Regulating surface terminals and interlayer structure of TiCT for superior NH sensing.

MXene materials have exhibited potential in electrochemistry, particularly in gas sensing, due to their excellent conductivity, large specific surface area of layered materials, and unique functional groups. However, the gas sensing performance of intrinsic 2D MXene materials is often limited by their fluorine-containing terminals and interfacial structure. In this study, based on intrinsic TiCT, we employed alkali treatment and annealing to prepare oxygen-rich TiC(OH)/TiCO with expanded interlayer spacing, achieving enhanced gas sensing performance for NH.

Interlink between Abnormal Water Imbibition in Hydrophilic and Rapid Flow in Hydrophobic Nanochannels.

Nanoscale extension and refinement of the Lucas-Washburn model is presented with a detailed analysis of recent experimental data and extensive molecular dynamics simulations to investigate rapid water flow and water imbibition within nanocapillaries. Through a comparative analysis of capillary rise in hydrophilic nanochannels, an unexpected reversal of the anticipated trend, with an abnormal peak, of imbibition length below the size of 3 nm was discovered in hydrophilic nanochannels, surprisingly sharing the same physical origin as the well-known peak observed in flow rate within hydrophobic nanochannels. The extended imbibition model is applicable across diverse spatiotemporal scales and validated against simulation results and existing experimental data for both hydrophilic and hydrophobic nanochannels.

Predictive Value of a Novel Baseline Diffusion-Weighted Imaging Posterior Circulation Score in Endovascular Treatment of Patients with Acute Vertebrobasilar Occlusion.

Rationale And Objectives: To investigate the predictive value of a novel posterior circulation score (novel-PC score) based on baseline posterior circulation diffusion-weighted imaging (DWI) for functional independence after endovascular treatment (EVT) in patients with acute vertebral-basilar artery occlusion (VBAO).

Materials And Methods: The baseline DWI brain stem score (BSS), posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS), and the novel-PC score were evaluated separately. A modified Rankin scale (mRS) ≤2 at 90 days was defined as a prognostic indicator of functional independence.

Magnetic resonance imaging indicators for neurological outcome after surgery in patients with intramedullary spinal ependymomas.

This is a retrospective study. The aim of this study was to determine the indicators of neurological outcome after surgery in patients with intramedullary spinal ependymomas by using magnetic resonance imaging (MRI).A total of 106 consecutive patients (mean age: 42.

A hydrogen bond-modulated soft nanoscale water channel for ion transport through liquid-liquid interfaces.

Ion transport through interfaces is of ubiquitous importance in many fields such as electrochemistry, emulsion stabilization, phase transfer catalysis, liquid-liquid extraction and enhanced oil recovery. However, the knowledge of interfacial structures that significantly affect ion transport through liquid-liquid interfaces is still lacking due to the difficulty of observing nanoscale interfaces. We studied here the evolution of interfacial structures during ion transport through the decane-water interface under different ionic concentrations and external forces using molecular dynamics simulations.

Surfactant desorption and scission free energies for cylindrical and spherical micelles from umbrella-sampling molecular dynamics simulations.

Hypothesis: The free energies associated with adsorption/desorption of individual surfactants from micelles and the fusion/scission of long micelles can be used to estimate the rate constants for micellar kinetics as functions of surfactant and salt concentration.

Experiments: We compute the escape free energies △G of surfactant from micelles and the scission free energies △G of long micelles from coarse-grained molecular dynamics simulations coupled with umbrella sampling, for micelles of both sodium dodecylsulfate (SDS) in sodium chloride (NaCl) and cetyltrimethylammonium chloride (CTAC) in sodium salicylate (NaSal).

Findings: For spherical micelles, △G values have maxima at certain aggregation numbers, and at salt-to-surfactant molar concentration ratios R near unity, consistent with experiments.

Extending the Classical Continuum Theory to Describe Water Flow through Two-Dimensional Nanopores.

Water flow through two-dimensional nanopores has attracted significant attention owing to the promising water purification technology based on atomically thick membranes. However, the theoretical description of water flow in nanopores based on the classical continuum theory is very challenging owing to the pronounced entrance/exit effects. Here, we extend the classical Hagen-Poiseuille equation for describing the relationship between flow rate and pressure loss in laminar tube flow to two-dimensional nanopores.

Theoretical description of molecular permeation via surface diffusion through graphene nanopores.

We establish a theoretical model to describe the surface molecular permeation through two-dimensional graphene nanopores based on the surface diffusion equation and Fick's law. The model is established by considering molecular adsorption and desorption from the surface adsorption layer and the molecular diffusion and concentration gradient on the graphene surface. By comparing with the surface flux obtained from molecular dynamics simulations, it is shown that the model can predict well the overall permeation flux especially for strongly adsorbed molecules (i.

Wall friction should be decoupled from fluid viscosity for the prediction of nanoscale flow.

The accurate determination of fluid viscosity based on the microscopic information of molecules is very crucial for the prediction of nanoscale flow. Despite the challenge of this problem, researchers have done a lot of meaningful work and developed several distinctive methods. However, one of the common approaches to calculate the fluid viscosity is using the Green-Kubo formula by considering all the fluid molecules in nanospace, inevitably causing the involvement of the frictional interaction between fluid and the wall into the fluid viscosity.

Nanoconfined Fluids: What Can We Expect from Them?

Nanoconfined fluids (NCFs), which are confined in nanospaces, exhibit distinctive nanoscale effects, including surface effects, small-size effects, quantum effects, and others. The continuous medium hypothesis in fluid mechanics is not valid in this context because of the comparable characteristic length of spaces and molecular mean free path, and accordingly, the classical continuum theories developed for the bulk fluids usually cannot describe the mass and energy transport of NCFs. In this Perspective, we summarize the nanoscale effects on the thermodynamics, mass transport, flow dynamics, heat transfer, phase change, and energy transport of NCFs and highlight the related representative works.

Effects of Molecular Chain Length on the Contact Line Movement in Water/-Alkane/Solid Systems.

The movement of the contact line in liquid-liquid-solid systems is a major phenomenon in natural and industrial processes. In particular, -alkanes are widely occurring in the oil, soil pollution, and chemical industries, yet there is little knowledge on the effects of molecular chain length on the contact line movement. Here, we studied the effects of molecular chain length on the contact line movement in water/-alkane/solid systems with different surface wettabilities.

Evidence for water ridges at oil-water interfaces: implications for ion transport.

Understanding ion transport across interfaces is of fundamental importance in many processes such as liquid-liquid extraction, phase transfer catalysis, enhanced oil recovery and emulsion stabilisation. However, the factors that control ion transport across interfaces are poorly known due to a lack of knowledge of structural changes at interfaces. We studied here the effects of ionic concentration and external force on the transport of ions across the decane-water interface using classical molecular dynamics simulations.

Selective Molecular Sieving through a Large Graphene Nanopore with Surface Charges.

The precise control of the pore sizes at an atomic level has proved to be the biggest challenge of all for nanoporous graphene membranes for gas separation. Here, we propose a simple method to realize the selective molecular sieving through originally nonselective graphene nanopores by adding charges on the graphene surfaces. Molecular dynamic simulations show that the CO/N selectivity of the graphene nanopore with a diameter of 0.

Release of a trapped droplet in a single micro pore throat.

The critical condition (i.e., critical capillary number Ca) for the release of trapped droplets is of practical importance in enhanced oil recovery and droplet microfluidics.

Moving mechanisms of the three-phase contact line in a water-decane-silica system.

The movement of the three-phase contact line with chain molecules in the liquid phase displays more complex mechanisms compared to those in the usual liquid-liquid-solid systems and even to the gas-liquid-solid systems controlled by the traditional single-molecule adsorption-desorption mechanisms. By introducing decane molecules with chain structures, we demonstrate from molecular dynamics insights that the moving mechanism of the contact line in a water-decane-silica system is totally different from traditional mechanisms. Three different wettability-related moving mechanisms including "Roll up", "Piston" and "Shear" are revealed corresponding to the hydrophilic, intermediate and hydrophobic three-phase wettability, respectively.

Experiment and Numerical Simulation on Gas-Liquid Annular Flow through a Cone Sensor.

The cone meter has been paid increasing attention in wet gas measurement, due to its distinct advantages. However, the cone sensor, which is an essential primary element of the cone meter, plays a role in the measurement of wet gas flow that is important, but not fully understood. In this article, we investigate the gas-liquid annular flow through a cone sensor by experiment and numerical simulation.

Nanoparticle-induced ion-sensitive reduction in decane-water interfacial tension.

The synergistic effect of ions and nanoparticles on the interfacial tension is of great significance for extensive applications in interface-related industrial processes. However, its mechanisms are still unclear owing to a lack of understanding on the interaction between nanoparticles/ions at the interface. Here, we employ the molecular dynamics method to explore the synergistic effect of ions and nanoparticles on reducing the decane-water interfacial tension and reveal the dominant role of the three-phase contact angle and the interaction between nanoparticles.

Oil Contact Angles in a Water-Decane-Silicon Dioxide System: Effects of Surface Charge.

Oil wettability in the water-oil-rock systems is very sensitive to the evolution of surface charges on the rock surfaces induced by the adsorption of ions and other chemical agents in water flooding. Through a set of large-scale molecular dynamics simulations, we reveal the effects of surface charge on the oil contact angles in an ideal water-decane-silicon dioxide system. The results show that the contact angles of oil nano-droplets have a great dependence on the surface charges.

Molecular Dynamics Study on the Effect of Surface Hydroxyl Groups on Three-Phase Wettability in Oil-Water-Graphite Systems.

In this paper, a hydroxylated graphite surface is generated as a hydrophilic oleophobic material for the application of oil-water separation, and the effects of hydroxyl density on the three-phase wettability are studied in oil-water-graphite systems. We analyze the adsorption of water molecules on the hydroxylated surfaces and obtain the relationship between water-oil-solid interfacial properties and the hydroxyl density, which results from the synthetic effects of the orientation of molecules and hydrogen bonds. With the increase of hydroxyl density, the water-solid contact angle first decreases rapidly, and then remains constant.

Ionic hydration-induced evolution of decane-water interfacial tension.

Building a connection between the variations in interfacial tension and the microstructure of the oil-water interface is still very challenging. Here, we employ a molecular dynamics method to study the effect of monovalent ions on the decane-water interfacial tension and reveal the relationship between ionic hydration and the variation of interfacial tension. Our results indicate that interfacial tension presents a non-monotonic dependence on the ionic concentrations owing to the distinctive adsorption characteristics of ions.

Molecular sieving through a graphene nanopore: non-equilibrium molecular dynamics simulation.

Two-dimensional graphene nanopores have shown great promise as ultra-permeable molecular sieves based on their size-sieving effects. We design a nitrogen/hydrogen modified graphene nanopore and conduct a transient non-equilibrium molecular dynamics simulation on its molecular sieving effects. The distinct time-varying molecular crossing numbers show that this special nanopore can efficiently sieve CO and HS molecules from CH molecules with high selectivity.

Gas diffusion on graphene surfaces.

Graphene provides a possibility where gas adsorption energy is comparable with molecular collision energy for physically adsorbed gases, resulting in the incompetence of the traditional hopping model to describe graphene-related surface diffusion phenomena. By calculating surface diffusion coefficients based on the Einstein equation, we exactly demonstrate that the gas diffusion on a graphene surface is a two-dimensional gas behavior mainly controlled by the collisions between adsorbed molecules. The surface diffusion on the graphene film just follows the bulk diffusion qualitatively, namely the diffusion coefficients decrease with increasing gas pressure.

Deformation of a single mouse oocyte in a constricted microfluidic channel.

Single oocyte manipulation in microfluidic channels via precisely controlled flow is critical in microfluidic-based fertilization. Such systems can potentially minimize the number of transfer steps among containers for rinsing as often performed during conventional fertilization and can standardize protocols by minimizing manual handling steps. To study shape deformation of oocytes under shear flow and its subsequent impact on their spindle structure is essential for designing microfluidics for fertilization.

Three-Dimensional Numerical Simulation of Vesicle Dynamics in Microscale Shear Flows.

Flow behaviors of blood strongly depend on dynamics of red blood cells (RBCs) under flow. Due to the simplicity, vesicles have been extensively used as a model system to investigate RBC dynamics. Despite its significance in microfluidics, the effect of confinement (i.

Inhibition effect of a non-permeating component on gas permeability of nanoporous graphene membranes.

We identify the inhibition effect of a non-permeating gas component on gases permeating through the nanoporous graphene membranes and reveal its mechanisms from molecular dynamics insights. The membrane separation process involves the gas mixtures of CH4/H2 and CH4/N2 with different partial pressures of the non-permeating gas component (CH4). The results show that the permeance of the H2 and N2 molecules decreases sharply in the presence of the CH4 molecules.