The Effects of Ions and Surface Charge Density on Water Distribution in Silicon Nanochannel

2012 ◽  
Author(s):  
Yinghua Qiu ◽  
Qiyan Tan ◽  
Weichuan Guo ◽  
Yunfei Chen
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Water Distribution ◽  
Pure Water ◽  
Water System ◽  
Water Layer ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Nacl Solution

Water distributions are obtained in the silicon nanochannels filled with NaCl solution and pure water with molecular dynamics simulation, respectively. Taking into account the reality at the solid-liquid interface, the silicon atoms of channel walls in the model are allowed to vibrate at their own equilibrium positions. Results show that: The water distribution vertical to the channel wall changes notably due to the introduction of Na+ ions and Cl− ions. In pure water case, there are three water aggregation peaks within 0.4nm from surface, in contrast to two in NaCl solution case. Also, the locations and values of the corresponding peaks alter except the first one. However, the water distribution for NaCl solution beyond 0.5nm shares the same trend with that in pure water and the water molecules alignments in the first layer have almost the same trend in the two cases. Furthermore, in pure water system, the influence range of surface charge is 0.55nm and with surface charge density increasing, the first concentration peak changes into three ones within 0.4nm perpendicular to the surface and the water molecules in the first water layer align more orderly.

Molecular Dynamics Simulation of Water and Ion Profiles Near Charged (100) and (111) Silicon Surfaces

2008 ◽  
Author(s):  
Dongyan Xu ◽  
Deyu Li ◽  
Yongsheng Leng ◽  
Yunfei Chen
Keyword(s):  
Molecular Dynamics ◽  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Silicon Surface ◽  
Silicon Surfaces ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Wall Region ◽  
Surface Charges

Fundamental studies in nanofluidics have attracted significant attention in the past decade since the success of nanofluidic devices depends on a thorough understanding of the fluidic, ionic, and molecular behaviors in highly confined nano-environments. In this work, molecular dynamics simulations of the effect of surface charge densities on the ion and water distribution in the near wall region has been performed for both (100) and (111) silicon surfaces. We demonstrate that surface charges not only interact with mobile ions in the electrolyte, but also interact with water molecules due to their polarizability and hence influence the orientation of water molecules close to the charged surface. It is shown that as the surface charge density increases, water molecules within ∼ 5 Å from the (100) silicon surface can evolve from one layer into two layers and meanwhile, the orientation of water molecules is more aligned instead of randomly distributed. However, no extra water layer is observed near a (111) silicon surface even under a surface charge density of as high as −0.2034 C/m2. The above phenomenon may be related to the different surface atom densities of (100) and (111) silicon surfaces.

The Rheological Properties of Nanoscale Fluid

2009 ◽  
Author(s):  
JiaPeng Li ◽  
Yunfei Chen ◽  
Min Chen ◽  
Changzheng Xiang ◽  
Zan Wang
Keyword(s):  
Shear Rate ◽  
Charge Density ◽  
Surface Charge ◽  
Rheological Properties ◽  
Shear Viscosity ◽  
Surface Density ◽  
Surface Charge Density ◽  
Fluid Film ◽  
Dynamics Simulation ◽  
Fluid Viscosity

Nonequilibrium molecular dynamics simulation is used to simulate the rheological properties of the nanoscale fluid. A physical model of the “bulk – nanochannel – bulk” that resembles a fluid film confined between two solid walls was simulated. The simulation is performed at variable wall speeds, nanochannel heights and surface charge densities. Simulation results indicate that the effective densities of water decrease with the size as the channel size below 1 nm when the surface charge density is −0.30 C/m2. And it is also demonstrated that the water density increases with the surface charge density. The fluid viscosity keeps at around 1.78 cp when the thickness of the film more than 1.5 nm, the −0.30 C/m2 surface charge density and the 5×1010 S−1 shear rate, which is quite close to the bulk value. The fluid viscosity keeps at around 1.69 cp when the surface charge density is −0.15 C/m2, and 1.28 cp when the surface density is 0 C/m2. In addition, the shear rate shows strong influence on the nanoscale fluid film. Compare to the surface density −0.30 C/m2 and −0.15 C/m2, the fluid density of the 0 C/m2 has different properties when the shear rate varied from 0.1×011 S−1 to 1.0×1011 S−1. Especially, when the nanochannel height is 0.8 nm, the shear viscosity begins to increase and reach the peak when the shear rate is 0.2×1011 S−1, then the shear viscosity decreases with the shear rate increase. The shear viscosity of the height of 2.5 nm and 3.0 nm show a constant value which is quite close to the bulk value, and shear viscosity of 1.5 nm height increases and reaches plateau when the shear rate exceeds 0.2×1011 S−1.

scholarly journals Mapping Surface Charge Distribution of Single-Cell via Charged Nanoparticle

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1519
Author(s):  
Leixin Ouyang ◽  
Rubia Shaik ◽  
Ruiting Xu ◽  
Ge Zhang ◽  
Jiang Zhe
Keyword(s):  
Cell Surface ◽  
Charge Density ◽  
Surface Charge ◽  
Charge Distribution ◽  
Surface Charge Density ◽  
Single Cells ◽  
Fluorescent Light ◽  
Fluorescent Nanoparticles ◽  
Cell Surface Charge ◽  
Surface Charge Distribution

Many bio-functions of cells can be regulated by their surface charge characteristics. Mapping surface charge density in a single cell’s surface is vital to advance the understanding of cell behaviors. This article demonstrates a method of cell surface charge mapping via electrostatic cell–nanoparticle (NP) interactions. Fluorescent nanoparticles (NPs) were used as the marker to investigate single cells’ surface charge distribution. The nanoparticles with opposite charges were electrostatically bonded to the cell surface; a stack of fluorescence distribution on a cell’s surface at a series of vertical distances was imaged and analyzed. By establishing a relationship between fluorescent light intensity and number of nanoparticles, cells’ surface charge distribution was quantified from the fluorescence distribution. Two types of cells, human umbilical vein endothelial cells (HUVECs) and HeLa cells, were tested. From the measured surface charge density of a group of single cells, the average zeta potentials of the two types of cells were obtained, which are in good agreement with the standard electrophoretic light scattering measurement. This method can be used for rapid surface charge mapping of single particles or cells, and can advance cell-surface-charge characterization applications in many biomedical fields.

Triboelectrification of nanocomposites using identical polymer matrixes with different concentrations of nanoparticle fillers

2021 ◽  
Author(s):  
Linards Lapčinskis ◽  
Artis Linarts ◽  
Kaspars Mālnieks ◽  
Hyunseung Kim ◽  
Kristaps Rubenis ◽  
...  
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Polymer Layers

In this study, we investigate triboelectrification in polymer-based nanocomposites using identical polymer matrixes containing different concentrations of nanoparticles (NPs). The triboelectric surface charge density on polymer layers increased as the...

scholarly journals Effect of Selected Anionic and Cationic Drugs Affecting the Central Nervous System on Electrical Properties of Phosphatidylcholine Liposomes: Experiment and Theory

2021 ◽  
Vol 22 (5) ◽  
pp. 2270
Author(s):  
Joanna Kotyńska ◽  
Monika Naumowicz
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Barbituric Acid ◽  
Membrane Surface ◽  
Adsorption Equilibria ◽  
Two Component ◽  
The Central Nervous System

Interactions between phospholipid membranes and selected drugs affecting the central nervous system (CNS) were investigated. Small, unilamellar liposomes were used as biomimetic cell membrane models. Microelectrophoretic experiments on two-component liposomes were performed using the electrophoretic light scattering technique (ELS). The effect of both positively (perphenazine, PF) and negatively (barbituric acid, BA) charged drugs on zwitterionic L-α-phosphatidylcholine (PC) membranes were analyzed. Experimental membrane surface charge density (d) data were determined as a function of pH. Quantitative descriptions of the adsorption equilibria formed due to the binding of solution ions to analyzed two-component membranes are presented. Binding constants of the solution ions with perphenazine and barbituric acid-modified membranes were determined. The results of our research show that both charged drugs change surface charge density values of phosphatidylcholine membranes. It can be concluded that perphenazine and barbituric acid are located near the membrane surface, interacting electrostatically with phosphatidylcholine polar heads.

Surface charging parameters of charged particles in symmetrical electrolyte solutions

2020 ◽  
Vol 22 (35) ◽  
pp. 20123-20142
Author(s):  
Hadi Saboorian-Jooybari ◽  
Zhangxin Chen
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Electrolyte Solution ◽  
Surface Charge Density ◽  
Potential Surface ◽  
Research Work ◽  
Charged Particles ◽  
Electrolyte Solutions ◽  
Surface Charging ◽  
Curvature Dependence

This research work is directed at development of accurate physics-based formulas for quantification of curvature-dependence of surface potential, surface charge density, and total surface charge for cylindrical and spherical charged particles immersed in a symmetrical electrolyte solution.

A multi-dielectric-layered triboelectric nanogenerator as energized by corona discharge

Nanoscale ◽  
2017 ◽  
Vol 9 (27) ◽  
pp. 9668-9675 ◽  
Author(s):  
Jia Jia Shao ◽  
Wei Tang ◽  
Tao Jiang ◽  
Xiang Yu Chen ◽  
Liang Xu ◽  
...  
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Corona Discharge ◽  
Surface Charge Density ◽  
High Surface ◽  
Cycling Stability ◽  
Triboelectric Nanogenerator ◽  
Excellent Cycling Stability ◽  
Vertical Contact ◽  
High Surface Charge Density

A multi-dielectric-layered vertical contact-separation mode TENG through a corona discharge approach results in outstanding output performances, i.e., a high surface charge density of 283 μC m−2 and excellent cycling stability (92.6% retention after 200 000 cycles).

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