Hydration waters

Hydration water, fat, and flavor binding gelation emulsifying foaming and whipping characteristics vary among different soy protein products and complete substitution of animal proteins by these products is not always possible (114). 

Hydration. Water adds to the triple bond to yield acetaldehyde via the formation of the unstable enol (see Acetaldehyde). The reaction has been carried out on a commercial scale using a solution process with HgS04/H2S04 catalyst (27,28). The vapor-phase reaction has been reported at... 

Crystals of uranyl perchlorate, U02(C10[13093-00-0] have been obtained with six and seven hydration water molecules. The uranyl ion is coordinated with five water molecules (4) in the equatorial plane with a U—O(aquo) distance of 245 nm (2.45 E). The perchlorate anion does not complex the uranyl center. The unit cells contain two [0104] and one or two molecules of hydration water held together by hydrogen bonding (164). 

The tetrahydrate loses three hydration waters above 100°C and becomes anhydrous at 380°C. Many complex sulfates are formed with aLkah-metal sulfates. 

Drying and other chemical processes can have significant effects on this stmcture, there being loss of hydrate water as weU as physically adsorbed water, and coUapse of the stmcture to form more stable aggregations of particles (29,30). 

KUCHEROV - DENIGES Hydration Water addition to a triple bond (Kucherov) or to a double borxl (Oeniges) under mercury salt catalysis... 

The NMR study by Wiithrich and coworkers has shown that there is a cavity between the protein and the DNA in the major groove of the Antennapedia complex. There are several water molecules in this cavity with a residence time with respect to exchange with bulk water in the millisecond to nanosecond range. These observations indicate that at least some of the specific protein-DNA interactions are short-lived and mediated by water molecules. In particular, the interactions between DNA and the highly conserved Gin 50 and the invariant Asn 51 are best rationalized as a fluctuating network of weak-bonding interactions involving interfacial hydration water molecules. 

The surface behavior of Na is similar to that of Cs, except that inner sphere complexes are not observed. Although Na has the same charge as Cs, it has a smaller ionic radius and thus a larger hydration energy. Conseguently, Na retains its shell of hydration waters. For illite (Figure 6), outer sphere complexes resonate between -7.7 and -1.1 ppm and NaCl... 

Sodium octanoate (NaO) forms reversed micelles not only in hydrocarbons but also in 1-hexanol/water. The hydration of the ionogenic NaO headgroups plays an important role in this case too. For this reason Fujii et al. 64) studied the dynamic behaviour of these headgroups and the influence of hydration-water with l3C and 23Na NMR measurements. Below w0 = [H20]/[NaO] 6 the 23Na line-width... 

In one of the cages within which gas molecules are trapped in methane hydrate, water molecules form a pentagonal dodecahedron, a three-dimensional figure in which each of the 12 sides is a regular pentagon. 

FIG. 4 Onion model of spherical water-containing reversed micelles. Solvent molecules are not represented. A, surfactant alkyl chain domain B, head group plus hydration water domain C, hulk water domain. (For water-containing AOT-reversed micelles, the approximate thickness of layer A is 1.5 nm, of layer B is 0.4 nm, whereas the radius of C is given hy the equation r = 0.17R nm.)... 

For many solubilized enzymes the greatest catalytic activity and/or changes in conformation are found at R < 12, namely, when the competition for the water in the system between surfactant head groups and biopolymers is strong. This emphasizes the importance of the hydration water surrounding the biopolymer on its reactivity and conformation [13], It has been reported that enzymes incorporated in the aqueous polar core of the reversed micelles are protected against denaturation and that the distribution of some proteins, such as chymotrypsine, ribonuclease, and cytochrome c, is well described by a Poisson distribution. The protein state and reactivity were found markedly different from those observed in bulk aqueous solution [178,179],... 

One of the major uses of DTA has been to follow solid-state reactions as they occur. All decomposition reactions (loss of hydrates, water of constitution, decomposition of inorganic anions, e.g.- carbonate to carbon dioxide gas, etc.) are endothermic and irreversible. Likewise are the synthesis reactions such as... 

For Ca and Ba, whose n values are larger than 10, however, it is thought that some hydrated water molecules not only in the first hydration shell but also in the second hydration shell are cotransferred into NB. Accordingly, it can be supposed that some water molecules in the first hydration shell (i.e., in the vicinity of the ion) are covered with the second hydration shell, so that they cannot be associated with outer solvent... 

As seen in Fig. 10, in accordance with Eq. (44), AGfr° (z-dep) per hydrated water becomes progressively greater as E is enhanced. Since the contribution from the interaction in W to AGf ° " (z-dep) is probably more significant than that from the interaction in NB, the dependences shown in Fig. 10 seem to suggest that the hydrogen bonds, which are formed around a hydrated ion in W and which must be broken in its transfer to NB, are strengthened by the surface field of the hydrated ion. 

Fig.2 IR spectra of 4,4 -dipyridyl N,N -dioxide in the vo-h stretching region for the hydrated compound (black line, bottom) and the complex it gives with 1,4-DITFB (grey line, top). Hydration water disappears on complex formation...

Drugs that associate with water to produce crystalline forms are called hydrates. Water content of the hydrate forms of sodium cefazolin as a function of relative humidity is seen in Fig. 1. As shown in Fig. 1, the sesquihydrate is the most stable structure when exposed to extreme humidity conditions [6], This figure also shows the importance of choosing the proper combination of hydrate and humidity conditions when designing a manufacturing process or facility. 

Biological membranes consist of lipids, proteins and also sugars, sometimes mutually bonded in the form of lipoproteins, glycolipids and glycoproteins. They are highly hydrated—water forms up to 25 per cent of the dry weight of the membrane. The content of the various protein and lipid components varies with the type of biological membrane. Thus, in... 

Figure 2. Hydration Water As A Function of Concentration and Method of Determination.

Of special interest is the dehydration of polynuclear technetium bromide clusters, which contain hydroxonium cations with different numbers of hydration water molecules. Analysis of the results obtained leads us to conclude that at 140-200 °C dehydration occurs with a partial decomposition of the [H30(H20)3] + cations (30). 

After loss of the hemi-hydrate water, the anhydrous complex decomposes explosively on further heating. 

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