April 22, 2019
Magnets are probably on of the most fascinating things in existence. Apparently, magnets behave like fluid when they come in contaxct with a laser. Who knew?! Magnets are so cool.
Learn about this and more interesting stories from the scientific community in today's issue.
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*-- When zapped with a laser, magnets behave like fluids --*
Scientists have managed to figure out how a magnet manages to recover after being demagnetized by a brief laser blast. The discovery suggests lasers make magnets behave like fluids.
When an ultra thin magnet is hit with a laser, it suddenly becomes demagnetized.
Materials with magnetic properties feature subatomic building blocks all spinning in the same direction. There is order to the organization of the magnet's particles -- a laser blast disrupts this order.
Scientists have previously detailed the atomic chaos that ensues in the wake of the laser strike. And researchers know what a magnet looks like once it's reorganized. The recovery process, which lasts just a fraction of a second, has, until now, remained poorly understood.
"Researchers have addressed what happens 3 picoseconds after a laser pulse and then when the magnet is back at equilibrium after a microsecond," mathematician Ezio Iacocca, researcher at the University of Colorado, Boulder, said in a news release. "In between, there's a lot of unknown."
In the lab, researchers blasted gadolinium-iron-cobalt alloys with lasers. They compared the results of their experiments with computer simulations designed to predict the behavior of laser-blasted atoms.
The mathematical formulas describing the atoms showed the magnetized particles behave like a fluid in the wake of a laser blast. The material, or magnet, itself doesn't become fluid-like, but the atomic spins behave like a fluid. The spin directions of the magnet's atomic units slosh around like ocean waves.
"We used the mathematical equations that model these spins to show that they behaved like a superfluid at those short timescales," said Mark Hoefer, researcher at CU Boulder.
Researchers shared the results of their analysis this week in the journal Nature Communications.
If the surface of a calm pond on a windless day represents a magnet and its atomic spins, all perfectly synchronized, a laser blast is like a big rock tossed into the middle. Slowly but surely, the violent splash that results turns into gentle ripples, and soon enough, the surface of the pond is glassy smooth again.
Hoefer likens the phenomena to a jar of oil and water that gets shaken. Once the shaking stop, bits of oil start to coalesce, forming larger and larger clumps until the oil and water are separated once more.
"In certain spots, the magnet starts to point up or down again," Hoefer said. "It's like a seed for these larger groupings."
Sometimes magnets reorganize their spins in the opposite direction after a disruption. Computer engineers take advantage of spin flips when they store information on computer hard drives. If scientist could find a way to engineer magnets capable of flipping their spins faster, they might be able to boost computer processing speeds.
"That's why we want to understand exactly how this process happens, so we can maybe find a material that flips faster," Iacocca said.
*-- Solar evaporator to enable cheaper small-scale desalination technology --*
The development of a new type of solar evaporator promises to power a new generation of cheaper and more efficient small-scale desalination technology.
Roughly a billion people are without access to clean water. Desalination can help turn salt water into potable fresh water, but for many water-starved people and places, the technology is both impractical and prohibitively expensive.
Thankfully, engineers at the University of Maryland have created a cheaper, more efficient evaporator, a critical component for cost-effective desalination.
The wooden evaporator uses interfacial evaporation to generate steam with the energy of the sun. The component is inexpensive, eco-friendly, portable and efficient.
"These features make it suitable for off-grid water generation and purification, especially for low-income countries," Liangbing Hu, associate professor of materials science and engineering, said in a news release.
Interfacial vaporators work by absorbing heat from above and pulling salt water up from below. Water evaporates from atop the thin, floating layers, leaving salt behind.
Scientists built their evaporator of thin layers of basswood, which boasts tiny channels that carry water and nutrients up the tree trunk. Researchers drilled additional millimeter-wide channels. To encourage absorption of solar energy, scientists carbonized the top of the wooden layer using high heat.
The tiny channels in the basswood help draw up saltwater, as well as return salt to the solution below after the water on top evaporates. The wood is also self-cleaning.
Their creation showed great promise in lab tests.
"In the lab, we have successfully demonstrated excellent anti-fouling in a wide range of salt concentrations, with stable steam generation with about 75 percent efficiency," said lead researcher Yudi Kuang.
Scientists described their invention this week in the journal Advance Materials. Researchers are now working to pair the evaporator with a steam condenser in order to create a working desalination device.