https://www.selleckchem.com/btk.html Melatonin is a natural hormone from the pineal gland that regulates the sleep-wake cycle. We examined the structure and physico-chemical properties of melatonin using electronic structure methods and molecular-mechanics tools. Density functional theory (DFT) was used to optimise the ground-state geometry of the molecule from frontier molecular orbitals, which were analysed using the B3LYP functional. As its electrons interacted with electromagnetic radiation, electronic excitations between different energy levels were analysed in detail using time-dependent DFT with CAM-B3LYP orbitals. The results provide a wealth of information about melatonin's electronic properties, which will enable the prediction of its bioactivity. Molecular docking studies predict the biological activity of the molecules against the coronavirus2 protein. Excellent docking scores of -7.28, -7.20, and -7.06 kcal/mol indicate that melatonin can help to defend against the viral load in vulnerable populations. Hence it can be investigated as a candidate drug for the management of COVID.Study designs where follow-up samples are collected through multiple attempts have been called repeated attempts designs. In this note we explore the monotonicity thought to underly the models fit for these designs and show it does not always hold.Understanding processing-property relationships for directed-energy-deposition (DED) parts remains a major roadblock to widespread process implementation. Herein we investigate the effect of scanning-strategy and testing-orientation on the fatigue response of as-printed Ti6Al4V components. At ~106 cycles, samples tested in the build-direction exhibited ~ 45% decrease in fatigue strength relative to the horizontally-tested samples, owing to higher overall porosity and the testing orientation relative to residual pores. Samples failing 106 cycles exhibited smoother-surfaces. Our results indicate that DED-produced parts can exhibit directi