New highly fluorinated poly(arylene ether sulfone)s (FPAES), poly(arylene ether ketone)s (FPAEK), and poly(arylene ether)s with several types of NLO chromophores as pendant groups were obtained by a polycondensation reaction using very mild conditions. The different polymer structures were designed with the objective to investigate the influence of both the polarity of the chromophore and the nature of the tether between the NLO chromophore and the chain. The resulting copolymers have glass transition temperatures (T
g’s) varying between 160 and 215 °C, and they are stable up to 280 °C under nitrogen. Although these copolymers are soluble in common organic solvents, cyclohexanone gave the best film quality and was used for the film preparation. After optimization of the poling conditions, the in situ second harmonic generation (SHG) measurements gave nonresonant values of the second-order susceptibilities d
33 ranging from 2 to 8 pm/V, and the SHG signals of the poled polymer films were found to be thermally stable below 130 °C. Although being comparable with the values obtained for similar polymers and chromophores in the literature, d
33 are smaller than those obtained for more conventional NLO polymers like PMMA−Disperse Red One (PMMA-DR1), which was taken as a reference. An unusual drop of the SHG signal during cooling was found in the thermally assisted orientation process. This drop occurred at a characteristic temperature below T
g. In this relaxation process which has never been observed, intra- and interchain dipolar interactions are shown to play an important role, which is amplified in the case of chromophores which have their donor group embedded in the main chain, connected by two rigid tethers.
Carotenoids, a group of phytochemicals, are naturally found in the Plant kingdom, particularly in fruits, vegetables, and algae. There are more than 600 types of carotenoids, some of which are thought to prevent disease, mainly through their antioxidant properties. Carotenoids exhibit several biological and pharmaceutical benefits, such as anti-inflammatory, anti-cancer, and immunity booster properties, particularly as some carotenoids can be converted into vitamin A in the body. However, humans cannot synthesize carotenoids and need to obtain them from their diets or via supplementation. The emerging zoonotic virus severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), originated in bats, and was transmitted to humans. COVID-19 continues to cause devastating international health problems worldwide. Therefore, natural preventive therapeutic strategies from bioactive compounds, such as carotenoids, should be appraised for strengthening physiological functions against emerging viruses. This review summarizes the most important carotenoids for human health and enhancing immunity, and their potential role in COVID-19 and its related symptoms. In conclusion, promising roles of carotenoids as treatments against emerging disease and related symptoms are highlighted, most of which have been heavily premeditated in studies conducted on several viral infections, including COVID-19. Further in vitro and in vivo research is required before carotenoids can be considered as potent drugs against such emerging diseases.
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