Microdroplet Surface Drives and Accelerates Proton-Controlled, Size-Dependent Nitrate Photolysis DOI
Xiaowu Zhang, Qishen Huang, Yuxin Liu

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: June 1, 2025

Particulate nitrate photolysis regenerates reactive oxidized nitrogen species (HONO and NOx) in the atmosphere, influencing tropospheric ozone, atmospheric oxidation capacity, particulate matter formation. However, reported rates vary by orders of magnitude, roles protons air-water interface accelerating deliquesced aerosols (i.e., microdroplets) remain unclear. Using confocal Raman spectroscopy aerosol optical tweezer, we measured rate coefficients (j) microdroplets, ranging from 5.28 × 10-8 to 9.07 10-6 s-1, depending on pH (3.2-7.4) radius (3.7 μm 6.0 mm). j remained pH-independent under proton-sufficient conditions (pH < 6.5) but decreased with increasing proton-deficient > 6.5), resolving discrepancies previous studies. Moreover, identified a tipping-point (r* = 706 μm), below which scales inversely droplet above plateaus at aqueous bulk value (6.73 ± 2.12 s-1). These findings demonstrate that occurs predominantly microdroplets. With radii typically these tipping points (pH* 6.5, r* surface-driven size-dependent likely explains variations rates.

Language: Английский

Kinetics of hydrogen migration and string of conformation transformation for pyruvic acid under bioelectric stimulation DOI Creative Commons

Rui-zhi Feng,

Xiao‐Jiang Li,

Anyao Liu

et al.

Research Square (Research Square), Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 3, 2025

Abstract Context The competition between the proton migration and conformational transformation of biomolecules stimulated by bioelectric currents is importance for maintaining normal biochemical reaction process organisms. To reveal mechanism pyruvic acid under currents, effect external electric field on bi-proton cooperativity dimer was investigated, accompanied a comparison with finite temperature string (FTS) enhanced sampling molecular transformation. results indicate that influences fields along x- y-axis directions transition state are more significant than those z-axis direction, x-axis direction most significant. induced + x- or y- tends to form products from in which hydroxyl group same side as ‒CH3 ‒CF3 group. There some good linear relationships bond length changes, atoms molecules (AIM) surface electrostatic potential statistical changes state, barrier free energy strengths. spatial order parameters (φ, ψ) can be quickly converged through umbrella parameter averaging, thereby obtaining mean force (PMF) Under bioelectricity, activation energies double much greater PMF barriers its transformation, indicating stimulation majority undergo rather migration. bioelectricity greatly affects migration, while it has little molecules. This study important theoretical significance scientific value further investigations processes sports human science. Methods effects pathway, barrier, rate constant were studied using M06-2X/6-311 G**, M06-2X/aug-cc-pVTZ CCSD(T)/6-311 G(2d,p) methods Gaussian 09 packages. A chaotic FTS model constructed, pyruvate CHARMM22 NAMD software packages, PLUMED program.

Language: Английский

Citations

0
Accelerated peptide bond formation at air–water interfaces DOI Creative Commons
Deming Xia, Fanlong Zeng, Wanting Chen

et al.

Proceedings of the National Academy of Sciences, Journal Year: 2025, Volume and Issue: 122(12)

Published: March 21, 2025

Peptides and proteins, essential components of living organisms, are composed amino acids linked by peptide bonds. However, the mechanism bond formation during prebiotic era remains unclear. In this study, advanced Born–Oppenheimer molecular dynamics (BOMD) simulations were used to investigate mechanisms kinetics at air–water interfaces using diglycine, simplest dipeptide, as a model molecule. The results show that bonds can be rapidly formed via unique isomerization-then-OH − -elimination pathway. mechanism, diglycine initially isomerizes into its acidic form interface, followed reaction releases an OH anion rather than previously hypothesized H 2 O. free-energy barriers for interfacial pathway with assistance electric field much lower those in gas phase >25 kcal/mol. Further calculations suggest extended some larger peptides, such tetraglycine. This offers insights origin life could inform development methods synthesis.

Language: Английский

Citations

0
A compartmentalized model of multiphase chemical kinetics DOI

Alexander Prophet,

Kevin R. Wilson

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(19)

Published: May 20, 2025

There are significant challenges in predicting multiphase chemical kinetics due to the complex coupling of reaction and mass transport across a phase boundary (i.e., interface). Here, we describe framework for that embeds elementary kinetic steps reaction, solvation, diffusion into coarse grain spatial description two phases. The model is constructed bridge short-timescale interfacial dynamics observed molecular simulations with longer timescales experiments. A simple set governing differential equations derived, which, when solved numerically or analytically, yield accurate predictions microdroplets. Although formulated gas–liquid reactions, underlying conceptual general can be applied transformations other two-phase systems (solid–liquid, liquid–liquid, etc.).

Language: Английский

Citations

0
Microdroplet Surface Drives and Accelerates Proton-Controlled, Size-Dependent Nitrate Photolysis DOI
Xiaowu Zhang, Qishen Huang, Yuxin Liu

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: June 1, 2025

Particulate nitrate photolysis regenerates reactive oxidized nitrogen species (HONO and NOx) in the atmosphere, influencing tropospheric ozone, atmospheric oxidation capacity, particulate matter formation. However, reported rates vary by orders of magnitude, roles protons air-water interface accelerating deliquesced aerosols (i.e., microdroplets) remain unclear. Using confocal Raman spectroscopy aerosol optical tweezer, we measured rate coefficients (j) microdroplets, ranging from 5.28 × 10-8 to 9.07 10-6 s-1, depending on pH (3.2-7.4) radius (3.7 μm 6.0 mm). j remained pH-independent under proton-sufficient conditions (pH < 6.5) but decreased with increasing proton-deficient > 6.5), resolving discrepancies previous studies. Moreover, identified a tipping-point (r* = 706 μm), below which scales inversely droplet above plateaus at aqueous bulk value (6.73 ± 2.12 s-1). These findings demonstrate that occurs predominantly microdroplets. With radii typically these tipping points (pH* 6.5, r* surface-driven size-dependent likely explains variations rates.

Language: Английский

Citations

0