38541 research outputs found
Sort by
Exploring self-optimisation methods for hydrogenation reactions in supercritical CO2
No full textThe work described in this Thesis investigates the use of self-optimisation methods to improve the efficiency of hydrogenation reactions in supercritical CO2 (scCO2) in continuous flow. Chapter 1 introduces the concepts of flow chemistry, emphasising its advantages. An overview of various optimisation methods used in flow chemistry, with a focus on recent advancements in self-optimisation methods is outlined. There is a brief description of supercritical fluids and discussion of previous work related to hydrogenation reactions in scCO2. The Chapter concludes with the Aims of the Thesis.
Chapter 2 details the development of an automated high temperature and high pressure reactor designed for the self-optimisation of hydrogenation reactions in supercritical CO2. The chapter begins by outlining the reactor’s components, which were based on previous iterations of similar reactors used by the research group. This reactor design incorporates various optimisation algorithms and utilises an on-line Gas Chromatography (GC) system for monitoring the reactions. The reactor was commissioned with a test reaction of hydrogenation of isophorone with a palladium based catalyst (up to 800 mg) in scCO2. The hydrogenation of isophorone was successful with the formation of a single product 3,3,5-trimethylcyclohexanone (TMCH), with the optimum yield of >99% achieved.
In Chapter 3, the reactor was used to investigate the hydrogenation of isophorone for self-optimisation, where reactant was pumped into the system, and the reaction conditions were optimised automatically for the product (TMCH) yield by varying different parameters such as temperature, pressure, CO2 and isophorone flow rates, and H2:isophorone ratios. Three different optimisation algorithms, Super Modified Simplex (SMSIM), Stable Noisy Optimisation by Branch and FIT (SNOBFIT) and Bayesian, were used, all producing comparable results for the hydrogenation of isophorone. When comparing the performance of these algorithms at different catalyst loadings (400, 200, and 100 mg of 2% Pd/type31 SiO2-Al2O3), the Bayesian algorithm outperformed the others by requiring the fewest experiments to achieve the optimal yield of TMCH.
In Chapter 4, a new accelerated self-optimisation method was developed using kinetic modelling, applied to the same model reaction of hydrogenation of isophorone. Kinetic models were employed to predict the optimal conditions, which then guided the optimisation algorithms more efficiently. This approach reduced the number of required experiments to obtain the optimum by more than 50% compared to the previous self-optimisation method, resulting in significant savings in time, materials, and resources, while also minimising waste production. Further improvements in efficiency were achieved through the integration of in-line ReactIR, which offers a much faster sampling rate compared to on-line GC, contributing to a more sustainable self-optimisation process for the hydrogenation of isophorone. In this case, the SMSIM algorithm performed best, requiring the least number of experiments to reach the optimum when guided by the kinetic model.
In Chapter 5, the substrate scope for the self-optimisation of hydrogenation reactions was expanded to include x,β-unsaturated carbonyl compounds, specifically x-methyl-trans-cinnamaldehyde. The initial strategy focused on selecting a suitable catalyst capable of selectively hydrogenating the starting material into the desired products, 2-methyl-3-phenylpropanal and 2-methyl-3-phenyl-2-propen-1-ol, by precisely optimising reaction parameters. Initial Design of Experiment (DoE) studies were carried out using 5% Ru/Al2O3 to determine the conditions required for forming each product. These DoE results then informed the Bayesian algorithm for self-optimisation. The optimal conditions for high yields of each product differed, with milder conditions required for selective hydrogenation of the aldehyde functional group in x-methyl-trans-cinnamaldehyde compared to the alkene functional group. Through self-optimisation, the system successfully optimised the production of the desired products using a single catalyst. To improve on the yield for the hydrogenation of x-methyl-trans-cinnamaldehyde towards the 2-methyl-3-phenyl-2-propen-1-ol product, catalytic transfer hydrogenation (CTH) was explored using ethanol as both the solvent and hydrogen donor, in the presence of acidic alumina as the catalyst. This approach achieved 100% selectivity and a 97% yield of the desired product, with no by-products formed.
Chapter 6 of this Thesis outlines details of the experimental work conducted. Chapter 7 summarises the Thesis, evaluates the success of the techniques and approach outlined in the aims of Chapter 1, and offers suggestions for future research based on the findings
The influence of Conservation Agriculture on soil biophysical properties, crop growth and yield in the UK
No full textThe global intensification of agricultural land use has been driven by the need to maximise crop yields, often through practices such as tillage and the application of agro-chemicals. However, this intensification has revealed significant challenges in maintaining long-term soil structure and function. The actions of common soil cultivation practices can physically disrupt key soil properties, leading to diminished biological activity, the breakdown of soil aggregates, and the depletion of key organic carbon compounds. Consequently, conventionally managed soils are subject to erosion rates that are 1–2 orders of magnitude higher than natural soil formation rates.
In response to these challenges, Conservation Agriculture (CA) is seen as a sustainable farming approach aimed at improving soil structure, enhancing soil function, and reducing the labour and fuel demands associated with conventional soil management. The principles of CA—minimal soil disturbance, permanent soil cover, and crop rotation—have shown promise in enhancing soil water use efficiency in arid and semi-arid regions. However, the effects on the final yield of CA techniques have been seen to be highly variable and heavily dependent on crop type, aridity, climate, and time. In the UK, CA practices have, in some cases, been found to be effective and profitable, but the causes of profit losses in others. Additionally, there are few studies that have attempted to link the changes CA practices cause in the soil to differences in the final yield.
This thesis investigates the long-term effects of CA practices, including zero tillage, reduced tillage, and mouldboard ploughing followed by rolling, both with and without crop residue retention, on the physical, biological, and chemical properties of soil. The trial site was conducted as a long-term (c. 7-9 years) trial at the University of Nottingham, England, and supplemented by field samples from long-term zero tillage farms. Traditional soil assessment methods were used alongside advanced X-ray Computed Tomography (CT) to evaluate soil structure, function, and pore arrangement.
The first experimental chapter examines the effects of CA practices on soil physical, biological, and chemical properties approximately 7–10 years after their adoption. Initial results showed that zero tillage led to an increase in soil bulk density; however, after nine years of CA management, the bulk density in zero tillage plots decreased to 0.991 g cm-3, compared to 1.03 and 1.04 g cm-3 under minimum tillage and ploughing, respectively. This reduction in bulk density was associated with increases in soil organic carbon, earthworm activity, and soil moisture content. Additionally, reduced tillage systems, including both zero and minimum tillage, exhibited higher soil organic matter, soil organic carbon content, and microbial biomass. These findings suggest that the benefits of CA practices in the UK become more pronounced over time, with key improvements in soil health being most evident from 8-9 years post-adoption.
The subsequent chapter explored the impact of these soil changes on crop growth and yield. While crop establishment rates were consistently lower under reduced tillage systems, these differences did not result in consistent, significant yield disparities over the course of the trial, which began in 2014. Notably, the effects of tillage practices varied by crop species. For instance, wheat was able to compensate for reduced establishment rates through tillering, whereas faba beans showed a significant yield reduction under zero tillage, likely due to a lower capacity to compensate for poor initial establishment. Despite these variations, the average yields in zero and minimum tillage plots since establishment of the trial in 2014 were not significantly different from those in ploughed plots, whilst benefitting from the lower input requirements associated with CA practices.
To investigate the hypothesis that poor crop establishment under zero tillage is caused by suboptimal seed-soil contact, X-ray CT was employed to image seeds and the surrounding soil after drilling. It was revealed that zero tillage seedbeds exhibited a similar porosity to ploughed seedbeds (17% versus 18%), while minimum tillage seedbeds had a significantly higher average porosity (22%). The minimum tillage plots also displayed significantly larger macropores (770 mm3) than either the zero tillage (200 mm3) or ploughed plots (220 mm3). However, despite lower average porosities and smaller macropores which are usually associated with increased seed-soil contact, the seed-soil contact of the zero tillage (78%) and ploughed plots (70%), were significantly lower than the minimum tillage plots (82%). The increased seed-soil contact in minimum tillage plots may be attributed to a deeper sowing depth and resulting compression of the soil around the seeds. However, seed-soil contact did not correlate with crop establishment rates, suggesting that other factors may contribute to the reduced establishment observed under zero tillage.
An additional experiment utilising the zero tillage and ploughed plots in the trial alongside samples from long-term (c. 20 year) zero tillage fields in practise in the UK, focused on the stocks, distribution, and lability of soil carbon. X-ray CT scans revealed that zero tillage soils had larger and deeper macropores, with pore networks extending twice as far into the soil as those in ploughed soils. This consolidation of pore space into larger, deeper pores is theorised to provide physical protection to organic matter in the soil from decomposition by soil biota such as earthworms and microbes. Consequently, significantly higher total soil organic carbon stocks were observed in all sites under zero tillage longer than five years, and all zero tillage sites regardless of age saw higher soil organic carbon stocks at the soil surface. Additionally, Rock-eval (6) analysis was conducted to investigate the stability of the carbon stocks present in the soil. It was found that there was an increase in both labile and recalcitrant carbon pools under zero tillage, but of labile carbon to a greater degree, suggesting enhanced physical protection of organic carbon.
The data from this study underscores the potential long-term benefits of Conservation Agriculture in temperate climates, particularly in terms of soil health, carbon storage, and reduced input requirements. While initial challenges such as lower crop establishment rates under reduced tillage were observed, these were offset by significant improvements in soil structure, function, and carbon sequestration over time. Over nine years of study, while some years saw significant differences in yield, there were no overall trends, and no tillage system performed best. The study highlights the importance of sustained commitment to CA practices to fully realise their benefits, demonstrating that long-term adoption of CA can lead to enhanced agricultural productivity and sustainability
Design and Development of Organic Electrocatalysts for CO2 Reduction
Get PDFThe electrochemical carbon dioxide reduction reaction (CO2RR) represents a promising method for converting carbon waste streams into valuable chemicals. Current CO2RR electrocatalysts often rely on expensive and rare platinum group metals, highlighting the need for more sustainable and cost-effective alternatives. This thesis explores the use of aromatic nitro group-bearing catalysts for the CO2RR, focusing on their performance in different electrolyte systems. Cyclic voltammetry was employed to evaluate catalytic efficiency. Additionally, the influence of the electrolyte and gas environment (N2 vs. CO2) on the catalytic activity was investigated. Results demonstrated that aromatic nitro group catalysts exhibited improved CO2 reduction activity in both electrolyte systems. This study provides insights into the relationship between catalyst structure, electrolyte composition, and gas environment, suggesting that further optimization of these catalyst-electrolyte systems could enhance the efficiency and selectivity of the CO2RR, advancing sustainable chemical production processes
Establishment of Genome Editing in Symbiodinium
No full textSymbiodinium microadriaticum is a symbiotic algae that is crucial to coral reef ecosystems. It plays a vital role in coral health through its symbiosis with corals, supplying them with nutrients via photosynthesis. However, environmental stressors such as increasing sea temperatures and overexposure to sunlight have led to widespread coral bleaching, threatening reef ecosystems. This project explored the potential of applying CRISPR-Cas9 gene-editing technology to S. microadriaticum. This technique could be a tool for enhancing its resilience to such stressors. The project focused on several key objectives: determining whether D-amino acids, specifically D-alanine, could serve as practical selectable markers, optimising transformation conditions using Lonza electroporation, and inserting foreign genes into the Symbiodinium genome.
CRISPR-Cas9 gene editing targeted the D-amino acid oxidase (DAAO) gene in S. microadriaticum, conferring resistance to D-alanine in transformed cells. D-alanine was confirmed as a practical selectable marker at specific concentrations. Additionally, this study highlighted the challenges of working with Symbiodinium, particularly in achieving consistent transformation efficiency, long-term viability, and overcoming contamination. The work established a proof of concept for the genetic manipulation of S. microadriaticum, opening new avenues for further genetic research in symbiotic dinoflagellates.
This research marks an essential step toward developing genetic engineering techniques that could help mitigate coral bleaching by enhancing Symbiodinium's stress tolerance
Linking physicochemical properties and sensory data in fibre-enhanced chocolate-based systems
No full textSugar consumption is an increasingly significant public health concern, motivating the confectionery industry to explore alternative sweetening strategies in chocolate formulation. Chocolate is a mechanically complex fat-based suspension comprising sugar, cocoa, and milk solids, and is highly appreciated for its distinctive sensory properties and oral processing behaviour. These attributes contribute to consumer perceptions of chocolate as an ‘indulgent’, ‘restful’, and ‘luxurious’ treat. Importantly, many of these sensory qualities are linked to the presence of sucrose crystals, their size, solubility, and characteristic sweetness. The challenge lies in reducing or replacing sucrose without compromising the sensory experience or structural integrity of the final product.
This thesis addresses this challenge through a comprehensive, multi-methodological research programme with two primary objectives: (i) to investigate the mechanical and sensory attributes of fat-based suspensions enriched with dietary fibres, and (ii) to explore ball milling as a modification technique to enhance the functional performance of fibres for sugar reduction in chocolate
The processing, microstructure, properties and performance of abradable environmental barrier coatings
Get PDFThermal performance of 3D-printed buildings
No full text3D printing in construction offers a sustainable alternative to conventional methods, with advantages such as geometric flexibility, reduced waste, cost and time savings. However, the high costs associated with large-scale 3D printers constrain the widespread adoption of additive manufacturing in construction. This research addresses this limitation by designing, calibrating, and evaluating an affordable lab-scale 3D printer tailored for cement-based materials, aiming to lower the entry barriers for additive manufacturing research in construction.
A systematic literature review revealed that while many studies have explored the benefits of 3D printing in construction, the thermal and energy performances of 3D-printed structures remain underexplored. To address this gap and provide a holistic understanding of the heat transfer properties of 3D-printed structures, this study presents a multi-scale analysis of the influence of the 3D printing process on thermal performance. At the microscale, this study investigates the impact of printing parameters on the thermal conductivity and defect development in 3D-printed concrete structures. Experimental techniques, including heat flow meter analysis, scanning electron microscopy, and infrared imaging, were employed to assess the thermal properties and microstructure of 3D-printed samples. The findings reveal that printing parameters significantly impact porosity, void formation, and microstructural characteristics, affecting thermal performance. At the component scale, the thermal performance of 3D-printed wall segments was experimentally analysed using a hot box apparatus. The results indicate that strategic cross-section design can improve thermal performance, potentially reducing material consumption while eliminating the need for additional insulation. Thermal transmittance values ranged from 1.94 to 2.64 W/m²K, depending on cross-section design and testing orientation. At the macro-scale, the study evaluated the impact of wall design on the thermal performance of a whole building under urban wind and cold climate conditions using Computational Fluid Dynamics (CFD) modelling, validated with wind tunnel experiments. The results demonstrate that cross-section design significantly influences temperature distribution, thermal bridge formation, and convective heat transfer coefficients (CHTC). Heat flux values at the windward surface varied between 9.38 and 59.19 W/m² across different wall designs. Some wall designs effectively minimised heat loss; the wall design with continuous air gap exhibited the lowest heat transfer values and achieved more uniform temperature distribution and CHTC, demonstrating superior performance. The findings highlight the significant influence of wind speed and direction on heat flux and CHTC, reinforcing the importance of wind orientation in designing thermally efficient building envelopes.
This study provides a multi-scale analysis of the thermal performance of 3D-printed structures, revealing that printing parameters and geometric design significantly influence thermal performance. The findings support the development of environmentally friendly construction practices and promote the broader adoption of additive manufacturing in the building sector
Decoding AI art: from motivation to manifestation
Get PDFThis thesis explores the integration of Artificial Intelligence (AI) art into artistic practices from an HCI and practice-led perspective. It centres on understanding the 'why' behind AI art practice, moving beyond technical implementations to explore the underlying stated motivations and conceptual goals driving artists to engage with AI technologies.
The research employs methods primarily from Human-Computer Interaction (HCI) and practice-led research, drawing on theoretical analysis and critical reflection.
The thesis makes three primary contributions to HCI and practice-led research on AI art practice. First, it presents the 'Five Tropes of AI Art', a flexible framework for analysing AI artworks based on observable practices and stated artistic motivations, offering a lens for HCI researchers and curators in related fields.
Second, it offers a practice-led case study of the 'Cat Royale' project, providing insights into the practical challenges of creating AI artwork. Third, it proposes a set of guidelines for AI art practice analysis, integrating theoretical understanding with practical experience from the case study. These guidelines, which include the Five Tropes framework, offer additional analytical lenses for navigating the complex landscape of AI art creation and presentation.
A key finding of this research is the critical importance of clear stated or inferred artistic motivation and effective framing in creating impactful AI art. It challenges the notion that AI art is solely about technological implementation, instead emphasising the human context of its creation and interpretation. This thesis constructs a series of analytical lenses focused on the observed motivations, tensions, and challenges that emerge during the development process of AI artwork. It examines how these factors can impact initial artistic goals, often requiring adaptations and compromises in response to AI's implications. By starting with the fundamental question of 'why' AI is used in art practice, the research provides a framework for understanding how artistic observed motivations evolve and are reflected in the framing of AI artworks.
While touching upon concepts relevant to the Humanities, the thesis's primary contribution lies within HCI and the understanding of contemporary AI art practices and their creation.
Primarily aimed at researchers within HCI and curators working with AI art practice, this thesis provides a framework for analysing and interpreting AI artworks. While artists may find the insights informative, the intention is not to prescribe rules for artistic practice but to offer analytical tools for understanding this evolving field
The influence of usable security on security culture
Get PDFCybersecurity threats are becoming more complex, and organizations must implement security measures that are technically robust and practical. The lack of usability of these measures can lead to uncompliant behavior, risky workarounds, and a weak security culture, making the organization susceptible to security breaches. To improve cybersecurity posture and resilience, organizations need to understand and strengthen their security culture.
This study adopts a mixed-method approach to explore the influence of usable security on security culture. It centers on three core objectives. First, it seeks to understand the concepts of usability, usable security, and security culture by examining their representation in studies and authoritative sources. It also formulates a comprehensive set of definitions to identify the factors that influence these key elements. Second, it aims to characterize the relationship between usable security and security culture by framing the study variables and investigating whether usable security can positively impact security culture, drawing on both quantitative and qualitative analyses. To achieve this, a survey was conducted with over 200 participants, followed by interviews with a smaller sub-population. The study then employed statistical descriptive analysis and thematic analysis to understand the relationship between usable security and security culture. Third, it sought to design a means that leverages the influence of usable security, identifying specific areas where usability improvements can promote a stronger and positive security culture.
A thorough review of previous and related studies informs the study’s direction and methodology, laying the groundwork for developing the instruments required to investigate the impact of usable security on security culture. An important outcome of this research is the development of a framework for fostering a strong security culture by employing usable security alongside other necessary elements. This framework, which forms a key contribution to the study, was validated by two groups: participants who completed the survey and interviews and a group of experts. The validation process highlighted the framework's practical value and contributed to enhancing the framework's clarity, presentation, and potential for integration.
The research intends that organizations may overcome pitfalls that hinder the development of a positive security culture by establishing a structured approach that addresses common usability barriers. Ultimately, the study has the potential to help organizations achieve greater compliance, reduce cybersecurity risks, and enhance their resilience to evolving threats
Evaluation of novel anti-cancer drugs using a D.melanogaster cancer model coupled to AP-MALDI mass spectrometry imaging
No full textCancer therapeutics is a continuous challenge to develop treatment options that are sufficient in bypassing clinical issues of cancer resistance and recurrence. Combination chemotherapy strategies have been successful due to synergistic interactions arising from multiple agents. As such, novel insights in modern pharmacology aim to develop multi-target drug compounds capable of influencing multiple biological processes using a singular agent. Currently, most multi-target agents have utilised a histone deacetylase (HDAC) inhibiting pharmacophore as a scaffold. Here, a novel tubulin and HDAC inhibiting dual-target agent, TH-6, was evaluated alongside its single-target tubulin-inhibiting backbone, TH-9, using an in vivo Drosophila melanogaster pupal cancer model coupled to analytical atmospheric-pressure matrix-assisted laser desorption/ionisation (AP-MALDI) mass spectrometry (MS) imaging.
An established in vivo Drosophila pupal model system was used to generate a hyperproliferative tumour phenotype in the pupal notum. The hyperproliferation is driven by aberrant mTOR signalling induced through the knockdown of TSC1. To facilitate drug investigation using this Drosophila model, a 6-/12-well plate system of drug screening was developed to improve the model’s robustness for drug research. Quantitative confocal microscopy analysis of proliferation-related clonal phenotypes demonstrated the model’s capability for pharmacological studies when analysing the impact of rapamycin, a direct inhibitor of the model, against tamoxifen, an agent without a functional target in flies. The drug-dose dependency of rapamycin was achieved in the model serving as a foundation for dosage selection when testing other agents. To prepare Drosophila cancer model pupae for MS analysis, a procedure to freeze, embed and cryosection of the samples was developed. AP-MALDI MS imaging (MSI) was performed on rapamycin-treated cancer pupae demonstrated that the drug-induced metabolomic and lipidomic alterations could be detected.
Following this, novel agents, TH-6 and TH-9, and commercial single-target counterparts, combretastatin A-4 (CA-4) and vorinostat (SAHA), were analysed using the established workflow. The conventional microscopy approach demonstrated that TH-6 and TH-9 performed comparably with rapamycin and better than the commercial agents. AP-MALDI MSI detected stark differences in the metabolomic and lipidomic response profile of drug-treated pupae against those untreated. Several metabolites, namely arginine, lysine, and carnitine metabolites, were found to be strongly associated with the drug activity of TH-6 and TH-9. Suppression of hyperproliferation in the model was also found to be related to the reduction of glycerophospholipids for all drug agents. This study demonstrates the potential for the novel dual-target agent TH-6 as an anticancer agent for highly proliferative cancer subtypes. These findings also highlight the established platform’s ability to integrate traditional and advanced workflows, offering a versatile tool for drug discovery and mechanistic studies
Access Repository Dashboard
Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇