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Abstract: Using quasielastic neutron scattering, we compare dynamics in single-element liquids, glass-forming selenium and non glass-forming gallium. There is a single jump-diffusion process in gallium, whereas in selenium there is also a faster, spatially localized process. The fast and slow processes describe β- and α-relaxation, respectively. We then analyze an archetypical glass-former, glycerol, to show that the two-component fit, with β- and α-relaxations explicitly separated, yields the correct value for the translational diffusion coefficient and provides information on the spatial localization of the β-relaxation that is not experimentally accessible otherwise. [Copyright &y& Elsevier]

[Display omitted] • Apilimod and tetrandrine reportedly work better than remdesivir against SARS-CoV-2. • We find that apilimod and tetrandrine show much reduced methyl rotational barriers. • Low potential barriers lead to pronounced quantum effects at low temperatures. • Low potential barriers lead to fast methyl rotation at physiological temperatures. • Screening studies of the energy landscape can help identify promising drug candidates. A recent screening study highlighted a molecular compound, apilimod, for its efficacy against the SARS-CoV-2 virus, while another compound, tetrandrine, demonstrated a remarkable synergy with the benchmark antiviral drug, remdesivir. Here, we find that because of significantly reduced potential energy barriers, which also give rise to pronounced quantum effects, the rotational dynamics of the most dynamically active methyl groups in apilimod and tetrandrine are much faster than those in remdesivir. Because dynamics of methyl groups are essential for biochemical activity, screening studies based on the computed potential energy profiles may help identify promising candidates within a given class of drugs. [ABSTRACT FROM AUTHOR]

Abstract: Energy barriers for rotation of –NH3 and –BH3 in the orthorhombic phase of ammonia borane, NH3BH3, were determined using quasielastic neutron scattering (QENS). QENS confirms the 3-site jump model of rotational diffusion and yields barrier heights of 23.6±1.0kJ/mol and 14.8±0.4kJ/mol for the borane and amine groups, respectively, which are comparable to barrier heights determined by recent 2H and 15N NMR studies suggesting no significant isotope effect on rotational motion in the orthorhombic phase of ammonia borane. [Copyright &y& Elsevier]