Water entrapment

Differential scanning calorimetry measurements have shown a marked cooling/heat-ing cycle hysteresis and that water entrapped in AOT-reversed micelles is only partially freezable. Moreover, the freezable fraction displays strong supercooling behavior as an effect of the very small size of the aqueous micellar core. The nonfreezable water fraction has been recognized as the water located at the water/surfactant interface engaged in solvation of the surfactant head groups [97,98]. 

The Eh of connate waters (water entrapped in the interstices of sediment at the time of deposition) ranges from 0 to -200 mV. For example, formation water from two monitoring wells in the lower limestone of the Florida aquifer near Pensacola ranged from +23 to -32 mV,67 and formation fluids from a Devonian limestone in Illinois used for injection at a depth of about 3200 ft had an Eh of -154 mV.16... 

Proteins are important food components mainly due to their nutritional and functional value. Dietary proteins provide amino acids and nitrogen necessary for organisms. They also play a major role in determining the sensory and textural characteristics of food products. The functional properties are related to their ability to form viscoelastic networks, bind water, entrap flavors, emulsify fat and oil, and form stable foams [105]. 

One consequence of roughness at the surface of the micellar core is an increased contact between water and hydrocarbon. Figure 8.3b seems unrealistic because the water-hydrocarbon contact is scarcely less than in the bulk solution, a situation that apparently undermines an important part of the driving force for micellization. Figure 8.3c minimizes this effect without eliminating it. At the same time it allows for some water entrapment, which accounts for that part of the micellar hydration that was unexplained by the hydration of ions and charged groups. 

Gelation Water entrapment and Meats, gels, cakes, Muscle proteins, egg... 

Fig. 13.5 Noble gases dissolved in thermal waters in the Jordan Rift Valley. (Data from Mazor, 1972.) The nonsaline waters lie between the values of air-saturated water (ASW) at 15 and 25 °C, demonstrating the meteoric (atmospheric) origin and the closed-system conditions that prevailed in the ground. The saline Tiberias hot water is suggested to have originated by saline water entrapment, a hypothesis supported by the lower noble gas content (Mazor, 1972).

The accumulation of radiogenic helium in confined groundwaters is mainly determined by the duration of water entrapment. Applying the data available on uranium and thorium concentrations in the host rocks and rock water ratios, reliable, though semiquantitative, dating is possible in the range of 104 10s years. 

Connate water entrapped in rock-compartments (section 2.14)... 

In sum, there are four major sources of soluble salts in river basins (i) meteoric salts (ii) salts derived from water-rock interaction (e.g., dissolution of evaporitic rocks) (iii) salts derived from remnants of formation water entrapped in the basin and (iv) anthropogenic salts (e.g., waste-water effluents). Meteoric salts are concentrated via in-stream net evaporation and evapotransprra-tion along the river flow. In addition, meteoric salts can be recycled through irrigation in the watershed and development of saline agricultural drainage water that flows to the river. 

The dried urban sludge, composed of particles of diameter < 0.3 mm, was shaken with distilled water for 8 hours (ratio 1 100 w/v) in order to eliminate the soluble species contained in the water entrapped in the original sludge. It was then dried again at 105 C. 

A third type of nonessential moisture is occluded water, liquid water entrapped in microscopic pockets spaced irregularly throughout solid crystals. Such cavities often occur in minerals and rocks (and in gravimetric precipitates). 

The structure of the AOT micellar system, as well as the state of water entrapped inside swollen micelles, have been characterized using different techniques, such as photon correlation spectroscopy (25), positron annihilation (26), NMR (27, 28), fluorescence (29-32) and more recently small angle neutron scattering (33). The existence of reversed micelles has been demonstrated in the domain of concentrations explored by protein extraction experiments. Their size (proportional to the molar ratio of water to surfactant known as wo), shape and aggregation number have been determined. Furthermore, the micelle size distribution is believed to be relatively monodisperse. 

Figure 5. Time-resolved fluorescence of pyranine at the wavelength of maximum

Water absorption and binding Hydrogen-bonding of water, entrapment of water, no drip Meats, sausages, breads, cakes F,C... 

Water in foods and biological materials can be grouped in three categories free water, entrapped water, and bound water. Free water is easily removed from foods or tissues by cutting, pressing, or centrifugation. Entrapped water is immobilized within the lattices of large molecules, capillaries. 

Structurally, microemulsions consist of microdroplets of oil- or water-entrapped pockets, which is the dispersed phase, stabilized by a layer of surfactant (or a mixture or surfactant and cosurfactant) on the surface, similar to conventional emulsions (Figure 13.1). ... 

During skirt penetration, the water entrapped within the skirt compartments flows out through outlet valves. The acceptable rate of penetration is therefore governed by the capacity of the outlet valves. If the penetration is too fast, an excess water pressure will build up... 

Figure 8 Echo inteasity for the entrapped water in droplets fonned in a low-calorie spread containing 60% fat vs. the experimental parameter S. The solid line corresponds to the fit of a model of water entrapped in droplets of varying size. The size distribution obtained from the fit is given as an insert. (Figure adapted from Ref 25.)...

To overcome the use of polar aprotic solvents, enzymes have been incorporated within reverse micelles using the anionic surfactant Aerosol-OT [AOT, bis(2-ethylhexyl)sodium sulfosuccinate]. AOT forms thermodynamic water droplets surrounded by a surfactant monolayer in oil (isooctane). Water entrapped within the reverse micelles resembles the polar pockets in cells(ll). IiKXirporation of enzymes within reverse micelles soluble in non-polar media facilitates productive collisions and reactions between enzymes and non-polar... 

The system failures of concern in the recirculation mode are the containment spray recirculation and the emergency coolant recirculation systems. Water entrapment in the containment can happen anywhere from the spray nozzles to the recirculation sump. 

Previous studies performed in our group have shown very peculiar and interesting water properties inside RMs that emerges from the confinement effect and the interaction with the surfactant at the interface [27,39,40,42]. For example, water properties differ between RM systems formed with anionic and cationic surfactants. The water molecules entrapped inside the AOT/benzene RMs show enhanced electron donor ability compared with bulk water, while water entrapped inside the BHDC/benzene RMs appears nonelectron donating due to its interaction with the cationic surfactant polar head group [27,38, 39, 42]. These results have tremendous impact when RMs are used as nanoreactors [40,47]. 

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