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Novel donor-pi-bridge-acceptor-pi-bridge-donor (D-pi-A-pi-D) type 2,1,3-benzothiadiazole fluorescent dyes connected to the N,N-diarylamino terminus via various type pi-conjugate spacers exhibits large two-photon absorption cross-sections and high fluorescent quantum yields in orange-red color.

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The emission of microplastics into nature poses a threat to aquatic and terrestrial ecosystems. Their penetration of the food chain presents a danger to human health as well. Wastewater treatment plants can be seen as the last barrier between microplastics and the environment. This review focuses on the impact of waste treatment plants in retaining microplastics. Studies show that no wastewater treatment method leads to a complete retention of microplastics, and so wastewater treatment plants themselves are viewed as point sources for the discharge of microplastics into the aquatic environment. Problems associated with the utilization of microplastic loaded sewage sludge are also discussed in the review. Journal of Water Resource and Protection found as micropellets in cosmetic formulations and in facial cleaners and body scrubs (median size of 0.2 -0.4 mm), as microspherules in toothpastes (2 -5 μm in size), as well as in scrubbers used for air-blasting surfaces to remove paints and rust [25] and as drilling fluids in oil and gas exploration. A newer application is their use in drug delivery systems [26] [27]. In addition, synthetic polymer containing microparticles can also be released by the degradation of materials. The release of microfibers as a result of the washing of textiles has been widely reported as a source of microplastics [28] [29] [30] [31] [32]. These synthetic fibers, released by washing machines, are transported to waste water treatment plants [29] [33], where a considerable amount of them pass through the different treatment stages into the effluents due to their smaller size and enter the aquatic environment. It is estimated that around 35% of microplastics reaching the ocean are from synthetic textiles [34].Inventories of microplastics entering the environment have been attempted by organizations in different countries. A breakdown of the sources of microplastics in Sweden has been provided by Magnusson [35], which is given in detail below as an example of typical microplastic streams in developed countries. There is microplastic emission from plastic production, sandblasting material, cosmetic products, pharmaceutical drugs, textiles, road material and coatings. Using a spill factor of 0.04%, which was also used by Sundt et al. [26] for the estimation of pellet loss from the Norwegian plastic production plants, K. Magnusson et al. [35] have calculated a direct micropellet emission of 298 tons per year. In addition to that, there is loss due to the handling of plastic pellets which is set at between 0.0005% and 0.01%, adding another 12 -235 tons of microplastics emitted into the environment. These numbers were modeled on emission factors proposed by Lassen et al. [36] for the Danish production industry. However, no actual measured numbers of emissions of microplastics during production exist.The use of microplastics (e.g. of urea formaldehyde resins) in abrasive products for sandblasting has been deemed to be limited, and the use of these materials in Swedish shipyards is strictly regulated...