Saudi Cultural Missions Theses & Dissertations
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Item Restricted Design and Synthesis of Graphene-Based Sensors(The University of Manchester, 2024) Alelyani, Zarah; Gardiner, JohnThe work embodied in this thesis describes the synthesis of polyvalent pyrene scaffolds decorated with maleimide and carbohydrate moieties for use in the fabrication of graphene-supported field effect transistors. This thesis describes three areas of research that were investigated for the development of graphene-based sensors: The first strand of research concerned the synthesis of multivalent graphene binding scaffold containing nitrogen-based linkers for the non-covalentl attachment to the surface of graphene. For this reason, pyrene-based tripods 57 and 74 were synthesized and fully characterized. Incorporation a versatile functional group to the centre of the graphene binding scaffold was also considered. The synthesis of a series of dipod and tripod scaffolds incorporating an alkyne moiety was undertaken. Dipods 68 and 69 as well as quaternized tripod 58 were successfully constructed. Unfortunately, none of the attempts to introduce an alkyne appendage to tripod 74 were successful. The second component was concerned with the identification of a chemosensing domain capable of attachment to a graphene binding scaffold. To this end N-(4-azidophenyl)-maleimide 91 was prepared and its viability in participating in click reactions investigated. Compounds 93a and 94a were prepared via (CuAAC) click reaction while 94b was synthesized using (RuAAC) click reactions. Dipod-maleimide compounds 95 and 96 were also prepared via (CuAAC) click reaction. Finally, several attempts to link maleimide 91 and its derivatives to tripods 57 and 74 were undertaken. The success of a CuAAC click reaction between tripod 58 with azido-pyrene 52 leading to the synthesis of triazole 98a is noteworthy. Sensing reaction of the maleimide appendage of compounds 64, 93a, and 113 as well as dipod 95 with 1-dodecanethiol 110 was achieved via a thiol-Michael addition reaction. The course of these reactions was also investigated using fluorescence spectroscopy. The enhancement of the excimer emission at 488 nm of the pyrene fluorophore in products during the course of these reactions is an indicator of the course of the addition reaction. The reaction between N-(t-butoxycarbonyl)-L-cysteine methyl ester 111 and representative maleimides was also investigated. Finally, the fabrication of 126 a sensor candidate containing two pyrene "feet" and a model carbohydrate binding site was accomplished using a CuAAC reaction in the conjugating step.48 0Item Restricted Influence of Consuming Rare Sugars on the Consumption of Energy and Carbohydrate Intake in Healthy Individuals(Saudi Digital Library, 2023-12-12) Altwejry, Hussah; Jethwa, PreetiBackground: Food manufacturers have been challenged to decrease the sugar content of their products by 20% as the prevalence of non-communicable diseases such as type 2 diabetes mellitus increases. Rare sugars, therefore, have been highlighted for their potential role in controlling blood glucose, improving weight, and decreasing food intake. However, little is known about their mechanisms and effects on humans, particularly in terms of food intake. Objective: To investigate whether D-tagatose and L-arabinose influence the consumption of participants’ energy and carbohydrate intake, particularly starch, fibre, sugars, and free sugars. Methodology: Three data analysts conducted a secondary data analysis of 48 food diaries. These diaries were collected by a PhD student from healthy participants (≥18 years) who underwent a double-blind crossover RCT, in which participants were divided into 6 groups: full sucrose (dose of sucrose = 35.72g), control or reduced sucrose (half dose of sucrose = 21.43g), D-tagatose40 (14.29g D-tagatose), L-arabinose40 (14.29g L-arabinose), D-tagatose20 (7.14g D-tagatose), and L-arabinose20 (7.14g L-arabinose). Food diaries were analysed using Nutritics software to analyse energy and macronutrient intake. Decisions regarding the items' nutritional facts, homemade recipes, and searching for food alternatives have been made. Results: A total of 12 participants (66.6% were females, average age: 21.13 ± 0.51 years, average height: 1.67m ± 0.02, average weight: 70.7kg ± 4.45, average BMI: 25.19 ± 1.60) were included. Consumption of rare sugars had no effect on 24-hour energy (p = 0.55) or carbohydrate (p = 0.38) intake between all study groups. Furthermore, there was no significant difference in any type of carbohydrate, including starch (p = 0.78), fibre (p = 0.15), sugars (p = 0.15), and free sugars (p = 0.97). Conclusion: The present research paper concluded that rare sugars, D-tagatose and L-arabinose, had no effect on 24-hour energy and carbohydrate consumption in healthy adults. Limited human trials have studied the effects of those sugars on dietary intake, highlighting the need for further long-term and large-scale research on their impact on human dietary consumption.16 0