What's the best way to find out if an [--1--] contains a specific substance, like an environmental contaminant? You could use an expensive, bulky gas chromatograph—but Harvard researchers have developed an instrument you can carry in your pocket. They describe the device, called an inverse opal, in the Journal of the American Chemical Society.

An inverse opal is a chip of layered glass that includes [--2--]. This mini-labyrinth gets treated with chemicals to modify its inner surfaces. The resulting porous chip then sucks up only liquids that have specific surface tensions. When such a liquid enters the network, it changes the chip's color over a set area. An inverse opal designed to determine if ethanol is [--3--] methanol could thus reveal the letter M if the poison is present.

With this so-called Watermark Ink writing, the chips could also serve as secret code devices. For example, [--4--] a chip with water might make a decoy word like “hello” visible. While exposure to, say, benzene, could expose a secret message, such as “ditch your gas chromatograph.
【视听版科学小组荣誉出品】
unknown mixture numerous tiny channels laced with swabbing
能“识物”的晶片 在一种未知混合物中找出它所包含的一个指定物质最好的方法是什么？比如说一种空气污染物。当然，你可以使用昂贵又笨重的气体色谱仪。但是，哈佛大学研究人员已经开发了一种可以随身装在你的口袋中的仪器。他们所描述的这种仪器被称之为逆蛋白石，刊登在《美国化学协会期刊》中。 逆蛋白石是夹层玻璃中的一种晶片，有着数目众多的微小通道。这种迷你迷宫通过化学物质的处理修改其内表面产生的多孔性晶片，只吸收具有特定表面张力的液体。当一种液体进入其构造后边会在设定的区域内改变晶片的颜色。这种逆蛋白石可以设计用该鉴别乙醇中是否掺有甲醇，有毒的话，则显示字母M。 随着所谓的水印墨水的应用，这种晶片也可以用作为秘密代码设备。例如，用清水擦拭晶片可以显示假代码“hello”，用苯才会显示真正的秘密信息，比如说“把你的气体色谱仪扔了吧！”。