Saudi Cultural Missions Theses & Dissertations
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Item Restricted Machine Learning for Peaks Detection in Nuclear Magnetic Resonance Spectra(University of Liverpool, 2024-07) Alghamdi, Hadeel; Lisitsa, Alexei; Barsukov, IgorThis research addresses the challenge of accurately detecting and automating the peak picking process in both pure and mixture Nuclear Magnetic Resonance (NMR) spectra. Peak picking is a crucial step in NMR analysis, but manual methods are often time-consuming and prone to errors, particularly in complex mixture spectra. Recent advancements in machine learning provide an opportunity to automate this process, improving both efficiency and accuracy; however, many of those methods focus more on one type of peak than the other and still require pre-processing steps. A machine learning system was developed to automate the detection and extraction of peaks in both pure and mixture NMR spectra, and it was systematically evaluated against several established techniques. The approach tackles key issues, including enhancing the detection of small peaks, and overlapping peaks, and managing the limited availability of labeled training data by generating synthetic datasets. Despite being trained on synthetic data, the model demonstrated strong performance on real NMR spectra, effectively automating peak detection. The model employs well-established machine learning techniques for object detection and segmentation, achieving 97% accuracy on synthetic data with no missed detections and few false positives, and 92% accuracy on real data. These results, compared to existing methods, suggest that the automated system can improve the accuracy and efficiency of peak picking in both pure and mixture NMR spectra, providing a valuable tool for researchers and practitioners in the field.11 0Item Restricted Characterising the structure, bioactivity and bioavailability of active compounds from complex herbal extracts(The University of Queensland, 2024-06-25) Saqer, Alaa; Blanchfield, JoanneHerbal and natural medicines have long been a critical part of medical practice. Medicinal plants are a rich source of bioactive phytochemicals. This project aimed to investigate the phytochemistry of two native Australian plants, Cymbopogon procerus and Asparagus racemosus, from the Northern Territory. In our project, we investigated the phytochemistry of plant material via extraction, fractionation of crude extract through solid phase extraction (SPE) and purification of compounds using reverse phase high-performance liquid chromatography (RP-HPLC). Compounds are then identified using analytical techniques, including one and two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) and liquid chromatography mass spectrometry (LCMS). Cymbopogon procerus (native lemon grass) contained phenylpropanoids and volatile aromatic terpenes. A total of 16 known compounds, including phenylpropanoids compounds (2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.10, and 2.11), C11-terpene lactone (2.12), truncated sesquiterpenes (2.13, 2.14), cis-3-hexenyl-β-D-xylose (2.15) and fatty acid (2.16) were isolated from this species. Among these compounds, twelve compounds (2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.10, 2.11, 2.12, 2.13, 2.14, 2.15 and 2.16) were reported for the first time from C. procerus. The methanolic extract of stem and grass parts of this plant displayed high antimicrobial activity against Burkholderia humptydooensis and Staphylococcus aureus. The phytochemistry of the native Asparagus racemosus, from two locations in Australia, consists of saponins, the major bioactive compounds responsible for many medicinal properties of this herb. A total of twenty compounds were isolated from this species, including four new spirosteroids, asparacemosone E (3.1), asparacemosone F (3.2), asparacemosone G (3.3), asparacemosone H (3.4) and one new sulphated saponin, filicinoside sulphate B (3.7), one known spirosteroid (3.5), one known aromatic compound (3.20), and thirteen other known saponins (3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13, 3.14, 3.15, 3.16, 3.17, 3.18, and 3.19). Four of these compounds were isolated for the first time in A. racemosus; these were 25R-spirostan-4-ene-3,12-dione (3.5), filicinoside B (3.7), disporoside D (3.14) and trigoneside III (3.15). The structures of isolated saponins contained either furstanol aglycone or spirostanol aglycone (sapogenin) with varying degrees of glycosylation. This study also provided a baseline for comparative studies of native A. racemosus from two locations in Australia and India which confirmed a variation in saponin constituents and concentrations in roots collected at different locations based on retention times and comparisons with published data. Finally, an in vitro intestinal bioavailability model, the Caco-2 cell monolayer permeability assay, was used to predict the bioavailability of saponins isolated from A. racemosus (compounds 3.10, 3.11, and 3.12) with variations in sugar moieties attached to the aglycone. Compounds (3.11, 3.12) showed low permeability across Caco-2 monolayers, while compound (3.10) exhibited high permeability across Caco-2 monolayers. Therefore, compound 3.10 is a strong candidate for human oral bioavailability, possibly due to sugar transporters but this hypothesis is yet to be tested.7 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 0