Interfacial Hydrodynamic Drag on Nanowires Embedded in Thin Oil Films and Protein Layers
Interfacial Hydrodynamic Drag on Nanowires Embedded in Thin Oil Films and Protein Layers
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DOI：
10.1021/la900408y
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发表时间：
2009-07-21
期刊：
影响因子：
3.9
通讯作者：
Leheny, Robert L.
中科院分区：
文献类型：
--
作者：
Lee, Myung Han;Lapointe, Clayton P.;Leheny, Robert L.
我们研究了在空气/水界面上被限制在纳米级油膜中的铁磁纳米线在外加磁场和场梯度作用下的运动。通过改变油粘度、膜厚度和导线长度，我们涵盖了理论提出的两种响应机制：一种是表面粘度预计将主导导线的运动，另一种是亚相粘度预计将主导[Levine， A. J.；利物浦，t.b.；f.c.麦金托什，物理学家。[j].中国机械工程，2004,9(2):555 - 557。对于平行于金属丝长轴的金属丝运动，观察到的阻力与理论预测相当一致。然而，在整个测量范围内，垂直于其长轴或绕短轴旋转的金属丝上的阻力出乎意料地对薄膜性能不敏感。这种行为与分子薄蛋白质层中纳米线的旋转和平移阻力形成对比，后者符合理论预期。在油膜中的观察结果，可以用金属丝在油膜和亚相中动态浸入的方式来解释，证明了被限制在流体界面上的非球面颗粒的有效阻力粘度如何取决于其运动方向。
We investigate the motion of ferromagnetic nanowires confined to nanometer-scale oil Films at an air/aqueous interface in response to the application of external magnetic fields and field gradients. By varying the oil viscosity, film thickness, and wire length, we cover two regimes of response suggested by theory: one where the surface viscosity is expected to dominate the wire's motion and one where the subphase viscosity is expected to dominate [Levine, A. J.; Liverpool, T. B,; MacKintosh, F. C. Phys. Rev. E2004, 69, 021503]. For wire motion parallel to the long axis of the wire, the observed drag agrees reasonably with theoretical predictions, However, the drag on wires moving perpendicular to their long axis or rotating about a short axis is unexpectedly insensitive to the film properties over the full range of measurements. This behavior is in contrast to the rotational and translational drag on nanowires in molecularly thin protein layers, which follow theoretical expectations. The observations in the oil films, which are explained in terms of the manner in which the wire immerses dynamically in the film and subphase, demonstrate how the effective drag viscosity of an aspherical particle confined to a fluid interface can depend on its direction of motion.