Browsing by Author "Seydel, T"

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    Neutron scattering quantification of unfrozen pore water in frozen mud
    (Elsevier, 2021-09) Gates, WP; Bordallo, HN; Bouazza, A; Carnero-Guzman, GG; Aldridge, LP; Klapproth, A; Iles, GN; Booth, N; Mole, RA; Seydel, T; Yu, DH; de Souza, NR
    The Earth's polar regions are experiencing a greater frequency of freeze-thaw events throughout the polar summer, contributing to atmospheric methane and destabilising clay-rich sediments. Clays in soils tightly bind pore water and thus substantially modify freeze-thaw events. While temperatures of phase transitions for confined pore water may be precisely assessed using calorimetric or thermal analyses to −30 or −40 °C, neutron scattering directly probes how pores in clay minerals control ice formation and melting to lower temperatures. We apply elastic neutron scattering to accurately quantify the unfrozen water content of clay gels and unambiguously identify different pore-water environments by their freezing temperatures. Using this approach, we conclude that cryosuction controls water mobility in frozen soils in the absence of soluble salts to much lower temperatures than observed by other techniques. Dyanmics determined from neutron scattering indicates that water in clay gel pores thaws at much lower temperatures than currently considered, and thus pose potential risks for contaminant migration at sub freezing temperatures. The general poor strength of wet clays can significantly impact infrastructure in cold regions undergoing an increased frequency of freeze-thaw events. © 2021 Elsevier Inc.
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    Strikingly different roles of SARS-CoV‑2 fusion peptides uncovered by neutron scattering
    (American Chemical Society (ACS), 2022-02-14) Santamaria, A; Batchu, KC; Matsarskaia, O; Prévost, SF; Russo, D; Natali, F; Seydel, T; Hoffmann, I; Laux, V; Haertlein, M; Darwish, TA; Russell, RA; Corucci, G; Fragneto, G; Maestro, A; Zaccai, NR
    Coronavirus disease-2019 (COVID-19), a potentially lethal respiratory illness caused by the coronavirus SARS-CoV-2, emerged in the end of 2019 and has since spread aggressively across the globe. A thorough understanding of the molecular mechanisms of cellular infection by coronaviruses is therefore of utmost importance. A critical stage in infection is the fusion between viral and host membranes. Here, we present a detailed investigation of the role of selected SARS-CoV-2 Spike fusion peptides, and the influence of calcium and cholesterol, in this fusion process. Structural information from specular neutron reflectometry and small angle neutron scattering, complemented by dynamics information from quasi-elastic and spin-echo neutron spectroscopy, revealed strikingly different functions encoded in the Spike fusion domain. Calcium drives the N-terminal of the Spike fusion domain to fully cross the host plasma membrane. Removing calcium, however, reorients the peptide back to the lipid leaflet closest to the virus, leading to significant changes in lipid fluidity and rigidity. In conjunction with other regions of the fusion domain, which are also positioned to bridge and dehydrate viral and host membranes, the molecular events leading to cell entry by SARS-CoV-2 are proposed. © 2022 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0.