Search for: All records

Abstract Satellite tobacco mosaic virus (STMV) is a model system for studying viral assembly and stability due to its architecture: a single-stranded RNA genome enclosed in an icosahedral capsid. Coupling a polarizable force-field to enhanced sampling, we explored at high-resolution the long-timescale structural dynamics of a complete ∼1M-atom STMV. RNA-free capsids exhibit remarkable stability at physiological salt concentrations, suggesting an evolutionary adaptation for capsid reuse during the viral life cycle. This observation challenges the notion that empty capsids are exclusively products of abortive assembly, positioning them instead as functional intermediates in viral reproduction. Additionally, RNA encapsidation creates electrostatic dependencies that magnesium ions mitigate, stabilizing both RNA and capsid through long-residence-time interactions with phosphate groups. Chloride ions further influence capsid permeability by modulating salt-bridge disruptions and interprotomeric interactions, with these effects being pH-dependent: enhanced at pH < 7, preserving nucleocapsid integrity, or weakened at pH = 7, facilitating disassembly and RNA release. 

Abstract This study focuses on the synthesis of fully renewable polycarbonates (PCs) starting from cellulose‐based platform molecules levoglucosenone (LGO) and 2,5‐bis(hydroxymethyl)furan (BHMF). These unique bio‐based PCs are obtained through the reaction of a citronellol‐containing triol (Triol‐citro) derived from LGO, with a dimethyl carbonate derivative of BHMF (BHMF‐DC). Solvent‐free polymerizations are targeted to minimize waste generation and promote an eco‐friendly approach with a favorable environmental factor (E‐factor). The choice of metal catalyst during polymerization significantly influences the polymer properties, resulting in high molecular weight (up to 755 kDa) when Na₂CO₃is employed as an inexpensive catalyst. Characterization using nuclear magnetic resonance confirms the successful incorporation of the furan ring and the retention of the terminal double bond of the citronellol pendant chain. Furthermore, under UV irradiation, the presence of both citronellol and furanic moieties induces singular structural changes, triggering the formation of three distinct structures within the polymer network, a phenomenon herein occurs for the first time in this type of polymer. These findings pave the way to new functional materials prepared from renewable monomers with tunable properties. 

Abstract Proton‐exchange membrane fuel cell vehicles offer a low‐carbon alternative to traditional oil fuel vehicles, but their performances still need improvement to be competitive. Raising their operating temperature to 120 °C will enhance their efficiency but is currently unfeasible due to the poor mechanical properties at high temperatures of the state‐of‐the‐art proton‐exchange membranes consisting of perfluorosulfonic acid (PFSA) ionomers. To address this issue, xx designed composite membranes made of two networks: a mat of hybrid fibers to maintain the mechanical properties filled with a matrix of PFSA‐based ionomer to ensure the proton conductivity. The hybrid fibers obtained by electrospinning are composed of intermixed domains of sulfonated silica and a fluorinated polymer. The inter‐fiber porosity is then filled with a PFSA ionomer to obtain dense composite membranes with a controlled fibers‐to‐ionomer ratio. At 80 °C, these obtained composite membranes show comparable performances to a pure PFSA commercial membrane. At 120 °C however, the tensile strength of the PFSA membrane drastically drop down to 0.2 MPa, while it is maintained at 7.0 MPa for the composite membrane. In addition, the composite membrane shows a good conductivity of up to 0.1 S cm −1 at 120 °C/90% RH, which increases with the ionomer content.