We present the derivation of a new model to describe neutron spin echo spectroscopy and quasi-elastic neutron scattering data on liposomes. We compare the new model with existing approaches and benchmark it with experimental data. The analysis indicates the importance of including all major contributions in the modeling of the intermediate scattering function. Simultaneous analysis of the experimental data on lipids with full contrast and tail contrast matched samples reveals highly confined lipid tail motion. A comparison of their dynamics demonstrates the statistical independence of tail-motion and height–height correlation of the membrane. A more detailed analysis indicates that the lipid tail relaxation is confined to a potential with cylindrical symmetry, in addition to the undulation and diffusive motion of the liposome. Despite substantial differences in the chemistry of the fatty acid tails, the observation indicates a universal behavior. The analysis of partially deuterated systems confirms the strong contribution of the lipid tail to the intermediate scattering function. Within the time range from 5 to 100 ns, the intermediate scattering function can be described by the height–height correlation function. The existence of the fast-localized tail motion and the contribution of slow translational diffusion of liposomes determine the intermediate scattering function for t < 5 ns and t > 100 ns, respectively. Taking into account the limited time window lowers the bending moduli by a factor of 1.3 (DOPC) to 2 (DMPC) compared to the full range.

中文翻译：

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模拟脂质体液相中的磷脂动力学

我们提出了一个新模型的描述，该模型描述了中子自旋回波谱和脂质体上的准弹性中子散射数据。我们将新模型与现有方法进行比较，并以实验数据为基准。分析表明在中间散射函数建模中包括所有主要贡献的重要性。对具有完全对比和尾部对比匹配样品的脂质的实验数据的同时分析显示，脂质尾部运动受限。对它们动力学的比较表明，尾部运动与膜的高度-高度相关性在统计上是独立的。更详细的分析表明，除了脂质体的起伏和扩散运动外，脂质尾部弛豫还局限于圆柱对称性。尽管脂肪酸尾部的化学性质存在显着差异，但该观察结果表明该行为是普遍的。对部分氘代系统的分析证实了脂质尾巴对中间散射功能的强大贡献。在5到100 ns的时间范围内，中间散射函数可以通过高度-高度相关函数来描述。快速定位的尾巴运动的存在和脂质体缓慢翻译扩散的作用决定了脂质体的中间散射功能 中间散射函数可以通过高度-高度相关函数来描述。快速定位的尾巴运动的存在和脂质体缓慢翻译扩散的作用决定了脂质体的中间散射功能 中间散射函数可以通过高度-高度相关函数来描述。快速定位的尾巴运动的存在和脂质体缓慢翻译扩散的作用决定了脂质体的中间散射功能t <5 ns和t > 100 ns。考虑到有限的时间窗口，与整个范围相比，弯曲模量降低了1.3（DOPC）至2（DMPC）。