Stories tagged light

May
22
2014

Scientists at University of California Berkeley have been able to use carbon nanotbues to create light activated "smart curtains" that respond automatically to light without batteries. The curtain material can bend or straighten in response to the flick of a light switch.

To create the smart curtain, carbon nanotubes are layered onto a plastic polycarbonate membrane. The carbon nanotubes absorb light, convert the light into heat, and then transfer the heat to the plastic membrane surface. The plastic responds to the heat by expanding, but the carbon nanotubes do not, causing the two-layered material to bend blocking the light.

To read more about this research visit:
https://newscenter.berkeley.edu/2014/01/09/smart-curtains/

Diagrams of Smart Curtains:
http://www.nature.com/ncomms/2014/140107/ncomms3983/fig_tab/ncomms3983_F...

Link to Smart Curtains YouTube video:

See video

To learn more about nanotechnology, science, and engineering, visit:
www.whatisnano.org

To see other nano stories on Science Buzz tagged #nano visit:
http://www.sciencebuzz.org/buzz_tags/nano

Growing nanowires horizontally yields "Nano-LEDs

Nano light emitters: Single row of nanowires (cylinders with red tops) with fin-shaped nanowalls extending outward (National Institute of Standards and Technology)
Nano light emitters: Single row of nanowires (cylinders with red tops) with fin-shaped nanowalls extending outward (National Institute of Standards and Technology)Courtesy NIST
These “nano-LEDs” may one day have their light-emission abilities put to work serving miniature devices such as nanogenerators or lab-on-a-chip systems. NIST.gov

In recent work published in ACS Nano,* Nikoobakht and Herzing increased the thickness of the gold catalyst nanoparticle from less than 8 nanometers to approximately 20 nanometers. The change resulted in nanowires that grew a secondary structure, a shark-like “dorsal fin” (referred to as a “nanowall”) where the zinc oxide portion is electron-rich and the gallium nitride portion is electron-poor. The interface between these two materials—known as a p-n heterojunction—allows electrons to flow across it when the nanowire-nanowall combination was charged with electricity. In turn, the movement of electrons produced light and led the researchers to dub it a “nano LED.”

Jewel  bug colors
Jewel bug colorsCourtesy arquera
Georgia Tech scientists provided a detailed explanation of how the jeweled beetle Chrysina gloriosa creates the striking colors using a unique helical structure that reflects light of two specific colors.

A cholesteric liquid crystalline material, which self-assembles into a complex arrangement of polygonal shapes each less than 10 microns in size, causes interference within reflected light resulting in bright green light with a wavelength of 530 nanometers mixed with yellow light in a wavelength of 580 nanometers.

Learn more by reading this Georgia Tech news release.

Learn more about the blackest black ever

Two researchers, Eduard Driessen, MSc, and Dr Michiel de Dood, have demonstrated that at a thickness of 4.5 nanometer niobiumnitride (NbN) is ultra-absorbent. They have recorded a light absorption of almost 100%, while the best light absorption to date was 50%. Science Daily

Click here to access the research paper "the perfect absorber" in American Institute of Physics. (3pg PDF)

Jul
11
2008

Spiral galaxy M81: The black hole in the center of this galaxy is 70 million times as massive as the Sun, but it behaves exactly the same as much, much smaller black holes.
Spiral galaxy M81: The black hole in the center of this galaxy is 70 million times as massive as the Sun, but it behaves exactly the same as much, much smaller black holes.Courtesy X-ray: NASA/CXC/Wisconsin/D.Pooley & CfA/A.Zezas; Optical: NASA/ESA/CfA/A.Zezas; UV: NASA/JPL-Caltech/CfA/J.Huchra et al.; IR: NASA/JPL-Caltech/CfA

This may fall under the heading of small comfort, but a new study has shown that all black holes, big or small, suck in matter in the same way. Using NASA’s Chandra X-ray observatory, astronomers studied the different types of light (X-ray, radio and visible) emanating from the region around a massive black hole in the center of galaxy M81. They found that this light was the same as light coming from smaller black holes, even though this one is some 10 million times bigger, and is sucking in matter from a different source. This confirms a part of Einstein’s theory of relativity, which predicted that black holes would be fairly simple objects, not subject to a lot of variation. Which doesn’t really help much if you find yourself getting sucked in, but at least you know it’s nothing personal.

You can learn more about Chandra and X-ray astronomy in our Be an Astronomer! web exhibit. And you can ask questions of Megan Donahue, a scientist who work with the Chandra observatory.

Plasma lights

by Gene on Jun. 25th, 2008

A California company has developed a new type of light bulb, the size of a breath mint, that pumps out as much light as a street lamp. The bulb is twice as efficient as an LED, and 10 times as efficient as an incandescent light. It also produces a full spectrum of light frequencies, illuminating objects in true color.

May
13
2008

You'd be blue, too: Compact fluorescent light bulbs save energy, but come with a number of problems.
You'd be blue, too: Compact fluorescent light bulbs save energy, but come with a number of problems.Courtesy Tiago Daniel

We’ve written before about compact fluorescent light bulbs – a new type of bulb you can buy for your home that uses a lot less electricity than standard bulbs, and thus reduces pollution and greenhouse gas emissions. But are they all they’re cracked up to be?

Some environmental groups warn that the bulbs contain mercury, which can be toxic and difficult to clean up in the event of a broken bulb.

Researchers in England claim the bulbs can trigger migraines, epilepsy and lupus.

And a review panel assembled by the New York Times concluded that most CFL bulbs do not give off attractive light.

Though a step in the right direction, clearly there are still some bugs to work out of the bulbs.

Nov
04
2007

An invisible tank: Right in front of that other tank.  (photo courtesy of wikimedia commons)
An invisible tank: Right in front of that other tank. (photo courtesy of wikimedia commons)
Great Britain has been making some progress in the field of “ways to kill people with out them seeing you do it.” In the past, we had to be satisfied with impersonal methods like booby traps and poisoning, but, with the help of science, before long we should be able to safely view our own nefarious deeds - while hiding in plain sight! Sort of.

The UK’s Ministry of Defense has recently unveiled a prototype “invisible” tank, and predicts that similar models will be ready for service (the service of blowing things up! Yeah!) by 2012.. Unlike a lot of other invisibility research, which often focuses on bending light around an object, the invisi-tank (as I like to call it) relies on “cameras and projectors to beam images of the surrounding landscape onto the tank.” I’m not sure if these cameras and projectors are on the tank itself, or nearby. That’s probably a secret.

A soldier who was present at the trials was quoted as saying, "This technology is incredible. If I hadn't been present I wouldn't have believed it. I looked across the fields and just saw grass and trees - but in reality I was staring down the barrel of a tank gun."

It is also believed that the Ministry of Defense is “testing a military jacket that works on the same principals.”

I recommend that you take a look at the original article. The picture of the scientist in charge of the project is great. He completely redefines the stereotypical image of a scientist. Oh wait, no, I mean he reinforces it.

Nov
02
2007

Nanotechnology sometimes borrows from nature.

Morpho butterfly: Pigments don’t cause these butterflies’ intense colors. Instead, super-small lattice-like structures on the wings reflect only certain wavelengths of light (or color). And the colors shift with your perspective. (Photo courtesy Lionoche, through Flickr)
Morpho butterfly: Pigments don’t cause these butterflies’ intense colors. Instead, super-small lattice-like structures on the wings reflect only certain wavelengths of light (or color). And the colors shift with your perspective. (Photo courtesy Lionoche, through Flickr)

Super-small, light-reflecting structures—instead of pigments—create a morpho butterfly's intense, iridescent wing color. Scientists are developing nanomaterials with similar properties.

Zoom in on a butterfly's wing
Zoom in on a butterfly's wing

If you used a special microscope to look at these butterfly wings, you’d see tiny scales made up of thin layers of transparent wing material with nanoscale gaps between them. Light waves bouncing off the bottom surfaces interfere with waves reflecting from the tops. Most light waves are cancelled and only certain wavelengths—or colors—bounce back to your eyes. The more light in the environment, the brighter the color.

Wing structures: These complicated structures on butterfly wings manipulate light to control the color that we see.
Wing structures: These complicated structures on butterfly wings manipulate light to control the color that we see.

How do transparent thin films create color?: Scientists haven't yet created materials that work exactly like the butterfly wings. But layers and layers of transparent, super-thin films--each with a different index of refraction--can be tuned so that they only reflect specific wavelengths of light (o
How do transparent thin films create color?: Scientists haven't yet created materials that work exactly like the butterfly wings. But layers and layers of transparent, super-thin films--each with a different index of refraction--can be tuned so that they only reflect specific wavelengths of light (o

Scientists are developing all sorts of products that, like the butterfly wings, use layers of transparent materials with nanoscale spacing between them to manipulate light and create color. With them, we can create computer and cell phone displays, fabrics and paints that change color, optical devices that improve telecommunications systems, and films that reflect much more light than glass mirrors. Can you imagine other uses?

We've discussed energy-saving compact fluorescent lightbulbs elsewhere on this blog. Now, Popular Science magazine has a round up of the next generation in low-energy lighting technology.