Hydration Values

It is well known that biopolymers adsorbed water during dry storage and its quality depends on water content. For example, the length of keratin depends on water content and therefore it is used as a hygrometer. The amount of adsorbed water depends on temperature and pressure of water vapor. 

Hydration consists of the binding of water dipoles to ions or ionic groups, to dipoles, or polar groups. Hydration takes place in solid substances as well as in solution. 

Since the components of a compound are linked to each other in such a way that they have lost some of their free translational mobility, the volume of the hydrated molecule is always smaller than the sum of the volumes of its components the hydration is accompanied by a decrease of the total volume. 

The amount of water bound to the proteins and polysaccharides depends primarily on the ratio of water to the biopolymer in the investigated system. The two extreme cases are the dry biopolymer [water content tend to zero] and highly diluted aqueous solutions of the biopolymers. The dry biopolymer undergoes hydration if is exposed to the water vapor of increased vapor pressure. The extent of hydration can be determined and measuring the increment in weight. It is much more difficult to determine the extent of hydration in aqueous solutions of biopolymers. Although hydration is accompanied by a volume contraction of the solute and the solvent, this change in volume is very small and difficult to measure directly. It is customary to measure the density of biopolymer solution. 

The amount of hydrated biopolymer and of free water in the biopolymer-water system, the thermodynamic notion of partial specific volume has been introduced and is frequently determined. 

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In this study we examined the influence of concentration conditions, acidity of solutions, and electrolytes inclusions on the liophilic properties of the surfactant-rich phases of polyethoxylated alkylphenols OP-7 and OP-10 at the cloud point temperature. The liophilic properties of micellar phases formed under different conditions were determined by the estimation of effective hydration values and solvatation free energy of methylene and carboxyl groups at cloud-point extraction of aliphatic acids. It was demonstrated that micellar phases formed from the low concentrated aqueous solutions of the surfactant have more hydrophobic properties than the phases resulting from highly concentrated solutions. The influence of media acidity on the liophilic properties of the surfactant phases was also exposed. 

Density of solution and solvent were measurement with Anton Paar densimeter DMA5N. For determining the hydration value is used the following concentrations of gelatin in aqueous solution 0.2, 0.4, 0.5 and 0.6%. 

Similar results were obtained by Hunke and Matheson [59], They found that copolymerization of polyurethane with PEG of different molecular weights yielded polymers with different properties than those of polyurethane. Percent hydration values increased with PEG as did the diffusion coefficients of the model drugs (Fig. 19). 

The hydration values for MTHP are different than those for sorbitol and mannitol. This is not surprising since most molecular properties are quite different. This result depends on the model since all were studied with the same simulation procedure. 

The dielectric constant values in Table 2.8 also suggest that, while hydrate water molecules reorient rapidly compared to molecules in other solids, reorientation rates are only one-half those in ice. The hydrate value is lower than that of ice due to the lower density of hydrogen-bonded water molecules. 

The most detailed method of U.S. hydrate resource estimation has been by Collett (1995, 1996). He assigned probabilities to 12 different factors to estimate the hydrate resources within the United States at 9 x 1015 m3 of gas. Collett (1995) notes the high degree of uncertainty places the above mean value between the 95% probability level (3x 1015 m3) and the 5% probability level (19x 1015 m3). However, in the United States, the mean hydrate value indicates 300 times more hydrated gas than the gas in the total remaining recoverable conventional reserves. 

There is no simple and reliable method of determining the water of hydration of mineral matter. The average value of 8% of the ash is used as the value for water of hydration of mineral matter in coals in the United States. This value is acceptable, although it is an average of values that range from 2 to 3% and up to 15 to 20%. Water of hydration values are used to correct ash to the form of hydrated minerals in mineral matter calculations. 

We conclude that pastes cannot be pooled in a single group and be generally characterized as drying and exudate binding. Lipophilic pastes did not bind any water at all and were highly occlusive. Thus, they are likely to hydrate the skin through an impairment of the transepidermal water loss. They should be preferably used for skin protection. Hydrophilic pastes, on the other hand, hydrated the skin or maintained an elevated hydration state if they contained humectants. Only an hydrophilic paste without any additional component was able to reduce a hydrated state and led to measurably decreased skin hydration values. 

Measurements of model polypeptides were consistent with the non-freezing water being primarily associated with ionic groups of the protein (Kuntz, 1971). A set of amino acid hydration values, constructed to calculate the amount of nonfreezing water according to the amino acid composition of a protein, gave estimates in close agreement with measurement (Kuntz, 1971). 

Halle et al. (1981) measured NMR relaxation for solutions of several proteins as a function of frequency and protein concentration. They estimated hydration by use of a two-state fast-exchange model with local anisotropy and with assumed values of the order parameter and several other variables. The hydration values ranged from 0.43 to 0.98 h for five proteins, corresponding approximately to a double layer of water about a protein. The correlation time for water reorientation was, averaged over the set of proteins, 20 psec, about eight times slower than that for bulk water. A slow correlation time of about 10 nsec was attributed to an ordering of water by protein at very high concentration. 

Accordingly, the transport of salt requires larger elementary free volume than does the transport of water molecules. Hydrated ions are much larger than water, and hydrated cation and hydrated anion must move together because of coulumbic attractive force between them. Consequently, salt ions cannot permeate an amphoteric hydrophobic/hydrophilic polymer, of which the hydration value is low, i.e., less than few volume percent, by the solution-diffusion principle. Therefore, salt permeation through a hydrophobic polymer film such as low-density polyethylene (LDPE) and parylene C film should not occur. 

The density of wet salt-free crystals was found to be 1.146, by immersion in bromobenzene-xylene mixtures of a series of different densities. After the crystals had remained 24 hours in the inmiersion medium, their density had risen to that of air dried crystals (1.260). On the other hand, the density of wet crystals equilibrated with a solution of saturated ammonium sulfate with added sodium sulfate was 1.240, showing the great increase in density of wet crystals due to the uptake of salt. The hydration values for wet crystals calculated from these density values agreed very w ell with those directly determined... 

The use of sedimentation measurements in solvents of differing density has been extensively employed in the studies on viruses to determine hydration values. A number of earlier workers varied the density by adding sodium chloride, sucrose and other substances to the solvent medium for example Smadel, Pickets and Shedlovsky (120) in the study of vaccinia virus in sucrose solution. If the size, shape and internal... 

By hypothesis, the difference between the compositional phase volume p and the total excluded volume p represents the volume fraction of hydration water. The calculated hydration, expressed as a ratio of (moles hydration water) (moles EO plus moles OH) is presented in Table II. From thermodynamic studies, the expected hydration of the EO and OH groups are 2 and 3 water molecules, respectively (13,14). While the hydration as obtained from the present transport measurements does not reflect stoichiometric binding but rather kinetic effects, the hydration values obtained are quite reasonable. 

They found that methods CPCM/HF/6-31G(d) (Radii=UAHF)//CPCM/HF/6-311+G(d,p)/ SM5.4/PM3 calculated from Spartan 04, SM5.4/AM1 taken from Reference [101] (AMSOL), and Monte Carlo QM/MM produced free energy of hydration values within 1 kcal/mol of experimental values. The free energy of hydration for the anion, A-gas A-aq, would be a vertical line on the right side of the thermodynamic cycle shown in Figure 1. 

Assuming that the volume of a single SOS subunit, observed by means of low-angle and X-ray scattering, is about 3 x 10 ml and that the subunit gives a hydration value of 58% in g water/g dry ribosomes [50], the internal-water volume of the subunit is (3 x 10 x 0.58) 1.7 x 10 ml per ribosomal subunit. 

Direct measurements of the hydration values AG, AH and AS are not feasible and they are usually calculated indirectly using semi-empirical methods (Born-Haber thermochemical cycles). These cycles lead to the general equations (Rosseinsky 1965, Morss 1976, Bratsch and Lagowski 1985b)... 

Tables 9-11 list the predicted thermodynamic functions for the hydration of divalent, trivalent and tetravalent lanthanides as calculated by Bratsch and Lagowski (1985b). Values for yttrium hydration are also included when available. The formation values refer to the reaction Ln, Ln"a while the hydration values relate to the use of eqs. (28)-(30). The standard state ionic entropies given in table 10 are corrected for...

The density values of Tara gum are shown in Fig. 2.3, which shows that with increasing gum concentration, the density Increases linearly. From this plot, we can determine the value of the partial specific volume, data with which the hydration value is determined as long as the specific volume is known (see Table 2.1). 

As seen in Table 2.2, the values of P and Va/b are far away from the spherical form and are accurate to form rod-like, as pectin [159], alginate [160]. The hydration value accounts for the high water adsorption capacity for this polysaccharide and its great industrial potential application in highly viscous and thick solutions. The of Tara gum is between the values specified by Wu et al. [161]. 

Montmorillonite hydrate values based on 200 ps MD simulations 17, 18) bulk solution values are experimental (52). 

The EM and titration data are also essential to evaluate the possibility of mixed reaction mechanisms. For example, both FTIR and EXAFS can be used to determine the presence of specific bonds or complexes. Pure inner-and outer-sphere complexes may in fact be endmembers in some systems, while a mixture of hydrated and nonhydrated bonds may result in average hydration values intermediate between zero and one. Indifferent ions such as Cl, CIO/, NOj, Na and do not shift the PZC of oxides (6). In contrast, 804 has been found to adsorb specifically and produce a shift in the PZC of hematite... 

Schmid R, Miah AM, Sapimov VN (2000) A new table of the thermodynamic quantities of ionic hydration values and some applications (enthtilpy-entropy compensation and Bom radii). Phys Orem Orem Phys 2 97-102... 

Here, the value 0.73 was used for the partial specific volume, v, and 0.53 gram of water per gram of protein as the hydration value, w. These are mean values calculated from an earlier study of the hydrodynamic properties of 21 globular proteins of known structure (ref. 74). Calibration constants in terms of molecular radii (r and r. ), given in Table 1, provide an estimate of the limiting values of these parameters for separation by the primary SEC process on the TSK-SW columns used. 

Persson I, Sandstrdm M, YokoyamaH, Chaudhry M (1995) Structure of the solvated strontium and barium ions in aqueous, dimethyl-sulfoxide and pyridine solution, and crystal-structure of strontium and barium hydroxide octahydrate. Z Naturforsch 50 21-37 Schmid R, Miah AM, Sapunov VN (2000) A new table of the thermodynamic quantities of ionic hydration values and some applications (enthtilpy-entropy compensation and Bom radii). Phys Chem Chem Phys 2 97-102... 

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