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The emergence of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) posed a serious worldwide threat and emphasized the urgency to find efficient solutions to combat the spread of the virus. Drug repurposing has attracted more attention than traditional approaches due to its potential for a time- and cost-effective discovery of new applications for the existing FDA-approved drugs. Given the reported success of machine learning (ML) in virtual drug screening, it is warranted as a promising approach to identify potential SARS-CoV-2 inhibitors. The implementation of ML in drug repurposing requires the presence of reliable digital databases for the extraction of the data of interest. Numerous databases archive research data from studies so that it can be used for different purposes. This article reviews two aspects: the frequently used databases in ML-based drug repurposing studies for SARS-CoV-2, and the recent ML models that have been developed for the prospective prediction of potential inhibitors against the new virus. Both types of ML models, Deep Learning models and conventional ML models, are reviewed in terms of introduction, methodology, and its recent applications in the prospective predictions of SARS-CoV-2 inhibitors. Furthermore, the features and limitations of the databases are provided to guide researchers in choosing suitable databases according to their research interests.

In order to find out whether any toothpastes commercially available in the United Arab Emirates (UAE) carry microplastic content in form of plastic microbeads, the filterable solid contents of 31 toothpastes from UAE markets and 2 toothpastes imported from Syria were analyzed. FT-IR studies of the solids revealed that the major solid components were hydrated silica and calcium carbonate, where the individual toothpaste product exhibited either one or the other as the dominant constituent. Titrimetric analysis of the alkalinity of the ash of the toothpastes was carried out. The solids, ashed at 600˚C were subjected to FT-IR and EDS (energy dispersive X-ray spectroscopic) analysis. The ash of some of the products was shown to have TiO 2 and Ca 3 (PO 4 ) 2 as minor components. Mostly organic dyes were used as colorants; however, iron oxide (Fe 2 O 3 ) was also found. Importantly, none of the toothpastes carried any solid microplastic particles. Only 3 toothpastes carried microbeads at all, which were made of either silica or microcrystalline cellulose. This finding indicates that toothpastes, at least in the UAE, are no longer a significant source of microplastic in the environment. The results were compared to a toothpaste bought through the internet with a formulation from 2014, which exhibited polythene microplastic at 1.31 ± 0.39 w% of the filterable solid content.

Roadsides and soil have been sampled for microplastic content in 7 locations in the Al Ain area, Eastern Region, Abu Dhabi, UAE. The collection sites constituted residential areas and fall-out roads, but also one Wadi and the shoreline of a man-make lake. The concentration of micro-tire particles was found to be high on the roadsides of the residential areas. While a significant amount of tire macroparticles could be found on the roadsides of fall-out roads, these exhibited less micro-tire particles. Here, significant amounts of micro-tires could be found off-road, along the fallout roads, indicating, in absence of run-off water, Aeolic transport of the particles. The Wadi and the lakeshore sites were essentially free of micro-tires, but in all sites, microfibers were found. Collection of run-off water from roads during a rare rainstorm event showed transport of plastic microparticles both into the storm drains as well as to the adjacent soil. High surface temperatures and extreme aridity in the summer leads to the evaporation of small organic additives from the plastic materials leaving them dry and brittle. This leads to easy further mechanical fragmentation of the particles.

Materials made of rubber are a source of polymers released into the environment, where tire abrasions are a major contributor. In many hot, arid environs, whole tire losses are more common than in moderate climates, and lead to the accumulation of additional tire material on road sides, which over time can be the source of secondary micro-tires. Other rubber containing material from cars such as mud-flaps and floor mats has been seen as an appreciable additional source of micro-rubber. Due to the lack of precipitation, it is expected that modes of micro-tire relocation are more limited in arid regions than in more moderate climates. This 2-year study examines the rubber/tire content from 34 sampling sites within the region of Al Ain, Eastern region of Abu Dhabi Emirate, United Arab Emirates. The samplings include road dust, soil along roadsides, storm water run-off samples and samples collected in Wadis (creek beds that seasonally carry water) and one artificial lake. The mean average number of micro-tires in road dust was found to be 44.4 ± 40.6 micro-tires/g. In soil samples alongside the roads, it was 22.8 ± 42.1 micro-tires/g. The mean average size of micro-tires for all 34 sampling sites was found to be 106.9 ± 98.5 µm. It could be seen that rubber/tire materials desiccate over time during the high temperatures of the Emirati summer, become hard, brittle and break into smaller pieces, resulting in secondary micro-tire particles. The study of run-offs showed that tire particles are swept into storm drains during larger, very infrequently occurring rain events. However, the predominant mode of micro-tire transport was found to be on road by physical contact with cars, off-road by a combination of physical contact with moving objects and air movement. Samples taken from an artificial lake and three Wadis within the confines of Al Ain have shown only few micro-tire particles, so that the dispersion of micro-tires is not as pervasive as had been expected prior to this study.