Saudi Cultural Missions Theses & Dissertations
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Item Restricted BIOFOULING AND BIOCORROSION IMPACTS ON TITANIUM CANISTER DURABILITY IN DEEP GELOGICAL REPOSITIORIES(Swansea University, 2024-09) Alshahrani, Abdullah; Ledo, Jesús OjedaNuclear waste is a byproduct of nuclear power generation. It consists of materials that have become radioactive or have been contaminated by radiation, and it is categorised, based on its level of radioactivity, as: low-level waste (LLW), intermediate-level waste (ILW), and high-level waste (HLW). Deep Geological Repositories (DGR) are a possible solution for the safe disposal of radioactive waste. Several materials including titanium could be used for the canisters that will contain the nuclear waste in the DGR. It is then important to understand the biofouling and biocorrosion of titanium canisters. The following research aims to evaluate the impact of microbial activity on titanium’s corrosion resistance, focusing on the role of sulphate- reducing bacteria (SRB) and their effect on the integrity of titanium in anaerobic environments. To investigate all the possible environmental conditions three distinct microcosms were created for the experiment that reflects the possible environmental conditions in the DGR. This included BeD microcosm (bentonite only), BeDaC microcosm (bentonite with aerobic bacterial consortia), and BeDanC microcosm (bentonite with anaerobic bacterial consortia) with electron donors (acetate and lactate) and an electron acceptor (sulphate) infused in all three microcosms. Following this, several analytical techniques were used to assess changes in the chemical composition of the titanium discs and surrounding liquids. IC results indicated higher sulphide production in the BeDanC microcosms, correlating with the activity of SRB. Whereas the BeDaC and BeD microcosms exhibited less sulphate reduction, showing that the respective microcosm conditions limit the sulphide production and therefore the threat of MIC. XPS analysis confirmed significant degradation of the protective titanium oxide layer (TiO2) in BeDanC samples, particularly at 30°C, where the SRB was most active. Visual inspections further supported these findings, with BeDanC samples showing darker supernatant colours after two months. In addition, the visual observation of the titanium discs showed the highest visible degradation effect on the discs collected from the BeDanC microcosms. In presence of aerobic microorganisms, titanium was more resistant to corrosion than in the presence of anaerobic consortia subjected to microbial influenced corrosion (MIC).7 0Item Restricted Towards Sustainable Construction: Experimental Approach and Multi-Scale Simulation in High-Strength Self-Compacting Concrete Design(Cardiff University, 2024-05) Alshahrani, Abdullah; Kulasegarama, Sivakumar; Kundu, AbhishekConcrete production constitutes approximately 10% of the yearly global carbon dioxide emissions while consuming substantial non-renewable resource quantities. The urgent need to mitigate the significant negative economic and environmental impacts necessitates sustainable design approaches for concrete production. This thesis explores the development of sustainable High-Strength Self-Compacting Concrete (HSSCC), investigates sustainable mix designs, evaluates elastic properties through multi-scale simulation, and assesses the effects of steel fibre properties on fresh and mechanical characteristics of such concrete. The research reported in this thesis is divided into three parts. The first part focuses on the development of an effective and robust mix-proportioning procedure for designing sustainable HSSCC based on targeted compressive strength and plastic viscosity, utilising 40% Supplementary Cementitious Materials (SCMs) as cement replacement and supported by design charts. Sixteen divergent HSSCC mixes were designed and produced using the proposed design method. The experimental test results for these mixes demonstrated that the proposed mix design method could produce HSSCC with excellent fresh and mechanical characteristics while being eco-efficient in terms of CO2 emissions and cement consumption. The second part of the thesis studies the elastic properties of HSSCC reinforced with steel fibre and varying proportions of coarse aggregate (CA). A two-step homogenisation method was developed to evaluate the elastic properties of HSSCC through mean-field homogenisation (MFH) and finite element modelling of the homogenised concrete. This method was used to determine the elastic modulus of HSSCC, considering variations in CA and steel fibre content, thereby facilitating mix design optimisation and constituent selection. Additionally, the effect of fibre content and orientation, CA content and particle shape, and porosity of the mix on the homogenised elastic modulus of HSSCC was evaluated. The last section reviews the effect of steel fibre properties on the rheological and mechanical properties of eco-friendly HSSCC, together with the combined effect of CA content and steel fibre. The results demonstrated that using steel fibres with higher tensile strength and smaller diameter significantly enhanced the splitting tensile strength, flexural strength, and fracture energy, compared to steel fibres with larger diameters and lower tensile strengths. It was thus concluded that CA content and fibre properties are two critical factors that impact the performance of HSSCC and should, therefore, be carefully considered in the mix design process.10 0Item Restricted Medicines Reconciliation: A Clinical Audit(Saudi Digital Library, 2023-09-22) Alshahrani, Abdullah; Allen, JaneBackground: Medicine reconciliation (MR) is a crucial strategy that aims to prevent medication errors and enhance patient safety. The National Institute of Health and Care Excellence (NICE) recommend ensuring that all admitted patients should have a completed MR within 24 hours of admission. Aim: This audit aimed to evaluate the MR procedure at Surrey and Sussex Healthcare NHS Trust (SaSH) and to identify any potential challenges that affect compliance with the standard. Methods: A cross-sectional clinical audit was conducted at SaSH with over 185 patients who were admitted between 5 June and 12 June 2023. Of these, 90 were from the medical division and 95 the surgery and gynaecology divisions. Data for this audit were collected retrospectively from 19 June to 30 June 2023 via the Electronic Prescribing and Medicines Administration (EPMA) system, and the collected data were wrangled, coded and analysed using the SPSS software (Armonk, NY: IBM Corp., version 28.0). Results: The findings reveal a significant decrease in the percentage of patients whose MR was completed within 24 hours (22%), as well as a general decline in the total number of completed MRs (51%), particularly compared to the previous audit (59% and 93%, respectively), indicating a lack of adherence to the standard. Such factors as admission division, admission specialty, day the MR was completed, admission time, number of medications upon admission and number of documented drug discrepancies have all shown statistical significance (p < 0.005). Conclusion: The MR process at SaSH failed to meet the standards and demonstrated a decline in completed MRs compared to the last audit performed. Thus, a further re-audit would be recommended after implementing recommendations based on the study findings.10 0