We use molecular dynamics simulations to study osmotically driven transport of water molecules through hexagonally packed carbon nanotube membranes. Our simulation setup comprises two such semipermeable membranes separating compartments pure and salt solution. The osmotic force drives flow from the pure-water salt-solution compartment. Monitoring at resolution reveals several distinct features nanoscale flows. In particular, thermal fluctuations become significant nanoscopic length scales,...

Proteins can be denatured by pressures of a few hundred MPa. This finding apparently contradicts the most widely used model protein stability, where formation hydrophobic core drives folding. The pressure denaturation puzzle is resolved focusing on pressure-dependent transfer water into interior, in contrast to nonpolar residues water, approach commonly taken models unfolding. Pressure proteins then explained destabilization aggregates using an information theory interactions....

A molecular model of poorly understood hydrophobic effects is heuristically developed using the methods information theory. Because primitive can be tied to probability observing a molecular-sized cavity in solvent, distribution number solvent centers volume modeled on basis two moments available from density and radial oxygen atoms liquid water. The then yields that no are found volume. This shown account quantitatively for central phenomena formation association inert gas solutes....

Hydrophobicity is often characterized macroscopically by the droplet contact angle. Molecular signatures of hydrophobicity have, however, remained elusive. Successful theories predict a drying transition leading to vapor-like region near large hard-sphere solutes and interfaces. Adding attractions wets interface with local density increasing attractions. Here we present extensive molecular simulation studies hydration realistic surfaces wide range chemistries from hydrophobic (-CF(3),...

We quantify the strength of interfacial thermal coupling at water-solid interfaces over a broad range surface chemistries from hydrophobic to hydrophilic using molecular simulations. show that Kapitza conductance is proportional work adhesion-a wetting property interface-enabling use transport measurements as probes environment and bonding an interface. Excellent agreement with experiments on similar systems [Z. B. Ge, Phys. Rev. Lett. 96, 186101 (2006)10.1103/PhysRevLett.96.186101]...

Water near hydrophobic surfaces is like that at a liquid-vapor interface, where fluctuations in water density are substantially enhanced compared to bulk water. Here we use molecular simulations with specialized sampling techniques show similarly enhanced, even of complex biomolecules, situating them the edge dewetting transition. Consequently, these sensitive subtle changes surface conformation, topology, and chemistry, any which can tip balance towards or away from wet state, thus...

A theoretical approach is developed to quantify hydrophobic hydration and interactions on a molecular scale, with the goal of gaining insight into origins effects. The model based fundamental relation between probability for cavity formation in bulk water resulting from molecular-scale density fluctuations, free energy simplest solute, hard particle. This estimated using an information theory (IT) approach, incorporating experimentally available properties -- radial distribution function. IT...

Small and large hydrophobic solutes exhibit remarkably different hydration thermodynamics. are accommodated in water with minor perturbations to structure, their is captured accurately by theories that describe density fluctuations pure water. In contrast, of accompanied dewetting surfaces requires a macroscopic thermodynamic description. A unified theoretical description these lengthscale dependencies was presented Lum, Chandler, Weeks [(1999) J. Phys. Chem. B 103, 4570–4577]. Here, we use...

An information theory model is used to construct a molecular explanation why hydrophobic solvation entropies measured in calorimetry of protein unfolding converge at common temperature. The entropy convergence follows from the weak temperature dependence occupancy fluctuations for molecular-scale volumes water. macroscopic expression contrasting entropic behavior between water and organic solvents relative insensitivity isothermal compressibility. provides quantitative description small...

Approaches to quantify wetting at the macroscale do not translate nanoscale, highlighting need for new methods characterizing hydrophobicity small scale. We use extensive molecular simulations study hydration of homo and heterogeneous self-assembled monolayers (SAMs) protein surfaces. For homogeneous SAMs, pressure-dependent analysis shows that water displays higher compressibility enhanced density fluctuations near hydrophobic surfaces, which are gradually quenched with increasing...

We probe the effects of solute length scale, attractions, and hydrostatic pressure on hydrophobic hydration shells using extensive molecular simulations. The shell compressibility water fluctuations both display a nonmonotonic dependence size, with minimum near solutes enhanced for larger ones. These results calculations proteins suggest that unfolded are more compressible than folded ones contributing to denaturation. More importantly, nonmonotonicity implies curvature-dependent sensitivity...

Interfaces are a most common motif in complex systems. To understand how the presence of interfaces affects hydrophobic phenomena, we use molecular simulations and theory to study hydration solutes at interfaces. The range size from subnanometer few nanometers. self-assembled monolayers with chemistries, hydrophilic hydrophobic. We show that driving force for assembly vicinity surface is weaker than bulk water decreases increasing temperature, contrast bulk. explain these distinct features...

Liquid water can become metastable with respect to its vapor in hydrophobic confinement. The resulting dewetting transitions are often impeded by large kinetic barriers. According macroscopic theory, such barriers arise from the free energy required nucleate a critical tube that spans region between two surfaces - tubes smaller radii collapse, whereas larger ones grow dry entire confined region. Using extensive molecular simulations of nanoscopic surfaces, conjunction advanced sampling...

Significance Numerous biological self-assembly processes, from protein folding to molecular recognition, are driven by hydrophobic interactions, yet characterizing hydrophobicity at the nanoscale has remained a major challenge, because it requires understanding of strength protein–water interactions and ease with which they can be disrupted. Water near responds its chemistry topography in manner that is collective complex cannot captured commonly used surface area models or hydropathy...

We present results on the thermodynamic and structural aspects of hydration hydrophobic solutes in three tetramethylammonium [N(CH3)4+] salt solutions at various concentrations obtained from molecular dynamics simulations. Monovalent counterions different sizesF-, Cl-, a relatively large model ion BI-are chosen order to cover range kosmotropic chaotropic behaviors. Chemical potentials hard-sphere using test particle insertions display both salting-in salting-out effects depending type salt....

The packing and orientation of water molecules in the vicinity solutes strongly influence solute hydration thermodynamics aqueous solutions. Here we study charge density dependent a broad range spherical monovalent ionic (with diameters from approximately 0.4 nm to 1.7 nm) through molecular dynamics simulations simple point model water. Consistent with previous experimental theoretical studies, observe distinct asymmetry structure ions. In particular, free energy negative ions is more...

We report results on the pressure effects hydrophobic interactions obtained from molecular dynamics simulations of aqueous solutions methanes in water. A wide range pressures that is relevant to denaturation proteins investigated. The characteristic features water-mediated between solutes are found be pressure-dependent. In particular, with increasing we find (1) solvent-separated configurations solute-solute potential mean force (PMF) stabilized respect contact configurations; (2)...

Salting-out of hydrophobic solutes in aqueous salt solutions and their relevance to effects on biophysical phenomena are now well appreciated. Although transfer have been studied, our knowledge, no quantitative molecular simulation study salt-induced strengthening interactions has yet reported. Here we present characterization at the nanoscopic length scales through dynamics simulations. Specifically, quantify effect NaCl potential mean force between (methanes) conformational equilibria a...

We present results from extensive molecular dynamics simulations of collapse transitions hydrophobic polymers in explicit water focused on understanding effects lengthscale the surface and attractive interactions folding. Hydrophobic display parabolic, protein-like, temperature-dependent free energy unfolding. Folded states small are marginally stable at 300 K, can be unfolded by heating or cooling. Increasing decreasing polymer-water attractions stabilizes folded significantly, former...