Phase transitional behavior

In a subsequent study, the effect of reducing the ELP molecular weight on the expression and purification of a fusion protein was investigated. Two ELPs, ELP [V-20] and ELP[VsA2G3-90], both with a transition temperature at 40°C in phosphate-buffered saline (PBS) containing 1 M NaCl, were applied for the purification of thioredoxin. Similar yields were observed for both fusion proteins, resulting in a higher thioredoxin yield for the ELP[V-20] fusion, since the ELP fraction was smaller. However, a more complex phase transition behavior was observed for this ELP and therefore a selection of an appropriate combination of salt concentration and solution temperature was required [39]. 

Polymerized SUVs prepared from surfactants containing styrene or vinyl moieties retained their phase transition behavior. Conversely, polymerized SUVs prepared from diacetylenic surfactants lost their phase transitions and those of methacrylamide surfactants had lower phase transition temperatures... 

The appearance of tubular myelin-like structures in swollen lecithin was observed by light microscopy well before the systematic investigation of liposomes [351-352]. Similarly, it was also demonstrated some time ago that the addition of calcium ions converted phospholipid liposomes to cochleate cylinders [353]. Subsequent studies have, however, revealed that the system is extremely complex. For example, examination of the phase-transition behavior of synthetic sodium di-n-dodecyl phosphate [(C12H2sO)2PO2Na+ or NaDDP] and calcium di-n-dodecyl phosphate [Ca(DDP)2] showed the presence of many diverse structures [354]. In particular, hydrated NaDDP crystals were shown to form lyotropic liquid-crystalline phases which transformed, upon heating to 50 °C, to myelin-like tubes. Structures of the tubes formed were found... 

Engel and coworkers [57] have reported the manufacturing process of phase stabilized ammonium nitrate (PSAN) by inducing metal complexes into AN lattices and by using surfactants to modify its properties. Kim [58] has prepared PSAN by precipitation with KN03 from a solution of their salts by the addition of acetone. Kempa et al. [59] have incorporated diammine copper (II) in the AN lattice to improve the phase-transition behavior. Krishnamurthy [60] has reported modification of phase IV—III transition by co-crystallization of AN with KF and KN03. On the other hand, Mishra [61] has reported KF as an effective phase stabilizer for... 

The NIPA gel has a molecular structure which contains not only hydrophilic (NH, C=0) but also hydrophobic (isopropyl) groups. Recently, Hirotsu [8] investigated the phase transition behavior of NIPA gel/water/alcohol systems and explained the thermoshrinking by the destruction of hydrogen bonds between water molecules and amino or carbonyl groups. However, Ulbrich and Kopecek [9] pointed out the importance of hydrophobic interactions in then-study on the mechanical properties of N-substituted acrylamide gels. 

Swelling equilibria obtained with the thermoshrinking /V-alkylacrylamide gels in water indicated that their phase transition behavior is strongly dependent on the hydrophobicity of the gels. In addition, the swelling behavior was shown to... 

Whether polymerized model membrane systems are too rigid for showing a phase transition strongly depends on the type of polymerizable lipid used for the preparation of the membrane. Especially in the case of diacetylenic lipids a loss of phase transi tion can be expected due to the formation of the rigid fully conjugated polymer backbone 20) (Scheme 1). This assumption is confirmed by DSC measurements with the diacetylenic sulfolipid (22). Figure 25 illustrates the phase transition behavior of (22) as a function of the polymerization time. The pure monomeric liposomes show a transition temperature of 53 °C, where they turn from the gel state into the liquid-crystalline state 24). During polymerization a decrease in phase transition enthalpy indicates a restricted mobility of the polymerized hydrocarbon core. Moreover, the phase transition eventually disappears after complete polymerization of the monomer 24). 

Compound Sample preparation Phase transition behavior Lattice parameter13 ... 

Liu, X.-M., Wang, L. S., Wang, L., et al. The effect of salt and pH on the phase-transition behaviors of temperature-sensitive copolymers based on IV-isopropylacry-lamide. Biomaterials 25 5659-5666, 2004. 

Hexadienes, cyclization-hydrosilylation, 11, 383-385 Hexaethyldigermane, synthesis, 3, 787 Hexafluoroarseniate salts, phase transition behavior, 12, 581 Hexakis(biphenyl)diplumbane, preparation, 3, 887 Hexakis(isocyanide)technetium(I) compound, synthesis,... 

Finklemann, H., Laub, R.J., Roberts, W.E., and Smith, C.A., Use of mixed phases for enhanced gas chromatographic separation of polycychc aromatic hydrocarbons. II. Phase transition behavior, mass-transfer non-equilibrium, and analytical properties of a mesogen polymer solvent with silicone diluents, in Polynuclear Aromatic Hydrocarbons, Phys. Biol. Chem. 6th Int. Symp., Cooke, M., Ed., Battelle Press, Columbus, OH, 1982, p. 275. 

The effects of small organic molecules such as n-alkanes, n-alkanols, fatty acids, and charged alkyl compounds on phase transition behavior of various phospholipids have been studied and reviewed by Lohner [29]. Although they are located differently in the membrane, all of these different molecules have been shown to induce similar effects on phospholipid phase transition. 

This chapter focuses on some aspects of phase transition behavior and other material properties of starch, particularly as they pertain to the structural order and interactions of the starch polysaccharides with water, lipids and other solutes. Understanding the thermally induced structural transitions of starch is helpful in controlling its physical properties and processing behaviors (e.g. plasticization, viscosity), as well as in designing products with improved properties (e.g. texture, stability). 

The following sections focus on the description of the state and phase transition behavior of starch systems, as schematically illustrated in Figure 8.5, with an emphasis on their molecular organization and their response to various environments (temperature, solvent, other co-solutes, etc.). Selected material properties are also discussed in an effort to demonstrate structure-function relationships of this biopolymer mixture in pure systems and in real food products. 

An explanation for this gel formation is sought in the phase transition behavior of span 60. At the elevated temperature (60 °C) which exceeds the span 60 membrane phase transition temperature (50 °C) [154], it is assumed that span 60 surfactant molecules are self-assembled to form a liquid crystal phase. The liquid crystal phase stabilizes the water droplets within the oil. However, below the phase transition temperature the gel phase persists and it is likely that the monolayer stabilizing the water collapses and span 60 precipitates within the oil. The span 60 precipitate thus immobilizes the liquid oil to form a gel. Water channels are subsequently formed when the w/o droplets collapse. This explanation is plausible as the aqueous volume marker CF was identified within these elongated water channels and non-spherical aqueous droplets were formed within the gel [153]. These v/w/o systems have been further evaluated as immunological adjuvants. 

Shishido A, Tsutsumi O, Kanazawa A, Shiono T, Ikeda T, Tamai N. (1997) Distinct photochemical phase transition behavior of azobenzene liquid crystals evaluated by reflection-mode analysis. J Phys Chem B 101 2806-2810... 

The phase transition behavior for the mixture of 13 and 16 is shown as a function of the mole fraction of 16 in Figure 25.8 [8]. Compounds 13 and 16 are miscible up to the mole fraction of 0.7 for 16 in the mixture. These mixtures exhibit smectic phases, while compound 13 alone gives a columnar phase (Col) from 79° to... 

Figure 25.8 Phase transition behavior for a mixture of 13 and 16 on the heating runs. Col columnar Cr crystalline G glassy Iso isotropic Sa smectic A Sb smectic B Sx unidentified smectic.

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