Brownian rotors play an important role in biological systems and in future nanotechnological applications. However the mechanisms determining their dynamics, efficiency, and performance remain to be characterized. Here the F0 portion of the F-ATP synthase is considered as a paradigm of the Brownian rotor. In a generic analytical model we analyze the stochastic rotation of F0-like motors as a function of the driving free energy difference and of the free energy profile the rotor is subjected to. The latter is composed of the rotor interaction with its surroundings, of the free energy of chemical transitions, and of the workload. The dynamics and mechanical efficiency of the rotor depend on the magnitude of its stochastic motion driven by the free energy difference and its rectification on the reaction-diffusion path. We analyze which free energy profiles provide maximum flow and how their arrangement on the underlying reaction-diffusion path affects rectification and--by this--the efficiency.
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http://dx.doi.org/10.1063/1.3026736 | DOI Listing |
Science
January 2025
Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Phase diagrams and crystallography are standard tools for studying structural phase transitions, whereas acquiring kinetic information at the atomistic level has been considered essential but challenging. The η-to-θ phase transition of alumina is unidirectional in bulk and retains the crystal lattice orientation. We report a rare example of a statistical kinetics study showing that for nanoparticles on a bulk Al(OH) surface, this phase transition occurs nondeterministically through an ergodic equilibrium through the molten state, and the memory of the lattice orientation is lost in this process.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China.
Polyimide (PI)-based gas separation membranes are of great interest in the field of H purification owing to their good thermal stability, chemical stability, and mechanical properties. Among polyimide-based membranes, intrinsically microporous polyimides are easily soluble in common organic solvents, showing great potential for fabricating hollow fiber gas separation membranes. However, based on the solution-diffusion model, improving the free volume or the movability of polymer chains can improve gas permeability, but would result in poor thermal stability.
View Article and Find Full Text PDFJ Chem Inf Model
January 2025
Schrödinger Incorporated, Cambridge, Massachusetts 02142, United States.
J Am Chem Soc
January 2025
Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States.
Hydrogen atom transfer (HAT) reactions and their kinetic barriers Δ are important in organic and inorganic chemistry. This study examines factors that influence Δ, reporting the kinetics and thermodynamics of HAT from various ruthenium bis(acetylacetonate) pyridine-imidazole complexes to nitroxyl radicals. Across these 36 reactions, the Δ and Δ can be independently varied, with different sets of Ru complexes primarily tuning either their ps or their °s.
View Article and Find Full Text PDFJ Mol Model
January 2025
School of Chemistry and Chemical Engineering, Xian Yang Normal University, Xian Yang, China.
Context: This study investigates the reaction mechanism of luteolin with selenium dioxide in ethanol. Through a detailed search for transition states and thermodynamic energy calculations, it was found that the reaction proceeds via two possible pathways, leading to the formation of products P1 and P2, respectively. A common feature of both pathways is that the first elementary step results in the formation of the intermediate INT1.
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