Electrostatic gradient

Ion-exchange Electrostatic Gradient Short column, wide... 

The ends of the internal lumen of nAChR are highly polar and negatively charged. This domain can be viewed as a cation selector in which noncompetitive inhibitors bearing a positive charge (e.g., amine moiety) are trapped and directed down the channel by an electrostatic gradient [67, 68]. 

In the case when there is an externally imposed electron injection/extraction into/from the electrode, ET processes between the electrode and electroactive species in solution can proceed continuously, which would result in a concentration distribution layer (CDL) of electroactive species at the interface due to their finite mass transport (MT) rates. If assuming that the solution species approximately have the same PCA, one can imagine that the CDL and diffuse EDL would start similarly at the OHP and would merge into each other at the electrode interface when an ET process proceeds continuously (Figure 2.1). To this end, the diffuse EDL will be dynamic in nature, and interfacial MT and ET processes will be impacted by the high electrostatic gradient (on the order of 10 V/m) in the EDL. 

Migration is the movement of ions due to a potential gradient. In an electrochemical cell the external electric field at the electrode/solution interface due to the drop in electrical potential between the two phases exerts an electrostatic force on the charged species present in the interfacial region, thus inducing movement of ions to or from the electrode. The magnitude is proportional to the concentration of the ion, the electric field and the ionic mobility. 

To display properties on molecular surfaces, two different approaches are applied. One method assigns color codes to each grid point of the surface. The grid points are connected to lines chicken-wire) or to surfaces (solid sphere) and then the color values are interpolated onto a color gradient [200]. The second method projects colored textures onto the surface [202, 203] and is mostly used to display such properties as electrostatic potentials, polarizability, hydrophobidty, and spin density. 

Vector field gradient of the electrostatic potential, i.e., force... 

In addition to total energy and gradient, HyperChem can use quantum mechanical methods to calculate several other properties. The properties include the dipole moment, total electron density, total spin density, electrostatic potential, heats of formation, orbital energy levels, vibrational normal modes and frequencies, infrared spectrum intensities, and ultraviolet-visible spectrum frequencies and intensities. The HyperChem log file includes energy, gradient, and dipole values, while HIN files store atomic charge values. 

For a quantum mechanical calculation, the single point calculation leads to a wave function for the molecular system and considerably more information than just the energy and gradient are available. In principle, any expectation value might be computed. You can get plots of the individual orbitals, the total (or spin) electron density and the electrostatic field around the molecule. You can see the orbital energies in the status line when you plot an orbital. Finally, the log file contains additional information including the dipole moment of the molecule. The level of detail may be controlled by the PrintLevel entry in the chem.ini file. 

Forces of Adsorption. Adsorption may be classified as chemisorption or physical adsorption, depending on the nature of the surface forces. In physical adsorption the forces are relatively weak, involving mainly van der Waals (induced dipole—induced dipole) interactions, supplemented in many cases by electrostatic contributions from field gradient—dipole or —quadmpole interactions. By contrast, in chemisorption there is significant electron transfer, equivalent to the formation of a chemical bond between the sorbate and the soHd surface. Such interactions are both stronger and more specific than the forces of physical adsorption and are obviously limited to monolayer coverage. The differences in the general features of physical and chemisorption systems (Table 1) can be understood on the basis of this difference in the nature of the surface forces. 

Dry Coal Cleaning. Developments in the areas of magnetic and electrostatic separation as a means of cleaning coals in the dry state include high gradient magnetic separation (HGMS), triboelectrostatic separation (TESS), and dry coal purifier (D-CoP). 

Electrostatic precipitation Electric-field gradient a. Attraction h. Induction / /5,-n/K D 5,e,2 l5, + 2/l nDtV, / Surface accommodation... 

It is seen that the symmetry of the non-coulombic non-local interaction in the bulk phase forces the symmetry of the localized interaction with the wall. If we omitted the surface Hamiltonian and set / = 0 we would still obtain the boundary condition setting the gradient of the overall ionic density to zero. The boundary condition due to electrostatics is given by... 

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