WEBVTT

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LORNA GIBSON: So I think
one of the special things

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about this course
and about my kind

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of research on
cellular materials

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is that I spend a fair
amount of time talking

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about materials in nature.

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So I talk about wood,
for instance, and what

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it is about the cellular
structure that gives rise

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to the density dependence
of wood properties

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and the anisotropy
in wood properties.

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I talk about
trabecular bone, and I

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talk about the structure
and properties of the bone,

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but also we do a
little bit of modeling

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on how you might look at
bone loss and osteoporosis.

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So if you lose a certain
fraction of the bone

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density, what residual
strength would

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you expect the bone to have.

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We have a project
on bamboo right now.

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We talk about the
structure of bamboo.

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Bamboo is actually a grass.

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And this is a Chinese species
of bamboo called moso bamboo,

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and you can see how
big this one is.

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They even get bigger, maybe
six or eight inches across.

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And what we're
interested in doing

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is making something called
structural bamboo products.

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And this is an example of a
bamboo oriented strand board.

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So the same way
people take wood,

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and they chop wood
up into strands

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and make oriented strand boards
for housing construction,

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you could, in principal, do
the same thing with bamboo.

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And we have a project
that's in collaboration

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with some colleagues at the
University of British Columbia.

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They're the ones
who are actually

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making the bamboo
oriented strand board.

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And with some architects in
England, in Cambridge, England,

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we're looking at things like how
you might modify wood building

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codes that talk about
wood structural products,

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how you would modify that for
bamboo structural products.

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And what we're
doing here at MIT is

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we're looking at the
structure of the bamboo

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and doing some modeling of
the mechanical properties

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of the bamboo itself.

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So that's one example.

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Here's another example.

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This is a bamboo laminate.

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So this is a little bit like
a glue laminated wood member,

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but in fact, this
one is made out

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of bamboo instead
of out of wood.

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So it's the same kind of idea.

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Let's see.

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We've also had a project
in the past on cork.

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So this is a cork
from a wine bottle,

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and we've looked at that.

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Cork has an unusual
mechanical property.

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You know, if you take a rubber
band and you pull on it,

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if you can make it longer this
way, it gets narrower that way.

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Well, if you load cork
in one direction, if you,

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say, pull on it
or compress it, it

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doesn't get any
wider or narrower

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in the other direction.

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It just stays the
same kind of size.

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And you can show
that that's related

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to the structure of the cells.

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The cells are like
little bellows,

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or like a little concertina.

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So you can imagine if you
have a little concertina,

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and you push on it this
way, it doesn't really

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get any bigger that way
or smaller that way.

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It just stays the
same dimension.

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And the cork cells look
a little bit like that,

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and that's why they do that.

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So we have all these
natural materials.

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We talk a little about
the hierarchical structure

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in plants.

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The cell walls are
fiber composites,

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and then there's a
cellular structure.

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And plant materials have a
sort of hierarchical structure,

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with several different
levels of hierarchy,

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and we talk about that
in the class as well.

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And we talk a
little bit about why

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that makes these materials
mechanically efficient

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and how you might look
at designing engineering

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materials based on that.

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So there's a little bit of
biomimicking in the class

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as well.