能够防雾的“金三明治”(上)

How to keep windows clear using gold and sunlight.

如何用金和阳光让窗户保持干净。

As the northern hemisphere’s winter arrives, the problem of fogged-up car windscreens becomes more pressing for drivers.

随着北半球冬季的到来，汽车挡风玻璃结雾成为了司机们亟待解决的问题。

When humid air hits a surface colder than it is, the water vapour it carries condenses onto that surface as myriad tiny droplets.

潮湿的空气接触到比自身更冷的表面时，它携带的水蒸气会凝结到该表面上，形成无数微小的水滴。

These scatter light at random.

这些水滴会散射一切光线。

The result, if the surface is transparent, looks to a human eye like fog.

因此，如果凝结水滴的表面是透明的，在人眼看来就像是形成了雾。

Depending on what is fogged, be it windows, spectacle lenses or windscreens, that can be a curiosity, a nuisance or a serious hazard.

无论是窗户、眼镜片还是挡风玻璃，起雾的东西不同，可能会产生不同的影响：让人感到好奇、妨碍人们做事，或者有可能成为一种严重的安全隐患。

Antimisting sprays are one way to deal with such fogging.

防雾喷剂是解决方案之一。

But they need frequent reapplication.

但需要经常使用喷剂来维持效果。

Another approach is to embed within the thing to be demisted a set of electrically powered heating wires.

还有一种方法是在要去雾的东西内嵌入一组电热丝。

That works for a car’s rear window but not (because of the visual distraction created) for its front windscreen.

这适用于汽车后挡风玻璃，但不适用于前挡风玻璃（因为视觉上会让司机分心）。

Nor does it suit the windows of buildings or the lenses of spectacles to be demisted in this way.

这种去雾方式也不适合建筑物窗户或眼镜镜片。

Iwan Hachler and Dimos Poulikakos of the Swiss Federal Institute of Technology in Zurich have, however, come up with another way of warming something up to stop condensation forming.

然而，苏黎世联邦理工学院的伊万·哈克勒和迪莫斯·普利卡科斯想出了一种新的方法，加热某样东西，防止水蒸气凝结。

Their new material, which they describe in Nature Nanotechnology, is a coating ten nanometres thick.

他们在《自然：纳米技术》上介绍了他们的新材料，一种10纳米厚的涂层。

It is flexible, easily made using existing processes, and can be applied as a coating to glass or plastic, or embedded inside such materials.

该涂层属于柔性材料，可以简单用现有工艺制造，作为玻璃或塑料的涂层材料，或者嵌入到这些材料中。

Its demisting properties are powered by sunlight.

它的除雾能力依赖于阳光。

In effect, this material is a gold sandwich.

该材料实际上是一个“金三明治”。

The “bread” of this butty is a pair of layers, top and bottom, of titanium dioxide, each three nanometres thick.

三明治的两片“面包”是二氧化钛，上下各有一层，每层有三纳米厚。

The filling is a four-nanometre deep golden filigree.

中间的“馅料”是四纳米厚的金团簇。

The whole kaboodle lets visible light pass untrammelled, while absorbing infrared and converting it into heat.

整个结构能够让可见光自由通过，同时吸收红外线并将其转化为热。

And there is plenty to be absorbed.

有大量的红外线需要吸收。

Only about 40% of solar radiation is visible to the eye.

太阳辐射中只有大约40%的光是肉眼可见的。

More than 50% of it is infrared.

还有超过50%都是红外线。