Molecular Dynamics Analysis of Surface-Modified Carbon Nanoparticle Reinforced Epoxy Resin.

Surface-modified carbon nanoparticles (CNPs) as reinforcement materials have attracted significant attention due to their potential for substantially enhancing mechanical properties. However, the development and application of CNP-enhanced polymeric materials are constrained by an incomplete understanding of their reinforcement mechanisms, impeding sustainable progress. In this study, we employed molecular dynamics simulations to investigate the mechanical properties of surface-modified CNP-reinforced epoxy resin composites at the microscopic scale.

Chiral inversion induced by aromatic interactions in short peptide assembly.

Although hydrophobic interactions provide the main driving force for initial peptide aggregation, their role in regulating suprastructure handedness of higher-order architectures remains largely unknown. We here interrogate the effects of hydrophobic amino acids on handedness at various assembly stages of peptide amphiphiles. Our studies reveal that relative to aliphatic side chains, aromatic side chains set the twisting directions of single β-strands due to their strong steric repulsion to the backbone, and upon packing into multi-stranded β-sheets, the side-chain aromatic interactions between strands form the aromatic ladders with a directional preference.

The mechanism of fluidity improvement of cement slurry by graphene oxide: a study on nanofriction.

Graphene oxide (GO) as a nano-reinforcing material has received extensive attention in cement composite materials. This paper employed molecular dynamics to simulate the friction process of calcium silicate hydrate (CSH) particles in the presence of double-sided and single-sided GCOOH (graphene oxide with a -COOH functional group, covering 10% of the surface). The investigation uncovered the lubricating effects of bifacial and unifacial GCOOH on the CSH interface.

What happens when left meets right under equimolar and non-equimolar co-assembly of short peptide stereoisomers?

The co-assembly of different peptide chains usually leads to the formation of intricate architectures and sophisticated functions in biological systems. Although the co-assembly of stereoisomeric peptides represents a facile and flexible strategy for the synthesis of peptide-based nanomaterials with novel structures and potentially interesting properties, there is a lack of a general knowledge on how different isomers pack during assembly. Through the combined use of simulations and experimental observations, we report that heterochiral pairing is preferred to homochiral pairing at the molecular scale but self-sorting dictates beyond the molecular level for the mixtures of the short stereoisomeric β-sheet peptides IK (Ile-Ile-Ile-Lys).

Unraveling the molecular freezing behavior of water on a calcium silicate hydrate matrix.

The hydration process of cement-based materials primarily results in the formation of calcium silicate hydrate (CSH), which is crucial in deciding how long concrete will last. This study utilizes molecular dynamics simulation technology to explore the freezing behavior of pure water solutions within various calcium silicate hydrate (CSH) matrices. The investigated matrices encompass four different Ca/Si ratios.

Atomic Insights into the Relationship between Molecular Structure and Dispersion Performance of Phenyl Polymer on Graphene Oxide.

The adsorption of organic polymers onto the surface of graphene oxide is known to improve its dispersibility in cement-based materials. However, the mechanism of this improvement at the atomic level is not yet fully understood. In this study, we employ a combination of DFT static calculation and umbrella sampling to explore the reactivity of polymers and investigate the effects of varying amounts of phenyl groups on their adsorption capacity on the surface of graphene oxide.

Surface Engineering of Migratory Corrosion Inhibitors: Controlling the Wettability of Calcium Silicate Hydrate in the Nanoscale.

Migratory corrosion inhibitors (MCIs) are regarded as effective additives to prevent harmful ion transmission and improve concrete durability, but their behavior in the porosity of concrete is still unclarified. This paper proposes a unique perspective to evaluate the effects of surfactant-like MCIs in calcium silicate hydrate (C-S-H) nanoporosity through molecular and electronic structural information. Advanced enhanced sampling methods and perturbation theory methods were applied to evaluate the role of different MCIs.

Human iPSC-derived microglia sense and dampen hyperexcitability of cortical neurons carrying the epilepsy-associated SCN2A-L1342P mutation.

Neuronal hyperexcitability is a hallmark of seizures. It has been recently shown in rodent models of seizures that microglia, the brain's resident immune cells, can respond to and modulate neuronal excitability. However, how human microglia interacts with human neurons to regulate hyperexcitability mediated by epilepsy-causing genetic mutation found in human patients remains unknown.

The inhibitory effect of excess calcium ions on the polymerization process of calcium aluminate silicate hydrate (CASH) gel.

Calcium ion, as an essential component in CASH, affects the aggregation and formation process of CASH, thereby influencing its microstructure and mechanical properties. However, the mechanism by which calcium ions affect the polymerization process of CASH is not yet fully understood. In this study, the effects of calcium ions on the polymerization process, coagulation state, and microstructure of CASH are investigated molecular dynamics simulation.

Controlling 1D Nanostructures and Handedness by Polar Residue Chirality of Amphiphilic Peptides.

Peptide assemblies are promising nanomaterials, with their properties and technological applications being highly hinged on their supramolecular architectures. Here, how changing the chirality of the terminal charged residues of an amphiphilic hexapeptide sequence Ac-I K -NH gives rise to distinct nanostructures and supramolecular handedness is reported. Microscopic imaging and neutron scattering measurements show thin nanofibrils, thick nanofibrils, and wide nanotubes self-assembled from four stereoisomers.

Treating solid tumors with TCR-based chimeric antigen receptor targeting extra domain B-containing fibronectin.

Background: The suppression of chimeric antigen receptor (CAR) T cells by the tumor microenvironment (TME) is a crucial obstacle in the T-cell-based treatment of solid tumors. Extra domain B (EDB)-fibronectin is an oncofetal antigen expressed on the endothelium layer of the neovasculature and cancer cells. Though recognized as a T cell therapy target, engineered CAR T cells thus far have failed to demonstrate satisfactory in vivo efficacy.

Acid Radical Tolerance of Silane Coatings on Calcium Silicate Hydrate Surfaces in Aggressive Environments: The Role of Nitrate/Sulfate Ratio.

Silane is known as an effective coating for enhancing the resistance of concrete to harmful acids and radicals that are usually produced by the metabolism of microorganisms. However, the mechanism of silane protection is still unclear due to its nanoscale attributes. Here, the protective behavior of silane on the calcium silicate hydrate (C-S-H) surface is examined under the attack environment of nitrate/sulfate ions using molecular dynamics simulations.

Atomistic Insights into the Deposition of Corrosion Products on the Surfaces of Steels and Passivation Films.

The deposition of corrosion products on the surface of the steel is a key step for understanding the generation of corrosion products. To clarify the molecular mechanism for corrosion product deposition, the reactive molecular dynamics were utilized to study the deposition process of ferric hydroxide (Fe(OH)) on iron and passivation film substrates. It is shown that the deposition phenomenon mainly occurs on the iron surface, while the surface of the passivation film cannot adsorb Fe(OH).

Molecular Insight into the Pozzolanic Reaction of Metakaolin and Calcium Hydroxide.

The reaction mechanism of the pozzolanic reaction of metakaolin (MK) from the atomic point of view has not yet been explored. To explain the process and mechanism of the pozzolanic reaction from the atomic point of view, molecular insight into the pozzolanic reaction of MK and calcium hydroxide (CH) was analyzed through the reaction molecular dynamics (MD) simulation. The results show that the pozzolanic reaction of MK and CH can be essentially regarded as the CH decomposition and penetration into MK.

Molecular Insights into the Reaction Process of Alkali-Activated Metakaolin by Sodium Hydroxide.

When metakaolin (MK) is alkalized with an alkaline activator, it depolymerizes under the action of the alkali. However, the process of MK alkalinization is still unrevealed. Here, we supplied a molecular insight into the process of MK alkalinization through reaction molecular dynamics (MD) simulation.

Understanding the wetting discrepancy in calcium alumino silicate hydrate induced by Al/Si ratio.

The application of supplementary cementitious materials (SCMs) in concrete can improve its durability in the marine environment. Calcium alumino silicate hydrate (CASH) is the main hydration product of SCMs; however, to date, the mechanism of the wetting discrepancy in CASH with different Al/Si ratios has not been revealed at the molecular scale. Herein, the molecular dynamics simulation method was used to study the wettability of water nanodroplets on the surface of CASH substrates with different Al/Si ratios, aiming to reveal the influence of CASH gel with different Al contents on the wettability of water molecules.

Unexpected Role of Achiral Glycine in Determining the Suprastructural Handedness of Peptide Nanofibrils.

Helical supramolecular architectures play important structural and functional roles in biological systems. Although their occurrence is widely perceived to correlate to fundamental chiral units including l-amino acids and d-sugars, the detailed relationship between molecular and supramolecular handedness is still unclear. At the same time, although achiral units are practically always in close proximity to chiral ones by covalent linkage along a polymeric chain, their effect on supramolecular handedness has received relatively less attention.

Concentration-induced wettability alteration of nanoscale NaCl solution droplets on the CSH surface.

Due to the hydrophilic nature of concrete, moisture and corrosive ions adsorbed on its surface pose a severe challenge to the durability of concrete structures; therefore, investigating the wettability of a concrete surface is an indispensable prerequisite for designing durable and sustainable concrete. This paper utilizes molecular dynamics to simulate the concentration-induced wettability alteration of nanoscale NaCl droplets on a CSH surface, and verifies the feasibility and rationality of predicting the contact angle of a droplet on the CSH surface based on the surface tension. Results suggest that the wetting ability of droplets on the CSH surface is weakened with the increase of the NaCl mass fraction.

Quantum Chemical Study of the Carbon Dioxide-Philicity of Surfactants: Effects of Tail Functionalization.

Carbon dioxide (CO)-philic surfactants have broad application prospects in organic synthesis, fracture-enhanced oil recovery, polymerization, extraction, and other fields and can be used to enhance the viscosity of supercritical CO (scCO). In this work, the relationship between the functional group of the surfactant tail and CO-philicity is studied from a new perspective using density functional theory. Three common functional group types (fluorinated, oxidative, and methyl groups) were investigated.

Microscopic insight into nanodiamond polymer composites: reinforcement, structural, and interaction properties.

Nanodiamond (ND)-reinforced polymer composites attract a great deal of attention; however, insufficient understanding of their reinforced behavior is greatly limiting their further design and application. In this paper, a microscopic investigation of the stretched processes of aminated ND and resin composites is undertaken to elucidate the reinforcement mechanism of ND in the polymer matrix by employing molecular dynamics and semi-empirical quantum chemistry simulations. The stretching process and reinforcement behavior are observed on the nanoscale, and the nano-pinning effect of ND on the resin matrix is clarified.

Atomistic insights into cesium chloride solution transport through the ultra-confined calcium-silicate-hydrate channel.

The transport of water and ions in the gel pores of calcium silicate hydrate (C-S-H) determines the durability of cement material. In this study, molecular dynamics was employed to investigate the capillary imbibition process of CsCl solution in the C-S-H channel. The advanced frontier of CsCl solution flow inside the C-S-H capillary shows a concave meniscus shape, which reflects the hydrophilic properties of the C-S-H substrate.

Optimal aggregation number of reverse micelles in supercritical carbon dioxide: a theoretical perspective.

The aggregation number is one of the most fundamental and important structural parameters for the micelle or reverse micelle (RM) system. In this work, a simple, reliable method for the determination of the aggregation number of RMs in supercritical CO2 (scCO2) was presented through a molecular dynamics simulation. The process of pulling surfactants out of the RMs one by one was performed to calculate the aggregation number.

Composite Nanotube Ring Structures Formed by Two-Step Self-Assembly for Drug Loading/Release.

Nanotube rings are barely reported novel structures formed by the self-assembly of soft matter, as compared with nanotube structures and ring structures. The two-step self-assembly of amphiphilic copolymer AB and solvophobic copolymer CDC was studied. We found that nanotube rings can be formed from a certain mass ratio of copolymer CDC to copolymer AB and block D of certain rigidity.

Dissipative Particle Dynamics Simulation on Vesicles Self-Assembly Controlled by Terminal Groups.

Block copolymer vesicles have been widely used in the field of drug delivery, microreactors, and cell membrane mimetics. Introducing terminal groups to the block copolymer can control the structures of vesicles, which is important for improving the application of vesicles. In this paper, the effects of terminal groups on the structure of vesicles were studied by dissipative particle dynamics simulation.