Local saturation

With continued heating, the local saturation temperature is reached and the steam bubbles move into the larger, bulk-water nucleate boiling region. Because the resulting steam bubble-water mixture close to the heated metal surface has a lower density than cooler water farther away from the heated surface, the steam bubble-water mixture rises. 

D Position Sensitive Detectors are multi-wire electrical-field detectors. The principal limitation of the total counting rate reduces the applicability at a synchrotron beamline in particular for 2D detectors. But even strong, narrow peaks pose a problem, because the whole image is distorted as soon as local saturation occurs. The detector response is changing, because the wires are worn out by use. 

D. E. Befroy, K. F. Petersen, G. I. Shulman and D. L. Rothman, Localized saturation transfer reveals differences in gastrocnemius and soleus rates of ATP synthesis in-vivo. Proc. Int. Soc. Magn. Reson. Med., 2008,16, 2565. 

Fox, J. S. and Bertrand, C. Measurement of local saturation current in flames, Combustion and Flame 43,1981,317-320... 

Unless carefully designed, non-uniform distribution of air over the trays results in variations in temperature and drying times within the oven. Variations of 7°C in temperature have been found from location to location during the drying of tablet granules. Poor air circulation may permit local saturation and the cessation of drying. 

The dependence of e on position allows to describe both local saturation effects, and, in salt solution, the dependence of e on concentration. In numerical grid methods (there are families of methods, called Finite Elements Methods, FEM, and Finite Differences Methods, FDM - see Tomasi and Persico (1994) for a short explanation of differences) there is nothing but a little increase in complexity in treating eq.(lll) instead of eqs.(109-110). The treatment of the latter model by means of a MPE method is more difficult, and a specialized PCM version (Cossi et al., 1994) is necessary to exploit it with a BEM-derived method (see Juffer et al., 1991, for another proposal based on the BEM technique). 

Perched aquifer A locally saturated zone or lense in the unsaturated zone that may overlay a low-permeability unit. 

In Figure 14.1, we plot the rationalized expression of the concentration profile C,(y, t)/Cf vs. the v coordinate (distance from the electrode to the bulk of the electrolyte) considering j = 0.5 A cm-2, Dt = 10 5 cm2 s t = 1 s. In this situation, we can observe a local saturation condition near the electrode surface, and then a fast increase in the concentration profile is observed, which reaches the maximum value (1) at y values that depend on the physicochemical constants of the system. 

The local saturation pressure is used for determining the local saturation temperature. 

The third important aspect of porous media is that at the pore level when flow rates are low and tension forces dominate (i.e., for bond and capillary numbers much less than unity), the capillary pressure is constant, set by the local saturation of the wetting phase and the value of the interfacial tension. Local imbalances in capillary pressure tend to equalize pri-... 

Condensation of vapor occurs in a variety of engineering applications. For example, when a vapor is cooled below its saturation temperature, or when a vapor-gas mixture is cooled below its dew point, homogeneous condensation occurs as a fog or cloud of microscopic droplets. Condensation also occurs when vapor comes in direct contact with subcooled liquid such as spraying a fine mist of subcooled liquid droplets into a vapor space or injecting vapor bubbles into a pool of subcooled liquid. The most common type of condensation occurs when a cooled surface, at a temperature less than the local saturation temperature of the vapor, is placed in contact with the vapor. Vapor molecules that strike this cooled surface may stick to it and condense into liquid. 

The overall rate of ZnO aqueous leaching might be controlled by mass transfer in the boundary layer solid-liquid (16). At this layer, a constant low pH in the aqueous phase suggests a saturation of dissolved Zr. Kakovskii et al. (16) have reported, that at high acid concentrations the rate of ZnO dissolution is controlled by diffusion of Zn away from the siuface. This local saturation appears to influence eq. 4 and suggests a pH dependent dissolution-desorption step. This step was estimated with the Avrami-Erofeev rate law applying the results of the aqueous leaching data. 

Although a limited amount of water (0-25% with respect to the solid salt) can form a local saturated water layer on the crystal surface that facilitates anion exchange, in some cases the faster reaction is obtained under strictly anhydrous conditions [45]. 

Under either reducing or oxidizing conditions, the solubilization of arsenic from sulfide phases can be subject to kinetic limitations. Mass transfer constraints, particularly in porous media, can result in localized saturation conditions near the surface of the solid. For oxidative dissolution, depletion of dissolved oxygen may limit dissolution kinetics. Microorganisms may also play a role in catalyzing such oxidative dissolution as has been demonstrated for pyrite oxidation (88) and thus dissolution rates may reflect the level of microbial activity (which may be subject, for example, to nutrient limitation). Thus, although equilibrium calculations indicate solubility constraints on dissolved arsenic concentrations, actual concentrations may be lower than the predicted equilibrium values due to slow dissolution kinetics or greater due to slow precipitation kinetics. 

Physical evidence supporting the Idea of solvent accumulation In amorphous regions due to crystallization Is discussed by Zachmann (23).) If this causes local saturation of the amorphous polymer, then continued crystallization would produce local phase separation, creating pockets of pure liquid solvent and a network of holes and cavities In the dried specimen. Accepting this, an Immediate conclusion Is that saturation of the amorphous component must precede complete crystallization for cavitation to develop. 

Now the equation for this regime can he written by assuming that the mass transfer rate to the microphase is so high as to ensure that it is locally saturated with A ... 

Water below the ground surface may be sorbed onto the surface of soil particles, flow downward as a thin liquid film through nnsaturated pores, flow in locally saturated pores, be held in place by capillary forces, or be stored in a saturated zone called an aquifer, as indicated in Fig. 4. Water in aqnifers is often moving as the resnlt of pressnre gradients generated by springs or by pnmping. 

Fig. 3. Film with collar inside circular tube (a) shapes having different neck radius (b) neck radius vs. capillary pressure (dimensionless variables) (c) volume of the collar (local saturation) vs. capillary pressure.

Stirring or agitating the solution—stirring ranoves locally saturated solution from the vicinity of the solute and allows unsatuiated solvent to take its place. 

Recently, pore network modeling has been applied to simulate the accumulation of liquid water saturation within the porous electrodes of polymer electrolyte membrane fuel cells (PEMFCs). The impetus for this effort is the understanding that liquid water must reside in what would otherwise be reactant diffusion pathways. It therefore becomes important to be able to describe the effect that saturation levels have on reactant diffusion. Equally important is the understanding of how the properties of porous materials affect local saturation levels. This requirement is in contrast to most continuum modeling of the PEMFC, where porous materials are treated with volume-averaged properties. For example, the relationship between bulk liquid saturation and capillary pressures foimd through packed sand and other soil studies are often employed in continuum models. ... 

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