As the weather turns spring-like, winter's ice build-up on power lines, windshields, and airplane wings becomes a fading memory. Professor Victor Petrenko, of Thayer School of Engineering at Dartmouth College (Dartmouth, NH), hopes to keep it that way. The physicist discovered that applying a small electric voltage across an ice-metal interface can break the bond between ice and metal surfaces. Technically, Petrenko says, ice is a semiconductor--included in a small class of substances in which protons, rather than electrons, carry an electrical current. When an electrically-charged surface comes into contact with any other surface, the charged surface induces an opposite charge in the facing surface and, because opposites attract, the two surfaces are drawn together. "This simple attraction accounts for most of ice adhesion," says Petrenko. Breaking the bond between ice and metal, he reasoned, should be as simple as neutralizing the surface charge with an equal amount of its opposite. He tested his theory using a sheet of ice, a globule of mercury--which stays liquid until temperatures dip below -40F--and a small battery with two wires attached. He touched one wire to the ice, the other to the mercury. The mercury drew itself up and away from the ice. Petrenko repeated the experiment using steel and other solid metals. In each case, the electricity caused the ice to lose adhesion. The effect could also be reversed, causing a surface to stick more firmly to the ice. "It may be possible to prevent or significantly reduce icing on the wings of an airplane using a battery no bigger than the one in your car," Petrenko theorizes. Surface-to-surface interactions are also important in manufacturing and machinery. Call: (603) 646-2117.
Enabling the Future is designing prosthetic appendages modeled more like superhero arms and hands than your average static artificial limbs. And they’re doing it through a website and grassroots movement inspired by two men’s design and creation in 2012 of a metal prosthetic for a child in South Africa.
In order to keep an enterprise truly safe from hackers, cyber security has to go all the way down to the device level. Icon Labs is making the point that security has to be built into device components.
Three days after NASA's MAVEN probe reached Mars, India's Mangalyaan probe went into orbit around the red planet. India's first interplanetary mission, and the first successful Mars probe launched by an Asian nation, has a total project cost of nearly $600 million less than MAVEN's.
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