https://www.um.edu.mt/library/oar/handle/123456789/929 2026-06-06T13:12:52Z https://www.um.edu.mt/library/oar/handle/123456789/147124 Title: Physicochemical characterisation of difluprednate and 6α9α-difluoroprednisolone : determination of solubility, pKa and LogP Authors: Baluci, Giulia; Buhagiar, Paul Immanuel; Vella Szijj, Janis; Attard, Everaldo; Sammut Bartolo, Nicolette Abstract: Steroids are used in the treatment of diverse pathological conditions for their anti-inflammatory and immunosuppressive effects, with the mode of action being affected by their physicochemical characteristics. To date, difluprednate (DFBA) has been characterised using computational methods which rely on the selected computational model and disregard external factors. The aim of the study was to determine the solubility, pKa and LogP of DFBA and its metabolite, 6α9α-difluoroprednisolone (DFP) using experimental methods. Methods using UV–Visible spectroscopy and High-Performance Liquid Chromatography (HPLC) were developed to determine the solubility and the pKa, LogD and LogP of the selected steroids. The steroids are soluble in acetonitrile and methanol, and are insoluble in water. DFBA achieved a solubility of 7.2 mg/mL and 0.7 mg/mL in acetonitrile and methanol, while DFP achieved solubility of 2.9 mg/mL and 0.2 mg/mL, respectively. DFBA had an average LogP value of 3.2, and DFP had an average LogP of 1.5. The pKa values for DFBA were 1.5 and 7.2 and for DFP, were 5.9 and 10.8. The characterisation of the physicochemical properties of DFBA and DFP can help support efficient formulation development. 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/147020 Title: Integrating environmental life cycle assessment in assistive technology selection for inclusive workstations : a novel multi-objective optimisation approach in industry 5.0 Authors: Bonello, Amberlynn; Refalo, Paul; Francalanza, Emmanuel; Gauci, Maria Victoria Abstract: Inclusive workstations embody human-centred design in manufacturing, the hallmark of Industry 5.0. Such workstations typically incorporate assistive technologies (ATs) that support understanding, training, assembly performance, and quality inspection for operators with various disabilities. That said, at present, ATs are normally only related to the social pillar of sustainability, with researchers typically overlooking the potential impacts of using ATs on environmental sustainability. This work contributes a novel approach that employs life cycle assessment (LCA) as a design-support tool to promote the cleaner engineering and sustainable selection of ATs without compromising on inclusivity on the manufacturing shopfloor. The outcomes of an LCA of nine different ATs, ranging from a collaborative robot to a projector, were integrated in a multi-objective optimisation (MOO) framework, to shortlist combinations of ATs that enhance physical, cognitive and sensory accessibility, whilst minimising adverse environmental impacts. From the resulting Pareto front, optimal (non-dominated) combinations of ATs were identified, providing up to 91% of the maximum normalised total accessibility. A 65% reduction in lifecycle environmental impacts was also achieved when compared to the maximum environmental impact, demonstrating the approach's capacity to inform cleaner engineering strategies in future assistive technology development. The proposed approach therefore serves as a design-feedback loop, enabling engineers to identify environmental ‘hotspots’ within AT devices and AT systems, and quantify how interventions at the design stage, may influence the Pareto-optimal combination in the age of Industry 5.0. 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/146775 Title: Seal-less vacuum venting for injection moulding : experimental evidence of faster, cleaner and more energy-efficient production Authors: Mifsud, Sarah; Rochman, Arif; Refalo, Paul Abstract: This study presents a seal-less active vacuum venting approach for macro-scale injection moulding, experimentally benchmarked against no venting and passive venting conditions. Industrially relevant trials on a purpose-designed mould show process, quality and sustainable improvements via short-shot analysis and inmould sensing. The novel approach reduced total cycle time by 23%, increased productivity to 96.9 cycles per hour, lowered energy consumption by 15%, and decreased sink mark depth by over 60% relative to the baseline, while eliminating burn marks even at high injection speeds. This work establishes a new, data-driven methodology for integrating advanced venting with in-mould sensing to optimise performance. 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/146238 Title: Investigation of 3D printing parameters on cooling rate, crystallinity, and tensile properties of recycled polyethylene terephthalate cooling rate, crystallinity, and tensile properties of recycled polyethylene terephthalate Authors: Zakaria, Zunaida; Rochman, Arif; Refalo, Paul Abstract: The successful implementation of fused filament fabrication (FFF) 3D printing using recycled plastics requires a deep understanding of the thermal behavior of the plastics throughout the printing process. This study investigated the influence of wall thickness of the printed sample, nozzle temperature, and cooling fan speed during 3D printing on the cooling rate, crystallinity, and tensile properties of recycled polyethylene terephthalate (rPET). The experimental process commenced with the collection of discarded rPET bottles, followed by thorough cleaning and washing to remove any adhesives and contaminants. Afterward, the bottles were cut and ground into flakes and then converted into filaments using a single-screw filament extrusion process. In-situ thermal analysis was conducted by integrating an infrared (IR) thermal camera into the 3D printing setup to monitor real-time temperature changes during the printing process. Results revealed that cooling rates increased markedly with reduced wall thickness, rising from 17.53 °C/min for the 3.6 mm wall thickness to 62.92 °C/min for the 1.2 mm wall thickness. Nozzle temperature exhibited a non-linear influence, with the highest cooling rate of 65.47 °C/min recorded at 240 °C, while enhanced cooling fan speed (100%) further accelerated cooling to 45.00 °C/min. Differential scanning calorimetry (DSC) and Raman spectroscopy confirmed that a slower cooling rate generally promoted crystallinity, which was observed in thick-walled and low-cooling speed prints. Tensile testing demonstrated a strong correlation between crystallinity and tensile performance, with ultimate tensile strength (UTS) reaching 55 MPa at 240 °C and 54.8 MPa at 25% cooling fan speed, outperforming previously reported rPET values. The use of rPET in FFF and the findings of this study contribute to the further exploration of rPET's potential in sustainable additive manufacturing practices. 2026-01-01T00:00:00Z