Processes of thematic analysis [24,25].

Processes of thematic analysis [24,25].</p

Near-peer tutor interview protocol.

(DOCX)</p

Student perceptions of staff tutors’ vs. near-peer tutors’ facilitation and skills.

Student perceptions of staff tutors’ vs. near-peer tutors’ facilitation and skills.</p

Correlations of the language-related factors when the contexts were presented in the foreign language.

Correlations of the language-related factors when the contexts were presented in the foreign language.</p

The percentages (%) of cooperation for the four games in each language group.

a: Percentage of cooperation in Prisoner’s Dilemmas; b: Percentage of cooperation in Volunteer’s Dilemmas.</p

Games used in the study.

(DOCX)</p

Electronic Structure of Twisted Bilayers of Graphene/MoS₂ and MoS₂/MoS₂

Vertically stacked two-dimensional multilayer structures have become a promising prototype for functionalized nanodevices due to their wide range of tunable properties. In this paper we performed first-principles calculations to study the electronic structure of nontwisted and twisted bilayers of hybrid graphene/MoS₂ (Gr/MoS₂) and MoS₂/MoS₂. Both twisted bilayers of Gr/MoS₂ and MoS₂/MoS₂ show significant differences in band structures from the nontwisted ones with the appearance of the crossover between direct and indirect band gap and gap variation. More interestingly, the band structures of twisted Gr/MoS₂ with different rotation angles are very different from each other, while those of MoS₂/MoS₂ are very similar. The variation of band structure with rotation angle in Gr/MoS₂ is, indeed, originated from the misorientation-induced lattice strain and the sensitive band-strain dependence of MoS₂

Polyelectrolyte Gels: Swelling and Deswelling upon Nonlinear Deformations

Polyelectrolyte gels, made by crosslinking of ion-containing polymers, showcase extraordinary swelling capabilities, with their volumes expanding up to 100 times in salt-free solutions. This swelling behavior of polyelectrolyte gels is attributed to the delicate balance between the gels’ elasticity and the osmotic pressure produced by counterions and salt ions localized within the gel volume due to the Donnan equilibrium. We use a combination of the nonlinear version of Flory–Rehner theory and coarse-grained molecular dynamics simulations to explore the swelling and deformation of polyelectrolyte gels undergoing large biaxial deformations in contact with a salt solution. The analysis of the gel deformation points out that the swelling ratio of the polyelectrolyte gels Qeq describing the volume change upon swelling is a nonmonotonic function of the gel deformation ratio α characterizing changes in a gel shape under biaxial deformation with respect to a free-standing swollen state. The swelling ratio first increases with increasing α and then starts to decrease. This intriguing behavior is due to the optimization of osmotic pressure and conformational entropy of charged strands in the nonlinear deformation regime. Furthermore, we observe that the location of the maximum swelling ratio shifts toward large gel deformations with increasing salt concentration and decreasing fraction of the charged groups on network strands. This behavior is a direct result of the reduced influence of the ions’ osmotic pressure on strand prestretching in the free-standing gels

Hydration of Spherical PEO-Grafted Gold Nanoparticles: Curvature and Grafting Density Effect

Nanoparticle modification by water-soluble polymers, such as poly­(ethylene oxide) (PEO), relies on polymer hydration to ensure nanoparticle solubility, dispersion, and protection from undesirable interactions. The state of polymer hydration in grafted polymer layers is not easily assessible experimentally but can be ascertained from computer simulations. Using atomistic molecular dynamics simulations, we studied the equilibrium and dynamic properties of spherical PEO brushes grafted to gold nanoparticles of different radii (1, 2, and 3 nm). We obtained the volume fraction of PEO (Φ­(<i>r</i>)) as a function of radial distance <i>r</i> (counted from micelle core center) which is found to follow the Daoud–Cotton model, Φ­(<i>r</i>) ∼ <i>r</i>^–4/3, except for low grafting density when PEO adsorption onto the gold surface is observed, in agreement with experimental observations. With an increase of grafting density σ (up to 4.17 nm^–2), the PEO chains become more stretched and oriented along the radial direction leading to an increase of the polymer brush height and a decrease in PEO hydration. We analyzed hydrogen bonding between PEO and water and found that similarly to a planar PEO brush, it depends only on the local polymer (water) content and can be predicted based on PEO solution behavior. While at low grafting densities and small nanoparticle size PEO chains are fully hydrated (except for the immediate gold surface vicinity), with an increase of grafting density and/or decrease of nanoparticle radius of curvature the dehydrated or low hydration zone substantially expands up to a few nanometers, in agreement with recent experimental data. Furthermore, we found that hydrogen-bonded water remains rather stable in the inner region of the spherical brush, implying slow water exchange with the surrounding solution which in turn may affect chain dynamics and the susceptibility of the PEO brush to protein adsorption

Defect Healing of Chemical Vapor Deposition Graphene Growth by Metal Substrate Step

The evolution of carbon structures and the kinetics of graphene nucleation on nickel step surfaces are investigated by classical molecular dynamics simulations and density functional theory calculations. It is found that the evolution mechanism of C structures on the step surface is the same as that on the flat terrace when no substrate Ni atom is pulled out of the surface. But the defects involved with the pulled-out Ni atoms can be efficiently healed with the assistance of the step atoms on the step surface, while they are rather difficult to be healed on the terrace. Compared with the terrace, the step significantly lowers the healing barrier of the defect involved with the pulled-out Ni atom and therefore results in a very fast healing of the defect. These results demonstrate that the presence of the step is beneficial to synthesize better graphene for chemical vapor deposition growth on Ni substrate