Electrostatic pressure

The influence of pressure has also been used to tune the ST properties of these ID chain compounds. Application of hydrostatic pressure ( 6 kbar) on [Fe(hyptrz)3] (4-chlorophenylsulfonate)2 H20 (hyptrz=4-(3 -hydroxypro-pyl)-l,2,4-triazole) provokes a parallel shift of the ST curves upwards to room temperature (Fig. 5) [41]. The steepness of the ST curves along with the hysteresis width remain practically constant. This lends support to the assertion that cooperative interactions are confined within the Fe(II) triazole chain. Thus a change in external pressure has an effect on the SCO behaviour comparable to a change in internal electrostatic pressure due to anion-cation interactions (e.g. changing the counter-anion). Both lead to considerable shifts in transition temperatures without significant influence on the hysteresis width. Several theoretical models have been developed to predict such SCO behaviour of ID chain compounds under pressure [50-52]. Figure 5 (bottom) also shows the pressure dependence of the LS fraction, yLS, of... 

Drozin (D7) presents an analysis corresponding to Eq. (4) for a polarizable liquid in the absence of any surface charge. However, he expresses the electrostatic pressure in terms of the electric field inside the drop rather than... 

Membrane potentials are determined by a balance between two physical forces chemical diffusion and electrostatic pressure. Chemical diffusion is the tendency of particles to move toward a uniform distribution throughout a volume. Electrostatic pressure is simply the tendency for like-charged particles to repel and oppositely charged particles to attract each other. 

Fig. 6-21. Charge distribution profile across a metal/aqueous solution interface (M/S) (a) the hard sphere model of aqueous solution and the jellium model of metal (the jellium-sphere model), (b) the effective image plane (IMP) and the effective excess charge plane x, (c) reduction in distance /lxd,p to the closest approach of water molecules due to electrostatic pressure, o, = differential excess charge on the solution side og = total excess charge on the solution side Oy = total excess charge on the metal side.

Next, we discuss the plane of the closest approach (x = of water molecules to the jellium metal edge (x = 0). At the zero charge interface, this plane of closest approach of water molecules is separated by a distance equal to the radius of water molecules from the metal siuface. As the interfadal excess charge increases, the electrostatic pressure (electrostriction pressiue) reduces the distance of Xdip in prop>ortion to the square of the interfadal charge, a (= om = - os) the electrostatic force in the compact layer is proportional to om x as. The change in Xitp due to the interfadal charge is then given by Eqn. 5-32 ... 

Such a change of the thickness of the compact layer (thickness reduction, Acdip< 0) due to the electrostatic pressure may be represented in terms of the conventional electric capacity Cm given by Eqn. 5-33 ... 

Riviere, S. Henon, S., Meunier, J. Electrostatic pressure and line tension in a Langmuir monolayer. Phys. Rev. Lett. 1995, 75 (13), 2506. 

The electrostatic contribution to the energy when the only ions present in the solution are those of the counterions of the surfactant molecules, hence in the absence of an added electrolyte, is calculated by integrating the electrostatic pressure from infinity to the distance xi. Denoting the surface charge o, = a, e/A, where a, is the degree of dissociation and A is the area per surfactant molecule adsorbed on the interface, the electrostatic energy per unit area is given by (see Appendix B)... 

Another source for a destabilizing force in thin films is electrostatic pressure. It has been found in substrate-fluid-fluid systems that if the central fluid layer is a dielectric and the substrate and top fluid layer are both conducting (with differing work functions), then an electric field across the dielectric can drive instabilities [21, 22]. In other words, the presence of the two different work functions (of the... 

The work of Rumpf on bulk powders confirms the relative importance of the van der Waals and electrostatic forces with theoretical strengths for the van der Waals force in the range 2 x 10 to 3 x 10 N/m. These adhesive pressures are relatively constant with change in material whilst electrostatic pressures are highly sensitive to the material, its surface characteristics and... 

This type of mechanism is present when the electrostatic pressure in the jet approaches the capillary pressure. Here, once the largest droplets have separated from the jet, their charge is such that they exceed the Rayleigh limit [25]. They then emit a jet themselves, which resembles a miniature Taylor cone, and break up into even finer drops. If the electrical field strength is slightly higher, lateral kink-type... 

The last term of the Eq. (7.8) is the disjoining pressure which is a result of the intermolecular forces exerted on the thin film [23] which plays a role in the near surface regirais only. Due to a strrMig electric field generated in a capacitor device, only the electrostatic pressure and the Laplace term need to be taken into consideration. 

Fig. 7.2 Graphic representation of the dispersion relation (Eq. 7.12). While in the absence of or for a positive electrostatic pressure, all modes are damped (t < 0), the dispersion relation yields a dominant mode with corresponding growth rate time for a negative Pei...

If a liquid is subjected to an electric field, a charge is induced on the liquid surface and mutual charge repulsion results in an outwardly directed force. Under suitable conditions, for example extrusion of the liquid through a needle, the electrostatic pressure at the surface forces the liquid drop to form a cone shape (Figure 31.1). 

The first term is the disjoining pressure in the film with A the Hamaker constant describing the van der Waals interaction of the film with the surrounding media. The second term represents the electrostatic pressure exerted on the film by an electrostatic potential difference, U, between the conducting media cladding the film, with s being the dielectric constant of the film material. Finally the third term describes the Laplace pressure in the film with cr donating the interface tension between the film and the upper (liquid) medium. 

Fig. 6 Logarithm of applied pressure (log P) plotted versus the distance between bilayers (if) for gel phase bilayers composed of mixtures of the zwitterionic lipid DPPE and the negatively charged lipid DPPA. The circle on the x-axis represents the fluid spacing of gel phase DPPE bilayers in water and the arrow indicates the fluid spacing for liquid-crystalline phase BPE bilayers. The line represents the repulsive electrostatic pressure calculated from double-layer theory for 80 20 DPPE DPPA bilayers. Data were taken from [19,51]...

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