Electrohydrodynamic process

There has recently been some interest in nanoflow LC as a mean of normalizing the mass spectrometric response [55-58], Nanospray is more than simply a reduction of ESI flow rate. ESI is an electrohydrodynamic process, with daughter droplets generated when Columb repulsion in a charged liquid (the parent droplet) overcomes... 

This period is determined solely by the elastic forces. In fact, the instability with the same period can be caused by other external factors, for example, by a magnetic field or by an electrohydrodynamic process caused by conductivity of the material [19]. 

Using an electrohydrodynamic processing method, a polyurethane-based core was coated with a polyanihne shell to produce stable aqueous emulsions. Using a chiral dopant, (lS)-(H-)-10-camphor sulphonic acid (HCSA) induced a high degree of optical activity in the particles. Dispersions of highly optically active colloids could be prepared both with and without polystyrenesulphonate. In both cases, the optical activity increased on standing after polymerisation. Particle size increased with polymerisation time. 16 refs. 

It is possible to observe the optical patterns induced by the electrohydrodynamic processes in strongly conducting samples of smectic A [108,... 

No theory has been published for this case. It can be expected, from general considerations, that the electrohydrodynamic processes will result in a change in the optical properties of the layer of the Sc phase, even when there is no change in the arrangement of the smectic layers, since the director has an extra degree of freedom—the possibility of rotation around the normal to the layers. Electrohydrodynamic instabilities in the 5c phase have been repeatedly observed in experiment. The formation of domains in smectic C under the influence of an electric voltage was first observed [127] with p-n-heptyloxybenzoic acid (HOBA) ... 

The effect is due to the formation of space charges, analogeous to Williams domain formation in nematic liquid crystals. The applied electric field exerts forces on these space charges and thus causes electrohydrodynamic processes that destroy the homogeneous planar texture. 

The second group of effects are phenomena of electrohydrodynamic instability (EHD) caused by the movement of a liquid in an external electric field. In liquid crystals, this instability only arises for sufficiently high impurity conductivity of the substance. There are two mechanisms of the onset of electrohydrodynamic instability in nematic liquid crystals. One of them, isotropic, is not specific for liquid crystals and can be observed for any values of Ae and Aa. In this case, the electrohydrodynamic process consists of movement of the liquid in an electrical force gradient which arises due to the inhomogeneous charge and field distribution in the bulk of the sample. 

Electrogalvanizing Electrography Electrogravimetry Electrohydrodynamics Electro-Katadyn process Electrokinetics Electroless deposition Electroless nickel Electroless plating... 

Electrospray ionization occurs by the same four steps as listed above for thermospray (see Section 4.6). In contrast to thermospray, and most other ionization methods nsed in mass spectrometry, it shonld be noted that electrospray ionization nnnsnally takes place at atmospheric pressure. A similar process carried out under vacuum is known as electrohydrodynamic ionization and gives rise to qnite different analytical results. This technique has not been developed into a commercial LC-MS interface and will not be considered further. 

Electrohydrodynamic ionization A process in which a high voltage is used to generate droplets from which ions are desorbed under conditions of high... 

Two-dimensional distributions of ground-state NO were detected by planar laser-induced fluorescence during the process of NO removal in a corona radical shower system in NO/dry air mixtures [57,58], The authors observed that the density of NO molecules decreased not only in the plasma region formed by the corona streamers and the downstream region of the reactor, but also in the upstream region of the reactor. They explained this behaviour by oxidation with ozone, which is transported upstream by electrohydrodynamic flow. 

Derived from standard desktop printers, drop-on-demand techniques, such as electrohydrodynamic jet (e-jet) printing, solid freeform fabrication (SFF), or piezoelectric inkjet printing, are among a few notable examples of rapid prototyping techniques that have been developed to pattern biomaterials. With the incorporation of a user friendly computer interface, these techniques have been employed to process a number of multiplexed, biomaterial constructs without the use of masks, stamps, or any other time consuming processing equipment. The design of such constructs with minimal feature sizes in the microliter to picoliter resolution has been demonstrated and will be discussed below. 

Magnetic effects in electrolytic processes have always held a special if somewhat distant interest for electrochemists. In Chapter 5, by Fahidy, an excellent account is given of the fundamentals of this topic and its applications, through magnetohydrodynamics, to electrodeposition and corrosion. Also treated is the basis of the electrolytic Hall effect, which is essential for understanding how electrohydrodynamic forces act on moving ions in a magnetic field. 

FIGURE 22.5 Forces acting on the Taylor cone in EHDA process. (Reprinted from J. Aerosol ScL, 30(7), Hartman, R.P.A., Bruimer, D.J., Camelot, D.M.A., Marijnissen, J.C.M., and Scarlett, B., Electrohydrodynamic atomization in the cone-jet mode physical modeling of the liquid cone and jet, 823-849. Copyright 1999, with permission from Elsevier.)... 

The other model for the ionic friction concerns the dielectric response of solvent to the solute perturbation. When an ion is fixed in polar solvent, the solvent is polarized according to the electrostatic field from the ion. If the ion is displaced, the solvent polarization is not in equilibrium with a new position of the ion, and the relaxation of the polarization should take place in the solvent. The energy dissipation associated with this relaxation process may be identified as an extra friction. The extra friction, called the dielectric friction, decreases with increasing ionic radius, thereby, with decreasing electrostatic field from the ion. The dielectric friction model developed by Born [66], Fuoss [67], Boyd [68] and Zwanzig [69, 70] has taken a complete theoretical form due to the work by Hubbard and Onsager [71, 72] who proposed a set of continuum electrohydrodynamic equations in which the electrostatic as well as hydrodynamic strains are incorporated. 

Jayasinghe, S.N., Qureshi, A.N., and Eagles, P.A, (2006) Electrohydrodynamic jet processing an advanced electric-field-driven jetting phenomenon for processing living cells. SmaU, 2 (2), 216-219. 

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