https://www.um.edu.mt/library/oar/handle/123456789/2066 Wed, 02 Sep 2026 23:08:41 GMT 2026-09-02T23:08:41Z https://www.um.edu.mt/library/oar/handle/123456789/148817 Title: A review of the aquatic environmental transformations of engineered nanomaterials Authors: Harrison, Daniel Mark; Briffa, Sophie M.; Mazzonello, Antonino; Valsami-Jones, Eugenia Abstract: Once released into the environment, engineered nanomaterials (ENMs) undergo complex interactions and transformations that determine their fate, exposure concentration, form, and likely impact on biota. Transformations are physical, chemical, or biological changes that occur to the ENM or the ENM coating. Over time, these transformations have an impact on their behaviour and properties. The interactions and transformations of ENMs in the environment depend on their pristine physical and chemical characteristics and the environmental or biological compartment into which they are released. The uniqueness of each ENM property or lifecycle results in a great deal of complexity. Even small changes may have a significant impact on their potential transformations. This review outlines the key influences and outcomes of ENM evolution pathways in aquatic environments and provides an assessment of potential environmental transformations, focusing on key chemical, physical, and biological processes. By obtaining a comprehensive understanding of the potential environmental transformations that nanomaterials can undergo, more realistic models of their probable environmental behaviour and potential impact can be developed. This will, in turn, be crucial in supporting regulatory bodies in their efforts to develop environmental policy in the field of nanotechnology. Sun, 01 Jan 2023 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/148817 2023-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/148411 Title: UV aging of PET microplastics in a custom-built weathering chamber replicating Mediterranean conditions Authors: Galea, Jack; Agius Anastasi, Anthea; Vella, Daniel A.; Briffa, Sophie M. Abstract: During their lifetime, microplastics undergo transformations and react in ways that change their behavior and properties over time. Current standard plastic weathering protocols, which were developed prior to the increased concern about plastic pollution, may not be fully suited for microplastic studies as they aim to monitor durability and understand bulk plastic behavior, with little concern about fragments or leachates produced during degradation. This work aims to age poly­(ethylene terephthalate) (PET) microplastics (MPs) in a custom-built weathering chamber replicating Mediterranean shoreline conditions (detailed in the authors’ previous work). This work studies the physicochemical changes of PET microplastic pellets (3–5 mm) following aging for a period of 90 days in dry and aquatic environments within a purposely designed weathering chamber. The chamber implemented UV-A, mechanical abrasion, and elevated temperatures to replicate the shore conditions. Micro-Raman spectroscopy was used to follow changes in the carbonyl content, crystallinity, and phenyl content of the PET MPs. Additionally, scanning electron microscopy (SEM) paired with energy-dispersive spectroscopy (EDS) was used to observe changes at the surface of the aged PET MPs. SEM showed that abrasion led to surface roughening and fibrillation. Despite changes being noted, no clear pattern emerged within the processed Raman spectroscopic results to elicit the contributions of UV radiation, salinity, and temperature. Loss of the surface layer by fragmentation and exposure of new surfaces could explain the fluctuating micro-Raman data. This work demonstrates early-stage degradation features including fluctuating chemical changes, fragmentation, abrasion, and salt crystallization under environmentally realistic Mediterranean shoreline conditions while laying methodological groundwork for future microplastic weathering research that seeks longer durations. Wed, 01 Jan 2025 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/148411 2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/148408 Title: Detection, quantification, and characterisation of microplastics in Maltese bottled water Authors: Camilleri, Josmar; Agius Anastasi, Anthea; Briffa, Sophie Marie Abstract: Plastics play a pivotal role in various industries owing to their versatility in engineering their physical, mechanical, and chemical properties while exploiting their remarkable durability, light-weight nature, and cost-effectiveness. Yet, their widespread use has led to the pollution of Earth’s water systems. Over time, plastic waste degrades into microplastics, particles smaller than 5 mm. Recent studies have highlighted the growing concerns associated with microplastics, especially in bottled beverages, including bottled water, with associated hazards still in the very early stages of being fully understood. Furthermore, the global understanding of the extent of microplastic contamination in the environment and along the food chain remains limited. This study aimed to detect, quantify, and characterise microplastics in bottled drinking water produced and sold in Malta. Samples from five brands were filtered, stained with Nile red, and quantified using fluorescence microscopy. The average microplastic concentration was found to be 35,877 ± 23,542 particles per litre, with 84% of samples exhibiting contamination, which was noted to be statistically significant. The average particle diameter was measured to be 2.3696 ± 0.0035 µm. Raman spectroscopy was used to chemically characterise 10 larger particles per brand (i.e., 50 samples), identifying the presence of cellulose, polyurethane, polymethyl methacrylate, polyethylene, and smaller quantities of other polymers. Morphological analysis classified 36 of the larger particles as fragments and 14 as fibres. Excluding laboratory-introduced contamination, the primary source of microplastic contamination in the analysed bottled water was traced to the bottle caps. Description: Supplementary material is available within this record. Wed, 01 Jan 2025 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/148408 2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/144944 Title: Advances toward self-healing coatings on Mg alloys for active corrosion protection Authors: Zhou, Xingxing; Xin, Jie; Wang, Cheng; Qian, Kun; Tao, Xuewei; Ba, Zhixin; Xue, Feng; Bai, Jing; Mallia, Bertram; Dong, Qiangsheng Abstract: Magnesium (Mg) alloys with high specific strength, light weight, and natural biodegradability are promising candidates for applications in automotive industry and biodegradable medical devices. However, their wide employment is hindered by their rapid corrosion behavior. Protective coatings provide a potential approach to extending the service period, but damage to these coatings often leads to local corrosion and even premature failure. To address this issue, self-healing coatings have been developed for providing long-term and reliable protection, even in the presence of defects. This paper summarizes recent progress in self-healing coatings on Mg alloys, with a focus on their uni- and multistimuli responsive mechanisms. A typical self-healing coating is composed of a physical layer, inhibitors, and inhibitor containers. Herein, the loading and release of inhibitors are crucial for the design of self-healing coatings. On the one hand, inhibitors can be directly doped/filled into the protective layer and released in response to environmental changes and coating degradation. On the other hand, inhibitors may be encapsulated into micro/nano-containers and released upon being triggered by ions, pH, light, heat, potential and moisture. Additionally, this review presents advanced characterization techniques and systematic evaluation methods for assessing self-healing functionality. Ultimately, the emerging challenges and research priorities in the development of self-healing coatings for Mg alloys are comprehensively discussed. Wed, 01 Jan 2025 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/144944 2025-01-01T00:00:00Z