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Investigation of the Influence of Geometry and External Field on Fluid Flow Through Carbon Nanotubes by Molecular Dynamics Simulation
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Water transportation through carbon nanotubes is key for designing nanodevices. The directed transport of water molecules through a rotating charged carbon nanotube (CNT) is investigated by molecular dynamics simulations. It is found that the net flux of continuous unidirectional water flow depended sensitively on the charge distribution, charge density and rotation of the CNT. we find that for a constant charge density, the water flux increases with the increase of the charge difference. Besides, we find that the water flux shows a nonlinear dependence on the angular velocity of the rotation. The rotation of the CNT with low angular velocities, can not generate a continuous water flux. The...
Enhanced autoionization of water at phospholipid interfaces
, Article Journal of Physical Chemistry C ; Volume 117, Issue 1 , 2013 , Pages 510-514 ; 19327447 (ISSN) ; Partovi Azar, P ; Jadidi, T ; Anvari, M ; Jand, S. P ; Nafari, N ; Tabar, M. R. R ; Maass, P ; Bakker, H. J ; Bonn, M ; Sharif University of Technology
2013
Abstract
The structure and autoionization of water at the water-phospholipid interface are investigated by ab initio molecular dynamics and ab initio Monte Carlo simulations using local density approximation (LDA) and generalized gradient approximation (GGA) for the exchange-correlation energy functional. Depending on the lipid headgroup, strongly enhanced ionization is observed, leading to the dissociation of several water molecules into H+ and OH- per lipid. The results can shed light on the phenomena of the high proton conductivity along membranes that has been reported experimentally
Investigation of salts behavior at liquid–liquid interfaces
, Article Springer Proceedings in Mathematics and Statistics, 26 August 2013 through 30 August 2013 ; Volume 117 , July , 2015 , Pages 265-270 ; 21941009 (ISSN) ; 9783319123066 (ISBN); 9783319123066 (ISBN) ; Bahramian, A ; Soltani, M ; Pourafshary, P ; Sarikhani, K ; Chen, P ; Ejtehadi, M. R ; Makarov R. N ; Melnik R. V. N ; Kotsireas I. S ; Shodiev H ; Cojocaru M. G ; Cojocaru M. G ; Makarov R. N ; Melnik R. V. N ; Kotsireas I. S ; Shodiev H ; Sharif University of Technology
Springer New York LLC
2015
Abstract
We have used molecular dynamics simulation to investigate hydrophilic– hydrophobic interfaces between calcium chloride (CaCl2) aqueous solutions and normal hexane. The results demonstrate the increasing impact of salt concentration on the liquid–liquid interfacial tension, hence, negative adsorption of CaCl2 according to Gibbs adsorption isotherm. Moreover, we calculated the density profiles of hexane, water, and the counter ions. The results reveal an electrical double layer near the interface and the less affinity of calcium cations toward the interface than that of chloride anions. Orientation of water molecules at the studied concentrations may result in developing a positively charged...
Effect of a monomeric sequence on the structure of hydrated Nafion in the sandwich model and solvent dynamics in nano-channels: A molecular dynamic study
, Article Molecular Physics ; Volume 108, Issue 24 , 2010 , Pages 3393-3404 ; 00268976 (ISSN) ; Akbarzadeh, H ; Taherkhani, F ; Parsafar, G ; Sharif University of Technology
2010
Abstract
Molecular dynamics simulations are performed to obtain insight into the structural properties of hydrated Nafion using the sandwich model of the polymer membrane. It is shown that a larger distance between the sulfonate groups of a chain leads to the polymer forming a better inverted micelles structure. Water- and hydronium-polymer interfaces are investigated. Comparing our results with others indicates that, from the perspective of distance, the formation of shells of water and hydronium ions is independent of the model and monomer type, but depends on both if the coordination number is considered. The behaviour of water molecules and hydronium ions is also studied dynamically. Our survey...
DFT study of NH3(H2O) n=0,1,2,3 complex adsorption on the (8, 0) single-walled carbon nanotube
, Article Computational Materials Science ; Volume 48, Issue 3 , 2010 , Pages 655-657 ; 09270256 (ISSN) ; Beheshtian, J ; Parsafar, G ; Hadipour, N. L ; Sharif University of Technology
Abstract
Theoretical study of NH3(H2O) n=0,1,2,3 adsorption on (8, 0) carbon nanotube was performed at the X3LYP/6-31G* level of density functional theory (DFT). The tube-NH3 interaction was discussed in the terms of binding energy (EB), coupling energy (EC), charge density, molecular orbitals, and dipole moments. The results reveal that addition of water molecules to tube-NH3 system increases the interaction between tube and ammonia molecule
Mechanism of water permeation through modified carbon nanotubes as a model for peptide nanotube channels
, Article International Journal of Nanotechnology ; Volume 6, Issue 10-11 , 2009 , Pages 926-941 ; 14757435 (ISSN) ; Parsafar, G. A ; Ejtehadi, M. R ; Sharif University of Technology
2009
Abstract
It is of interest to explore transfer of fluid through nanopores because of widespread applications for such systems. Carbon Nanotubes (CNTs) with their exceptional properties are the best candidates as building blocks for nanostructures. Water transfer in lots of biological systems acts as an important role for keeping the tissue working properly. Peptide nanotube is one of the best biological channels which was proposed recently. While the mechanism of water permeation through channels is very complex, however, investigations such as effect of charge distributions and temperature on water permeation could shed light on the determinants of water and proton conduction rates in biol ogical...
Ultrahigh permeable C2N-inspired graphene nanomesh membranes versus highly strained c2n for reverse osmosis desalination
, Article Journal of Physical Chemistry B ; Volume 123, Issue 41 , 2019 , Pages 8740-8752 ; 15206106 (ISSN) ; Akhavan, O ; Sharif University of Technology
American Chemical Society
2019
Abstract
The reverse osmosis (RO) desalination capability of hydrogenated and hydroxylated graphene nanomesh membranes (GNMs) inspired by the morphology of carbon nitride (C2N) has been studied by using molecular dynamics simulation. As an advantage, water permeance of the GNMs is found to be several orders of magnitude higher than that of the available RO filters and comparable with highly strained C2N (S-C2N) as follows: 6,6-H,OH > 12-H > S-C2N > 5,5-H,OH > 10-H. The reverse order is found for salt rejection, regardless of S-C2N. The hydrophilic character of the incorporated -OH functional group is believed to be responsible for linking the water molecules in feed and permeate sides via the...
Study of self-association of water in supercritical CO2 by Monte Carlo simulation: Does water have a specific interaction with CO2?
, Article Fluid Phase Equilibria ; Volume 267, Issue 2 , 2008 , Pages 181-187 ; 03783812 (ISSN) ; Khanlarkhani, A ; Sharif University of Technology
2008
Abstract
The extent of the self-association of water in supercritical CO2 has been investigated in a wide range of density and temperature by the test particle insertion technique. The results show that the association constant for water decreases with temperature and weakly depends on CO2 density. This weak density dependence provides evidence for the lack of a strong specific CO2-water interaction. Comparing calculated association constants with its gas-phase values shows that the association constant is at most ca. 38% lower than its gas-phase value in the high density-low temperature region. Inspection of the simulated radial distribution functions revealed that forming modest water-CO2 complexes...
Theoretical study of kinetics and mechanism of reactions of hydroxylamine and amineoxide anion with methyl iodide in gas and aqueous phases
, Article Progress in Reaction Kinetics and Mechanism ; Volume 32, Issue 1 , 2007 , Pages 29-50 ; 14686783 (ISSN) ; Irani, M ; Gholami, M. R ; Sharif University of Technology
Science Reviews Ltd
2007
Abstract
The kinetics and mechanism of the reactions of hydroxylamine and aminoxide anion with methyl iodide were studied with ab initio calculations, Monte-Carlo and QM/MM simulations in gas and aqueous phases. Geometrical parameters and charge calculations show that these reactions proceed through the SN2 (bimolecular nucleophilic displacement) mechanism only. The solvent effects on these reactions were studied by inserting water molecules in reaction media, Onsager model, Monte-Carlo and QM/MM simulations. Activation parameters indicate the expected variation in activation energy and rate coefficient in aqueous phase in comparison to the gas phase. The shift of potential energy barrier through the...
Structural and dynamical fingerprints of the anomalous dielectric properties of water under confinement
, Article Physical Review Materials ; Volume 5, Issue 2 , 2021 ; 24759953 (ISSN) ; Esfandiar, A ; Hassanali, A ; Ejtehadi, M. R ; Sharif University of Technology
American Physical Society
2021
Abstract
There is a long-standing question about the molecular configuration of interfacial water molecules in the proximity of solid surfaces, particularly carbon atoms, which plays a crucial role in electrochemistry and biology. In this study, the dielectric, structural, and dynamical properties of confined water placed between two parallel graphene walls at different interdistances from the angstrom scale to a few tens of nanometer have been investigated using molecular dynamics. For the dielectric properties of water, we show that the dielectric constant of the perpendicular component of water drastically decreases under sub-2-nm spatial confinement. The dielectric constant data obtained through...
Structural and dynamical fingerprints of the anomalous dielectric properties of water under confinement
, Article Physical Review Materials ; Volume 5, Issue 2 , 2021 ; 24759953 (ISSN) ; Esfandiar, A ; Hassanali, A ; Ejtehadi, M. R ; Sharif University of Technology
American Physical Society
2021
Abstract
There is a long-standing question about the molecular configuration of interfacial water molecules in the proximity of solid surfaces, particularly carbon atoms, which plays a crucial role in electrochemistry and biology. In this study, the dielectric, structural, and dynamical properties of confined water placed between two parallel graphene walls at different interdistances from the angstrom scale to a few tens of nanometer have been investigated using molecular dynamics. For the dielectric properties of water, we show that the dielectric constant of the perpendicular component of water drastically decreases under sub-2-nm spatial confinement. The dielectric constant data obtained through...
Friction reduction in grafted carbon nanochannels by applying an electric field
, Article Computational Materials Science ; Volume 213 , 2022 ; 09270256 (ISSN) ; Moosavi, A ; Hannani, S. K ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Water can be pumped in nanochannels by limiting it between the surfaces with different hydrophobicities and exerting a spinning electric field. The asymmetrical hydrophobicity combined with the spinning electric field and the fact that the water molecules have a dipole moment create a situation in which the angular momentum of water molecules is transformed into a linear momentum and the water is pumped into the nanochannel. The hydrophobicity of the surfaces can be manipulated by using nanostructures to reduce friction. In this study, two types of nanostructures have been used which are hierarchical nanostructures and polymer nanostructures made of Poly(N-isopropylacrylamide). The walls of...