Institute of Physics, University of Greifswald, Felix-Hausdorff-Straße 6, D-17489 Greifswald, Germany.
Langmuir. 2023 Jul 4;39(26):9078-9084. doi: 10.1021/acs.langmuir.3c00815. Epub 2023 Jun 26.
Tidal breathing is associated with a 30% change of the surfactant-covered alveolar surface occurring about 16 times per minute. To model this highly dynamic process, erucic acid monolayers at the air-water interface were compressed fast. Brewster angle microscopy imaged the fractal liquid-condensed (LC) domains and quantified the surface flow in size, direction, and duration. Radial branch distribution of the domains has a minimum in the flow direction, as was shown with directionality histograms. The fast Fourier transform of the domains shows a preferential growth perpendicular to the flow direction. Additionally, at the beginning of the flow, the downstream side of the domain grows faster than the upstream side. Surface flows act on the mm to cm scale, cause an anisotropic flow in the liquid expanded phase surrounding the LC domain, and affect the overall domain shape. On the μm-scale, the dendritic or seaweed domains' branches were only slightly disturbed. These results may help to understand pulmonary surfactant layers.
潮式呼吸与表面活性物质覆盖的肺泡表面发生约 16 次/分钟的 30%变化有关。为了模拟这个高度动态的过程，我们快速压缩了气液界面处的芥酸单层。布鲁斯特角显微镜对分形的液相凝聚（LC）畴进行成像，并对其大小、方向和持续时间进行了量化。畴的径向分支分布在流动方向上有一个最小值，这可以通过方向性直方图显示出来。畴的快速傅里叶变换显示出垂直于流动方向的优先生长。此外，在流动开始时，畴的下游侧比上游侧生长得更快。表面流的作用范围在毫米到厘米之间，导致围绕 LC 畴的液相膨胀相产生各向异性流动，并影响整个畴的形状。在微米尺度上，树枝状或海藻状畴的分支只是受到轻微干扰。这些结果可能有助于理解肺表面活性剂层。
