Crystals grown in space may hold an important key for the improvement and development of the next generation of computers and communication systems. "Better crystals would improve LEDs, photo detectors, lasers, and wireless devices," says John Walker, a professor of mechanical and industrial engineering at the University of Illinois. He is one of several engineers and scientists working with the Marshall Space Flight Center—NASA's lead center for microgravity research in materials science that is developing alloy crystals. Alloy crystals are blends of germanium and silicon that have highly desirable thermoelectric and electro-optic properties, according to Walker. He explains that NASA, for example, is interested in the crystals for use as solar panels. "The only problem with alloy crystals is that they are so far impossible to grow on Earth because of the effects of gravity. Germanium generally sinks to the bottom of the melt in the crucible because it's three time heavier than silicon," explains Walker. He says that gravity destroys the homogeneous concentration in the crystal. "On Earth, gravity presses the liquid against the walls of the container, resulting in the formation of faults, dislocations, and contact stresses in the growing crystal." The ingredients do not separate in the absence of gravity, which is why Walker proposes growing the crystals on the International Space Station. The pencil-thin crystals would be grown in special ampules within the magnetic damping furnaces on the space station. Walker wants to reproduce them on Earth. Contact Walker at (217) 333-7979.
Two different shape-shifting polymers have been announced from two different universities: Wyss Institute at Harvard University and Zhejiang University in eastern China. Both of them change their shapes when immersed in water, and the one from Wyss Institute was made with 3D-printing techniques.
When you think of the DARPA Robotics Challenge, you may imagine complex humanoid contraptions made of metal and wires that move like a Terminator Series T-90. But what actually happened at the much-vaunted event was something just a bit different.
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