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Optimising Na2Ti3O7 as Anode Material Candidate for Sodium-Ion Battery
No full textThe rising demand for large-scale, sustainable energy storage has accelerated research into
sodium-ion batteries (SIBs) as a cost-effective and safe alternative to lithium-ion systems.
Among various anode materials, Na2Ti3O7 stands out for its structural stability and favourable theoretical capacity. However, its practical application is hindered by poor electrical conductivity, sluggish sodium-ion diffusion, and structural changes during cycling.
Chapter 3 focused on the effects of thermal treatment on the structural evolution of Na2Ti3O7. By varying calcination temperatures, it was confirmed that structural changes previously attributed to symmetry transitions are predominantly caused by crystal growth. XRD and Raman analyses identified that 800 °C is the optimal temperature, achieving a balance between crystallinity, structural stability, and reasonable energy consumption.
Chapter 4 explored the effect of reduction treatments under H2/N2 atmospheres to produce reduced Na2Ti3O7 (RNTO). The presence of Ti3+ species introduced through controlled reduction substantially enhances conductivity and lowers activation energy, translating into superior electrochemical performance. After 100 cycles at 0.1 C, RNTO achieved a stable specific capacity of 94.27 mAh/g. Impedance spectroscopy confirmed improved conductivity, while maintaining structural integrity. At the same time, a rarely studied Na-Ti-O phase, Na0.8Ti4O8 was first time tested as anode material, and provided a stable cycle performance with less than 5 mAh/g specific capacity lost in 96 cycles.
Chapter 5 examined the effects of carbon coating on Na2Ti3O7 using polydopamine-derived carbon layers. TEM observations confirmed uniform and continuous coatings. Optimised carbon coating improved cycling performance and rate capability, with the best-performing samples retaining 82.23 mAh/g after 100 cycles compared to the pristine material’s 54.27 mAh/g. However, excessive carbon content induced phase transitions, highlighting the need for strict process control.
Overall, this work provides new insights into the structure–performance relationship of
Na2Ti3O7 and delivers practical synthesis guidance for scalable, cost-effective sodium-ion
battery anode development
Structural and Optical Properties of TiO2 and AgIn₅S₈ Nanoparticles for Optoelectronic Applications
No full textThe global demand for sustainable energy solutions has intensified research into advanced materials for high-efficiency solar energy conversion. This thesis examines the structural, optical, and functional characteristics of titanium dioxide (TiO₂) nanoparticles (NPs) and AgIn₅S₈ (AIS) quantum dots (QDs), aiming to enhance the performance and reliability of emerging photovoltaic devices. The first part focuses on TiO₂ NPs, utilizing in-situ environmental transmission electron microscopy (ETEM) and scanning transmission electron microscopy (STEM) to monitor their phase evolution under varying thermal and environmental conditions. These experiments revealed the formation of Magnéli phase titanium suboxides (Ti₆O₁₁, Ti₂O₃) and demonstrated reversible oxidation in reduced TiO₂ NPs. Electron Energy Loss Spectroscopy (EELS) confirmed the coexistence of Ti³⁺ and Ti⁴⁺ states, offering insight into changes in electronic structure. Additionally, in-situ heating STEM studies showed that controlled annealing modifies grain boundary formation, enabling targeted defect and structure engineering of TiO₂ for improved electronic behaviour. The second part examines AIS QDs synthesized using a bottom-up colloidal method. Ultrasound-assisted growth produced QDs that were an order of magnitude smaller than those produced without sonication. High-resolution TEM (HR-TEM) verified that most of the sonochemically synthesized QDs were single-crystalline with minimal structural disorder, consistent with low Urbach energy values. Post-synthesis thermal treatment at 200 °C in air caused the QDs to grow to ~35 nm (chemical method) and ~23 nm (sonochemical method), with their band gaps approaching the bulk value of 1.8 eV. Furthermore, Zn doping and ZnS shell formation enabled precise control of optical and electronic properties, achieving band gap tunability up to 2 eV. The non-toxic nature and tunable functionality of AIS QDs make them promising for optoelectronic and biomedical applications. Overall, this research advances understanding of synthesis strategies, phase stability, and defect control in TiO₂ and AIS-based materials, paving the way for the development of efficient, sustainable SCs devices
Dynamic Characterization and Optimization of High-Power IGBT Modules: Advanced Gate Driving Strategies
No full textIn contemporary power electronic systems, the primary workhorse for high-power applications is the Insulated Gate Bipolar Transistor (IGBT) power modules, playing an increasingly crucial role. These modules find applications in various domains such as renewable energy systems, transportation traction, high-voltage electric power transmission systems, and industrial motor drives. This thesis focuses on exploring the dynamic characteristics of IGBT modules and the latest techniques in gate driving.
To enhance the switching characteristics of high-power IGBT modules, this research
scrutinises and compares potential driving parameters for advanced active driving strategies.
Additionally, an innovative active gate driver based on a voltage-controlled current source is designed and experimentally validated. The characterization of high-power IGBT modules and the validation of the active gate driver's efficacy are conducted using a double pulse test platform, guided by a design procedure. The application of designed computer-aided software for control and data post-processing serves to enhance both the efficiency and accuracy of the test platform. Furthermore, the controllability of transient current and voltage slopes during the turn-off transition of high-power IGBT modules is investigated. An effective and efficient evaluation method is put forward and validated for assessing the controllability of the modules. Finally, an optimization method using the proposed gate driver is implemented. This optimization method employs a genetic algorithm to determine the optimal gate driving pattern, ensuring low switching losses and overshoot in the IGBT.
In conclusion, this work is concentrated on the dynamic characterization of the IGBT, the design of a voltage-controlled current source gate driver, and optimization using a genetic
algorithm
‘The Help Is Not Helping Us, but We Also Haven’t Done Enough’: Academic Writing Experiences and Perspectives of International Students on a One-Year MA TESOL Programme in the UK
No full textArchaeologies of bereavement: accessing historical grieving through object use, 1850-1900AD
Get PDFIn the second half of the nineteenth century, the ‘cult of mourning’ reached its height. This period saw a boom in material culture related to the funeral, and to mourning. However, this boom was short-lived, reaching its peak in the 1870s and 1880s, before waning into the twentieth century. However, while the performative material culture of the funeral, the cemetery and the elaborate mourning dress, have received scholarly attention, material has not often been studied with a focus on grief. Grief, and all emotional experience, can be considered a culturally constructed phenomenon. Though all people possess the same biological and psychological foundation for emotion, the expression, conception, and even experience of emotions, are constructed from the things we’ve seen, the culture we grew up in, and the communities of which we are a part. This project explores objects related to bereavement in the second half of the nineteenth century, with the aim of identifying how the enculturation of British society was drawn on in order to create a material culture of grieving, as well as considering how that material served to reflexively produce its
own cultural schemas.
Focusing on British working- and middle-class populations, in the period 1850-1900, this project analyses four classes of objects – postmortem photographs, funeral cards, domestically produced hairwork and death memoirs. Utilising a broadly qualitative approach, this project is exploratory, considering how the use of a lens which centres the impact of culture on the experience of grieving may provide new insight into the experience of bereavement. Overall, this thesis shows how the globalisation of media in the late nineteenth century, led to the spread of cultural tropes related to grieving, and provided people with more potential schemas through which to curate their own production of the material culture of grief
Understanding the impact of oral processing ability on food consumption behaviour and nutrient intake in older Thai adults
No full textBackground: Age-related declines in oral function can impair nutrient intake and increase malnutrition risk in older adults. Thailand is one of the fastest-aging countries in Southeast Asia, however, the relationship between oral processing ability and nutrient intake remains underexplored. This study investigated associations between oral processing ability, nutrient intake, and food consumption behaviour in community-dwelling older Thai adults.
Methods: The systematic review and meta-analysis identified associations between compromised oral factors and lower nutrient intake, highlighting gaps in oral physiological assessments. To address this, a cross-sectional study was conducted with 154 community-dwelling older Thai adults (median age: 71 years) in the Bangkok Metropolitan Region and Chonburi. Oral physiological measures, both subjective (denture status, oral dryness risk, and masticatory ability) and objective (maximum tongue pressure and biting force), were collected. Nutritional status was assessed using body mass index and 24-hour dietary recalls. Multiple linear regression examined associations between oral physiology and nutrition, with sensitivity analyses for location, low energy intake, and number of teeth.
Results: Oral processing was not associated with BMI and macronutrient intake. However, several micronutrients (vitamins C, E, B2, and calcium), as well as cereals and grains, were affected. Vitamin C was of particular concern, as a 14% higher self-perceived masticatory ability was associated with a 32 mg higher daily intake (95% CI: 2.5 to 61.8). Compared to other oral function measures, self-perceived masticatory ability showed the most statistically significant associations, highlighting the nutritional vulnerability of individuals with poor self-perceived masticatory ability.
Conclusion: Despite compromised oral processing, older Thai adults appeared to maintain nutrient intake, possibly through selective food choices. Several micronutrients, particularly vitamin C, were affected. Self-perceived masticatory ability showed the most associations with nutrient intake, likely because it best reflected oral processing and compensatory behaviours. Nonetheless, due to the study’s cross-sectional design, if compromised oral processing reduced nutrient intake or worsened existing issues remain inconclusive. Longitudinal studies in national samples are needed to confirm findings and guide targeted interventions
Horticultural Therapy and Acquired Brain Injury: A Mixed Methods Systematic Review
Get PDFBackground: Urbanisation drives reduced interactions between humans and nature, which has been suggested to negatively impact human health. Nature-Based Interventions are increasingly popular, and Horticultural therapy may improve depression, quality of life and cognition for people with acquired brain injuries. No systematic reviews of horticultural therapy and acquired brain injury have been conducted.
Methods: A mixed-methods systematic review was used to gather all available evidence. Theoretical supplementary searches were conducted to identify the relevant theories for horticultural therapy for the acquired brain injury population. A sequential exploratory approach to synthesis was adopted.
Results: 3522 records were identified through searches across seven database and. 14 studies were included in the final synthesis, five qualitative and nine quantitative. A logic model was developed, and the outcomes were tested using the quantitative studies.
Discussion: HT suggested to be effective for improving symptoms of depression and quality of life with mixed evidence for its effect on anxiety and cognition. Mechanisms of change include social interactions, restorative effects of nature and increasing self-efficacy. Future research should focus on high-quality quantitative research and consistent reporting of information. Clinicians should consider using HT alongside traditional rehabilitation for ABI and ensure the environment is accessible for all
The development of a new Patient Reported Outcome Measure assessing patients’ emotional well-being and perceptions of Total Knee Replacement for the treatment of knee arthritis
No full textChitosan/Alginate Polyelectrolyte Complexes (PECs) for Bioactive Peptide (BAP) Delivery
No full textShort bioactive peptides (BAPs) have gained significant traction given their potential health benefits, particularly, to aid in mitigating hypertension and diabetes. Hence, their potential application as functional food ingredients, supplements, or nutraceuticals, has been recognised, though not yet realised. However, BAPs are highly susceptible to degradation and instability when considering aspects of the product development process, and the most critical concern remains their susceptibility to hydrolysis in the gastrointestinal tract during digestion that compromises their bioaccessibility and bioavailability. One promising strategy to address this limitation is to encapsulate BAPs in a suitable encapsulation vehicle.
Polyelectrolyte complexes (PECs) obtained by electrostatic self-assembly of oppositely charged chitosan (CS) and alginate (ALG) represent a simple to prepare, sustainable and versatile biopolymer platform for bioactive compounds association and oral delivery. CS+ALG PECs protect against acid, salt hydrolysis, and proteases degradation. However, key underpinning factors such as the role of charge ratio (nˉ/n+) that can contribute to the PEC formation, stability and delivery, need further investigation.
This thesis focuses on studying CS+ALG PECs for the gastrointestinal delivery of BAPs derived from fish, with emphasis in understanding the role of the complexation charge ratio (nˉ/n+). The CS (Mw 111 kDa, degree of acetylation 10%) and two distinct ALG (Mw 21 kDa; M/G 1.4, and Mw 8 kDa; M/G 5.1), were selected to prepare PECs at varying (nˉ/n+). Then their biophysical characteristics were investigated using dynamic light scattering (DLS), small angle X-ray scattering (SAXS), and micro-viscosimetry measurements. The selected PECs (based on size/Rh and stability/z-potential) were then loaded with the BAPs, and the encapsulation efficiency was quantified using HPLC-UV
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