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I thought I'd talk a little bit
about how nature makes materials.

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I brought along with me an abalone shell.

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This abalone shell
is a biocomposite material

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that's 98 percent by mass
calcium carbonate

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and two percent by mass protein.

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Yet, it's 3,000 times tougher
than its geological counterpart.

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And a lot of people might use
structures like abalone shells,

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like chalk.

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I've been fascinated
by how nature makes materials,

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and there's a lot of secrets
to how they do such an exquisite job.

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Part of it is that these materials
are macroscopic in structure,

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but they're formed at the nano scale.

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They're formed at the nano scale,

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and they use proteins
that are coded by the genetic level

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that allow them to build
these really exquisite structures.

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So something I think
is very fascinating is:

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What if you could give life
to non-living structures,

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like batteries and like solar cells?

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What if they had
some of the same capabilities

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that an abalone shell did,

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in terms of being able
to build really exquisite structures

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at room temperature and room pressure,

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using nontoxic chemicals

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and adding no toxic materials
back into the environment?

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So that's kind of the vision
that I've been thinking about.

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And so what if you could grow
a battery in a Petri dish?

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Or what if you could give
genetic information to a battery

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so that it could actually become
better as a function of time, and do so

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in an environmentally friendly way?

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And so, going back to this abalone shell,

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besides being nanostructured,
one thing that's fascinating is,

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when a male and female
abalone get together,

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they pass on the genetic
information that says,

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"This is how to build
an exquisite material.

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Here's how to do it at room
temperature and pressure,

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using nontoxic materials."

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Same with diatoms,
which are shown right here,

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which are glasseous structures.

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Every time the diatoms replicate,

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they give the genetic
information that says,

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"Here's how to build glass in the ocean
that's perfectly nanostructured."

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And you can do it the same,
over and over again."

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So what if you could do the same thing
with a solar cell or a battery?

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I like to say my favorite
biomaterial is my four year old.

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But anyone who's ever had
or knows small children knows,

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they're incredibly complex organisms.

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If you wanted to convince them to do
something they don't want to do,

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it's very difficult.

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So when we think
about future technologies,

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we actually think of using
bacteria and viruses --

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simple organisms.

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Can you convince them
to work with a new toolbox,

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so they can build a structure
that will be important to me?

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Also, when we think
about future technologies,

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we start with the beginning of Earth.

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Basically, it took a billion years
to have life on Earth.

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And very rapidly,
they became multi-cellular,

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they could replicate,
they could use photosynthesis

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as a way of getting their energy source.

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But it wasn't until about 500
million years ago --

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during the Cambrian
geologic time period --

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that organisms in the ocean
started making hard materials.

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Before that, they were all
soft, fluffy structures.

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It was during this time
that there was increased calcium,

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iron and silicon in the environment,

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and organisms learned
how to make hard materials.

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So that's what I would like
to be able to do,

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convince biology to work
with the rest of the periodic table.

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Now, if you look at biology,

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there's many structures like DNA,
antibodies, proteins and ribosomes

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you've heard about,

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that are nanostructured --

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nature already gives us really exquisite
structures on the nano scale.

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What if we could harness them

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and convince them to not be an antibody
that does something like HIV?

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What if we could convince them
to build a solar cell for us?

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Here are some examples.

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Natural shells,
natural biological materials.

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The abalone shell here.

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If you fracture it, you can look
at the fact that it's nanostructured.

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There's diatoms made out of SiO2,

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and there are magnetotactic bacteria

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that make small, single-domain
magnets used for navigation.

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What all these have in common

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is these materials
are structured at the nano scale,

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and they have a DNA sequence
that codes for a protein sequence

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that gives them the blueprint

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to be able to build
these really wonderful structures.

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Now, going back to the abalone shell,

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the abalone makes this shell
by having these proteins.

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These proteins
are very negatively charged.

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They can pull calcium
out of the environment,

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and put down a layer of calcium
and then carbonate, calcium and carbonate.

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It has the chemical sequences
of amino acids which says,

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"This is how to build the structure.

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Here's the DNA sequence,
here's the protein sequence

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in order to do it."

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So an interesting idea is,

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what if you could take
any material you wanted,

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or any element on the periodic table,

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and find its corresponding DNA sequence,

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then code it for a corresponding
protein sequence to build a structure,

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but not build an abalone shell --

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build something that nature has never had
the opportunity to work with yet.

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And so here's the periodic table.

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I absolutely love the periodic table.

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Every year for the incoming
freshman class at MIT,

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I have a periodic table made that says,

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"Welcome to MIT.
Now you're in your element."

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(Laughter)

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And you flip it over,
and it's the amino acids

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with the pH at which they have
different charges.

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And so I give this out
to thousands of people.

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And I know it says MIT
and this is Caltech,

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but I have a couple extra
if people want it.

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I was really fortunate to have
President Obama visit my lab this year

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on his visit to MIT,

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and I really wanted to give
him a periodic table.

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So I stayed up at night
and talked to my husband,

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"How do I give President Obama
a periodic table?

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What if he says,
'Oh, I already have one,'

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or, 'I've already memorized it?'"

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(Laughter)

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So he came to visit my lab and looked
around -- it was a great visit.

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And then afterward, I said,

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"Sir, I want to give you
the periodic table,

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in case you're ever in a bind
and need to calculate molecular weight."

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(Laughter)

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I thought "molecular weight" sounded
much less nerdy than "molar mass."

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(Laughter)

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And he looked at it and said,

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"Thank you. I'll look at it periodically."

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(Laughter)

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(Applause)

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Later in a lecture
that he gave on clean energy,

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he pulled it out and said,

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"And people at MIT,
they give out periodic tables." So ...

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So basically what I didn't tell you

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is that about 500 million years ago,
the organisms started making materials,

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but it took them about 50 million years
to get good at it --

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50 million years to learn how to perfect
how to make that abalone shell.

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And that's a hard sell
to a graduate student:

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"I have this great project ...
50 million years ..."

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So we had to develop a way
of trying to do this more rapidly.

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And so we use a nontoxic virus
called M13 bacteriophage,

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whose job is to infect bacteria.

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Well, it has a simple DNA structure

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that you can go in and cut and paste
additional DNA sequences into it,

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and by doing that, it allows the virus
to express random protein sequences.

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This is pretty easy biotechnology,

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and you could basically
do this a billion times.

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So you can have
a billion different viruses

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that are all genetically identical,

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but they differ from each other
based on their tips,

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on one sequence,

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that codes for one protein.

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Now if you take all billion viruses,
and put them in one drop of liquid,

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you can force them to interact
with anything you want

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on the periodic table.

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And through a process
of selection evolution,

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you can pull one of a billion
that does something you'd like it to do,

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like grow a battery or a solar cell.

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Basically, viruses can't replicate
themselves; they need a host.

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Once you find that one out of a billion,

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you infect it into a bacteria,
and make millions and billions of copies

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of that particular sequence.

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The other thing
that's beautiful about biology

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is that biology gives you
really exquisite structures

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with nice link scales.

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These viruses are long and skinny,

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and we can get them to express the ability

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to grow something like semiconductors

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or materials for batteries.

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Now, this is a high-powered
battery that we grew in my lab.

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We engineered a virus
to pick up carbon nanotubes.

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One part of the virus
grabs a carbon nanotube,

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the other part of the virus has a sequence

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that can grow an electrode
material for a battery,

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and then it wires itself
to the current collector.

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And so through a process
of selection evolution,

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we went from being able to have
a virus that made a crummy battery

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to a virus that made a good battery

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to a virus that made a record-breaking,
high-powered battery

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that's all made at room temperature,
basically at the benchtop.

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That battery went to the White House
for a press conference,

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and I brought it here.

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You can see it in this case
that's lighting this LED.

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Now if we could scale this,

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you could actually use it
to run your Prius,

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which is kind of my dream --
to be able to drive a virus-powered car.

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(Laughter)

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But basically you can pull
one out of a billion,

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and make lots of amplifications to it.

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Basically, you make
an amplification in the lab,

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and then you get it to self-assemble
into a structure like a battery.

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We're able to do this also with catalysis.

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This is the example
of a photocatalytic splitting of water.

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And what we've been able to do
is engineer a virus

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to basically take dye-absorbing molecules

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and line them up
on the surface of the virus

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so it acts as an antenna,

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and you get an energy transfer
across the virus.

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And then we give it a second gene
to grow an inorganic material

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that can be used to split water
into oxygen and hydrogen,

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that can be used for clean fuels.

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I brought an example
of that with me today.

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My students promised me it would work.

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These are virus-assembled nanowires.

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When you shine light on them,
you can see them bubbling.

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In this case, you're seeing
oxygen bubbles come out.

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(Applause)

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Basically, by controlling the genes,

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you can control multiple materials
to improve your device performance.

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The last example are solar cells.

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You can also do this with solar cells.

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We've been able to engineer viruses
to pick up carbon nanotubes

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and then grow titanium
dioxide around them,

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and use it as a way of getting
electrons through the device.

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And what we've found
is through genetic engineering,

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we can actually increase
the efficiencies of these solar cells

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to record numbers

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for these types of dye-sensitized systems.

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And I brought one of those as well,

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that you can play around
with outside afterward.

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So this is a virus-based solar cell.

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Through evolution and selection,

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we took it from an eight percent
efficiency solar cell

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to an 11 percent efficiency solar cell.

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So I hope that I've convinced you

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that there's a lot of great,
interesting things to be learned

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about how nature makes materials,

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and about taking it the next step,

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to see if you can force or take advantage
of how nature makes materials,

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to make things that nature
hasn't yet dreamed of making.

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Thank you.

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(Applause)