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Examining cyclic carbonate synthesis under pure CO2 and simulated flue gas conditions using non-metal catalysts
No full textA promising method to recycle waste CO2 in post-combustion flue gas chemically is the cycloaddition of CO2 to epoxides, which yields cyclic carbonates. The procedure can use purified CO2 collected from a capture plant or flue gas directly as an impure CO2 source. Achieving good product yields at atmospheric pressure and low temperatures is highly beneficial for both options. For direct utilization of flue gas, the process should, in addition, be chemically stable under low CO2 partial pressure and in the presence of impurities. Current industrial processes for cyclic carbonate production, however, require high CO2 pressure (30 – 100 atmospheres) and high temperature (150 – 210 oC), consuming a significant energy input for operation. In addition, they are configured to use pure CO2 gas. This research investigates the synthesis of cyclic carbonate using either pure CO2 or simulated flue gas at 1 atmosphere (atm) to simulate the two process options. It assesses the performance of metal-free catalysts (tetrabutylammonium halides or amine bases) combined with a hydrogen bond donor (HBD) as a promoter under the two process options.
Low concentrations of hydroxyl or amino-containing hydrogen bond donors (HBDs) enhanced the catalytic activity of tetrabutylammonium salts and amine bases for cyclic carbonate synthesis. The extent of enhancement depended on the type of HBD as well as the type of tetrabutylammonium salt or amine base; however, tetrabutylammonium iodide (TBAI)/H2O and 4-dimethyl aminopyridine (DMAP)/N,N’-diphenyl thiourea (DPTU) pairs exhibited high performance. Whereas the HBDs (H2O and DPTU) showed no catalytic activity when used independently, TBAI and DMAP showed moderate activity when used independently for the reaction, indicating that H2O and DPTU acted as promoters while TBAI and DMAP catalyzed the reaction. With the optimum catalyst/promoter pair in hand, reaction parameters were tuned to maximize cyclic carbonate yield and CO2 utilization. A trade-off existed between the catalyst and promoter concentration and cyclic carbonate yield and selectivity. For TBAI/H2O catalyst/promoter pair, the peak yield and selectivity was observed at a H2O and TBAI concentration of 0.15 and 0.025 mole ratio relative to the epoxide, respectively. For DMAP/DPTU catalyst/promoter pair, this was at a DMAP+DPTU/ECH mole ratio of 0.067 relative to epoxide and DMAP/DPTU mole ratio of 7.5. Catalyst and promoter concentration above this threshold was not beneficial. A CO2 feed rate of ≤ 0.161 mmol/min was advantageous as almost all the CO2 fed was utilized. Therefore, at the optimum reaction condition, CO2 utilization of ≥ 94 %, cyclic carbonate yield of ≥ 90 % and cyclic carbonate selectivity of ≥ 98 % were obtained for both catalyst/promoter pair at 60 oC and 1 atm pure CO2. This result demonstrates that low-cost and readily available H2O and DPTU could promote the catalytic activity of TBAI and DMAP, respectively under mild reaction conditions, resulting in a high yield of cyclic carbonate at a reasonable reaction time.
It is of high interest for commercial applications to examine reaction efficiency with low CO2 partial pressure and flue gas impurities. Interestingly, both catalyst/promoter pair remained active for reactions under a simulated flue gas (15 % CO2/N2) atmosphere, even at a near room temperature of 30 oC. Although the reaction rate decreased as CO2 partial pressure decreased from 1 to 0.15 atm, both catalyst/promoter pair retained sufficient activity to produce cyclic carbonate in almost quantitative yield at 50 oC in 24 hours. The selectivity remained reasonably independent of CO2 partial pressure. Furthermore, a high concentration of H2O in the reactor had a negative impact on cyclic carbonate yield and selectivity due to phase separation, dilution effect and formation of side product. The presence of O2 in the simulated flue gas at a concentration of 5 % v/v had no effect on cyclic carbonate yield and selectivity for both catalyst/promoter pairs. For actual flue gas application, it will be necessary to allow the flue gas to cool below its dew point to lower its moisture content by condensation to avoid the formation of by-products.
A kinetic study was employed to explain the influence and role of catalytic components on reaction kinetics. The HBDs (H2O or DPTU) increased the observed rate constant (kobs) while decreasing the activation energy. This result implies that the HBDs enhanced the catalytic activity of the catalysts by reducing the energy barrier for activating the reactants to the transition state. kobs was found to decrease by a factor of 0.65 or 0.84 for TBAI/H2O or DMAP/DPTU, respectively as CO2 partial pressure decreased from 1 to 0.15 atm, which explains the decrease in cyclic carbonate yield observed under simulated flue gas condition. The catalyst/promoter concentration, CO2 partial pressure, and temperature were significant factors influencing reaction kinetics and must be carefully controlled in practical application. The performance of the TBAI/H2O and DMAP/DPTU catalyst/promoter pairs was explained in terms of a previously reported synergistic mechanism in which the HBDs (H2O and DPTU) activates the epoxide and stabilizes reaction intermediates/transition states through hydrogen bond interactions, while the catalysts (TBAI and DMAP) ring opens the activated epoxide by nucleophilic attack, allowing for cyclic carbonate to be facilely obtained in high yields even at 0.15 atm CO2 partial pressure. The TBAI/H2O and DMAP/DPTU catalyst/promoter pairs exhibited a higher rate constant and lower activation energy in the reaction of ECH and CO2 at 1 atm than a previously reported catalyst based on Co/Zn bimetallic complex
Novel Natural Products From Euglena
Full text linkDiscovering compounds from nature has equipped humanity to address dietary needs, protect crops, and combat diseases. As the environment changes, the population grows, and antibiotic resistance rises, finding new compounds is critical. Historically, natural sources have been a reliable route for antibiotic discovery, with most current antibiotics derived from natural products. While bacteria have been the primary focus, other organisms like algae, with complex and underexplored genomes and metabolic profiles, hold untapped potential for novel compounds. Traditional bioassay-led approaches often rediscover known compounds. In contrast, modern structure- or gene-first strategies reduce this risk and streamline the selection of novel compounds. To develop new antibiotics and treatments for infectious diseases and cancer, new sources and methods must be explored.
This thesis highlights Euglena as a promising source of novel natural products. Using analytical chemistry and cheminformatics, over 32 Euglena strains were grown under varied conditions to generate diverse metabolic profiles. High-performance liquid chromatography-mass spectrometry (HPLC-MS²) and Molecular networking via the Global Natural Products Social Molecular Networking Database identified potential new compounds. Three compounds were semi-isolated, with preliminary structural suggestions made through NMR analysis
Exploring the impact of work-family conflict on workplace safety and well-being (a case study of the Nigerian oil and gas industry)
No full textThis mixed-methods study examines the antecedents, consequences, and moderating factors of work–family conflict (WFC) in Nigeria’s oil and gas industry, with a focus on employee well-being, engagement, and safety behaviour. Guided by the Job Demands–Resources (JD-R) model and Conservation of Resources (COR) theory, the research was conducted in two sequential phases.
Phase 1 involved semi-structured interviews with 25 purposively selected employees (16 males, 9 females) across field, safety, administrative, and supervisory roles in both onshore and offshore operations. Participants had at least two years’ industry experience in positions where safety and family demands intersect. Data were thematically analysed using Braun and Clarke’s (2006) six-step method, with NVivo software and inter-coder reliability checks enhancing analytical rigour.
Phase 2 employed a cross-sectional survey of 525 employees from multiple oil and gas firms, recruited via purposive and snowball sampling. Validated scales measured WFC, family-to-work conflict (FWC), job autonomy, supportive manager behaviour (SMB), work engagement, well-being, and safety performance. Confirmatory factor analysis (CFA) was used to validate constructs, while structural equation modelling (SEM) tested hypothesised relationships, including mediation and moderation effects.
Results showed that high job and family demands significantly predicted WFC, which in turn reduced engagement and safety participation. WFC dimensions (work-to-family conflict and family-to-work conflict) partially mediated the relationships between work and family demands and safety performance. Quantitative results also showed that being older and female was associated with higher safety participation and compliance, offering nuanced insights into demographic effects in the Nigerian context. Furthermore, supportive managerial behaviour moderated the effects of WFC on safety, well-being, and engagement.
The study positions WFC as a critical workplace psychosocial risk, emphasising the importance of reducing WFC to enhance safety and well-being. Findings underscore the value of supportive leadership, job redesign, and culturally relevant interventions in mitigating WFC’s adverse effects. Methodologically, using a sequential mixed-methods design and multi-source validation strengthens the reliability of results. Overall, the research advances theoretical understanding of WFC in high-risk industries and offers actionable guidance for policy and practice in Nigeria and similar contexts
Quantification and Comparative Analysis of Arachnid Microbiomes via 16S rRNA Sequencing (Pholcus phalangioides, Argyrodes argyrodes, Nephila senegalensis)
Full text linkThis study presents a first analysis of the microbiome of the haplogyne spider Pholcus phalangioides alongside the characterisation of two ecologically and phylogenetically distinct species of entelegyne spider: Argyrodes argyrodes and Nephila senegalensis. Using 16S rRNA metabarcoding, the study examines the diversity and composition of microbial communities within these spiders, including the identification of endosymbionts, with a primary focus on describing community structure and identifying taxa shared both intraspecifically and interspecifically. Quantitative metabarcoding data from Pholcus phalangioides exemplify the feasibility of sequencing microbes from within this type of as yet unstudied species, which will provide a valuable comparison to the more fully characterised microbiomes of Argyrodes and Nephila.
This research aims to establish a baseline for understanding how microbial associations may vary with spider host ecology. While primarily exploratory, the findings offer foundational insights into the potential ecological and evolutionary roles of host–microbiome interactions in arachnids as a whole. In summary, this study found the microbial communities to vary significantly between individuals and species; Nephila are highly dominated by the bacteria Serratia, which therefore makes their microbiomes less diverse, and Argyrodes individuals, at an intraspecific level, have differing compositions of the endosymbiont Cardinium. Additionally, this study, for the first time, quantified the sequencing reads of Pholcus, which helps to identify successful methodologies for uncharacterised and previously unsequenced organisms
Driving the Locus Coeruleus: Pupillometry in a Driving Simulation Paradigm
Full text linkA naturalistic and continuous driving simulation paradigm is presented as a novel method for investigating the function of the locus coeruleus norepinephrine (LC-NE) system and its modulation of cognition and behaviour. The LC is one of the earliest sites of Alzheimer’s Disease (AD) related pathology, while the LC-NE system modulates multiple cognitive functions known to decline in ageing and AD. This paradigm provides a novel way of probing the LC-NE under conditions requiring attention, memory, and decision-making with the use of pupillometry and embedded psychological tasks. Pupil diameter results suggest an LC role in monitoring task demands and responding to errors, as predicted by the Adaptive Gain Theory (Aston-Jones & Cohen, 2005). The novel finding of a gradual increase in pupil diameter in response to the approach of a cognitively demanding situation was made possible by our continuous design. Significant pupil dilation responses to decision-making events support a role of the LC-NE, and the ability of this paradigm to examine its function
Measuring psychological flexibility across the lifespan: validation of the Adult and Adolescent Psychological FlexibiliTy Scale (ADAPTS)
Full text linkPsychological flexibility is regarded as a key component of mental wellbeing. It
is the proposed mechanism of change underpinning Acceptance and
Commitment Therapy (ACT) and is thought to be composed of six core
processes: acceptance, present moment awareness, defusion, self-as-context,
values, and committed action. These are further grouped to form the triflex
processes of openness to experience, behavioural awareness, and valued
action. Psychological inflexibility is the inverse of psychological flexibility
involving experiential avoidance and cognitive fusion and has been found to
have associations with poor mental health outcomes. Accurate measurement of
constructs thought to underpin mental wellbeing, such as psychological
flexibility, is key to the evaluation of interventions and development of
recommendations regarding treatment for mental health difficulties.
The AAQ-II is a widely used measure of psychological flexibility in ACT
research. However, it has been noted to not provide a comprehensive measure
of the six proposed core processes and demonstrates multicollinearity with
anxiety scores. The AFQ-Y is a youth measure of psychological flexibility
developed from the AAQ-II. The Adult and Adolescent Psychological FlexibiliTy
Scale (ADAPTS) has been developed in order to address some of the issues
found with existing measures and provides a comprehensive measure of
psychological flexibility across youth and adult populations. The ADAPTS uses
plain English making it appropriate for those who could benefit from accessible
language.
Exploratory factor analysis (EFA) was used to understand the structure of the
ADAPTS in youth and adult samples. The ADAPTS was also compared to
existing measures to assess concurrent, convergent, and discriminant validity.
EFA indicated a three-factor structure (Openness to experience (5 items),
behavioural awareness (5 items), and valued action (8 items)) across 18 items
for the ADAPTS in both populations. The ADAPTS demonstrated good
concurrent, convergent, and discriminant validity across both populations.
Subscale validity for the three factors is provided and further project data,
analysis, and materials are provided in the extended paper.
This project supports the ADAPTS as an accessible, reliable, and valid measure
of psychological flexibility for use across the lifespan in both clinical and
research settings
Essays on institutional environment and banking
No full textThis thesis comprises three distinct yet interrelated and essential studies that examine the relationship between the institutional environment and banking practices on a global scale. First, it explores the impact of judicial system inefficiencies on non-performing loans (NPLs) among banks within the European Union. Second, it investigates how various dimensions of country governance influence the effectiveness of banking supervision and regulation in mitigating earnings opacity across countries. Third, it assesses the role of culture -an informal institutional factor -in shaping managerial behaviour in banks worldwide. The findings from these studies offer timely and policy-relevant insights for both banking institutions and regulatory authorities, while also opening avenues for future research.
This thesis contributes to the broader literature on institutional determinants of banking stability and transparency by providing empirical evidence that enhancements in formal institutional structures -such as judicial efficiency and governance quality -can improve bank stability, particularly through reductions in NPLs and greater transparency in financial reporting. Moreover, the analysis underscores the importance of incorporating cultural considerations into regulatory and supervisory frameworks, suggesting that effective policy design and implementation must account for the informal institutional context in which banks operate in order to promote financial efficiency and stability
Conceptualising and performing: student engagement with university application processes in the UK
No full textDespite ongoing reforms to university admissions procedures, access to higher education in the UK is still stratified. Individual-specific social circumstances and experiences contribute to differential access as students are exposed to university-specific information in different ways and from different sources throughout their lives. The focus of this study was to ascertain the complex ways in which social factors influence how students conceptualise a university ideal and how they perform as this ideal during the university application process. To do so, I generated qualitative data from a set of socioeconomically and culturally diverse sixth form students regarding their experiences of the application process. Students completed a mock application designed to reflect actual admissions processes through personal statements, mock interviews and reflective focus groups. Thematic analysis was used to identify features students believed to signal ideality and their performances of these ideal features. Student performances of these ideal traits were categorised by complexity using a novel analytical framework. Divergences in complexity were investigated using Bourdieu’s concepts; specifically, fields capitals and habitus. Findings from the research indicated that students drew from their person-specific experiences and understandings of universities when advertising themselves as ideal candidates, with some students making more sophisticated advertisements of ideality based upon more elaborate understandings of the university and more opportunities to perform this ideality. This work is useful for teachers, students and practitioners to evaluate the way excellence is conceptualised in university spaces and how social factors differentially prepare applicants to envision and enact ideality
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