Saudi Cultural Missions Theses & Dissertations
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Item Restricted ‘Examining and comparing the setting reaction of an epoxy based novel endodontic sealer to the industry standard commercial sealer’(Queen Mary University of London, 2024-09-01) Alangary, Nasser; Mohsin, Chaudhary; Saroash, ShahidThis study investigates the polymerisation behaviour and setting characteristics of epoxy-based endodontic sealers, focusing on formulations incorporating polyethylene glycol (PEG) and comparing them to the commercially available AH Plus sealer. Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) were employed to evaluate the degree of epoxy conversion and the effects of PEG on curing kinetics. The addition of 25% PEG to the sealer formulation significantly accelerated the epoxy conversion process, achieving a higher conversion rate and faster setting time compared to other experimental formulations. FTIR analysis revealed that the PEG-modified formulation exhibited superior polymerisation efficiency, with an 86.7% epoxy conversion within 72 hours, indicating its potential for clinical use. However, due to technical limitations, DSC analysis was restricted to a control sample and AH Plus, with results indicating higher epoxy conversion rates than those observed via FTIR, though both techniques showed consistent trends. The study concludes that incorporating PEG into epoxy-based sealers enhances their curing speed and handling properties, making them more suitable for clinical application. The findings suggest that PEG-modified sealers could offer improved flow characteristics and better adaptation to complex root canal anatomy, thus optimising endodontic treatment outcomes. Future work should include comprehensive in vivo testing to validate these results and further refine the formulation.24 0Item Restricted Incorportation of Caesium into Potassium-Silicate Geopolymers(University of Sheffield, 2024-01-23) Alkhateeb, Khaled; Walkley, BrantThis dissertation explores the process of incorporating caesium into potassium silicate activated geopolymers providing insights into its effects. Geopolymers, known for their potential in construction serve as the context for examining the challenge of integrating caesium. The focus is on understanding the implications of caesium’s radius within geopolymerisation chemistry and kinetics. To investigate the geopolymer matrix, these two powerful analytical techniques are utilized; isothermal conduction calorimetry (ICC) and Fourier transform infrared (FTIR) spectroscopy. These tools enabled the team to uncover the relationship between caesium and the geopolymerisation process. They clarify how caesium interacts with the structure and evolution of geopolymers. The study also examines the characterization of geopolymers with an emphasis on how alkaline earth cations (Ca2+ and Sr2+) influence their molecular configurations and properties. Advanced analytical methods such as X ray Diffraction (XRD) Solid state Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR), and Isothermal Conduction Calorimetry (ICC) were employed to analyse geopolymers consisting primarily of metakaolin and alkali activators. XRD analysis revealed that the geopolymer structure was amorphous. Subtle changes were observed due to the presence of alkaline earth cations. Various solid state NMR techniques, including 29Si MAS, 1H 29Si CP MAS, 27Al MAS and 23 Na MAS NMR revealed changes, in the Si environments caused by the presence of Ca2+ and Sr2+ ions. These changes indicated alterations in polymerization states and connectivity. The analysis of aluminium species and local environment interactions was carried out using 27Al MAS and 23Na MAS NMR techniques, which were supported by absorption bands identified through FTIR spectroscopy. This combined approach provided insights into how composition molecular configuration and cation influence affect geopolymers. It also offered promising avenues for customizing these materials for construction and future advancements in the field. In summary this thorough review represents an understanding of the relationship between caesium and geopolymers. Its significance extends beyond academia as it aligns with efforts to improve containment and storage methods for waste. This signifies a step towards solutions, in construction, environmental preservation and nuclear energy safety.28 0Item Restricted Advanced Nanomaterial Composites for Enhanced Photocatalysis and Sensing(Saudi Digital Library, 2023-11) Alanazi, Ahmed; James, RiceRecent advances in nanostructuring techniques have contributed to the field of plasmonics. In current research, plasmonic plays an important role in sensing, including surface enhanced Raman spectroscopy (SERS). The fabrication of platforms for optical sensing has traditionally been carried out using costly techniques requiring specialized equipment. These techniques require precious metals, which have limitations in biocompatibility, high environmental impact, cost, and availability. Semiconductors are used in SERS since they provide enhanced Raman signals through their unique optical and electronic properties, allowing for tunability and reproducibility. Their stability and compatibility with various technologies render them valuable substrates for highly sensitive molecular analysis. Furthermore, their additional benefits include cost-effectiveness, recyclability, self-cleaning properties, and flexibility, which make them suitable for potential integration with other technologies. Even though semiconductor-based SERS have been the subject of numerous promising studies, current state-of-the-art designs are largely restricted due to their lower signal enhancements. New designs for SERS substrates are crucial to overcome some limitations and improve the performance of SERS. Existing designs may have limitations in terms of sensitivity, reproducibility, scalability, or compatibility with specific molecules or applications. The aim of the thesis is to investigate the combination of semiconductors and plasmonic nanomaterials in order to develop new designs implementing simple, cost-effective, and environmentally friendly strategies. The combination of plasmonic nanomaterials with semiconductors has great potential for sensing and photocatalysis. This thesis is divided into nine chapters: In Chapter 1, a brief description of Raman scattering and molecular dynamics is presented, as well as Raman-active modes selected based on vibration spectra, light-driven electronics. In the following section, examples are provided of how Raman spectroscopy is used in modern research. Following this, a brief overview of SERS is provided, including electromagnetic and chemical enhancements as well as effects related to wettability. Lastly, the chapter discusses photocatalysis mechanisms and applications, such as chemical oxidation reactions and self-cleaning photocatalysis. Chapter 2 provides an overview of the primary strategies which can be utilized in the design of optical sensing platforms for SERS. Several material classes are discussed as well as their properties that make them useful for chemical detection. First, the primary processes involved in the production of platforms fabricated from precious metals will be briefly reviewed. This method will also be discussed in terms of its advantages and disadvantages. In the following section, alternative semiconductor materials are examined; these materials have the advantage of being biocompatible and easy to fabricate. Several subgroups of semiconductor materials that have been demonstrated to be effective at enhancing optical signals are discussed following an introduction to the two primary categories of semiconductor materials - organic and inorganic. In Chapter 3, a brief overview is presented of the major spectroscopy and microscopy techniques utilized to explore the optical properties and morphology of the manufactured substrates investigated in this thesis, along with the methods utilized to analyze the data. The analysis methodology and experimental specifics of how the measurements were conducted are described in some depth in the text, which presents the overall ideas underlying the analysis. In Chapter 4, investigate the photocatalytic potential of transition metal chalcogenides (TMCs) cadmium sulfide (CdS) when coupled with plasmonic nanostructures. The synthesis of dimercaptoazobenzene (DMAB) from p-amino thiophenol (PATP) was demonstrated by the super bandgap irradiation of a silver nanowire (Ag NWs) and cadmium sulfide composite for PATP. For plasmonic photocatalysis applications, our findings indicate that cadmium sulfide can serve as an alternative to semiconductors, such as titanium dioxide. In Chapter 5 a combination of conducting polymers such as P3HT (poly-3-hexylthiophene) and PcBm (phenyl-C61-butyric acid methyl ester) with plasmonic nanomaterials is demonstrated to enhance Raman scattering spectroscopy signals up to five-fold and to support the oxidation of target molecules by supporting the charge transfer. The purpose of this chapter is to demonstrate how conducting polymers can be used as semiconductor platforms for the development of plasmonic catalysis and sensing techniques. Chapter 6 describes the development of nanocomposites consisting of metals and organic conducting semiconductors, which have the potential to provide a flexible, lightweight platform for plasmon-based sensing. The purpose of this chapter is to demonstrate the use of super band-gap irradiation to provide plasmon excitation and irradiation to remove analytes from a polymer-plasmonic composite based upon the conducting polymers P3HT and PCBM, as well as to support plasmon-enhanced spectroscopic detection. Our research demonstrates that such a polymer-plasmonic composite is an effective self-cleaning system for use as a reusable optical sensing substrate. In Chapter 7, plasmon active metal nanostructures and semiconductors are described as nanocomposites that support catalytic activity. As discussed in this chapter, transition metal dichalcogenides such as MoS2 when combined with metal oxides such as ZnO have the potential to control charge states in plasmonic nanomaterials. The objective of Chapter 7 is to demonstrate the possibility of controlling plasmonic reactions through the careful selection of semiconductors. In Chapter 8, we present a framework consisting of silver nanoparticles (Ag NPs) on Mg-doped lithium niobate surface. The activation of charge transfer processes on this substrate under white light irradiation is demonstrated to support the oxidation of compounds such as p-amino thiophenol. The purpose of this chapter is to highlight the use of doped lithium niobate materials as semiconductor platforms for plasmonic catalysis. Conclusions and future work are discussed in Chapter 9.17 0Item Restricted Histopathology Detection Using High-resolution Infrared Spectroscopic Imaging for Nodal Metastases in Oral Squamous Cell Carcinoma(University of Liverpool, 2023-11-21) AlJedani, Safaa Salem E; Weightman, Peter; Risk, JanetOral squamous cell carcinoma (OSCC) predominantly metastasises to lymph nodes and poses significant diagnostic challenges. The current gold standard for analysing OSSC biopsies is Hematoxylin and Eosin (H&E) staining, which provides essential tissue morphology information. Fourier Transform Infrared (FTIR) imaging can be used to complement (H&E) staining diagnosis. FTIR images provide information on chemical composition at diffraction-limited spatial resolution. This dissertation presents two novel approaches to overcome the spatial resolution limitations of FTIR imaging: a regression fusion model combining the high spatial resolution of (H&E) stains with the spectral information from FTIR and Optical Photothermal Infrared Micro-Spectroscopy (O-PTIR). The experiments utilised formalin-fixed, paraffin-embedded OSCC cervical lymph node metastases tissue microarrays (TMAs) with 1 mm diameter tissue cores. IR imaging was conducted using the Agilent Cary 620-FTIR imaging microscope, while O-PTIR micro-spectroscopy images were acquired in both reflection and transmission modes. The fusion models were employed to merge co-registered pairs of FTIR and H&E images, with the quality of fusion assessed using the structural similarity index measure (SSIM) and Spectral Angular Mapper (SAM). The results demonstrate minimal distortion and enhanced spatial resolution. Analysis of O-PTIR data in both reflection and transmission modes revealed that the reflection mode offered more detailed images with reasonable morphology and signal-to-noise ratio, while the transmission mode required higher laser power, posing potential sample damage risks. Ratio images from O-PTIR show contrast similar to H&E images. Pixel-wise models struggled to reproduce tissue discrimination, primarily due to information loss from neighbouring pixels. Substantial accuracy improvement was achieved with a spatial-spectral model employing a hybrid convolutional neural network-random forest (CNN-RF) approach. In summary, this research demonstrates that image fusion techniques and O-PTIR can surpass the diffraction limits found in traditional FTIR techniques. Overall, this dissertation contributes to the advancement of IR molecular histopathology, particularly in the challenging context of imaging highly complex tissues such as OSCC metastases in lymph nodes.20 0Item Restricted Investigating the Formation of Apatite and The Role of Bioactive Glass and Hydroxyethyl Methacrylate in Resin-Modified Glass Ionomer Cement(Saudi Digital Library, 2023-11-30) Alshehri, Bandar; Karpukhina, Natalia; Patel, MangalaBackground: Secondary caries is one of the most common causes of dental restoration replacement. A compromised marginal seal caused by polymerisation shrinkage might result in secondary caries. Therefore, the capacity of a restorative material to form apatite at the tooth-restoration interface could lower the incidence of secondary caries. Objective: This project aimed to evaluate the capability of resin-modified glass ionomer cements (RMGICs) to form apatite on immersion in a medium simulating the oral environment. The role of bioactive glass (BAG) incorporated in experimental RMGICs in forming apatite was evaluated. Factors that enhance apatite formation, including hydroxyethyl methacrylate (HEMA), were also explored. Methods: Novel RMGICs with varying HEMA concentrations, 30% (referred to as HEMA-RMGIC) or 15% (referred to as THFM-RMGIC), and different polyacrylic acid (PAA) concentrations, (20%, 10%, or 0%), with and without 10 wt% experimental BAG, were developed. These RMGICs were evaluated alongside an experimental glass ionomer cement (GIC) and a commercial restorative material (ACTIVA™ BioACTIVE-RESTORATIVE™). The ability of these materials to form apatite in set cement discs immersed in artificial saliva (AS) for up to 24 months was evaluated using 31P magic-angle spinning nuclear magnetic resonance (31P-MAS-NMR), 19F-MAS-NMR, X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The post-experiment AS solutions for each material were analysed using pH metre, ISE, and ICP-OES. A water absorption experiment was conducted for up to 6 months in AS, to evaluate the impact of the materials’ hydrophilicity on apatite formation. Three-point flexural strength (TFS) and modulus (TFM) were analysed after 24 hours and 1 month in AS. Results: 31P MAS-NMR, 19F MAS-NMR, XRD and FTIR of the experimental compositions demonstrated evidence of increasing apatite formation over time. No significant difference in apatite formation was found between the experimental RMGICs and the different HEMA and PAA concentrations, while the hydrophilicity of experimental compositions had a limited effect. The substitution of 10 wt% of the experimental glass with BAG accelerated apatite formation. Conversely, the commercial material showed no signs of apatite formation. High fluoride release was observed from HEMA-RMGIC and GICs. As the immersion time of experimental samples increased, substantial consumption of Ca and P ions from their immersion media was identified. THFM-RMGIC exhibited the lowest % weight changes among experimental compositions. Incorporating BAG into THFM-RMGIC increased the % weight change, however, it was comparable to HEMA-RMGIC. THFM-RMGICs displayed the highest TFS amongst the other experimental compositions. BAG incorporation did not significantly affect the TFS except for HEMA-RMGIC. Following immersion for 1 month in AS, a significant reduction in TFS was observed. TFM was also significantly reduced, only in RMGICs with BAG, after one month in AS. TFM of THFM was significantly higher than all experimental and commercial materials. Conclusions: Experimental RMGICs and GICs formed apatite, following immersion in AS, with time, however, the apatite formation within RMGICs was higher. In addition, substituting 10 wt% of ionomer glass powder with BAG significantly enhanced apatite formation by experimental RMGICs. The presence of HEMA played a role in enhancing apatite formation within RMGICs. Substituting 50% of HEMA for biocompatible monomer (THFM) in RMGIC significantly decreased % weight change, enhanced flexural strength and modulus, and did not compromise apatite formation. These materials could be beneficial in reducing microleakage at the tooth restoration interface and in preventing the development and progression of secondary caries.39 0