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Super job, you guys.

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Hey, did you know that NASA is working with students

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to develop new products and new experiments for space research?

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Dr. John Poiman, a professor of chemistry and biochemistry

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at the University of Southern Mississippi,

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has some cool applications for microgravity research,

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which students just like you can be working on someday.

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What is buoyancy induced convection?

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What is the relationship between density and volume?

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What is the trend in the density versus temperature graph?

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Hi.

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NASA's reduced gravity program began in 1959.

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But in the past five years, students from over 100 schools

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have performed experiments in a microgravity environment.

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Several of my students and I have flown on the KC-135,

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NASA's flying laboratory.

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It's science that's interesting, challenging, and fun.

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One experiment we are conducting involves

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making new space age materials by a really cool process

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called frontal polymerization.

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And the other involves studying how molecules attract

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each other in fluids that mix.

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Everything is made up of very, very small pieces

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of stuff called molecules.

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Molecules attract each other.

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How strongly they attract determines

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if the stuff is a liquid, solid, or a gas.

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Some materials mix completely.

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Others do not.

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Here's something you can try at home yourself.

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We have water here, which has food coloring in it,

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and syrup.

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And as I pour the syrup in and stir it up,

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it'll make one continuous liquid.

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But if I take something that's immiscible with water,

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like mineral oil, and pour it into the water with food

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coloring, and mix this solution up,

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it will separate into two layers with time.

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Water molecules attract each other more strongly

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than they attract oil molecules, and so the water

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stays separate.

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A monomer is a small molecule that

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can be made to form long chains of monomers connected

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end to end, called a polymer.

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It's sort of like boxcars hooked together to form a train.

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The mixing process is called convection.

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It's the term for liquid motion.

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There are two ways in which convection can spontaneously

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occur in a liquid.

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One is caused by gravity, and it's

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called buoyancy-induced convection.

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Differences between the densities of the liquids

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make the lighter fluid rise and separate

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from the heavier fluid.

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Another type of convection is called

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interfacial tension-induced convection.

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Interfacial what?

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Interfacial tension-induced convection.

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Let's split the term up.

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First, interfacial tension is like the surface tension,

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which holds up a water bug when it skitters across a pond.

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The surface is the result of the water molecules

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attracting each other.

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But heating a surface here on Earth

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causes buoyancy-induced convection.

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How can we study only the convection

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caused by interfacial effects alone?

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We need to eliminate gravity or its effects.

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We can never eliminate gravity, but by free-falling,

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we can create a system that acts as if there were no gravity.

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Performing experiments in weightlessness

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allows us to study phenomena we can't study on Earth

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and to answer questions we can't answer down here.

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By eliminating buoyancy-induced convection,

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we sometimes can create superior protein crystals

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in weightlessness that can help researchers design new drugs.

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Eliminating buoyancy-induced convection

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can also help us understand how to make better semiconductors

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here on Earth, like the ones used in your computer.

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We take a lesson from computer chip manufacturers

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who use light to make the circuit patterns.

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Microgravity research shows us that we

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can create patterns on fluids which would not

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be allowed on Earth, where buoyancy convection mixes

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up the patterns due to gravity.

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My students and I are studying how forces between molecules

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in fluids that mix can cause convection.

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We use light as an initiating agent

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to make the monomer turn into the polymer.

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By exposing the monomer to light with a specific pattern,

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we hope to observe how the monomer and polymer

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molecules pull on each other.

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For many minutes, we predict that the two fluids

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will act like oil on water.

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But in the long run, the molecules

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will diffuse into each other and make a single fluid.

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Why can't we do the experiment in the lab?

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Because buoyancy-driven convection

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will smear everything out.

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So there really is no way on Earth to do the experiment.

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We also study a process called frontal polymerization,

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in which plastics and foams can be

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made with a chemical reaction that

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spreads out like a liquid flame.

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Gases can be released by the hot reaction

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that makes bubbles, which can form the foam.

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Of course, bubbles float in a liquid because of gravity.

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But without the buoyant force, bubbles

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can become larger in a microgravity environment.

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How do you use math in your work?

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Math is essential to our work.

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For example, in order to predict how gravity will cause

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convection in our systems, we need

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to prepare graphs of the density of our materials

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as a function of temperature.

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We use a special instrument called a densitometer.

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But we have to know how to use the math to make

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sense of what it tells us.

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Let's look at some of the data from my lab.

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Here, we have plotted the densities

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of the monomer and the polymer on the y-axis

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and the temperature on the x-axis.

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First, notice that the density of the polymer

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is higher than the monomer.

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Next, we can draw straight lines through the points.

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The slope of each line is the ratio

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of the change in density to the change in temperature.

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The density of the polymer decreases 0.03 grams

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per cubic centimeters for a 50 degree centigrade

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increase in temperature.

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The density of the monomer also decreases,

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but it decreases 0.04 grams per cubic centimeter

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for the same temperature change.

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Remember that we said buoyancy-driven convection

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happens because of differences in density

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and that the less dense liquids will float to the top.

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Information from this graph tells us

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how the density changes when we heat the monomer and polymer.

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And so we can predict how much buoyancy-driven convection will

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occur during experiments on Earth.

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The graph also tells us how much the volume changes

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as we heat the liquids, essential information

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for designing our experiment on the International Space

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Station.

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As we go farther and farther from Earth into space,

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we're going to be required eventually

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to make our own materials in space.

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Foams are just one of the things we need to look at.

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Gaining an understanding of the opportunities in microgravity

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research today will be valuable knowledge

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for you, young researchers of tomorrow,

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when we are ready for our first manned flight to Mars.