms of treatment time, NaOH concentration and GF surface state and the effect on GF surface (i.e. OH groups on the surface) and reactions that occur with the glass. It is concluded that a number of very promising treatments with the potential to regenerate the mechanical properties of GFs recycled from composites have been identified.The processing and reuse of end-of-life composite products in an environmentally friendly manner is one of the most important challenges facing the industry and community. The development of an economically viable process for regenerating the properties of thermally recycled glass fibres (GFs) would have major technological, societal, economic and environmental impacts. The ultimate goal of this project is to enable cost-effective regeneration of the mechanical properties of GFs which have been produced from thermal recycling of end-of-life glass reinforced structural composites from automotive and wind energy applications. This work investigates the loss, and regeneration, of GF strength after thermal degradation at typical GRP recycling temperatures. The mechanical properties of APS sized and water sized (uncoated) Boron-free-E-glass fibres were first characterised using a conventional single fibre tension test. A substantial higher average strength was obtained from the APS sized fibres. Further investigation with GFs, coated with different silanes was carried out to determine any beneficial effect on GF mechanical properties. It was found that ɣ-Methacryloxypropyltrimethoxy Silane (MPS) and ɣ-Glycidoxypropyltrimethoxy Silane (GPS) prepared for 24 hours at RT and solution medium pH 5-5.5 in deionised water and ɣ-Aminopropyltriethoxy Silane prepared at 830C for 5 hours at solution medium natural pH (ET APS) in deionised water showed the higher increases in GF mechanical properties. Moreover, it was found that preparing the hydrolysed APS solution at elevated temperatures, had a beneficial effect on GF strength in comparison to a solution prepared at RT over 24 h (RT APS). Further investigation was carried out to identify any changes to the final products in solution and any structural differences between APS prepared at RT and at ET, that would lead to a conclusion about the difference in mechanical properties achieved. Using techniques such as Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infrared Spectroscopy (FTIR), several differences were identified. The results showed that ET APS contained less ethanol in solution after preparation, showing a relationship between the preparation temperature and the ethanol lost from the solution. On the other hand, the FTIR spectra indicated a higher polymerisation level of the ET APS, which suggested that a higher polymer may positively affect the mechanical performance of GFs. Hydrolysis at elevated temperature was found to be a novel and relatively easy way to prepare APS that improves the beneficial effect on GF strength. Thermal degradation of the APS sized Boron-free-E-glass fibres was also investigated across a wide range of temperatures. The results suggested that at temperatures around 3500C, the APS coating on the GFs surface starts to degrade and disappear, consequently reducing the protection provided by the APS layer. The effect of high temperature on GFs also creates cracks and flaws that may also contribute to the strength loss seen in these results which are consistent with the creation of defects for high temperature. Two other chemical treatments were investigated for their ability to regenerate the mechanical properties of the thermally conditioned GFs. An acidic treatment with hydrochloric acid (HCl) 37% v/v did produce a small increase of the average fibre strength, whilst a base treatment using concentrated sodium hydroxide (NaOH) solution at high temperature (950C) substantially improved the mechanical properties of thermal conditioned GFs, achieving up to 200% increase in fibre strength in comparison with the thermally degraded GFs. The optimum NaOH treatment conditions were further characterised in terms of treatment time, NaOH concentration and GF surface state and the effect on GF surface (i.e. OH groups on the surface) and reactions that occur with the glass. It is concluded that a number of very promising treatments with the potential to regenerate the mechanical properties of GFs recycled from composites have been identified
Production and characterisation of poly(vinyl chloride) (PVC) hollow fibre membranes for gas separation applications
No full textThe present work was focused in the development of polyvinylchloride (PVC) hollow fibre membranes suitable for gas separation applications using the dry/wet phase inversion technique.The first part of this work involved the preparation of quaternary polymer solutions containing polyvinylchloride (PVC), dimethylacetamide (DMAc), tetrahydrofuran(THF) and ethanol (EtOH) to study their phase inversion properties.Different solutions, with different compositions, were prepared and a visual evaluation was made in order to understand the properties of the ternary phase diagram for this system and the possible location of the binodal boundary that separates the one phase homogeneous region from the two phase region (nonhomogeneous).For all the solutions prepared, there was one composition that is suggested to be inside the non-homogeneous region, thus indication the potential position of the binodal curve in the region studied.During the spinning process, a polymer solution is subjected to shear stresses and deformation; therefore, the rheology of the quaternary PVC solutions was studied in detail. Oscillatory, creep and recovery and flow experiments were performed to fully characterize these solutions. Temperature and composition showed to have a big influence in the viscoelastic properties of the solutions investigated. The preparation of the solution used to spin the hollow fibre membranes followed a different procedure due to a larger quantity of solution needed and a different "ageing" time. Because of that, a rheological evaluation of this solution was also carried out and the effect of procedural differences on the viscoelastic properties of the spinning solution was analysed.;After the rheological studies, different spinning conditions were established to better understand the impact of the solutions' rheology features on the final performance of the PVC hollow fibre membranes. Spinning dope temperature, dope extrusion rate and external bath temperature were the parameters studied. The design of the experiments was done using the Taguchi method and a set of nine experiments with different experimental conditions were performed. Gas permeation results obtained for the different membranes showed poor selectivities, even after the two coating cycles. The analysis of variance (ANOVA) showed that the external bath temperature was the parameter that most contributed to the variability of the results.Scanning electron microscopy surface images revealed defects in the membranes surface (tearing). However, the Knudsen selectivity obtained for the uncoated membranes and the significant decline in the gas permeation through the membrane after coating cycles suggests that the fractures are not the main reason for the poor selectivities obtained.Mass transfer and resistance models available in the literature were used to predict the active layers thickness and the surface porosity of the membranes. Mass transfer model predicts thick active layers if high temperatures are used and is in accordance with the values obtained by the resistance modelling that also predict the existence of thick active layers with high surface porosity. The high surface porosity obtained is suggested to be due to the incomplete coalescence of the polymer nodules during the formation of the active layer in the dry gap and ispointed out as the possible reason for the poor selectivities.The present work was focused in the development of polyvinylchloride (PVC) hollow fibre membranes suitable for gas separation applications using the dry/wet phase inversion technique.The first part of this work involved the preparation of quaternary polymer solutions containing polyvinylchloride (PVC), dimethylacetamide (DMAc), tetrahydrofuran(THF) and ethanol (EtOH) to study their phase inversion properties.Different solutions, with different compositions, were prepared and a visual evaluation was made in order to understand the properties of the ternary phase diagram for this system and the possible location of the binodal boundary that separates the one phase homogeneous region from the two phase region (nonhomogeneous).For all the solutions prepared, there was one composition that is suggested to be inside the non-homogeneous region, thus indication the potential position of the binodal curve in the region studied.During the spinning process, a polymer solution is subjected to shear stresses and deformation; therefore, the rheology of the quaternary PVC solutions was studied in detail. Oscillatory, creep and recovery and flow experiments were performed to fully characterize these solutions. Temperature and composition showed to have a big influence in the viscoelastic properties of the solutions investigated. The preparation of the solution used to spin the hollow fibre membranes followed a different procedure due to a larger quantity of solution needed and a different "ageing" time. Because of that, a rheological evaluation of this solution was also carried out and the effect of procedural differences on the viscoelastic properties of the spinning solution was analysed.;After the rheological studies, different spinning conditions were established to better understand the impact of the solutions' rheology features on the final performance of the PVC hollow fibre membranes. Spinning dope temperature, dope extrusion rate and external bath temperature were the parameters studied. The design of the experiments was done using the Taguchi method and a set of nine experiments with different experimental conditions were performed. Gas permeation results obtained for the different membranes showed poor selectivities, even after the two coating cycles. The analysis of variance (ANOVA) showed that the external bath temperature was the parameter that most contributed to the variability of the results.Scanning electron microscopy surface images revealed defects in the membranes surface (tearing). However, the Knudsen selectivity obtained for the uncoated membranes and the significant decline in the gas permeation through the membrane after coating cycles suggests that the fractures are not the main reason for the poor selectivities obtained.Mass transfer and resistance models available in the literature were used to predict the active layers thickness and the surface porosity of the membranes. Mass transfer model predicts thick active layers if high temperatures are used and is in accordance with the values obtained by the resistance modelling that also predict the existence of thick active layers with high surface porosity. The high surface porosity obtained is suggested to be due to the incomplete coalescence of the polymer nodules during the formation of the active layer in the dry gap and ispointed out as the possible reason for the poor selectivities
Development of a microbially induced calcite and silica bio-grout for the sealing of fine aperture fractures
Get PDFGeological repositories are being considered as the best feasible solution for the storage of hazardous materials such as high level nuclear waste throughout the world, including the UK. However; when crystalline rock is the chosen storage medium, the construction of the underground tunnels and caverns can enhance discontinuities within the rock. These discontinuities can be pathways by which radio-nuclides can reach the biosphere, due to their higher permeability, connectivity and density (Blyth and Freitas, 1992). Thus, depending on aperture, density and predicted travel times, it may be necessary to grout all fractures, even small aperture ones, which over thousands of years can contribute significantly to subsurface flow. Conventional cementitious and chemical grouts are unsuitable within some regions of a geological disposal facility due to concerns regarding longevity, toxicity, reactions with other barriers and/or workability issues. The four main requirements of a grout are; to be of low viscosity as the lower the viscosity the easier it is to achieve good penetration, to have a controllable gel/setting time, to be chemically inert to prevent reactions within the subsurface or have any toxic consequences during preparation, and to be durable thus able to withstand exposure to varying physic-chemical condition. MICP (Microbially Induced Calcite Precipitation) and Colloidal Silica are novel grouts which may be suitable for the sealing of fine aperture fractures in rock. MICP research has been predominantly focussed on its application in sediments, whilst colloidal silica has shown its potential for reducing the liquefaction potential of non-cohesive soils and for sealing fractures. This research examines the influence of hydraulic controls (velocity, flow rate, aperture) on the spatial distribution of microbially induced calcite precipitation (MICP) within simulated fractures using flocculated Sporosarcina pasteurii.;The experimental results show that under flowing conditions, the spatial distribution of microbially induced calcite precipitate on fracture surfaces is controlled by fluid velocity. Even for a uniform initial fracture aperture with a steady flow rate, a feedback mechanism existed between velocity and precipitation that resulted in a precipitate distribution that focussed flow into a small number of self-organizing channels which remained stable. Ultimately, this feedback mechanism controlled the final aperture profile which governed flow within the fracture. To use MICP for field scale sealing operations (e.g., in aquifers and host rock surrounding nuclear waste storage sites), it is important to develop an injection strategy that ensures microbially precipitated calcite is distributed homogenously throughout the rock body to avoid preferential flow through high porosity pathways. Sporosarcina pasteurii was found to be able to hydrolyse urea for several days before the bacteria became encased within calcite preventing access to the cementing fluid. The higher rates of urea hydrolysis occurred within the first 9 hours, though significant rates of urea hydrolysis still occurred after this period. By reducing the size of bacterial flocs it is possible to reduce the impact of sedimentation and straining, promoting a more even distribution of bacteria thus calcite precipitate throughout the plate. By increasing the length of time that the bacteria flow through the fracture, more bacteria can become entrained upon the fracture surface giving a better distribution. The introduction of a filler (colloidal silica) that can also act as a nucleation site for calcite precipitation was examined as a way of reducing the time it takes for the sealing of a fracture. Both Sporosarcina pasteurii and colloidal silica have negative surface charges thus colloidal silica could be used as a nucleation surface, this plus its nanometre size which could allow for a better distribution of and could enhance calcite precipitation. A clear difference in the mass of grout retained within the fracture was seen, with MICP alone showing the greatest weight increase. During the 8 grouting cycles with MICP + colloidal silica there appeared to be pieces of calcite travelling through the open channels. This would indicate that the calcite is unable to attach to the fracture surface.;Thus, adding a small amount of colloidal silica to the cementing solution as a filler was not an efficient way to produce calcite fill. However, Sporosarcina pasteurii produces ammonium ions from the hydrolysis of the non-ionic urea, which as a cation can destabilise the silica sol resulting in gelation. Batch tests were used to determine what differences in gel point, gel rate and shear strength were created by different cations, including the chemical addition of ammonium ions and the biological production of ammonium ions by the bacterium Sporosarcina pasteurii. The sensitivity of colloidal silica to calcium chloride can result in dramatic differences in gel time with small changes in molarity having great impact on whether the colloidal silica gels or not. The direct addition of ammonium salts requires ten times the concentration, compared to CaCl2, to achieve similar shear strength values. However; this concentration produces very short gel times, potentially reducing the radius of penetration. The bacterial in-situ production of ammonium ions gives the greatest gel times yet still produces the same shear strength as that of a sodium chloride accelerator. This increasing of gel times, without adversely impacting grout properties, could be beneficial for penetrating greater distances into fractured rock reducing the number of injection points required. This would be particularly useful for subsurface engineering applications where large volumes of rock are required to be grouted.Geological repositories are being considered as the best feasible solution for the storage of hazardous materials such as high level nuclear waste throughout the world, including the UK. However; when crystalline rock is the chosen storage medium, the construction of the underground tunnels and caverns can enhance discontinuities within the rock. These discontinuities can be pathways by which radio-nuclides can reach the biosphere, due to their higher permeability, connectivity and density (Blyth and Freitas, 1992). Thus, depending on aperture, density and predicted travel times, it may be necessary to grout all fractures, even small aperture ones, which over thousands of years can contribute significantly to subsurface flow. Conventional cementitious and chemical grouts are unsuitable within some regions of a geological disposal facility due to concerns regarding longevity, toxicity, reactions with other barriers and/or workability issues. The four main requirements of a grout are; to be of low viscosity as the lower the viscosity the easier it is to achieve good penetration, to have a controllable gel/setting time, to be chemically inert to prevent reactions within the subsurface or have any toxic consequences during preparation, and to be durable thus able to withstand exposure to varying physic-chemical condition. MICP (Microbially Induced Calcite Precipitation) and Colloidal Silica are novel grouts which may be suitable for the sealing of fine aperture fractures in rock. MICP research has been predominantly focussed on its application in sediments, whilst colloidal silica has shown its potential for reducing the liquefaction potential of non-cohesive soils and for sealing fractures. This research examines the influence of hydraulic controls (velocity, flow rate, aperture) on the spatial distribution of microbially induced calcite precipitation (MICP) within simulated fractures using flocculated Sporosarcina pasteurii.;The experimental results show that under flowing conditions, the spatial distribution of microbially induced calcite precipitate on fracture surfaces is controlled by fluid velocity. Even for a uniform initial fracture aperture with a steady flow rate, a feedback mechanism existed between velocity and precipitation that resulted in a precipitate distribution that focussed flow into a small number of self-organizing channels which remained stable. Ultimately, this feedback mechanism controlled the final aperture profile which governed flow within the fracture. To use MICP for field scale sealing operations (e.g., in aquifers and host rock surrounding nuclear waste storage sites), it is important to develop an injection strategy that ensures microbially precipitated calcite is distributed homogenously throughout the rock body to avoid preferential flow through high porosity pathways. Sporosarcina pasteurii was found to be able to hydrolyse urea for several days before the bacteria became encased within calcite preventing access to the cementing fluid. The higher rates of urea hydrolysis occurred within the first 9 hours, though significant rates of urea hydrolysis still occurred after this period. By reducing the size of bacterial flocs it is possible to reduce the impact of sedimentation and straining, promoting a more even distribution of bacteria thus calcite precipitate throughout the plate. By increasing the length of time that the bacteria flow through the fracture, more bacteria can become entrained upon the fracture surface giving a better distribution. The introduction of a filler (colloidal silica) that can also act as a nucleation site for calcite precipitation was examined as a way of reducing the time it takes for the sealing of a fracture. Both Sporosarcina pasteurii and colloidal silica have negative surface charges thus colloidal silica could be used as a nucleation surface, this plus its nanometre size which could allow for a better distribution of and could enhance calcite precipitation. A clear difference in the mass of grout retained within the fracture was seen, with MICP alone showing the greatest weight increase. During the 8 grouting cycles with MICP + colloidal silica there appeared to be pieces of calcite travelling through the open channels. This would indicate that the calcite is unable to attach to the fracture surface.;Thus, adding a small amount of colloidal silica to the cementing solution as a filler was not an efficient way to produce calcite fill. However, Sporosarcina pasteurii produces ammonium ions from the hydrolysis of the non-ionic urea, which as a cation can destabilise the silica sol resulting in gelation. Batch tests were used to determine what differences in gel point, gel rate and shear strength were created by different cations, including the chemical addition of ammonium ions and the biological production of ammonium ions by the bacterium Sporosarcina pasteurii. The sensitivity of colloidal silica to calcium chloride can result in dramatic differences in gel time with small changes in molarity having great impact on whether the colloidal silica gels or not. The direct addition of ammonium salts requires ten times the concentration, compared to CaCl2, to achieve similar shear strength values. However; this concentration produces very short gel times, potentially reducing the radius of penetration. The bacterial in-situ production of ammonium ions gives the greatest gel times yet still produces the same shear strength as that of a sodium chloride accelerator. This increasing of gel times, without adversely impacting grout properties, could be beneficial for penetrating greater distances into fractured rock reducing the number of injection points required. This would be particularly useful for subsurface engineering applications where large volumes of rock are required to be grouted
Development and validation of a functional outcome measure package for total knee arthroplasty
Get PDFFunctional improvement is an important outcome following total knee arthroplasty (TKA). According to recent research, three-dimensional motion analysis is the most scientific method of measuring dynamic knee function. Nevertheless, current protocols are too time consuming and complicated for routine clinical use. This study developed a clinic-appropriate motion capture system, and investigated the feasibility of its use in a clinical environment. A compact motion capture system (Dimensions: 3.5(L)x2.1(H)x1.1(W)m) and bespoke cluster-based biomechanical model were developed. Assessments for quantifying knee range of motion (ROM), knee strength, gait kinematics, and gait stability were incorporated into the software. Most results were reported in real-time. Validation studies of the assessments against clinical standard tools showed few clinically significant differences between the results, suggesting that the assessments could be used as accurate and reliable alternatives to the traditional tools. The system was then used clinically to report the functional outcome of Medacta GMK Sphere TKA patients. Patients underwent functional testing pre-, 6-weeks, and 1-year post-operatively. Average recorded assessment time was 16.8±2.4 minutes. On average, knee ROM, gait kinematics, spatio-temporal parameters of gait and gait stability improved post-operatively. Knee strength decreased over the first year however, suggesting that TKA patients require strength training post operatively in order to optimise functional outcome. The results reported in this trial were generally consistent with the current literature, implying that the system returned valid data for this patient cohort, and that the Medacta GMK Sphere TKA was successful at improving knee function, especially in frontal and transverse planes during gait.To conclude, this thesis has shown that motion capture technology can feasibly be used in the clinical environment to assess the function of TKA patients in an acceptable clinical time frame. The system developed and presented here can therefore justifiably be used clinically to better report the functional outcome of TKA.Functional improvement is an important outcome following total knee arthroplasty (TKA). According to recent research, three-dimensional motion analysis is the most scientific method of measuring dynamic knee function. Nevertheless, current protocols are too time consuming and complicated for routine clinical use. This study developed a clinic-appropriate motion capture system, and investigated the feasibility of its use in a clinical environment. A compact motion capture system (Dimensions: 3.5(L)x2.1(H)x1.1(W)m) and bespoke cluster-based biomechanical model were developed. Assessments for quantifying knee range of motion (ROM), knee strength, gait kinematics, and gait stability were incorporated into the software. Most results were reported in real-time. Validation studies of the assessments against clinical standard tools showed few clinically significant differences between the results, suggesting that the assessments could be used as accurate and reliable alternatives to the traditional tools. The system was then used clinically to report the functional outcome of Medacta GMK Sphere TKA patients. Patients underwent functional testing pre-, 6-weeks, and 1-year post-operatively. Average recorded assessment time was 16.8±2.4 minutes. On average, knee ROM, gait kinematics, spatio-temporal parameters of gait and gait stability improved post-operatively. Knee strength decreased over the first year however, suggesting that TKA patients require strength training post operatively in order to optimise functional outcome. The results reported in this trial were generally consistent with the current literature, implying that the system returned valid data for this patient cohort, and that the Medacta GMK Sphere TKA was successful at improving knee function, especially in frontal and transverse planes during gait.To conclude, this thesis has shown that motion capture technology can feasibly be used in the clinical environment to assess the function of TKA patients in an acceptable clinical time frame. The system developed and presented here can therefore justifiably be used clinically to better report the functional outcome of TKA
MobiBot : personifying telepresence communication
Get PDFThe smartphone has become an intrinsic part of daily life, taking the role of a trusted companion in the context of communication technology. A persistent and widely documented issue in the domain of embodied technology, however, is the lack of natural interaction. As communication takes place not only through speech, but also through gestures such as facial expressions, gaze, head movements, hand movements and body posture. This research believe these are needed to fully support non-verbal communication and make interactions more engaging and efficient. In this research, This research focus on a telepresence (TP) robotic system (MobiBot) that affords the ability to convey non-verbal behaviours such as gesture and posture that can make the interactions more natural and life-like. Our expletory study focused specifically on the head rather than any other body part as it is a rich source of information for speech-related movement. This investigated the value of incorporating head movements into the use of telepresence robots as communication platforms by means of evaluating a system that manually reproduces head movement as closely as possible. Then, expanding the consideration of the physical embodiment of the system to include the head, shoulders and proximity, this research proposes a new protocol for the translation of the vocal stream into gesture to generate human-like behaviour and support more natural interaction within the embodied technology system. A modified version of the Undefined Technology of Acceptance and Use of Technology model (UTAUT) has been used to explore social and cognitive experience when using the system. Subjects' acceptance of the gesturally-supported video communication using for the MobiBot system was examined by comparing of the different methods of interaction on video calls using the MobiBot TP system. The comparison was between mimicking movement (where the operator replicates the movement by pressing buttons) and automated movement triggered by the user vocal stream. This was carried out in order to evaluate their effect. The results of the comparative analysis indicated that the mimicking interaction of the MobiBot system for video calls was preferred by the users over the vocal-triggered automatic interaction movement method. Evaluation and feedback of the movements incorporated suggests a mix of both vocal-triggered automatic and mimicking movements, using fewer large movements and more small and steady movements, is optimal. In addition, a set of guidelines was developed using the findings from both studied, for 'personifying' telepresence conversations and development of such systems. This research, in general, demonstrated significantly greater benefits from incorporating movement with such systems.The smartphone has become an intrinsic part of daily life, taking the role of a trusted companion in the context of communication technology. A persistent and widely documented issue in the domain of embodied technology, however, is the lack of natural interaction. As communication takes place not only through speech, but also through gestures such as facial expressions, gaze, head movements, hand movements and body posture. This research believe these are needed to fully support non-verbal communication and make interactions more engaging and efficient. In this research, This research focus on a telepresence (TP) robotic system (MobiBot) that affords the ability to convey non-verbal behaviours such as gesture and posture that can make the interactions more natural and life-like. Our expletory study focused specifically on the head rather than any other body part as it is a rich source of information for speech-related movement. This investigated the value of incorporating head movements into the use of telepresence robots as communication platforms by means of evaluating a system that manually reproduces head movement as closely as possible. Then, expanding the consideration of the physical embodiment of the system to include the head, shoulders and proximity, this research proposes a new protocol for the translation of the vocal stream into gesture to generate human-like behaviour and support more natural interaction within the embodied technology system. A modified version of the Undefined Technology of Acceptance and Use of Technology model (UTAUT) has been used to explore social and cognitive experience when using the system. Subjects' acceptance of the gesturally-supported video communication using for the MobiBot system was examined by comparing of the different methods of interaction on video calls using the MobiBot TP system. The comparison was between mimicking movement (where the operator replicates the movement by pressing buttons) and automated movement triggered by the user vocal stream. This was carried out in order to evaluate their effect. The results of the comparative analysis indicated that the mimicking interaction of the MobiBot system for video calls was preferred by the users over the vocal-triggered automatic interaction movement method. Evaluation and feedback of the movements incorporated suggests a mix of both vocal-triggered automatic and mimicking movements, using fewer large movements and more small and steady movements, is optimal. In addition, a set of guidelines was developed using the findings from both studied, for 'personifying' telepresence conversations and development of such systems. This research, in general, demonstrated significantly greater benefits from incorporating movement with such systems
Control of wave energy converters using machine learning strategies
Get PDFWave energy converters are devices that are designed to extract power from ocean waves. Existing wave energy converter technologies are not financially viable yet. Control systems have been identifed as one of the areas that can contribute the most towards the increase in energy absorption and reduction of loads acting on the structure, whilst incurring only minimal extra hardware costs. In this thesis, control schemes are developed for wave energy converters, with the focus on single isolated devices.;Numerical models of increasing complexity are developed for the simulation of a point absorber, which is a type of wave energy converter with small dimensions with respect to the dominating wave length. After investigating state-of-the-art control schemes, the existing control strategies reported in the literature have been found to rely on the model of the system dynamics to determine the optimal control action;This is despite the fact that modelling errors can negatively affect the performance of the device, particularly in highly energetic waves when non-linear effects become more signficant. Furthermore, the controller should be adaptive so that changes in the system dynamics, e.g. due to marine growth or non-critical subsystem failure, are accounted for. Hence, machine learning approaches have been investigated as an alternative, with a focus on neural networks and reinforcement learning for control applications.;A time-averaged approach will be employed for the development of the control schemes to enable a practical implementation on WECs based on the standard in the industry at the moment.;Neural networks are applied to the active control of a point absorber. They are used mainly for system identifcation, where the mean power is related to the current sea state and parameters of the power take-off unit. The developed control scheme presents a similar performance to optimal active control for the analysed simulations, which rely on linear hydrodynamics.;Reinforcement learning is then applied to the passive and active control of a wave energy converter for the first time. The successful development of different control schemes is described in detail, focusing on the encountered challenges in the selection of states, actions and reward function. The performance of reinforcement learning is assessed against state-of-the-art control strategies.;Reinforcement learning is shown to learn the optimal behaviour in a reasonable time frame, whilst recognizing each sea state without reliance on any models of the system dynamics. Additionally, the strategy is able to deal with model non-linearities. Furthermore, it is shown that the control scheme is able to adapt to changes in the device dynamics, as for instance due to marine growth.Wave energy converters are devices that are designed to extract power from ocean waves. Existing wave energy converter technologies are not financially viable yet. Control systems have been identifed as one of the areas that can contribute the most towards the increase in energy absorption and reduction of loads acting on the structure, whilst incurring only minimal extra hardware costs. In this thesis, control schemes are developed for wave energy converters, with the focus on single isolated devices.;Numerical models of increasing complexity are developed for the simulation of a point absorber, which is a type of wave energy converter with small dimensions with respect to the dominating wave length. After investigating state-of-the-art control schemes, the existing control strategies reported in the literature have been found to rely on the model of the system dynamics to determine the optimal control action;This is despite the fact that modelling errors can negatively affect the performance of the device, particularly in highly energetic waves when non-linear effects become more signficant. Furthermore, the controller should be adaptive so that changes in the system dynamics, e.g. due to marine growth or non-critical subsystem failure, are accounted for. Hence, machine learning approaches have been investigated as an alternative, with a focus on neural networks and reinforcement learning for control applications.;A time-averaged approach will be employed for the development of the control schemes to enable a practical implementation on WECs based on the standard in the industry at the moment.;Neural networks are applied to the active control of a point absorber. They are used mainly for system identifcation, where the mean power is related to the current sea state and parameters of the power take-off unit. The developed control scheme presents a similar performance to optimal active control for the analysed simulations, which rely on linear hydrodynamics.;Reinforcement learning is then applied to the passive and active control of a wave energy converter for the first time. The successful development of different control schemes is described in detail, focusing on the encountered challenges in the selection of states, actions and reward function. The performance of reinforcement learning is assessed against state-of-the-art control strategies.;Reinforcement learning is shown to learn the optimal behaviour in a reasonable time frame, whilst recognizing each sea state without reliance on any models of the system dynamics. Additionally, the strategy is able to deal with model non-linearities. Furthermore, it is shown that the control scheme is able to adapt to changes in the device dynamics, as for instance due to marine growth
Batch to continuous organic salt crystallisation : model based design
Get PDFOrganic salt crystallisation is of great importance to the pharmaceutical industry as the majority of pharmaceutical products are sold as salts with salt formation being an essential step in drug development. In this research a solution speciation model was developed to predict pH and solution composition during salt crystallisation processes. This tool allows for the entire salt crystallisation design space to be explored in terms of process pathways in the concentration vs. pH phase diagram. This allows for greater process understanding to be obtained and for theoretical solid yields to be determined.The model compound used in this work is the polymorphic organic salt ethylenediammonium 3,5-dinitrobenzoate (EDNB) which is the 2:1 salt of 3,5-dinitrobenzoic acid (3,5-DNBA) with ethylenediamine. In this system one of the two EDNB polymorphs (monoclinic and triclinic) or the 3,5-DNBA starting material may crystallise. The solution speciation model was used to predict the crystallisation pathway for each solid form and to guide the development of semi-batch and fully continuous crystallisation processes. In addition, aqueous pH-solubility measurements of EDNB triclinic and 3,5-DNBA were made to better understand EDNB salt solubility in high ionic strength solutions and to establish the operating space where 3,5-DNBA crystallisation is avoided.In this study EDNB crystallisation was experimentally performed in semi-batch and fully continuous processes. The semi-batch experiments demonstrated the scale up of the EDNB crystallisation process to 400 ml compared to 50 ml in literature. The fully continuous processes demonstrated that continuous mixing approaches could be used to crystallise the EDNB salt with consistent yield and PSD. Control over which polymorphic form crystallised was successfully demonstrated in both semi-batch and continuous mixing processes.Organic salt crystallisation is of great importance to the pharmaceutical industry as the majority of pharmaceutical products are sold as salts with salt formation being an essential step in drug development. In this research a solution speciation model was developed to predict pH and solution composition during salt crystallisation processes. This tool allows for the entire salt crystallisation design space to be explored in terms of process pathways in the concentration vs. pH phase diagram. This allows for greater process understanding to be obtained and for theoretical solid yields to be determined.The model compound used in this work is the polymorphic organic salt ethylenediammonium 3,5-dinitrobenzoate (EDNB) which is the 2:1 salt of 3,5-dinitrobenzoic acid (3,5-DNBA) with ethylenediamine. In this system one of the two EDNB polymorphs (monoclinic and triclinic) or the 3,5-DNBA starting material may crystallise. The solution speciation model was used to predict the crystallisation pathway for each solid form and to guide the development of semi-batch and fully continuous crystallisation processes. In addition, aqueous pH-solubility measurements of EDNB triclinic and 3,5-DNBA were made to better understand EDNB salt solubility in high ionic strength solutions and to establish the operating space where 3,5-DNBA crystallisation is avoided.In this study EDNB crystallisation was experimentally performed in semi-batch and fully continuous processes. The semi-batch experiments demonstrated the scale up of the EDNB crystallisation process to 400 ml compared to 50 ml in literature. The fully continuous processes demonstrated that continuous mixing approaches could be used to crystallise the EDNB salt with consistent yield and PSD. Control over which polymorphic form crystallised was successfully demonstrated in both semi-batch and continuous mixing processes
Establishment of a novel predictive reliability assessment strategy for ship machinery
Get PDFThere is no doubt that recent years, maritime industry is moving forward to novel and sophisticated inspection and maintenance practices. Nowadays maintenance is encountered as an operational method, which can be employed both as a profit generating process and a cost reduction budget centre through an enhanced Operation and Maintenance (O&M) strategy. In the first place, a flexible framework to be applicable on complex system level of machinery can be introduced towards ship maintenance scheduling of systems, subsystems and components.;This holistic inspection and maintenance notion should be implemented by integrating different strategies, methodologies, technologies and tools, suitably selected by fulfilling the requirements of the selected ship systems. In this thesis, an innovative maintenance strategy for ship machinery is proposed, namely the Probabilistic Machinery Reliability Assessment (PMRA) strategy focusing towards the reliability and safety enhancement of main systems, subsystems and maintainable units and components.;In this respect, the combination of a data mining method (k-means), the manufacturer safety aspects, the dynamic state modelling (Markov Chains), the probabilistic predictive reliability assessment (Bayesian Belief Networks) and the qualitative decision making (Failure Modes and Effects Analysis) is employed encompassing the benefits of qualitative and quantitative reliability assessment. PMRA has been clearly demonstrated in two case studies applied on offshore platform oil and gas and selected ship machinery.;The results are used to identify the most unreliability systems, subsystems and components, while advising suitable practical inspection and maintenance activities. The proposed PMRA strategy is also tested in a flexible sensitivity analysis scheme.There is no doubt that recent years, maritime industry is moving forward to novel and sophisticated inspection and maintenance practices. Nowadays maintenance is encountered as an operational method, which can be employed both as a profit generating process and a cost reduction budget centre through an enhanced Operation and Maintenance (O&M) strategy. In the first place, a flexible framework to be applicable on complex system level of machinery can be introduced towards ship maintenance scheduling of systems, subsystems and components.;This holistic inspection and maintenance notion should be implemented by integrating different strategies, methodologies, technologies and tools, suitably selected by fulfilling the requirements of the selected ship systems. In this thesis, an innovative maintenance strategy for ship machinery is proposed, namely the Probabilistic Machinery Reliability Assessment (PMRA) strategy focusing towards the reliability and safety enhancement of main systems, subsystems and maintainable units and components.;In this respect, the combination of a data mining method (k-means), the manufacturer safety aspects, the dynamic state modelling (Markov Chains), the probabilistic predictive reliability assessment (Bayesian Belief Networks) and the qualitative decision making (Failure Modes and Effects Analysis) is employed encompassing the benefits of qualitative and quantitative reliability assessment. PMRA has been clearly demonstrated in two case studies applied on offshore platform oil and gas and selected ship machinery.;The results are used to identify the most unreliability systems, subsystems and components, while advising suitable practical inspection and maintenance activities. The proposed PMRA strategy is also tested in a flexible sensitivity analysis scheme
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