Usually, we trust ___1___ to solve problems. Is a runny mixture too thick? Add some fluid. That’ll make it runnier. Except when the fluid makes it thicker. Scientists now think they know why.
The flow of a runny mixture, technically a suspension, is generally controlled by the size, shape and amount of the solid particles. The researchers started out with tiny hydrophilic glass beads in an organic solvent. Then they added just one percent weight of water. And like when you add water to sand and it ___2___ together, the mix turned into almost a gel. Microscopic analysis showed that a few beads stick tightly to each water drop.
Then the scientists made the glass beads hydrophobic. But ___3___. Turns out that in this case the beads form loose rings around the water droplets, as this formation minimizes each beads contact with water. The research was published in the journal Science. [Erin Koos and Norbert Willenbacher, "Capillary Forces in Suspension Rheology"—link to come]
The scientists say this effect could be used to keep solids from ___4___, or to ___5___ the viscosity of a liquid in engineering. Because sometimes, to make a mixture thicker, just add water.
【视听版科学小组荣誉出品】
common sense clumps the addition of water still made the mixture firmer separating out of liquids fine-tune
靠常识解决问题，这是常理。流质混合物太黏稠么？那就加点水，这样就可以稀薄一点。不过有的时候会适得其反。科学家们貌似已经发现了个中奥秘。 流质混合物流动比较缓慢，且有一定限制，这是由其大小、形状以及固体微粒的数量决定的。科学家们首先对有机溶剂中的微型亲水性玻璃珠进行了实验，先加入溶剂重量1%的水，这时候有机溶剂近似胶化，就像往沙子里灌水，微粒都凝结起来了。通过显微镜分析，科学家们发现有一部分玻璃珠和水滴紧密结合在了一起。 科学家们继而用憎水性玻璃珠来做实验。但是，加了水之后，有机溶剂仍然更黏稠。这就表明这项实验中，玻璃珠在水滴周围形成了松圈，因此玻璃珠与水的接触也就少之又少了。这项研究结果刊登在《科学》杂志上。 科学家们表示这项发现可用于防止固体物析水，也可用于调节工程用液体的黏度。因为——加点水，就可以更黏稠~