Hydration behavior

A. N. Scian, Lopez. J. M. Porto, and E. Pereira. Mechanochemical activation of high alumina cements— hydration behavior Pt 1. Cement Concrete Res, 21(l) 51-60, January 1991. 

Sierra, M.B., Morini, M.A., Schulz, P.C. and Ferreira, M.L. (2005) Unusual volumetric and hydration behavior of the catanionic system sodium undecenoate sodium decyltrimethylammonium bromide. Colloid and Polymer Science, 283 (9), 1016-1024. 

Remmele et al. [3.55] studied with infrared spectroscopy the structure-hydration behavior of a 49.4 mg/mL lysozyme D20 solution with and without 10 % sucrose. The sample was cooled n in the measuring chamber to -100 °C and then connected to a freeze drying installation, after which the temperature of the sample was raised to +40 °C ... 

Remmele, R. L., Stushoff, Carpenter, J. F. Real-time spectroscopy analysis of lysozyme during Lyophilization structure-hydration behavior and influence of sucrose. American Chemical Society Symposium, Ser. 567 (Formulation and delivery of proteins and peptides) 1994. 1994 American Chemical Society... 

The initial hydration rate v and the equilibrium hydration amount were obtained as parameters reflecting the hydration behavior of LB films (see Figure 8). Temperature dependencies of the hydration behavior (v0and W ) of 10 layers of DMPE (Tc = 49 °C) LB films are shown in Figure 9. Large W and v0 values were observed only around the phase transition temperature (7C) of DMPE membranes. Thus, DMPE LB films were hydrated only near the Tc, but not in the solid state below the Tc and in the fluid state above the Tc. This indicates that the... 

Figure 10 shows effects of the membrane thickness of DMPE LB films on the hydration behavior at three different temperatures. The hydration amount (W ) increased linearly with increasing the number of layers of LB films only around Tc, but not temperatures below and above Tc. This indicates that water molecules deeply penetrate into LB layers around Tc. The hydration rate (v<,) was very large and hardly depended on the membrane thickness around Tc. This means that water can penetrate from the top surface of the membrane, but not from the side part of LB films. 

Figure 11 shows effect of acyl chain length of phospholipid on the hydration behavior around the each Tc of 10 layers of LB films of DLPE (Ci2, Tc = 30 °C), DMPE (Cm, Tc = 49 °C), and DPPE (C16, Tc = 63 °C). The hydration amount W was constant and independent of acyl chain length, which indicates that the hydration water exists around... 

The hydration behavior of DPPS (Tc = 55 °C) LB films is shown in Figure 13. The DPPS LB film having phosphoserine head groups little hydrated (Am = 600 10 ng, 20 mol of water per lipid) even near the phase transition temperature. Hydration ability has been reported from adsorption experiments of water vapor to lipid powder to be in the order of PC > PE > PS lipids [43], It has been determined from calorimetry that the amount of non-frozen water around lipid molecules is 10 mol, 7-8 mol, and 0 mol for 1 mol of PC, PE, and PS lipids, respectively [44]. This tendency is consistent with our results that PC molecules are easily hydrated and flaked from the substrate, and PE and... 

In order to confirm the large hydration behavior of phospholipid LB films only around their Tc, two-dimensional morphology of DMPE monolayers was observed by a fluorescence microscope. The two-... 

We observed also the morphological pictures of cholesterol LB films. The small disordered (white) area was frequently observed in the prepared cholesterol LB films and they were largely decreased after aging at 70 °C for 1 h (photographs are not shown). This is consistent with the hydration behavior that the hydration of cholesterol LB films was largely decreased with increasing temperatures (see Figure 14). 

From the frequency measurements of the LB-film-deposited QCM plate in water, the behavior of phospholipid LB films can be classified into three types (i) phospholipids having relatively hydrophilic head groups such as DPPC and DPPG are hydrated and then easily flaked from the substrate in the fluid liquid crystalline state above Tc (ii) DPPE and DPPS having the less hydrophilic head groups are hydrated only near their Tc (iii) cholesterol LB films show relatively large hydration behavior even at low temperatures due to the water penetration into the structure defects in the membrane. 

This is the first example to demonstrate directly and quantitatively the hydration behavior of phospholipid membranes in water. The combination of the QCM and the LB method is a useful tool for characterization of lipid membranes in water. 

Recent 620.6 MHz nmr results on sorbitol and mannitol (9) confirm that sorbitol rotates more freely in water than mannitol. This suggests that there is less solute-solvent interaction in sorbitol. Calorimetric results (J ) predict that sorbitol and mannitol should have hydration behavior similar to that described above. Those workers, however, referred to structure breaking properties, even though no structural data was obtained. 

For water-soluble coatings that consist mainly of polymers, dissolution or erosion of the coat is the rate-limiting step toward the controlled release. After the coat is dissolved, the drug substance in the core is released, and the release kinetics depend on the core properties. Based on Eq. (5.2), solubility and dissolution/hydration behaviors of the pri-... 

Yakubu, P. I., Baianu, I. C., and Orr, P. H. (1990). Unique hydration behavior of potato starch as determined by deuterium nuclear magnetic resonance./. Food Sci. 55 458-461. 

Kano L, Yamashita H., Saito F. Effect of heat-assisted grinding of a calcium hydroxide - gibbsite mixture on formation of hydrated calcium alummate and its hydration behavior. Powder Technology 1998, 98 279-80. 

From the observation that such layered oxides, which undergo easy hydration under normal humidity, are associated with better catalytic activity, it appears that hydration behavior is one of the factors affecting the catalytic activity. 

It is conceivable that the dynamic features of bR are strongly related to the hydration behavior of the protein, in addition to the cation binding described above. To gain insight into this problem, Fig. 24 illustrates how the 13C NMR spectra of [3-13C]Ala-labeled bR vary with the regulated relative humidity (RH). 

In this chapter, studies on the modification of ion exchange membranes to change the permselectivity between cations and that between anions are separately explained because ionic size and, especially, the hydration behavior of cations and anions are different (Table 5.1).11,12... 

We will attempt to (a) tabulate the available measured and derived thermodynamic data for the protonation of important representative bases in aqueous acids, superacids, and the gas phase (b) show how these data may be used to estimate the ionization ratios of the different bases in aqueous acid media, including their pA"-values in water at 25° and at different temperatures (c) estimate the solvation energies of the onium ions of the protonated bases (d) relate the acidity function and hydration behavior of the different classes of bases in order to provide the necessary data for a practical theory of acidity functions. 

The purpose of this chapter is to discuss mainly the hydration behavior of ions in NB and its significance in the theory of... 

Other chemical derivatives of xanthan gum would be expected to have altered dispersibility and hydration behavior. 

---