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Engineered viscoelastic hydrogels to investigate the mechanoresponse of mesenchymal stem cells
No full textAbstract not currently available
Investigation of treated Incinerated Bottom Ash (IBA) as fine aggregate replacement in structural concrete – from waste to construction material
Get PDFWith the shortage of sand and its ever-increasing needs for urbanisation due to concreting, researchers have been seeking alternative materials to replace natural sands in concrete. Among the potential fine aggregate alternatives is the cement-treated Incinerated Bottom Ash (IBA), which is a granular byproduct of incinerating municipal solid waste. However, leaching of hazardous substances from untreated IBA is a major issue that hinders its usage in engineering applications. In this study, treated IBA (GO-IBA™) was adopted, where the pollutants are encapsulated within the pellet structure, hence reducing the leaching of hazardous substances.
This work aims at experimentally investigating the effects of replacing natural fine aggregates in structural concrete with treated and untreated IBA on fresh properties, hardened properties and durability. Secondly, in order to reduce the reliance on natural sands, the performance of concrete mixes using manufactured sand with IBA replacement is also assessed. Moreover, to further bring down the CO2 emissions during concrete production, the feasibility of replacing fine aggregates with IBA in concrete using blended cement is also experimentally studied.
Accordingly, experimental investigations on four series of speimens were carried out: (1) C Sand mixes with rIBA – untreated IBA (rIBA) replacing natural sand (C Sand) with OPC as binder, (2) C Sand mixes with GO-IBA™ – treated IBA replacing C Sand with OPC as binder, (3) M Sand mixes with GO-IBA™ – treated IBA replacing manufactured sand (M Sand) with OPC as binder, and (4) PBFC mixes with GO-IBA™ – treated IBA replacing M Sand with CEM III/B cement as binder. In each test series, fine aggregate replacement levels were set at increments of 25% to study the effects better. Different test are employed to study the individual concrete properties which are categorised into three main properties: (1) Fresh properties (slump, bleeding, setting time and air pore content), (2) Hardened properties (compressive strength test and modulus of elasticity (MOE) test) and (3) Durability properties (water penetration (WPT), water absorption (WAT), rapid chloride penetration test (RCPT) and accelerated carbonation test.
The test results show that using untreated IBA to replace fine aggregates leads to inferior workability, significantly reduced mechanical properties and degraded durability, making it not suitable as a fine aggregate replacement for structural concrete.
When using treated IBA as the fine aggregate replacement (for both C Sand mixes and M Sand mixes), the workability still tends to reduce with the replacement level, possibly due to the porous nature and high water absorption properties of GO-IBA™, while the compressive strength exhibits insignificant reduction till 75% replacement level. In terms of durability, both the C Sand mixes and M Sand mixes with treated IBA replacement show improved water penetration depths till 75% replacement level and better RCPT and accelerated carbonation test results till 100% replacement level. Nevertheless, increasing the treated IBA replacement level leads to higher water absorption, which affects the workability of the mix and yields higher air pore content. In this work, it is also found that pre-wetting of the GO-IBA™ results in improved workability and compressive strength development.
In the last series of the test, with the addition of Ground Granulated Blast furnace Slag(GGBS) as the binder, most of the fresh properties were improved over the cement counterparts (M Sand mixes), except for the delayed setting time due to the longer hydration time involving GGBS. Hardened properties of the PBFC mixes with GO-IBA™ remain broadly similar in trend to the cement counterpart. In terms of durability, the WAT and WPT results exhibit degraded performance compared with the cement counterparts, due to the longer hydration time needed for GGBS. RCPT results remain similar in trend, while accelerated carbonation test results show poorer performance than the cement counterparts
Essays on firm performance and investment efficiency
Get PDFThe thesis comprises three independent essays on various aspects of corporate finance. The first essay focus on the impact of regional foreign investment on Chinese domestic mergers and acquisitions (M&As). The second essay examines the relationship between corporate social responsibility (CSR) and export performance in the United States. The third essay explores the influence of corporate reputational risk on firms’ investment inefficiency in the United States. The introduction provides a brief overview of the background, and the conclusion summarizes the main findings across the three chapters.
The first empirical study (Chapter 2) investigates the impact of regional foreign investment on domestic mergers and acquisitions in China during the period between 2011 and 2019. First, the empirical results indicate that the regional foreign investment exerts no significant effect on firms’ short-term stock performance surrounding M&A announcements. Second, this study aims to explore the moderating role of regional corporate income tax and stateowned enterprises (SOEs) in the relationship between regional foreign investment and firms’ short-term stock performance after mergers and acquisitions. The findings indicate that regional corporate income tax plays a partially negative moderating role in the relationship between regional foreign investment and short-term M&A stock performance. However, there is no evidence that state-owned enterprises status of acquiring firms exerts any significant moderating influence in this relationship. Furthermore, the analysis provides limited support for the view that the foreign investment in China’s western region may have a positive impact on firms’ short-term M&A stock performance. Finally, the study reveals that regional foreign investment fails to have a statistically significant impact on the number of M&A transactions.
The second empirical study (Chapter 3) examines the effect of corporate social responsibility on firm export sales, utilizing a panel of U.S. firms over the period from 1995 to 2013. First, the results demonstrate that corporate social responsibility has a positive and significant impact on export sales. Second, the study also aims to explore the moderating role of financial constraints and firm location in the effects of corporate social responsibility on firm export sales. The study indicates that neither financial constraints nor firm location have a significant moderating effect on the relationship between CSR and export sales. Moreover, the findings reveal that state-level GDP per capita has a positive and statistically significant moderating effect on the relationship between CSR and export sales to some extent. Finally, the results also reveal that CSR strength is positively associated with corporate export sales to a certain extent, while CSR concern exerts a detrimental effect. Furthermore, CSR related to employee, diversity and product aspects significantly enhance a company’s export sales to some degree.
The final empirical study (Chapter 4) assesses the impact of a firm’s reputational risk on corporate investment inefficiency. This chapter analyzes a dataset consisting of 3602 firmyear observations from 588 distinct U.S. firms spanning from 2007 to 2020. The results reveal that reputational risk significantly and positively affects corporate investment inefficiency. Then, the findings indicate that while reputational risk increases overinvestment, it does not have a considerable effect on underinvestment. Moreover, reputational risk positively impacts investment inefficiency across firms of varying levels of reputational risk and sizes. Notably, firms with low reputational risk and larger firms experience greater adverse effects. In addition, reputational risk does not significantly affect either overinvestment or underinvestment in both large and small firms. Furthermore, this chapter also demonstrates that social and governance-related reputational risk positively affect corporate investment inefficiency, whereas environmental reputational risk does not exert a significant influence. Additionally, the analysis further reveals that financial constraints do not have a significant moderating effect on the relationship between reputational risk and corporate investment inefficiency
Investigating glymphatic system and AQP4 water channels with novel drugs and MRI techniques
Get PDFThe glymphatic system serves as a vital low resistance pathway for the efficient removal of toxic waste products from the brain and its malfunction is implicated in numerous neuropathological conditions. Aquaporin-4 (AQP4) water channels are membrane-tied and highly expressed at the end-feet of astrocytic cells in the brain. They are thought to be crucial to the glymphatic clearance system, water circulation, and homeostasis of the brain. Pharmacologically targeting AQP4 presents a promising therapeutic strategy for various neurological diseases. In 2009, Huber et al. developed TGN-020, a potent AQP4 inhibitor that significantly reduced cerebral oedema in stroke models. In 2018, they introduced TGN-073, a novel AQP4 facilitator that enhanced fluid turnover and interstitial fluid clearance. This thesis investigates the effects of these AQP4 modulators, with a particular focus on TGN-073, using advanced MRI techniques and immunofluorescence staining in rat models to elucidate their potential therapeutic benefits.
The initial objective was to employ an H2 17O tracer to evaluate the effect of the novel AQP4 facilitator TGN-073 on glymphatic transport. Despite extensive optimization efforts, the tracer signal remained low and unreliable, precluding its use in conducting our studies. Consequently, we assessed the impact of TGN-073 on glymphatic transport using dynamic contrast-enhanced MRI. This involved catheterizing the cisterna magna to infuse the MRI contrast agent Gd-DTPA into the cerebrospinal fluid. Our findings indicated that rats treated with TGN-073 exhibited a more extensive distribution and higher parenchymal uptake of GdDTPA compared to the vehicle group, suggesting TGN-073's potential in enhancing glymphatic function. Following this, I developed and established an immunohistochemistry protocol for AQP4 staining using immunofluorescence, a first in our department. The aim was to optimize this technique to its fullest potential, ensuring precision and reliability for the following experiments.
Given the invasive nature of the method used to investigate the impact of TGN073 on glymphatic transport, which requires cisterna magna cannulation, noninvasive alternatives were explored. Therefore, the impact of both AQP4 modulators, TGN-020 and TGN-073, was assessed without the necessity of exogenous contrast agents. These evaluations utilized T2 mapping and stimulated echo diffusion-weighted echo planar imaging (STE-DW-EPI), followed by immunofluorescence labelling of AQP4. No significant changes in the diffusion coefficient were observed across all observation times in any animal group, indicating no substantial alterations in brain microstructure. However, T2 values significantly decreased following the administration of TGN-073, suggesting enhanced water exchange. In contrast, T2 values significantly increased following the administration of TGN-020, while remaining unchanged in the vehicle group. These findings underscore the role of AQP4 in modulating water exchange between tissue compartments. Immunofluorescence staining revealed significantly higher AQP4 expression in the brains treated with TGN-073, contrasting with a significant decrease in AQP4 expression in the brains treated with TGN-020, compared to the vehicle-treated group.
To advance our understanding of the positive effects of AQP4 facilitators on glymphatic function, we investigated the impact of TGN-073 in a rat model of vascular cognitive impairment, specifically the bilateral common carotid artery stenosis (BCAS) model. This model, known for inducing chronic cerebral hypoperfusion and vascular dementia, represents a novel application within our institution. To our knowledge, this is the first study to evaluate glymphatic transport in BCAS rat models and to assess the impact of an AQP4 facilitator in this context. We successfully established cerebral hypoperfusion in the BCAS model, as evidenced by a significant reduction in cerebral blood flow (CBF). Our findings demonstrated glymphatic dysfunction and altered AQP4 expression associated with BCAS. Importantly, TGN-073, effectively mitigated these effects by restoring AQP4 expression, enhancing glymphatic function, and alleviating CBF reduction. This study highlights the potential of AQP4 facilitators in ameliorating the adverse effects of cerebral hypoperfusion and associated glymphatic dysfunction. TGN-073 shows promise for preventing the progression of neurodegenerative diseases and improving the quality of life for affected individuals
The creative uses of Irish literature in works by J.R.R. Tolkien
Get PDFThe aim of this thesis is to examine the significant and sustained influence of Irish literature across the corpus of J.R.R. Tolkien’s mythopoeic writings— what is frequently termed as his “legendarium” —and to analyse how he adapted and creatively revised Irish sources in his writings. Some of Tolkien’s statements have given the impression that he did not like, nor was he influenced by, Irish language or literature, and yet scholars have long identified Irish elements in his writings and called for a deeper appreciation of them. This thesis presents the first book-length, systematic critical analysis of the role of Irish literature in Tolkien’s legendarium. It includes the identification and critical analysis of specific works of Irish (and Irish-themed) literature and language study that Tolkien owned, read, is suspected to have read, and/or referenced, including his volumes donated to the Bodleian and English Faculty Libraries at the University of Oxford, and it presents a curated selection of new observations and findings on Irish influences in his writings. As the question of how Tolkien’s work relates to Irish antecedents has been under-researched, this thesis breaks new ground by approaching Irish literature as a major category of Tolkien’s sources and influences
A research project focused on carers of individuals with borderline personality disorder features
No full textAbstract not currently available
The guitar performance practice in Spanish neoclassicism, focusing on El Grupo de los Ocho
Get PDFAs a classical guitar performer for the past two decades, I have encountered a diverse range of repertoire from various periods. Although each style commands a different musical and technical approach, there is always a need to establish a solid starting point from which the performer can springboard in an objective yet flexible way. Examining the history of the guitar, I became convinced that the best place to search for this foundation would be the “Big Bang” from which the modern guitar has evolved. The period during which the renaissance of the guitar as a modern instrument took place is none other than Spain’s 1920s and 1930s. Going back to the sources of the period, I realised that there was a field of diverse aesthetic perceptions, many of which contradicted the very qualities of the instrument per se. According to my understanding, these qualities are intimacy, purity, integrity, simplicity, transparency, flexibility, adaptability, dynamism, and the sublime. The established guitar “universe” led most guitarists, as well as luthiers and composers, to strive for grandeur, the colossal, and the flamboyant, going against the very nature of the instrument. However, it seems that there has been a parallel “universe” reflecting the qualities I identify with the guitar, which has disappeared for extramusical reasons, not being able to deploy a monumental guitar canon.
By delving more into that period, I came across a set of pieces by Spanish composers from the so-called El Grupo de los Ocho that seemed to conceal the qualities that I identify with the guitar. They sounded simple yet complex. The compositional style could be likened to the contrapuntal style of Scarlatti, yet they sounded modern. The woven Spanishness was presented discreetly and elegantly. At the same time, different sections, phrases, or even bars within a piece could be attributed to a different era in music history, without disregarding the present. What I realised when I learned those pieces for performance is that their multifaceted musical attributes responded to equally varied technical and theoretical challenges, revealing themselves one by one in my attempt to expose what was beneath the surface of the presumed simple presence. The apparent simplicity, as well as the density and diversity of these concealed elements, sparked my interest in researching how these pieces should be performed. In my pursuit of the ideal performance for these pieces, I had to reform and expand or even regenerate my musical, technical, and intellectual capacity, bringing me closer than ever to the answer to my primordial question, to form a context where the guitarist will operate in accordance with the nature of the instrument
To C or not to C: an exploration of disulfide bond formation and replacement with triazole bridges
No full textAbstract not currently available
Play, care and gender: exploring the perceptions and practices of out of school care practitioners
Get PDFThis study examines the gender perceptions and understandings of Out of School Care (OSC) practitioners in the provision of play. Whilst many studies focus on gendered play within Early Years (EY) settings, this research exclusively involves OSC practitioners and their views on gender influences in facilitating play, rather than the perspectives of children. Acknowledging the global call for increased male presence within the entire Early Learning and Childcare (ELC) sector, this study explores OSC practitioners' considerations and perceptions regarding the role of men in OSC. Adopting a poststructuralist approach and interpretative paradigm, the study utilised a two-phase data collection method. Research data was gathered from seven OSC practitioners who participated in an online Padlet responding to proposed questions, followed by individual semi-structured interviews. The dissertation's analysis applied a Foucauldian lens and Connell’s theories on masculinities, identifying three key themes: professional play, the playworker’s role, and the provision of play, all influenced by the participants' gender perceptions. The findings suggest that although male presence is advantageous, it should not serve as the sole rationale for achieving a gender-balanced workforce. The study suggests that OSC's feminised origins contribute to a perception that play and care are low-skilled tasks associated with women's work, despite being a degree led sector. The limited hours available in OSC are identified as the primary obstacle deterring men from entering the workforce, reinforcing the traditional view of men as breadwinners. Despite participants advocating for gender neutrality in the provision of play, there remains a risk of practitioners becoming gender blind. There is a recognised need to revisit the role of the playworker and OSC sector with an emphasis on gender awareness and sensitivity training, particularly regarding the provision of play for children and gender responses. The study also suggests areas for further research and implications for practice, including a review of the OSC sector and guidelines, as well as an examination of the gender perceptions held by OSC service users
Genomics of adaptation in triatomines (Hemiptera: Reduviidae: Triatominae), vectors of Chagas disease
No full textAbstract not currently available
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