Chains melting temperature

Applications to fluorescent or fluorescently labeled proteins and nucleic acids, and to fluorescent lipid probes in phospholipid bilayers, have been reported. In the latter case, the diffusion coefficients measured above the chain melting temperature were found to be 10 7 cm2 s 1, which is in agreement with values obtained by other techniques. 

Ionic surfactants actually only form micelles when their hydrocarbon chains are sufficiently fluid, that is at temperatures above their chain melting temperature. Below a specific temperature for a given surfactant, the Krafft temperature, the surfactant becomes insoluble rather than self-assembles. For CTAB this temperature is around 20 °C and only above this temperature are micelles formed. In general, the longer the hydrocarbon chain length, the higher the Krafft temperature. For this reason, shorter-chain-length surfactants or branched chain soaps... 

Liquid crystalline phases form more commonly in the presence of water (these solvated phases are called "lyotropic"). Above a critical hydrocarbon chain melting temperature, water penetrates the polar region, and a lamellar... 

Holder, A.J., Yourtee, D.M., White, D.A., Glares, A.G. and Smith, R. (2003) Chain melting temperature estimation for phosphatidyl cholines by quantum mechanically derived quantitative structure-property relationships./. Comput. Aid. Mol. Dos., 17, 223-230. 

GlvcoDhorin-Lioid Monolayers at the Air-Water Interface. Further to the study of pure glycophorin monolayers we investigated the interaction between the glycophorin and dipalmitoyl-phosphatidylcholine (DPPC) in mixed monolayers at the air-water interface (27). Pure DPPC undergoes the characteristic liquid expanded (L ) to intermediate state (I) transition in monolayers at temperatures below the chain-melting temperature (- 42 C) of... 

The melting properties are of crucial importance to the technical functionality of emulsifiers, in addition to their amphiphilic properties. Most food and feed emulsifiers are based on natural fat sources, thus giving different melting properties. The consequences of the melting properties can be expressed as the Krafft temperature (i.e. the temperature at which the solubility is above the critical micelle concentration) or as the transition temperature (chain melting temperature, i.e. the melting temperature of the fatty acids in a semicrystaline bilayer). The transition temperature in an emulsifier water system forming a lamellar liquid crystalline phase... 

In crystals, formed below the chain melting temperature , the state is more or less solid-like . The more... 

Figure 8.12 Main features of monoglyceride-water phase diagrams at different hydrocarbon chain lengths (Lam, Cub and Hex correspond to regions of lamellar, cubic and hexagonal Hu phases respectively). Below the hydrocarbon chain melting temperature there is solid (s) in equilibrium with water. Small two-phase regions are shaded.

Lipids which form liquid-crystalline phases with water give II-A isotherms of two types. The first type is obtained above the chain melting temperature in the actual lipid-water system. Under these conditions there is only one monolayer phase which exists up to a film pressure of about 40 mN m . As discussed above the structure is considered to be the same as in the lipid monolayer of the L -phase. Below the chain transition temperature the second type of II-A isotherm is obtained. A phase with liquid chains is formed at low surface pressure but at a certain film pressure it is transformed into a monolayer phase with crystalline chains. It is also possible that other phases with crystalline chains can be formed under further compression as shown in Section 8.10. 

The equilibrium spreading pressure (ESP) of monolayers from polar lipids has the same value as the plateau pressure defining the transition between the form with liquid chains and that with crystalline chains. Above the chain melting temperature the ESP value is the same as the collapse pressure of the monolayer phase with liquid chains. 

For PI, a highly natured unsaturated phospholipid, the chain melting temperature occurs well below 0 C as shown by Figure 1. The urea of these very low temperature distinct peaks provide the molcur enthedpy of chain melting A Hpj for PI. 

Differential scanning calorimetry was performed to measure the chain melting temperature for non-cross-linked phospholipids (NCP) 1-3. Non-cross-linked vesicle dispersions (NCVD) and cross-linked vesicle dispersions (CVD) of 1 and 2 were also measured along with the chain melting transition of CVD-1 with a hydrophobic dye entrapped. Parent phospholipids DPPE and DLPE were used as references for NCP 1 and 2. Parent phospholipid EGGPE was used as reference for phospholipid 3. NCPs were weighed directly into the DSC pans. Vesicle dispersions were used for the non-cross-linked vesicle samples and freeze-dried powder was used for the cross-linked vesicle dispersion samples. 

Li and F NMR linewidths t ersus temperature for C1805 LiBp4 (1 )d second heating cycle data, denotes the side chain melting temperature. Filled symbols are for Li and open symbols are for F. (a) , O, x= 0.7, salt-deficient sample (b) M, x= 1, equimolar sample (c) A, A, x= 1.3 excess salt sample (d) selected Li NMR signals from (b). From Y-P. Liao, D. C. Apperley, J. Liu, Y. Zheng,... 

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