scholarly journals SEMICLASSICAL THEORY OF PROTON TRANSPORT IN ICE

1967 ◽  
Vol 45 (4) ◽  
pp. 1507-1516 ◽  
Author(s):  
Dong-Yun Kim ◽  
V. Hugo Schmidt
Keyword(s):  
Ion Mobility ◽  
Proton Transport ◽  
Electrostatic Interactions ◽  
Cutoff Frequency ◽  
Water Molecules ◽  
Collision Term ◽  
Lattice Vibrations ◽  
Semiclassical Theory ◽  
Boltzmann Transport ◽  
Proton Mobility

A method is described for calculating proton or other ion mobility which is applicable if mobility is limited by lattice scattering rather than by barrier jumping. The Boltzmann transport equation is used, with the collision term calculated from the electrostatic interactions between the mobile ion and the vibrating lattice. In particular the proton mobility in ice is calculated. The lattice vibrations are approximated by a Debye spectrum for translational vibrations of water molecules, plus an Einstein spectrum for modes in which protons vibrate almost as independent particles. Scattering by phonons somewhat below the Debye cutoff frequency is of the greatest importance in determining the mobility, and the proton modes have negligible effect. The calculated mobility agrees reasonably well with the experimental value.

Das Kombinationsschwingungsspektrum von Gips im Bereich von 10 000—1200 cm-1

1968 ◽  
Vol 23 (5) ◽  
pp. 708-715 ◽  
Author(s):  
V. Hohler ◽  
H. D. Lutz
Keyword(s):  
Hydrogen Bonds ◽  
Ir Spectrum ◽  
Room Temperature ◽  
Polarized Light ◽  
Water Molecules ◽  
Lattice Vibrations ◽  
Frequency Range ◽  
Sulfate Ions ◽  
Normal Vibrations

The IR-spectrum of gypsum (CaSO4·2 H2O) in the frequency range from 10 000 to 1200 cm-1 has been investigated with polarized light at room temperature. Between 3700 and 1200 cm-1, the measurements confirm the data of HASS and SUTHERLAND and as well as those of SCHAAK derived from IR and reflection measurements. The IR-spectrum shows a great number of bands, most of which can be assigned to combination and fundamental vibrations in terms of normal vibrations of the water molecules and the sulfate ions. The influence of the lattice vibrations is briefly discussed. The existence of hydrogen bonds between the water molecules and the sulfate ions gives rise to combinations of fundamental vibrations of both complexes.

scholarly journals Separation of water–ethanol solutions with carbon nanotubes and electric fields

2016 ◽  
Vol 18 (48) ◽  
pp. 33310-33319 ◽  
Author(s):  
Winarto Winarto ◽  
Daisuke Takaiwa ◽  
Eiji Yamamoto ◽  
Kenji Yasuoka
Keyword(s):  
Carbon Nanotubes ◽  
Electric Field ◽  
Electric Fields ◽  
Electrostatic Interactions ◽  
Water Molecules ◽  
Ordered Structure

Under an electric field, water prefers to fill CNTs over ethanol, and electrostatic interactions within the ordered structure of the water molecules determine the separation effects.

β-cyclodextrine and Water: Semiempirical Calculations

1996 ◽  
Vol 51 (8) ◽  
pp. 950-956 ◽  
Author(s):  
C. Margheritis ◽  
C. Sinistri
Keyword(s):  
Electrostatic Interactions ◽  
Pure Water ◽  
Water Molecules ◽  
Atomic Charges ◽  
Compensation Mechanism ◽  
Interaction Energies ◽  
Water Interaction ◽  
Circular Arrangement ◽  
Unfavorable Condition ◽  
Consequent Increase

Abstract AM1 and PM3 calculations were carried out on ß-cyclodextrine (ß-CD) undecahydrate in the experimental conformation at 120 K. The calculated ß-CD/water interaction energies are very small and indicative for each water molecule of an unfavorable condition in respect to that of pure water. The conformationally optimized system was also studied: ß-CD appears highly symmetrical with negligible dipole moment, mainly because of the circular arrangement of the single vectors. Primary hydroxyls can easily rotate, while the secondary ones are stabilized by heteroannular hydrogen bonds and homoannular electrostatic interactions due to the consequent increase of the atomic charges. The ß-CD/water interaction energies in the optimized hydrated system are not significantly different from the experimental ones. This almost hydrophobic character is also shown by MM equilibrated solutions: all water molecules are rejected beyond 2.4 Å; between 2.4 and 2.9 Å highly structured water is present. From a purely enthalpic standpoint the molecule hydration appears highly improbable, thus the formation of ß-CD 11 H20 must involve a compensation mechanism.

Membranes Assembled from Narrow Carbon Nanotubes Block Proton Transport and Can Form Effective Nano-Filtration Devices

2006 ◽  
Vol 3 (2) ◽  
pp. 237-242 ◽  
Author(s):  
Anton Burykin ◽  
Arieh Warshel
Keyword(s):  
Carbon Nanotubes ◽  
Proton Transport ◽  
Computational Study ◽  
Water Channel ◽  
Water Transfer ◽  
Water Molecules ◽  
Nano Technology ◽  
Nano Filtration ◽  
Double Wall ◽  
Aquaporin Water Channel

The use of carbon nanotubes in various filtration devices is a promising current direction in nano-technology. The direction of progress is, however, far from obvious when it involves devices that can allow water to be transferred while blocking proton transport. This problem is addressed in the present paper by exploiting the perspective that emerge from our recent studies of the mechanism of proton blockage in aquaporins. The paper focuses on a computational study of the free energy barriers for transfer of proton and water molecules through the membrane assembled from the double wall (5;5)@(10;10) armchair carbon nanotubes. It shows that such system can be used as a water nano filter that allows water transfer while blocking protons. Thus such carbon nanotube membrane will work as an artificial analog of aquaporin water channel. The general mechanisms of proton transfer/blockage in biological and artificial nanosystems are also discussed.

The Conductance of Tetraalkylammonium Iodides in Aqueous Proline and Hydroxyproline Solutions

1979 ◽  
Vol 34 (10) ◽  
pp. 1225-1229
Author(s):  
B. Sesta ◽  
C. La Mesa ◽  
C. Cantale ◽  
M. Vincenzini
Keyword(s):  
Dielectric Constant ◽  
Electrostatic Interactions ◽  
Hydrophobic Interactions ◽  
Molecular Water ◽  
Water Molecules ◽  
Destructive Effect ◽  
Iodide Ions ◽  
Tetraalkylammonium Ions ◽  
Equivalent Conductance ◽  
Tetrabutylammonium Iodide

Abstract The density, viscosity and dielectric constant of aqueous proline and hydroxyproline solutions have been determined at 25 °C. The results appear to indicate that the two aminoacids have a destructive effect on the molecular water aggregates. The equivalent conductance of tetramethylammonium iodide and tetrabutylammonium iodide in aqueous proline and hydroxyproline solutions has been measured at 25°C. The aminoacids increase the viscosity of the solutions and decrease the limiting equivalent conductance of the two electrolytes. Electrostatic interactions of the iodide ions with the water molecules and hydrophobic interactions of the tetraalkylammonium ions with the aminoacids also seem to affect the conductometric behaviour of the electrolytes.

Zur Quantentheorie des elektrischen Restwiderstandes * I. Systeme kleiner Störstellendichte

1969 ◽  
Vol 24 (1) ◽  
pp. 170-181
Author(s):  
A. Rauh
Keyword(s):  
Cross Section ◽  
Transition Probability ◽  
Convergent Series ◽  
Collision Term ◽  
Boltzmann Transport ◽  
High Concentration ◽  
Free Electrons ◽  
Quasi Particle ◽  
Residual Resistance ◽  
The Individual

For the tensor of electrical conductivity of a crystal with static impurities a convergent series expansion is found in which the individual terms represent the multiple scattering of a quasi particle. The theory is suited to calculate quantum mechanically the residual resistance for both low and high concentration of impurities. For a small concentration and for free electrons the Boltzmann transport equation can be rigorously justified using the exact scattering cross section for the transition probability in the collision term rather than the cross section in the Born approximation.

scholarly journals Lattice Vibrations of the Water Molecules in Ba(ClO3)2.H2O and K2C2O4.H2O.

1978 ◽  
Vol 32a ◽  
pp. 737-746 ◽  
Author(s):  
Anders Eriksson ◽  
Jan Lindgren ◽  
Heikki Saarinen ◽  
Elina Näsäkkälä ◽  
Otto Bastiansen ◽  
...  
Keyword(s):  
Water Molecules ◽  
Lattice Vibrations

Characterizing the Water Wire in the Gramicidin Channel Found by Monte Carlo Sampling Using Continuum Electrostatics and in Molecular Dynamics Trajectories with Conventional or Polarizable Force Fields

2020 ◽  
pp. 1-20
Author(s):  
Yingying Zhang ◽  
Kamran Haider ◽  
Divya Kaur ◽  
Van A. Ngo ◽  
Xiuhong Cai ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Dipole Moment ◽  
Electrostatic Interactions ◽  
Hybrid Methods ◽  
Force Fields ◽  
Proton Channel ◽  
Water Molecules ◽  
Implicit Solvent ◽  
Continuum Electrostatics ◽  
Hydrogen Bond Networks

Water molecules play a key role in all biochemical processes. They help define the shape of proteins, and they are reactant or product in many reactions and are released as ligands are bound. They facilitate the transfer of protons through transmembrane proton channel, pump and transporter proteins. Continuum electrostatics (CE) force fields used by program Multiconformation CE (MCCE) capture electrostatic interactions in biomolecules with an implicit solvent, which captures the averaged solvent water equilibrium properties. Hybrid CE methods can use explicit water molecules within the protein surrounded by implicit solvent. These hybrid methods permit the study of explicit hydrogen bond networks within the protein and allow analysis of processes such as proton transfer reactions. Yet hybrid CE methods have not been rigorously tested. Here, we present an explicit treatment of water molecules in the Gramicidin A (gA) channel using MCCE and compare the resulting distributions of water molecules and key hydration features against those obtained with explicit solvent Molecular Dynamics (MD) simulations with the nonpolarizable CHARMM36 and polarizable Drude force fields. CHARMM36 leads to an aligned water wire in the channel characterized by a large absolute net water dipole moment; the MCCE and Drude analysis lead to a small net dipole moment as the water molecules change orientation within the channel. The correct orientation is not as yet known, so these calculations identify an open question.

scholarly journals Humidity-Mediated Anisotropic Proton Conductivity through the 1D Channels of Co-MOF-74

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1263 ◽  
Author(s):  
Ali Javed ◽  
Ina Strauss ◽  
Hana Bunzen ◽  
Jürgen Caro ◽  
Michael Tiemann
Keyword(s):  
Relative Humidity ◽  
Proton Conductivity ◽  
Solvothermal Synthesis ◽  
Electrical Potential ◽  
Water Molecules ◽  
Temperature Dependent ◽  
Proton Mobility ◽  
Structure And Morphology ◽  
Ir And Raman ◽  
Scanning Electron

Large Co-MOF-74 crystals of a few hundred micrometers were prepared by solvothermal synthesis, and their structure and morphology were characterized by scanning electron microscopy (SEM), IR, and Raman spectroscopy. The hydrothermal stability of the material up to 60 °C at 93% relative humidity was verified by temperature-dependent XRD. Proton conductivity was studied by impedance spectroscopy, using a single crystal. By varying the relative humidity (70–95%), temperature (21–60 °C), and orientation of the crystal relative to the electrical potential, it was found that proton conduction occurs predominantly through the linear, unidirectional (1D) micropore channels of Co-MOF-74, and that water molecules inside the channels are responsible for the proton mobility by a Grotthuss-type mechanism.

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