With the rapidly developing wireless communication technology, electromagnetic pollution problems have become more prominent. Electromagnetic pollution has caused great harm to wireless equipment, precision instruments, military safety, etc., which urgently requires the development of lightweight, high-efficiency, broadband electromagnetic waves (EMW) absorbing materials. MXene is an emerging two-dimensional (2D) material with the advantages of lamellar structure, excellent conductivity, and abundant surface groups. At the same time, conducting polymers (CPs) have excellent performance in terms of conductivity, surface activity, quality, and electromagnetic loss, making them have excellent potential in EMW absorbing direction. This article examines the preparation, structure, and performance of MXene and CPs-based radar absorbing materials (RAM). A comprehensive summary and objective analysis of the nowaday study progress on the EMW absorbing performances of MXene and CPs, and a comprehension of the absorbing mechanism are reviewed. Finally, the research direction of absorbing materials has been prospected.

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Quercetin is a phenolic flavonol compound with established antioxidant, anti-inflammatory, and immuno-stimulant properties. Recent studies demonstrate the potential of quercetin against COVID-19. This article highlighted the prophylactic/therapeutic potential of quercetin against COVID-19 in view of its clinical studies, inventions, and patents. The literature for the subject matter was collected utilizing different databases, including PubMed, Sci-Finder, Espacenet, Patentscope, and USPTO. Clinical studies expose the potential of quercetin monotherapy, and also its combination therapy with other compounds, including zinc, vitamin C, curcumin, vitamin D3, masitinib, hydroxychloroquine, azithromycin, and ivermectin. The patent literature also examines claims that quercetin containing nutraceuticals, pharmaceuticals, and dietary supplements, alone or in combination with other drugs/compounds, including favipiravir, remdesivir, molnupiravir, navitoclax, dasatinib, disulfiram, rucaparib, tamarixin, iota-carrageenan, and various herbal extracts (aloe, poria, rosemary, and sphagnum) has potential for use against COVID-19. The literature reveals that quercetin exhibits anti-COVID-19 activity because of its inhibitory effect on the expression of the human ACE2 receptors and the enzymes of SARS-CoV-2 (MPro, PLPro, and RdRp). The USFDA designated quercetin as a “Generally Recognized as Safe” substance for use in the food and beverage industries. It is also an inexpensive and readily available compound. These facts increase the possibility and foreseeability of making novel and economical drug combinations containing quercetin to prevent/treat COVID-19. Quercetin is an acidic compound and shows metabolic interaction with some antivirals, antibiotics, and anti-inflammatory agents. Therefore, the physicochemical and metabolic drug interactions between quercetin and the combined drugs/compounds must be better understood before developing new compositions.

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