scholarly journals Confined Water Molecules in Binary Mixtures of Water and 2,6-Lutidine Near Lower Solution Critical Temperature

2020 ◽  
Author(s):  
Alexander A. Korotkevich ◽  
Huib J. Bakker
Keyword(s):  
Critical Temperature ◽  
Binary Mixtures ◽  
Lower Solution ◽  
Water Molecules ◽  
Confined Water

scholarly journals Hydration Dependent Band Gap Tunability of Self-Assembled Phenylalanine-Tryptophan Nanotubes

2020 ◽  
Author(s):  
Hugo Souza ◽  
Antonio Chaves Neto ◽  
Francisco Sousa ◽  
Rodrigo Amorim ◽  
Alexandre Reily Rocha ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Building Block ◽  
Density Functional ◽  
Tight Binding ◽  
Water Molecules ◽  
Confined Water ◽  
Functional Theory ◽  
Tight Binding Method

In this work, we investigate the effects of building block separation of Phenylalanine-Tryptophan nanotube induced by the confined water molecules on the electronic properties using density-functional theory based tight-binding method. <div><br></div>

scholarly journals Dynamic Properties of Water Confined in Graphene-Based Membrane: A Classical Molecular Dynamics Simulation Study

Membranes ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 165 ◽  
Author(s):  
One-Sun Lee
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Free Energy ◽  
Graphene Sheets ◽  
Water Molecules ◽  
Energy Profile ◽  
Confined Water ◽  
Graphene Surface ◽  
Dynamics Simulations ◽  
Density Of Water

We performed molecular dynamics simulations of water molecules inside a hydrophobic membrane composed of stacked graphene sheets. By decreasing the density of water molecules inside the membrane, we observed that water molecules form a droplet through a hydrogen bond with each other in the hydrophobic environment that stacked graphene sheets create. We found that the water droplet translates as a whole body rather than a dissipate. The translational diffusion coefficient along the graphene surface increases as the number of water molecules in the droplet decreases, because the bigger water droplet has a stronger van der Waals interaction with the graphene surface that hampers the translational motion. We also observed a longer hydrogen bond lifetime as the density of water decreased, because the hydrophobic environment limits the libration motion of the water molecules. We also calculated the reorientational correlation time of the water molecules, and we found that the rotational motion of confined water inside the membrane is anisotropic and the reorientational correlation time of confined water is slower than that of bulk water. In addition, we employed steered molecular dynamics simulations for guiding the target molecule, and measured the free energy profile of water and ion penetration through the interstice between graphene sheets. The free energy profile of penetration revealed that the optimum interlayer distance for desalination is ~10 Å, where the minimum distance for water penetration is 7 Å. With a 7 Å interlayer distance between the graphene sheets, water molecules are stabilized inside the interlayer space because of the van der Waals interaction with the graphene sheets where sodium and chloride ions suffer from a 3–8 kcal/mol energy barrier for penetration. We believe that our simulation results would be a significant contribution for designing a new graphene-based membrane for desalination.

scholarly journals Enhanced methane gas storage in the form of hydrates: role of the confined water molecules in silica powders

RSC Advances ◽  
2020 ◽  
Vol 10 (30) ◽  
pp. 17795-17804
Author(s):  
Pinnelli S. R. Prasad ◽  
Burla Sai Kiran ◽  
Kandadai Sowjanya
Keyword(s):  
Methane Hydrate ◽  
Gas Storage ◽  
Water Molecules ◽  
Confined Water ◽  
Methane Gas

Rapid and efficient methane hydrate conversions by utilising the water molecules confined in intra- and inter-granular space of silica powders.

scholarly journals A theory of the rotations of molecules in solids and of the dielectric constant of solids and liquids

1935 ◽  
Vol 149 (866) ◽  
pp. 1-28 ◽  
Keyword(s):  
Dielectric Constant ◽  
Critical Temperature ◽  
Simple Model ◽  
Essential Feature ◽  
Water Molecules ◽  
Polar Molecules ◽  
Rochelle Salt ◽  
Low Frequencies ◽  
Lower Critical Temperature ◽  
Upper Critical Temperature

It is well known that Rochelle salt, NaKC 4 H 4 O 6 . 4H 2 O, for a limited range of temperature may, for practical purposes, he said to have an infinite dielectric constant analogous to the infinite permeability of iron in its ferromagnetic state. Such states, it is now realized, occur in a number of phenomena and a common description is of value; we shall refer to them as co-operative states . The co-operative state in Rochelle salt is limited by an upper critical temperature T u (or Curie Point) such that for T > T u the susceptibility though large is finite and decreases rapidly as T increases. Unlike the corresponding magnetic substances there is also a lower critical temperature T l such that for T < T l the susceptibility is again finite and decreases as T decreases. It is agreed that these phenomena are to be explained by the orientation of polar molecules in the crystal—the polar molecules in these particular crystals being undoubtedly water molecules present as water of crystallization. The co-operative state and the upper critical temperature T u can be explained by an exact analogy of the Weiss-Langevin theory of ferromagnetism, and no difficulties are raised by the large size of the necessary molecular field. The interaction energy of electrical dipoles is so large that it supplies precisely the necessary term which it fails to do in the magnetic case. The explanation of this part of the phenomenon requires the polar water molecules to be orientating freely under the influence of the effective applied electric field. The lower critical temperature T l can and must then be explained, it is believed, by a failure of the free rotations at lower temperatures which can so cut down the efficiency of the response to the applied field that the material is no longer self- polarizing. Again the dielectric constant of ice or water is finite at all temperatures, and falls to low values even for low frequencies as the temperature is decreased below 150° K. This can only be understood, assuming that the H 2 O molecule in ice or water carries the same dipole as in steam, or even a comparable one. if its orientations are not free but severely restricted by the local Held of its neighbours, even at the highest temperatures for which the dielectric constant of water has been investigated. The water dipoles are so numerous and so strong that water and ice would be co-operative at all temperatures if the dipole carriers were even approximately free. Somewhat similar phenomena occur for other polar liquids such as some of the alcohols and nitrobenzene which arc believed to be explicable in the same way. Rochelle salt, and its variants in which ammonium replaces potassium, arc the only known substances with a co-operative state. While there is probably general agreement about these qualitative explanations, it seems that no quantitative discussion has yet been given, even of any simplified model, which really displays behaviour of the types observed. Such a discussion of a simple model will be given in this paper. The exact results for the simple model reproduce many of the features observed, but naturally the model is too much simplified to expect it to provide a faithful representation of every detail. It is, however, possible to sec the modifications necessary in the model to make it the better fit the facts, and to see. moreover, that these modifications arc physically reasonable. The need for such a quantitative theory was first brought clearly to my notice at a conference on the solid state held in Leningrad in 1932. As will appear, however, an essential feature of the theory is an application of the ideas of order and disorder in metallic alloys, where the ordered state is typically co-operative, recently put forward by Bragg and Williams.* As soon as their ideas are incorporated the theory “ goes."

Vibrational states of nano-confined water molecules in beryl investigated by first-principles calculations and optical experiments

2017 ◽  
Vol 19 (45) ◽  
pp. 30740-30748 ◽  
Author(s):  
M. A. Belyanchikov ◽  
E. S. Zhukova ◽  
S. Tretiak ◽  
A. Zhugayevych ◽  
M. Dressel ◽  
...  
Keyword(s):  
Optical Spectroscopy ◽  
First Principles ◽  
Comprehensive Analysis ◽  
Water Molecules ◽  
First Principles Calculations ◽  
Confined Water ◽  
Vibrational States

Using the DFT approach and optical spectroscopy, we provide a comprehensive analysis of IR excitation of water molecules confined in beryl nanopores.

Hydration effects and negative dielectric constant of nano-confined water between cation intercalated MXenes

Nanoscale ◽  
2021 ◽  
Author(s):  
Hossein Jalali ◽  
Farhad Khoeini ◽  
Francois M. Peeters ◽  
Mehdi Neek-Amal
Keyword(s):  
Dielectric Constant ◽  
Double Layer ◽  
Electric Double Layer ◽  
Water Molecules ◽  
Electric Double Layer Capacitor ◽  
Two Dimensional ◽  
Confined Water ◽  
Double Layer Capacitor

A model for the electric double layer capacitor is constructed where water molecules are strongly confined in two-dimensional slits of MXene.

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