Mitaku S, Jippo T, Kataoka R
Biophys J. 1983 May;42(2):137-44. doi: 10.1016/S0006-3495(83)84379-3.
Ultrasonic relaxation of multilamellar liposomes formed from dipalmitoylphosphatidylcholine was measured near the gel-to-liquid crystal transition by a differential ultrasonic resonator. The relaxation time and strength increased remarkably near the transition temperature, indicating a pseudocritical phenomenon. A quantitative analysis of the relaxation in terms of thermodynamic relationships between specific heat, thermal-expansion coefficient, and compressibility showed that more than 90% of the total endothermic heat of the transition arises from the latent heat. The temperature dependence of the ultrasonic relaxation parameters was also analyzed by the Landau theory; we obtain a small but finite difference, 0.6 degree C, between the pseudocritical temperature and the transition temperature. These results provide a quantitative description of both the first-order and second-order characters of the gel-to-liquid crystal transition.
利用差动超声谐振器，在接近凝胶 - 液晶转变温度的条件下，测量了由二棕榈酰磷脂酰胆碱形成的多层脂质体的超声弛豫。在转变温度附近，弛豫时间和强度显著增加，表明存在准临界现象。根据比热、热膨胀系数和压缩率之间的热力学关系对弛豫进行定量分析表明，转变的总吸热热量中超过90%来自潜热。还通过朗道理论分析了超声弛豫参数的温度依赖性；我们得出准临界温度和转变温度之间存在一个小但有限的差值，为0.6摄氏度。这些结果对凝胶 - 液晶转变的一级和二级特征都提供了定量描述。
