Science2014-06-11 1:50 PM

水黾水上行走的秘密——水面张力 Water's Tough Skin

论文摘要 

挑战重力。沿着水面大力划船,水黾创建漩涡帮助推进它们前进。

你无法再水上行走有一个最简单原因:人类太大其重力超过了水面张力,是的我们会下沉。但小型动物例外,占有优势,表面张力是水分子粘附在一起时产生的,允许昆虫和其他小型动物能够轻松地在池塘和其他液体上行走。长期以来,多数生物学家忽视了空气-水接触面。但越来越多的研究揭示接触面——自身表面张力——是如何塑造了很多的生活世界。

以水黾为例,利用燃料和高速影像,研究人员学习到长腿昆虫是如何轻松的研究池塘表面溜冰的。沿着表面大力划船,水黾创造漩涡来帮助推动它们前行,所有睡眠都没有破裂。水黾甚至能在水上起飞和降落不穿透水面——在这个视频中,放慢20倍。

物理学家有一种很好理解表面张力是如何发生的。粘附的水分子试图尽量减少与其他类型分子的连接。因此当一些事物使水面变形,移位的水分子转回到最小能量构型,除非入侵者自身吸收水分子,在这种情况下水分子粘附在一起就像胶水一样。

Abstract 

SurfAce tension is a force to be reckoned with, especially if you are small. It enables a water strider to skate along the water's surface and not sink. It makes water cling like quicksand to ants unlucky enough to blunder in. BioLogists have tended to ignore the air-water interface, but at a recent symposium, the power of surface tension became clear and not just for small creatures. Surface tension helps seeds bury themselves by causing awns to coil and uncoil. It enables a floating fern to maintain an air layer, even when submerged. And it makes a beetle fly in two dimensions, not three. Surface tension also allows human and agricultural pathogens to travel long distances in tiny, buoyant droplets. We hardly notice surface tension, but it plays a big role in life at large.

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