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Natural polysaccharides, e.g., starch, cellulose and sodium alginate have been highlighted as unconventional chromophores owing to their chain structures containing clustered electron-rich groups and the rigidification imposed by inter/intramolecular interactions. On account of the abundant hydroxyl groups and dense packing of low-substituted (< 5 %) mannan chains, we have investigated the laser-induced fluorescence of mannan-rich vegetable ivory seeds (Phytelephas macrocarpa), both in the native state and after thermal aging. The untreated material emitted fluorescence at 580 nm (yellow-orange) when excited at 532 nm (green). This luminescence is intrinsic to the polysaccharide matrix abundant in crystalline homomannan, as demonstrated by lignocellulosic analyses, fluorescence microscopy, NMR, Raman, FTIR and XRD. Thermal aging at 140 °C and above intensified the yellow-orange fluorescence and caused the material to fluoresce when excited by a near-infrared laser (785 nm). In view of the clustering-triggered emission mechanism, the fluorescence of the untreated material can be attributed to hydroxyl clusters and the conformational rigidification in mannan I crystals. On the other hand, thermal aging caused dehydration and oxidative degradation of mannan chains, inducing the substitution of hydroxyl groups by carbonyls. These physicochemical changes may have affected cluster formation and increased conformational rigidification, enhancing fluorescence emission., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Context: In the absence of any specific treatment available for COVID-19, people started practicing traditional nonpharmacological preventive home remedies such as salt water gargling and steam inhalation. The available research evidence on some of these measures opines that steam inhalation, saline gargling, and povidone-iodine gargling does have virucidal properties and do provide symptomatic relief., Aims: The aim is to test this hypothesis, and the present trial was undertaken with an objective to assess the effect of steam inhalation, saline gargling, and povidone-iodine gargling among the COVID-19-positive patients with respect to early test negativity and clinical recovery., Methodology: Open-labeled, parallel, randomized controlled trial was conducted among asymptomatic or mild COVID-19-positive patients in Bangalore from September 2020 to February 2021. In each group of steam inhalation, saline gargling, povidone-iodine gargling, and control, twenty participants were allocated. Daily follow-up was done for 21 days to assess early test negativity and clinical recovery. Trial Registry Number: Clinical Trial Registry India/2020/09/027687., Results: Among 80 participants recruited, 65 (81.3%) were symptomatic. Early test negativity was seen in povidone-iodine gargling group of 6 days (KaplanMeier survival curve, BreslowGeneralized Wilcoxon test P = 0.7 as per the intention-to-treat and as per-protocol P = 0.8). Significant clinical recovery was seen in saline gargling group (4 days, P = 0.01)., Conclusion: Povidone-iodine gargling was effective in providing early test negativity, whereas saline gargling was effective in early clinical recovery., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Indian Journal of Community Medicine.)