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NanoDays 2008
A FREE event for families!
Gateway to Science participated in a NanoDays event, along with science centers around the country, to highlight the many applications of nanotechnology. The event was held April 5, 2008 from 1-4PM.
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Liquid Metals
Understand that nano-scale structure of amorphous metals determines their elasticity.
The atomic structure of a solid material is extremely important in determining its physical and chemical properties. A typical metal is polycrystalline , meaning that it is made up of many small crystalline grains (i.e chunks) that are stuck together. Each grain consists of a single ordered crystalline arrangement of atoms.
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Seeing Scale
Appreciate the magnitude of different metric scales as required to see objects at each level. Various visualization tools allow us to make observations that we may not see with the naked eye.
Observation of objects in nature at the nano-scale has inspired new technologies for consumer goods. For example, butterflies with iridescent wings (not monarchs) have nanostructures called photonic crystals that reflect light and regulate temperature. Scientists are now developing manmade photonic crystals that could provide thermal protection for humans in extreme environments.
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Anti-bacterial Silver
Understand that the increased surface to volume ratio of nano-scale particles can enhance chemical reactivity.
The anti-bacterial properties of silver have long been recognized. In ancient times, people stored food and drink in silver containers to prevent spoiling; more recently, newborn infants received silver drops in their eyes to fight infection. Nano-silver is being applied to many commercial products including socks, washing machines, and band-aids, as well as to food storage containers.
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Environmental Clean Up
Understand how the size and chemistry of nano-iron enables it to be used for groundwater detoxification.
Treating polluted areas with nano-iron is a new method of environmental remediation based on nanotechnology. Nano-iron is made up of particles of zero valent iron (iron in its metallic state) that are approximately 100nm in size. The iron is treated with a noble metal catalyst that speeds up its ability to reduce or donate electrons to other compounds. Iron's reducing power is shown in this demonstration through its reaction with the deep blue colored starch/iodine. When starch/iodine is reduced by iron, the color disappears.
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Carbon NanoTubes
Carbon nanotubes (CNTs) are allotropes of carbon with a nanostructure that can have a length-to-diameter ratio greater than 10,000,000.
These cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat.
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Exploring Ferrofluid
Ferrofluid is a unique magnetic material that acts like a liquid. Ferrofluid is made of nano-sized particles of magnetite suspended in a liquid.
Ferrofluid is superparamagnetic, a property that is found only at the nanoscale. At the macroscale, ferromagnetic materials (like refrigerator magnets) are permanently magnetic. But when ferromagnetic materials are nano-sized, they become paramagnetic, which means that they behave like magnets only in the presence of a magnetic field.
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Exploring Reactions
Small things have a greater surface area to volume ratio than larger things do. Some things that aren't reactive at all in big pieces are very reactive when they're tiny. Steel wool catches fire but you can't easily light a lump of metal on fire!
The greater reactivity of small things is important in nanotechnology because it means that nano-sized things react much more easily and quickly than they would if they were larger.
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Exploring Forces
At the nanoscale, different physical forces and material properties dominate. If you were nano-sized, you'd hardly notice gravity. Instead, you'd be concerned with how bumpy, shaky, and sticky the nano-landscape is.
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Exploring Solutions
Nanoscale science focuses on the building blocks of our world, atoms and molecules. Scientists use special tools and equipment to detect and manipulate tiny, nano-sized particles.
In the field of Nanotechnology, scientists and engineers make new materials and tiny devices. Nanotechnology allows scientists and engineers to make things like smaller, faster computer chips and new medicines to treat diseases like cancer.
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Exploring Liquid Crystals
Liquid crystals represent a phase in between liquid and solid. The molecules in a liquid crystal can move independently, as in a liquid, but remain somewhat organized, as in a crystal (solid).
A material acts differently when it's nano-sized than it does when it's bigger. Nanotechnology takes advantage of the special properties at the nanoscale to create new materials and devices. Liquid crystals are being used to create nanosensors - tiny, super-sensitive devices that react to changes in their environment. Liquid crystal nanosensors can detect certain chemicals, electrical fields, and changes in temperature.
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Reversible Sunglasses
Understand how nano-scale switches in molecular structure can make plastic lenses darken in ultraviolet light.
The most common use of photochromic dyes today is in eyeglass lenses. These are often referred to as "Transitions" lenses, after the well-known brand of the same name. The first photochromic lenses were popularized in the 1960s and made of glass. Glass lenses used the reversible reaction of a silver salt compound to change color. Modern photochromic lenses are made from plastic coated with photochromic molecules that reversibly change their structure when exposed to different wavelengths of light.
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Exploring Measurement
A nanometer is a billionth of a meter.
You might think a freckle or a strand of hair is pretty small, but they're many, many times bigger than a nanometer. That's why it takes special tools to make and study nano-sized things. Regular macro-sized tools, like scissors and your fingers, are too big.
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Invisible Sunblock
Understand how nano-scale particles are used in mineral sunblocks to increase their transparency.
Nanoparticles used in sun blocks are some of the most extensively researched topics in nanotechnology. The words 'sunblock' and 'sunscreen' are used interchangeably although they technically refer to two different types of sun protectants. Sun blocks refer to sun protectants that contain minerals such as zinc oxide or titanium dioxide. They block about 99% of UV radiation but non-nano formulations are opaque in nature and users rarely apply the amount recommended for effective protection as a result. Sunscreens refer to chemically based sun protectants, few of which individually protect against both UV-A and UV-B radiation and are usually combined into broad-spectrum products. Typically chemical sunscreens tend to be more popular than mineral sun blocks, even though mineral sun blocks are better at blocking UV radiation and are better for the skin because they do not degrade.
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Stain Resistant Fabric
Understand how the nano-scale construction of Nano-Tex fabric results in its stain-resistant properties.
The invention of Nano-Tex fabric was inspired by the observation of the water-repellant and self-cleaning properties of the leaves of the lotus plant. Two factors are central to this natural phenomenon: physical structure and chemistry. First, the surface cells form dense microstructures that look like round spikes. These tiny structures decrease the contact area between the leaf and a water droplet and create a cushion of air that minimizes absorption. Second, the lotus leaf microstructures are covered in nano-scale wax crystals which are hydrophobic and therefore repel water.
Nano-tex fabric is produced by immersing cotton in a water-based suspension of nano-whiskers (rough, hydrophobic molecules). The soaked fabric is then heated so the water evaporates, leaving the nano-whiskers to form a chemical bond with the cotton fibers. As a result, this treatment is much longer lasting than other stain-proofing treatments that merely coat the surface of the fabric without bonding.
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