Coffee Stains: Applications

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All the world’s a physics experiment. And who knows where casual observation can lead? I’m Jim Metzner, and this is the Pulse of the Planet. Sydney Nagel, is a professor of physics at the University of Chicago where he studies nonlinear systems. He explores such questions as, how come drops of liquids are densest in the middle when wet, and their dry stains always more concentrated in color around the edges? This problem bothered him especially because it was everywhere he looked, from coffee stained papers to the kitchen floor.

“In Chicago we bring in salt on our boots in our winter and we see the drips of the salty water from our boots onto the linoleum floors and they always have this white outline where the drop formed, this is what happens at the end of the evaporation process. So you can see that this thing happens everywhere, and it’s not what you would have expected, gee don’t you think we should understand it?”

It turns out, the liquid’s quick evaporation at the shallow edges draws more of the spilled solution from the center of the drop.

“If you look at these things under the microscope you see these things streaming to the outside edge of this drop, like rush hour where everybody is trying to rush out from the middle of the city to the edges, and that’s what all these particles are doing.”

Among other things, scientists are hoping to use this information about a stain’s behavior, to find new, easier methods for sequencing DNA.

“So if a molecule like a DNA molecule is in the water, and it’s getting brought out to the edge, to the perimeter, the molecule is actually being stretched out into this linear line, and then you can come along and sequence which amino acids are in which order on this chain, rather than having to resort to chemical means which is how many of the sequencings are done at the moment.”

Pulse of the Planet is presented with support provided by the National Science Foundation. I’m Jim Metzner.

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Coffee Stains: Applications

A new method for DNA sequencing was inspired by observing salt water stains on linoleum.
Air Date:08/16/2002
Scientist:
Transcript:


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All the world's a physics experiment. And who knows where casual observation can lead? I'm Jim Metzner, and this is the Pulse of the Planet. Sydney Nagel, is a professor of physics at the University of Chicago where he studies nonlinear systems. He explores such questions as, how come drops of liquids are densest in the middle when wet, and their dry stains always more concentrated in color around the edges? This problem bothered him especially because it was everywhere he looked, from coffee stained papers to the kitchen floor.

"In Chicago we bring in salt on our boots in our winter and we see the drips of the salty water from our boots onto the linoleum floors and they always have this white outline where the drop formed, this is what happens at the end of the evaporation process. So you can see that this thing happens everywhere, and it's not what you would have expected, gee don’t you think we should understand it?"

It turns out, the liquid's quick evaporation at the shallow edges draws more of the spilled solution from the center of the drop.

"If you look at these things under the microscope you see these things streaming to the outside edge of this drop, like rush hour where everybody is trying to rush out from the middle of the city to the edges, and that’s what all these particles are doing."

Among other things, scientists are hoping to use this information about a stain's behavior, to find new, easier methods for sequencing DNA.

"So if a molecule like a DNA molecule is in the water, and it’s getting brought out to the edge, to the perimeter, the molecule is actually being stretched out into this linear line, and then you can come along and sequence which amino acids are in which order on this chain, rather than having to resort to chemical means which is how many of the sequencings are done at the moment."

Pulse of the Planet is presented with support provided by the National Science Foundation. I'm Jim Metzner.

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