Nanoscience in Nature

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Nanoscience in Nature

• Or
• Why Dont Water Striders Get Wet?
• and Other Burning Questions

By Jeannie Nye Lake Mills Middle School Lake
Mills, WI
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So, Why Dont Water Striders Get Wet?
Water striders are able to walk on water for a
number of reasons. Striders are assisted by five
things

• surface area
• gravitational forces
• surface forces (van der Waals force)
• a waxy (hydrophobic) surface on their legs

Tell me more! (Click here.)

• And most important -
  
• The microhairs on their feet are
• nano-groovy !

Tell me more!
Microhairs
Nanogrooves on microhairs
http//whyfiles.org/shorties/walk_on_water.html
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Surface Forces and Gravity are Important to the
Water Strider.
Sure they are! If, by chance, the water
strider did break the water tension and take a
plunge, it would not be able to dry off with a
bug-sized towel. At this size, surface adhesion
forces (van der Waals force) would keep the towel
stuck to the water strider. Besides, the water
strider could put on a bathing suit for it's dip
and it would never have to worry about the suit
coming off when it hit the water during a high
dive. First, because its so small, the water
strider would float gently down because the
frictional forces acting upon the water striders
surface overcome the weak influence of gravity at
this size. Also adhesion forces would keep the
suit on the strider for life. It would also be
impossible for the bug to read a book by the
pool, since once the pages were scaled down to
bug-size, surface adhesion would keep the pages
stuck together.
More information can be found on the web at
http//www.exploratorium.edu/ronh/bubbles/bubbles.
htm . Activities can be found at
http//www.lessonplanspage.com/ScienceExAddPennies
ToFullGlassMO68.htm or http//www.iit.edu/smile/p
h9205.html
http//invsee.asu.edu/nmodules/sizescalemod/unit4.
htm
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Nano-groovy Hair
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Sticky Spider Toes

• These are the single hairs (setae) that make
  up the tuft of hair on the bottom of a jumping
  spiders foot.
• The oval represents the approximate size of
  the foot magnified to 270x.

Water strider toes help keep it dry, but this
spiders toes help make him sticky!
This picture, magnified 8750x, shows the very
dense nanosized setules on the underside of just
one of those many seta (hairs) shown in the
picture above. http//www.primidi.com/2004/04/26
.html
Tell me more!
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Spider Toes

• Check out this jumping spiders foot. Jumping
  spiders use nanoscale structures, too! Below
  thicker hairs on this spiders leg are the
  nanoscale fibers that look like toes. These
  fibers are on the bottom of the spider's leg, and
  each individual hair is covered in more hairs.
  These smaller hairs are called setules. Because
  these setules are so small they can use van
  derWaals force to make the spider stick to
  surfaces. The van der Waals force acts between
  individual molecules that are within a nanometer
  of each other (about ten thousand times smaller
  than the width of a human hair.) What makes the
  van der Waals force an interesting form of
  adhesion is that, unlike many glues, the
  surrounding environment does not affect it. The
  only thing that affects it is the distance
  between the objects (in this case, setules and
  the surface).
• These nanofibers are small enough that the van de
  Waals force create a very high degree of
  waterproof, grease-proof, dirt-proof stickiness.
  When all 600,000 tips are in contact with a
  surface the spider can produce an adhesive force
  of 170 times its own weight. That's like
  Spiderman clinging to the flat surface of a
  window on a building by his fingertips and toes
  only, while rescuing 170 adults who are hanging
  onto his back!
• The total van der Waals force on the spider's
  feet is very strong, but since it is due to many
  very small forces on each molecule the spider can
  lift its leg so that the nanosized setules are
  lifted successively, not all at once. It doesnt
  need to be strong to do that.
• http//www.sciencedaily.com/releases/2004/04/0404
  26054407.htmhttp//www.primidi.com/2004/04/26.htm
  l

Spider leg
Hairy toe
Setules on one hair
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Lots of nano-toes!

• Beetles and flies also have nanostructures that
  help them stick to walls, ceilings and what
  appear to be smooth surfaces. Tell me more!

http//shasta.mpi-stuttgart.mpg.de/research/Bio-tr
ibology.htm
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Tribology
Tribology is the study of friction, lubrication
and wear. When applied to living organisms this
study is called bio-tribology.
Why do you think these nanostructures on my toes
are important in biotribology?
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How sticky? As sticky as a
Gecko?
http//pubs.acs.org/cen/critter/gecko.html
http//www.cbid.gatech.edu/resources.htm
If their feet are that sticky, how do they pick
up their feet?
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How Can a Gecko Lift Its Foot Off of a Surface?
These lizards uncurl their toes like a paper
party favor whistle when putting their feet down
and peel the toes back up as if removing a piece
of tape when they step away. http//pubs.acs.org/
cen/critter/gecko1.html
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How strong? As Strong as Silk?

• The nanometer-sized biodegradable threads of
  spider silk are stronger, by weight, than
  high-tensile steel.
• It is also elastic enough to stretch up to 10
  times its initial length.

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Toucan Beaks - Strong and Light

• The exterior of the toucan beak is made up of
  overlapping nanosized tiles of keratin, the same
  protein that makes up hair, fingernails, and horn.

Keratin tiles glued together
http//www.nuthatch.birdnature.com/jan1897/toucan.
html
The interior of the beak is a rigid foam made of
a network of nanosized bony fibers connected by
membranes. This allows the beak to absorb
high-energy impacts.
Foam-like interior made of bony fiber and
drum-like membranes
http//search.eurekalert.org/e3/query.html?qttouc
ancolev3relqcev3rel
http//pubs.acs.org/cen/news/83/i50/8350toucan.htm
l
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Nature uses Light on the Nanoscale
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What Makes Color?
There are three possible reasons for color

• One reason is pigment. If color is due to
  pigment, the color never changes.

For example, a bluejay is always blue. Though
pigment isnt based on nanoscience, the next two
examples of ways to create color are based on
nanoscience.
http//acept.la.asu.edu/PiN/rdg/interfere/interfer
e.shtml
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Or Could Color Be Nanoscopic?
These nanostructures dont just make me pretty.
They also keep me clean by shedding water and
dirt!
2. The colors of beetle and butterfly wings come
from the scattering of light. Light hits the
nanostructures on their scales. These
nanostructures are typically smaller than the
wavelengths of visible light (smaller than 400
nanometers, for example). Tell me more! (weblink)
http//pubs.acs.org/cen/critter/butterfly.html
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Color Can Be Iridescent,
Too!
3.The third reason for color is the interference
of different wavelengths of light (like oil on
water).
Thin films are made of
nanoparticles, smaller than 400 nanometers, that
produce iridescent (rainbow-like) colors when
light strikes them. Iridescent colors change
when you look at the object from different
angles. Tell me more! (weblink)
http//acept.la.asu.edu/PiN/rdg/interfere/interfer
e.shtml http//www.ptfe.gatech.edu/faculty/mohan/M
SLAB-research-nanobiooptics.htm
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Squid Lightson a Nanoscale
Would somebody turn on the lights, please?
The Hawaiian bobtail squid uses a two part
process to hide from predators at night.

• First, it has a light-producing organ on its
  underside. How does it produce light? Why, it
  contains bacteria that produce luminescent light
  on the nanoscale.
• Secondly, the squid has stacks of silvery
  nanoplatelets made of proteins behind the tissue
  to reflect the light downward from the squid.
• The light prevents it from casting a shadow when
  seen from above or forming a silhouette when seen
  from below.

http//pubs.acs.org/cen/topstory/8202/8202notw3.ht
ml
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You Light Up My Life orBioluminescence Basics

• Bioluminescence in fireflies is nanoscale. The
  glow is caused by the exciting of electrons by a
  fireflys enzyme.
• When the electrons quiet down and go back to
  their stable state, they give off light.
• They glow to attract mates and communicate.

Whats an enzyme?

• Angler fish use bioluminescent lures to attract
  fish.

http//pubs.acs.org/cen/science/84/8414biolum.html
http//www.anglerfish.info/
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A Blue Light Special

• Tiny crustaceans, Ostracods, also known as "seed
  shrimp" or "sea fireflies," also use this enzyme
  to produce bioluminescence in courtship. The
  males produce blue dots in the water, which are
  used to attract mates.

A close-up using a scanning electron microscope
http//www.pisces-conservation.com/index.html?soft
ost.htmlsoftebookmenu.html
http//pubs.acs.org/cen/science/84/8414biolum.html
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Jellyfish Lights
A jellyfish-type invertebrate, called a
siphonophore, uses red bioluminescent lures
created at the nanoscale to attract prey.
Doesnt it seem odd that it would use red light
since red isnt easily visible underwater?
Click here for a weblink to a video and lesson on
bioluminescent deep sea organisms.
http//www.coml.org/medres/high2005/highlightimage
s.htm
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Bioluminescence Lesson

• Theres an interesting, though high level, video
  clip at http//pubs.acs.org/cen/multimedia/84/biol
  um/Biolum_content.html
• NSTA provides a lesson on bioluminescence. It
  can be found at http//www.nsta.org/main/news/stor
  ies/science_scope.php?category_ID87news_story_ID
  52197

http//www.mbayaq.org/efc/living_species/default.a
sp?hOri0hab9inhab182
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Hippo Sweat is
Nanoscience?

• Hippo sweat contains compounds that absorb
  light in the range of 200 600 nanometers. This
  compound protects the hippos skin like sunscreen.

http//www.pbs.org/kratts/world/africa/hippo/index
.html
One of the compounds in hippo sweat,
hipposudoric acid, inhibits bacterial growth and
is hydrophilic, too. Can you think of ways the
hippo benefits from these properties?
http//pubs.acs.org/cen/news/8222/8222notw9.html
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Get Ready, Get Set, Drink!

• Imagine youre a very thirsty tiny beetle in a
  desert. How can you get a drink?
• The Namib desert beetle in the deserts of
  southwest Africa has a novel idea.
• First it must collect drinking water using its
  wings, which are waxed and covered with raised
  unwaxed nanobumps. The bumps attract water
  (hydrophilic). When enough water collects it
  rolls down the waxy areas, which repel water
  (hydrophobic), into the beetles mouth.
• Click here for more information!

http//www.newscientist.com/article.ns?iddn1508
A closeup of the nanobumps on a beetles back.
http//biomechanics.bio.uci.edu/_html/nh_biomech/n
amib/beetle.htm
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But How Does the Water Get to Its Mouth?

• Six times a year when the fog blows in from the
  Atlantic the Namib beetle turns a 45 degree angle
  to the wind so that the droplets of water from
  the fog stick to the unwaxed bumps on its back.
  This water builds up before rolling down the
  water-repelling waxed troughs on the beetle's
  back and into its mouth.

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Speaking of WaterLets Look at Snowflakes!

• Have you ever looked closely at a snowflake
• and wondered why theyre all different?

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Its Because Theyre Nano-Flakes!

• They build up on the nanoscale, one molecules
  at a time. Their size and shape is determined by
  the altitude and air pressure where they are
  formed.

Use the same bottom up construction to make your
own snowflakes by clicking on this web link
http//profhorn.meteor.wisc.edu/wxwise/snowflake/m
akesnow.html
For more information click on the following link
http//www.its.caltech.edu/atomic/snowcrystals/p
rimer/primer.htm
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Nanoscience Is Everywhere in Nature

• Living cells have been using their own nanoscale
  devices to create structures one atom or molecule
  at a time for millions of years.
• To be specific, DNA is copied, proteins are
  formed, and complex hormones are manufactured by
  cellular devices far more complex than the most
  advanced manufacturing processes we have today.

Click here for an example!
http//dallas.bizjournals.com/dallas/stories/2001/
09/10/focus2.html?page3
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Mighty Oaks from
Little Acorns Grow

• For example, an acorn uses the energy within it
  to read nanoscale DNA. The DNA is coded to
  sprout roots and leaves. These structures can
  gather more energy from the soil and the sun. The
  DNA tells the acorn to rearrange the atoms in
  soil, air and water to produce an oak tree, a
  material far more complex than today's material
  science can produce.

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Mother Nature
Mankind has always found inspiration in Mother
Nature. Today developingtechnologies allow us
to probe and better understand the nanoscience of
Mother Nature.