Liquid crystalline phase-time-temperature

Phospholipid was hardly detectable in ATPase fraction purified by Mono Q column [6]. Exogenously added phospholipids at a concentrations of 50 ig to 100 lg/ml (0.005% to 0.01%) was sufficient to induce the activity. Constituents of phospholipids, such as Polar head groups, fatty acids and glyceride failed completely to activate the ATPase. In case of fatty acids, unsaturated fatty acids were 10-times more inhibitory than saturated fatty acids (Fig.l.). pc with unsaturated and saturated faty acids and dimyristoyl-PC activated ATPase activity. Fig.2 summarizes the relationship between ATPase activity and liquid-crystalline phase transtion temperature of molecular species of PC. Every molecular species of PC with a phase-transition temperature below 50 C seemes to be able to activate the purified ATPase at 38 C. Dipalmitoy-pc having at 41.5 C phase transition temperature was slightly activated the ATPase activity at 38°C, however, when it was assayed at above 40°C, the activity was sharply increased. Thus, the ATPase activity increased sharply at around the pahse-transition temperature of the phospholipids that had been added. It is clear that the phospholipids must be in a liquid-crystalline state to activate the ATPase. These date suggest that fluidity of tonoplast is closely related to the... 

As there exists a phase equilibrium both phases must have reached in the internal thermodynamic equilibrium with respect to the arrangement and distribution of the molecules the measuring time. Therefore, no time effects or path dependencies of the thermodynamic properties in the liquid crystalline phase should be expected. To check this point for the l.c. polymer, a cut through the measured V(P) curves at 2000 bar has been made (Fig. 6) and the volume values are inserted at different temperatures in Fig. 7, which represents the measured isobaric volume-temperature curve at 2000 bar 38). It can be seen from Fig. 7 that all specific volumes obtained by the cut through the isotherms in Fig. 6 he on the directly measured isobar. No path dependence can be detected in the l.c. phase. From these observations we can conclude that the volume as well as other properties of the polymers depend only on temperature and pressure. The liquid crystalline phase of the polymer is a homogeneous phase, which is in its internal thermodynamic equilibrium within the normal measuring time. 

These azobenzene LCs display the liquid crystalline phase only when the azobenzene moiety is in the trans form, and no liquid crystalline phase at any temperature when the azobenzene moiety is in the cis form. In these azobenzene LC system, it was predicted that phase transition should be induced on essentially the same time-scale as the photochemical reaction of the photoresponsive moiety in each mesogen, if the photochemical reactions of a large number of mesogens were induced simultaneously by the use of a short laser pulse (Figure 7).1391 On the basis of such a new concept, the photoresponse of azobenzene LCs with the laser pulse was examined, and it was found that the N to I phase transition was induced in 200 xsJ39 40 This fast response, on the microsecond timescale, had been demonstrated for the first time in NLCs. From the viewpoint of application of LCs to photonic devices, such a fast response is quite encouraging. 

Analysis of the results and comparison with the lipid phase transition observed iq the bulk lipid/water systems allows to conclude that the lowest temperature during heating at which measurable diffusion occurred correlates with the onset of formation of the lamellar Ln liquid crystalline phase of the given phospholipid. Therefore, the data support a correlation between the surface and bulk phase transitions. This was confirmed in recent studies where the lipid surface phase transition was successfully measured for the first time in foam film by independent means involving the detailed investigations of the temperature dependences of the W(C) curve for the foam film and its thickness. 

Unlike the experiments carried out below the cloud point temperature, appreciable solubilisation of oil was observed in the time frame of the study, as indicated by upward movement of the oil-microemulsion interface. Similar phenomena were observed with both tetradecane and hexadecane as the oil phases. When the temperature of the system was raised to just below the PITs of the hydrocarbons with C12E5 (45°C for tetradecane and 50°C for hexadecane), two intermediate phases formed when the initial dispersion of Li drops in the water contacted the oil. One was the lamellar liquid crystalline phase La (probably containing some dispersed water). Above it was a middle-phase microemulsion. In contrast to the studies below the cloud point temperature, there was appreciable solubilisation of hydrocarbon into the two intermediate phases. A similar progression of phases was found at 35°C using n-decane as the hydrocarbon. At this temperature, which is near the PIT of the water/decane/C Es system, the existence of a two-phase dispersion of La and water below the middle-phase microemulsion was clearly evident. These results can be utilised to optimise surfactant systems in cleaners, and in particular to improve the removal of oily soils. The formation of microemulsions is also described in the context of the pre-treatment of oil-stained textiles with a mixture of water, surfactants and co-surfactants. 

Transient EMR has also been reported on the triplet state of retinal dissolved in liquid crystalline phase (Munzenmaier et al., 1992). The simulation of the transients with the stochastic Liouville equation provides the motional and order parameters of the pigment. The anisotropy ofmotional correlation times is high as expected for such an extended linear molecule and the correlation times couldbe followed with temperature over a range of two orders of magnitude in the nematic and smectic phase. 

In the DSC cooling curve of the LC-PI, the first exothermic peak has been confirmed to be the transition from isotropic melt to liquid crystalline phase. A grainy texture is developed within seconds when the system is cooled to just below 290°C as shown in Figure 3.9. The transition temperature and heat of transition for the sample crystallized at 280°C are independent of crystallization time,... 

---