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Millimeter-wave power detectors
Get PDFThe power measurement traceability above 100 GHz has been challenging due to the unavailability of commercial power transfer standards above 100 GHz. As the frequency increases, the sensor mounting becomes difficult in the increasingly small waveguides, posing fabrication challenges and losses. The commercial transfer standards based on thermistor mount were only operating up to W-band (75-110 GHz), and production has stopped. The emerging applications above the W-band demand the establishment of new power metrology capabilities. This thesis aims to develop new power detectors to meet this urgent demand.
This thesis primarily focuses on the bolometric power detector as a transfer standard in the D-band (110-170 GHz). The bolometric detector consists of a thin film sensor element in the E-plane of the waveguide. The element is designed to be a dual-line thin film on a quartz substrate and has proven to improve the bandwidth. The equivalent circuit analysis is presented on single and dual-line structures inside the waveguide. The power detector body is designed in plastic PEEK (polyether ether ketone). It is enclosed in dual shielding layers; the inner is PEEK, and the outer is aluminium. All these measures have helped achieve a power detector with a competitive response time of fewer than 2.6 seconds (a limitation of the external measurement system/facility). The device can operate at ambient temperature, benefiting from additional dummy sensors within the inner shielding. It has shown a very good short-term time response with only ∼0.19% deviation in a given time interval, which is very close to a commercial PM5 sensor with ∼0.27% deviation. The long-term time response is also impressive, with a deviation of less than 0.6%, similar to a commercial PM5 sensor. The fast response time, good thermal isolation, and ambient compensation ability make it suitable for transfer/working standards, which can be used in ambient temperature environments.
This thesis also demonstrated a Schottky diode power detector. Schottky diodes are most suitable for applications such as imaging, communication and particle accelerators where fast response time (in picoseconds or ps) is vital over absolute power measurement. The device has been successfully designed, fabricated and tested. This is a square law power detector, where the output voltage is proportional to the square of the input voltage. The detector split blocks are fabricated in aluminium and plated with gold. The measurement shows an average responsivity of 5000 V/W over the D-band, and the minimum is 1900 V/W at 160 GHz for -20 dBm input power
How do bacteria glide? A structural perspective into the gliding motility of Bdellovibrio bacteriovorus
Get PDFBdellovibrio bacteriovorus is a bacterial predator that invades and kills Gram-negative bacteria. B. bacteriovorus’s ability to kill pathogenic strains highlights the possibility of its use as a therapeutic and biocontrol agent. Motility is key for efficient predation; B. bacteriovorus uses gliding motility to traverse biofilms in search of prey and to escape the exhausted prey cell. Gliding is controlled by cGAMP signalling which regulates the
formation of an envelope-spanning gliding machinery called the Agl-Glt complex. Whilst genetic, microscopy and interaction studies have provided initial insights into the assembly of the gliding machinery, the mechanisms by which the proteins of the Agl-Glt complex interact to facilitate gliding remain to be uncovered.
This work primarily focusses on the structural characterisation of the components of the Agl-Glt complex. The primary targets for this study are GltD1 and GltE1, periplasmic components of the Agl-Glt complex proposed to transduce force across the cell envelope. We demonstrate that GltD1 and GltE1 interact with nanomolar affinity and present the crystal structures of GltE1 and the complex of GltD1:GltE1. The GltD1:GltE1 complex provides the first structural insights into the connectivity within the Agl-Glt complex and provides information on orientation of the Agl-Glt complex in the cell envelope. A secondary focus of this study was on Bd1996 and MglA, proteins associated with the regulation of gliding motility. We experimentally confirmed that the PilZ domain of Bd1996 binds to both c-di-GMP and cGAMP, which represents the first case of a PilZ domain with dual affinity for both second messengers. We also present a combined experimental and computational characterisation of the ras-like GTPase MglA and reveal that MglA undergoes GTP dependent conformational changes to interact with binding partners. Finally, we present the crystal structure of Bd1431, a nuclease belonging to the staphylococcal nuclease family, that is upregulated during invasion. Bd1431 contains a novel dimeric fold previously unseen in the staphylococcal nuclease family
Development of ceramics for use in proton conducting ceramic cells
Get PDFProton conducting ceramics (PCCs) can incorporate water molecules into oxide ion vacancies and then transfer protons (H+) via the oxide ions. Thus, enabling these PCCs to be implemented as part of a fuel cell or an electrolyser, that can operate within the intermediate temperature range of 500°C to 700°C. Within a proton conducting ceramic electrolyser (PCCE) dry H2 is able to be produced, unlike in oxide conducting solid oxide electrolyser (OC-SOE).
The electrolyte materials used in these cases have been firmly established, however there is still an array of materials that can be explored as electrodes for proton conducting ceramic cells (PCCCs). Previously, compositions used for oxide conducting solid oxide cells (OC-SOCs) have been utilised in PCCCs. This thesis aims to develop electrode materials that can be utilised in PCCC within the intermediate temperature range.
The electrode material barium ferrite (BaFeO3-δ) was synthesised and doped with niobium (Nb) and bismuth (Bi); their lattice parameters were confirmed by X-ray diffraction (XRD). Nb-doped samples were chemically stable in humid N2 atmospheres. Conversely, Bi doped samples only remained stable in humid N2, in dry N2 these samples formed two phases.
Ruddlesden-Popper; La2-x(Ba/Sr)xNiO4+δ, La3-xPrxNi2O7-δ and La4-xPrxNi3O10-δ were synthesised for electrode materials; again XRD confirmed their lattice parameters. Under humid N2, La2NiO4+δ, La1.5Sr0.5NiO4+δ, La3Ni2O7-δ, La2PrNi2O7-δ, La4Ni3O10-δ, La3.75Pr0.25Ni3O10-δ and La3PrNi3O10-δ were shown to maintain their XRD pattern.
BaCe0.6Zr0.3Y0.1O3-δ electrolyte pellets were manufactured by pressing and sintering with 1 wt% nickel oxide (NiO) as a sintering aid. Symmetrical cells tests were performed in dry and humid air conditions. La2NiO4+δ and La1.5Sr0.5NiO4+δ were shown to have a decrease in polarisation resistance when measurements were taken in humid air, below 600°C. All other samples showed an increase in polarisation resistance when measurements were taken in humid air, suggesting p-type conductivity.
Following symmetrical cell testing, fuel cell tests were performed on La2NiO4+δ. A power density of 4.94 mWcm-2 was achieved, the cell was then tested in electrolyser mode and a current density of 3.29 mAcm-2 was achieved at 700°C. Electrolysis testing was then performed using La3Ni2O7-δ as the air electrode 21.3 mAcm-2 was achieved at 700°C, suggesting La3Ni2O7-δ to be a better performing electrode then La2NiO4+δ for electrolysis.
Overall, it has been shown that La2NiO4+δ and La3Ni2O7-δ can be utilised in PCCCs. Implying other Ruddlesden-Popper compositions may also be viable for use in a fuel cell or electrolyser, such as La3 xPrxNi2O7-δ and La4-xPrxNi3O10-δ. With La4Ni3O10-δ possibly being a better performing air electrode, for electrolysis, than La3Ni2O7-δ, as it has a greater number of corner linked NiO6 octahedra
Adoption of building information modelling for assessing the life cycle cost of sustainable buildings: a case study in Saudi Arabia
Get PDFThis doctoral research has investigated the use of Building Information Modelling (BIM) on the life cycle cost (LCC) and sustainability of construction in the context of Saudi Arabia. Addressing a significant deficit in region-specific studies, it conducted a comprehensive review of extant BIM-related research in the Saudi construction industry. Utilising a mixed-methods approach, the study integrated extensive literature reviews, empirical research, and advanced BIM tools to achieve its objectives. The primary goal was to survey the current research landscape, revealing a profound scarcity of studies specifically focused on the challenges and opportunities of BIM in Saudi Arabia. Subsequent goals included identifying enablers and constraints to BIM technology adoption, quantifying the extent of BIM utilisation, analysing its application during the design phase, assessing impacts on building life cycle costs and sustainability, exploring contractual practices and construction technologies in the Saudi market, and developing a strategic framework for BIM application in government projects. The study aims to systematically review existing literature on BIM implementation within Saudi Arabia, identify key enablers and constraints affecting BIM adoption, quantify the current extent of BIM usage in the industry, explore its impact on building life cycle costs and sustainability, comprehend the integration of contracts and building technologies within the Saudi Arabian construction sector, and propose a strategic framework for BIM application in government projects.
Findings revealed that despite the global insights provided by extant literature, there is a pressing need for more localised research tailored to Saudi Arabia’s unique socio-economic and regulatory contexts. The use of sophisticated BIM tools such as Autodesk® Revit 2023, Autodesk® Insight, and Autodesk® Green Building Studio markedly improved the study’s precision and efficiency, underscoring the critical role of BIM in enhancing construction practices for better sustainability and cost-efficiency. The application of One Click LCA demonstrated the advantages of integrating circular design principles. A significant discovery was the potential for substantial cost savings and environmental benefits through optimised design and lifecycle analysis. For instance, Scenario 4, developed through an interactive optimisation process, demonstrated a 39.53% reduction in life cycle costs over 30 years compared to Scenario 1, translating to potential savings of approximately $25 million for a project of 900 residential units. Additionally, design adjustments in Scenario 4 led to a 48.8% reduction in CO2e emissions, according to the comprehensive LCA, Scenario 4 led to a 48.8% reduction in CO2e emissions, according to the comprehensive LCA, while the social cost of carbon decreased to €9,453.
The integration of green BIM tools like Autodesk Insight and Green Building Studio directly supported design decisions promoting energy efficiency and lower life cycle costs with minimal environmental impacts. At the conclusion of Scenario 4, a 21% reduction in Energy Use Intensity was recorded relative to Scenario 1. The deployment of One Click LCA also enhanced the study’s analytical capabilities, enabling the evaluation of circularity metrics such as material recovery potential, advocating for the early adoption of circular economy principles in design.
Critically, the results indicate that an integrated BIM approach can significantly influence construction projects in Saudi Arabia. Establishing a BIM standard, educating personnel, raising stakeholder awareness, and developing supportive regulations are crucial for accelerating widespread BIM adoption across the region.
The conclusions of this research highlight the importance of context-specific knowledge in developing effective BIM adoption strategies in Saudi Arabia. Future research should investigate regional variations, advanced BIM applications, dynamic simulation models, and strategies related to the circular economy
Empirical essays in corporate finance: implications of market participants and corporate social responsibility
Get PDFIn the first empirical investigation discussed in Part II, we study the impact of corporate culture on corporate social responsibility (CSR). We employ text analysis on companies’ annual 10-K to measure corporate-level culture quantitatively based on the competing values framework (CVF). We find that collaborative culture promotes corporate CSR by circumventing environmental and social controversies and seizing environmental and social opportunities, while creative and competitive cultures diminish CSR by discounting environmental and social opportunities and aggravating their controversies, respectively. We also examine the moderating role of blockholders, documenting empirical evidence that blockholders substitute the culture-CSR relationship flagging the impact of corporate culture on CSR. Our results are robust after accounting for endogeneity using the instrumental variable (IV) approach, entropy balancing method, matched sample, alternative statistics approaches, and alternative measures of cultural dimensions, blockholders, and CSR.
In the second empirical investigation discussed in Part III, this study examines whether ESG blockholders drive the issuance of corporate green bonds, whose proceeds are primarily used to finance environmentally friendly activities. We show that ESG blockholders exert a positive influence on the issuance of green bonds. The issuance, in turn, benefits the existing shareholders as it lowers the cost of external financing over the following years. Moreover, we find that ESG blockholders effectively alter the positive relationship between green bond issuance and the cost of debt financing in the long term, compensating for the inadequacy of the long-term effects of green bond issuance on issuers’ financing costs in the debt market. It suggests that ESG blockholders are value-enhancing for green bond issuers. Furthermore, we indicate that after a temporary impact of the climate policy shock, ESG blockholders give higher emphasis to green action by driving green bond issuance to avoid exposure to more environmental risks. Overall, our findings imply that large financial institutions paying attention to environmental and social issues can play an important role in developing green bond markets.
In the third empirical investigation discussed in Part IV, we examine the impact of analyst activity on investor demand for bonds. Using comprehensive data on orderbook size in the primary market of corporate bonds, we provide robust evidence that higher analyst coverage and higher forecast accuracy have a positive impact on investor demand, whereas forecast dispersion has a negative impact. We also find that the impact is more pronounced if the bond has a less informative issuance procedure, such as non-green bonds, and if bond issuers have higher information asymmetry and low ESG performance. This evidence suggests that bond investors’ demands overcome the information asymmetry associated with bond issuers using analysts’ activity. Overall, our results are consistent with the bright side view and imply that analyst activity is a critical determinant of investor demand for corporate bonds
Studies aimed at improving the properties of conjugative pCURE plasmids
Get PDFIn recent years, the escalating issue of microbial antibiotic resistance has become a global concern. To reduce this challenge and tackle this problem, we need to act quickly by finding and developing new ways of treating infections different from the usual antibiotics. One promising strategy involves addressing multidrug-resistant infections by displacing the resistance plasmid from bacteria exhibiting resistance. This PhD thesis focuses on the concept of antimicrobial resistance plasmid curing (displacement) through incompatibility, aiming to improve the technology for displacing antibiotic resistance plasmids from bacterial strains. The primary objective was to make a derivative of plasmid pUB307, the basis for the curing plasmid pCURE-F-307, that is resistant to suppression of its conjugative transfer (Fertility Inhibition) by competitor plasmids. Initial results showed that when traG, the target gene for the inhibition, was provided on a multi-copy plasmid, Fertility Inhibition was reduced. Based on this finding traG was deleted from pUB307 and reinserted at a new location with its own strong promoter. The new plasmid was able to transfer much more efficiently without suppression by other plasmids. This solution is more general than isolating point mutations in traG because not all Fertility Inhibition proteins interact with TraG in the same way. This progress could help to increase efficiency of plasmid curing strategies and thus help reduce the spread of antimicrobial resistance plasmids
La Resistenza: Gendered narratives on women’s contributions to the Resistance
Get PDFThis thesis examines women’s narratives on the Italian Resistance over the span of 50 years. Through analysing three sources, Liliana Cavani’s La donna nella Resistenza (1965), Bianca Guidetti Serra’s Compagne (1977) and Lidia Menapace’s Io partigiana, La mia Resistenza (2014), I compare and contrast women’s representation and narratives over time. Through analysing these texts in light of the social context of the time, and through a gender-political lens, I identify a shift over time in the representation of women’s Resistance narratives and contributions to the Resistance. A shift can be seen, from an essential narrative of women’s roles in the 1960s, through a progression of these roles in the 1970s, to a more emphatic focus on women as political agents in the 2010s. In analysing these texts as both gendered political narratives and testimonies, this thesis proposes a more nuanced and varied understanding of women’s experiences of the Resistance. Considering women’s normative gender role in Fascist Italy during the Resistance, this thesis demonstrates a more diversified and nuanced experience of the Resistance that has been neglected in general Italian historiography
Industrial heritage and regeneration: Hanyang Iron Works, Wuhan, China
Get PDFIndustrial heritage and subsequent values placed upon it has been a way of dealing with de-industrialisation in many parts of the world. Now, as China has begun to move away from traditional heavy industry and primary production, it too has been embracing industrial heritage as a means of preservation, commemoration, and economic development with regard to the legacies of its industrial past. The number of designated industrial heritage sites in China continues to grow as does the need to re-purpose and regenerate the previous industrialised landscape and communities.
Relatively little research has been undertaken with regard to the processes and variety of stakeholders involved with the regeneration of heavy industrial sites in China. This thesis recognises that such processes take place over a long period of time and during that time there are changes amongst the differing interest groups involved in both the production and consumption of any re-development. I focus on the case of the Hanyang Iron Works in Wuhan China. The Iron Works were founded in the 1890s and at their height were one of the largest such works in China, and particularly important in the modernisation of the country. When the works finally closed a huge expanse of land was in need of being transformed.
Based upon document collection, on-site observations and semi-structured interviews with stakeholders involved in the re-development of the site and its subsequent use and daily consumption, this thesis examines the transformation of the Hanyang Iron Works. It highlights the particular role that the private commercial sector has played in the process and the relatively minor role that has been given to developing the site as an industrial heritage. In part, this is due to the weak voice of industrial heritage proponents matched by the increasing dominance of powerful commercial interests, but I argue that contextual aspects of the location, size and complexity of the site, together with the wider frameworks of economic need and local / regional governance have also been significant. Moreover, beneath this there has been a weak grasp with regard to the value of the site’s industrial heritage value, compounded by the ways by which the memory of the site is rapidly being lost amongst the younger generations now using the transformed site. While there are still remains of the former Iron works as heritage markers, without interpretation and reminders, these too are easily overlooked by those who now consume the site making it difficult to imagine the industrial past of the site
Investigating the potential of a metabolomic biomarker for pancreatic exocrine insufficiency
Get PDFPancreatic exocrine insufficiency (PEI) is a reduction in pancreatic enzymes to a level below that required to maintain normal digestion. It is a consequence of many diseases, leading to malnutrition, impaired of quality of life and poor clinical outcomes. Diagnosis of PEI is challenging. This thesis investigates the potential for a novel diagnostic measure of PEI using metabolomics as a discovery tool.
The use of metabolomics, the study of the small products of metabolism, in developing novel biomarkers is a rapidly expanding field. This body of work is based on the hypothesis that: A fatty test meal will create a dynamic, measurable response in the food metabolome and that response will be different in those with PEI compared to healthy controls. To test this hypothesis, a trial called DETECTION was designed to obtain fed and fasted plasma samples from patients with PEI alongside healthy controls and use untargeted metabolomics to explore differences in their metabolomic response to a test meal. To accurately determine PEI status, the Carbon mixed triglyceride breath test (C MTGT) has been used alongside other markers of PEI. Much of this work has been directed towards developing and refining the C MTGT for use alongside blood metabolite analysis.
In summary, I have created an evidence-based protocol and novel test meal for the C MTGT that is compatible with post-prandial metabolite analysis. With the results of the DETECTION trial PEI screen, I have evaluated the prevalence of PEI in various patient groups and explored concordance between existing diagnostic tests for PEI. Finally, I have compared the postprandial metabolome of those with and without PEI and found significant differences that have the potential to be used as a biomarker for PEI, this is novel, ground-breaking and has the potential to greatly improve diagnosis and treatment of PEI
The digital transformation in HSSC from the perspective of patient co-creation
Get PDFThis study purposed to explore the digital transformation in the healthcare service supply chain (HSSC) from the perspective of patient co-creation with the research question of how digitalization influences co-creation in the healthcare service supply chain. This aligns with literature gaps for service operations and digital healthcare management. First, the current service operation literature needs more clarity on co-creation in service supply chain (SSC). In particular, no literature has introduced or thoroughly explored the form of co-creation in SSC. Second, the study of co-creation literature leaves a significant gap in the study of conditions of co-creation, while the research on conditions of co-creation is vital and in line with the upgraded service concept for integrating resources in service provision. Third, in the field of medical management, with the development of patient-centered care and people's demand for refined medical care, PCC's solutions from the service operation field need to be explored.
To address the problem and fill the gaps in the literature, this study uses case study methodologies with examples from digital orthodontics practice, integrated primary care in internet hospitals, and chronic disease management. The digital development in these three cases has been tremendous in recent years and profoundly requires patient co-creation. To collect data, this study conducts interviews. A total of 45 individuals were interviewed in this study, each lasting between 40 to 70 minutes. The interviewees included doctors, product managers, IT developers, operation managers, nurses, and researchers.
Linking the research gaps, this study has both theoretical and practical contributions. The contributions in theory can be summarized mainly from three aspects. First, this paper proposes to explore and explain three co-creation forms in the service supply chain, which are co-design, co- delivery in SSC from the service providers’ perspective and co-delivery in SSC from customers’ perspective, which helps researchers improve their understanding of SSC and co-creation phenomena. Second, this research creatively proposes a “conditions of co-creation” model and studies the co-creation phenomenon from four aspects: policy and social, patients, suppliers and digitalization. Finally, this research discovers and proposes the promotion of the service operation model of co-creation with digitalization in relation to the progress of medical management, especially PCC. To the practitioner, this research provides a solid theoretical foundation for current and future digital health platforms and operations managers and summarizes the direction for past, present, and future digital health trends. In practice, this research provides a solid theoretical foundation for current and future digital health platforms and operations managers and summarizes the direction for past, present, and future digital health trends
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