SACM - United Kingdom
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9667
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Item Restricted Layered Extrusion of engineering Metal Alloys (LEMA) using Semi-Solid Thixotropic Feedstock(The University of Sheffield, 2023-08-31) Alharbi, Abdullah; Mumtaz, KamranAdditive manufacturing (AM) has gained significant attention in low- and medium-volume industries due to its ability to create custom products with complex shapes, design freedom, material savings, and short lead times. While most AM processes focus on thermoplastics, there is increasing interest in metal AM systems, including powder bed fusion processes. However, these methods often involve high acquisition and operating costs, limiting accessibility. To address this, this study focuses on developing and investigating the Layered Extrusion of Engineering Metal Alloys (LEMA) system as a cost-effective alternative metal AM approach. The LEMA system manipulates alloys in the semi-solid thixotropic state. Utilising semi-solid metal slurry in extrusion-based AM can result in metal components with substantially lower operating costs and reduced thermal stresses compared to laser-based method. Experimental work initially conducted (Phase I) using the LEMA system involved in-situ creation of semi-solid thixotropic metallic alloys, particularly focusing on the Zn-Sn binary system, but improvements were made to the LEMA system for the subsequent phase to enhance performance. In Phase II, thermodynamic simulations and thermal analysis have indicated that Zn-40Sn holds promise for semi-solid thixotropic applications. Cold extrusion and heat treatment processes were employed to produce thixotropic feedstock with proper microstructures before being additively manufactured. The 3D printed components were evaluated and the result suggested that the adapted method for semi-solid billets preparation was feasible technique which then helped in a successful printing metallic material. Additionally, printing experiments were conducted to study the effects of major process parameters on the quality of deposited single-layer. It was demonstrated that single layers could be printed under 1.5 mm diameter orifice, extrusion speed of 20 mm/min, substrate moving velocity of 200 mm/min, and extrusion temperature of ≈313 ℃. The optimized printing process parameters from these experiments were then utilized for multilayer printing. It was found that substrate temperature is a key factor for achieving good metallurgical layer bonding at the interface of the printed layers. The research results support LEMA's feasibility as an alternative for the metal additive manufacturing route and lays the groundwork for processing SSMs with higher melting points in the future.4 0Item Restricted The assessment of GDF-15 and GDF-15 glycoforms as diagnostic biomarker for interstitial lung disease(UNiversity College London, 2024) Alharbi, Abdullah; Porter, Joanna; Beatson, RichardBackground: Interstitial lung disease (ILD) is a complex and various condition characterized by inflammation and fibrosis in the lung parenchyma. The identification of novel biomarkers is vital for improving diagnosis, prognosis, and treatment of ILD. Objectives: To investigate the role of GDF-15 as a biomarker for ILD, with a focus on its glycosylation patterns and dietary influences. Methods: We conducted a cross-sectional study of 32 BAL and 111 plasma samples from ILD controls. GDF-15 levels were measured using enzyme-linked immunosorbent assay (ELISA), and glycosylation patterns were analysed using lectin-based assays. Results: GDF-15 levels were significantly elevated in ILD patients compared to non-ILD controls (p < 0.001). We also found that GDF-15 was modified by Neu5Gc, a sialic acid acquired through dietary consumption, which was associated with higher levels of inflammation and fibrosis in ILD patients. Conclusion: Our findings suggest that GDF-15 and its glycoforms, particularly Neu5Gc-modified GDF-15, may serve as novel biomarkers for ILD diagnosis and prognosis. This study highlights the importance of considering dietary influences on disease pathogenesis and the potential for personalized treatment strategies. This study provides new insights into the pathogenesis of ILD and identifies GDF-15 as a promising biomarker for diagnosis and prognosis. The findings have important implications for the development of novel diagnostic and therapeutic strategies for ILD.29 0Item Restricted The Influence of Iron and Lignin on Molecules of the Gastrointestinal Microbiome and Its Effect on the Conjugation of Carbapenem Resistance Plasmids(University of Birmingham, 2022-09) Alharbi, Abdullah; Buckner, MichelleThe gastrointestinal microbiome has acted a reservoir for antibiotic resistance genes by harbouring favourable conditions for the the conjugative transfer of resistance plasmids. Resistance against carbapenems, the last resort β-lactam antibiotics, has been on the rise and is mainly mediated by the spread of carbapenemase-encoding plasmids by Klebsiella pneumoniae. Dietary intake of iron and iron chelators can modulate the metabolic and microbial profile of the gastrointestinal microbiome. This project focused on investigating the influence that molecules produced by the gastrointestinal microbiome might have on the conjugation of carbapenem resistance plasmids in K. pneumoniae in reaction to iron and lignin supplementation. A fluorescence reporter system was used to determine the effect of iron and lignin co-supplementation to an ex-vivo colonic supernatant on the conjugation of an endemic carbapenemase-encoding plasmid called pKp-QIL. This was followed by plating-based conjugation assays which measured the frequency of conjugation of a plasmid from clinical isolate called pCPE16_3 in an iron and lignin co-supplemented ex-vivo colonic supernatant. This project has revealed that lignin has no effect on the conjugation of resistance plasmids in iron- available gastrointestinal microbiome.18 0