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article imageCorn flour and water, are they a magical combination?

By Melissa Horrocks     Jul 12, 2012 in Food
Corn flour could lead researchers into creating new weapons for defense. Scientists are starting to understand the mechanism behind the familiar "kitchen chemistry" experiment that utilises water with corn flour.
The mixture pours like water, but when it is struck it is hard; the same concept is used with body armour according to BBC News.
It has remained a mystery what is happening with these mixtures. Researchers trying to work the mechanism out have discovered that how compression of the particles just underneath the strike area lodge together when struck.
Corn flour, or corn starch in US and water act as one example of what is known as non-Newtonian fluids, whose resistance to flow act differently from more familiar Newtonian fluids that are found in every day situations.
The behaviour of corn flour (quicksand) occurs ahead of a receding wave because of interactions between the particles.
The importance of this discovery is that these properties are extremely powerful. These properties will pour or drip, but when exposed to quick movements, they start to get much thicker. Many people have attempted to walk on pools of corn flour mixture or, make corn flour monsters from a speaker cone.
Study author Scott Waitukaitis, of the University of Chicago in the US said, "The corn starch grains are like tiny little rocks bobbing around in the water, very densely packed but not so densely that they're touching each other,"
Previously, the reaction was explained away as a solidification process, but it has never been explained very clearly. To look further into the process, researchers set up a hi-tech version of the well known kitchen experiment, equipping an aluminium rod with an accelerometer and firing a laser line across the surface of a bowl of corn flour mixture.
A camera set up in slow motion filmed the reaction as the rod struck the surface of the mixtures, special sensors measured where the forces were distributed at the bottom of the bowl, according to Zee News.
Tracer particles were used in the mixture to capture slow-motion X-ray pictures of the activity in the centre of the bowl, discovering the two effects that were at work in the process.
The film displayed how a depression surrounding the rod became larger over time, drawing an amount of mixture down and making it seem like it was sinking into the surface.
The research was detailed in Journal Nature by researchers who said a similar reaction can be observed when walking on a beach where a wave has just receded; the foot that is weight-bearing is surrounded by a dry-looking area as the water around the impact region is drawn downward.
Trying to understand the reason for this reaction will help researchers in numerous ways. There is a much wider implication that goes beyond the kitchen, Waitukaitis explained.
"It's a lot more than just running across pools for game shows in Japan," he said. "The big picture is that this is a kind of material that knows how to change its properties, which is very powerful."
According to Red Orbit, this news could be far stretching. New types of cement or foundation materials could be developed using this technology. Lives could be saved as more robust armored vests are created that conform to an individual's torso in a fluid manner, but become hard when stuck by weapons.
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