September 16, 2019
Here's something that cool as it is scary... sicentists have created a new "smart skin" that's color-changing much like a chameleons. We're getting into strange new tech, much like that monster guy in that
movie with Arnold Schwarzenegger. Cool and scary.
Learn about this and more interesting stories from the scientific community in today's issue.
*-- Contest yields new technologies for finding natural gas leaks --*
As detailed in a study, the participants in Stanford University's Mobile Monitoring Challenge have developed a variety of technologies for finding natural gas leaks.
Though a "challenge" by name, the effort yielded no winners. Most participants focused on very specific aspects of mobile gas detection, like how to pinpoint the precise location or size of a methane leak. Participants developed technologies for trucks, drones and airplanes.
"The technologies are generally effective at detecting leaks, and can act as a first line of defense," Adam Brandt, an associate professor of energy resources engineering, said in a news release. "Gas system operators will often want to confirm leaks with conventional optical gas imaging systems, but these mobile technologies usually tell you where to look for leaks very quickly."
Traditional optical gas imaging systems must be deployed by people. Two workers can typically use imaging systems to identify leaks at four to six wells per day. It's a time consuming and costly way to detect leaks.
Mobile technology can help gas companies monitor leaks cheaper and more efficiently.
Scientists at Stanford detailed the results of the Mobile Monitoring Challenge this week in the journal Elementa: Science of the Anthropocene.
Eight of the nine technologies successfully located natural gas leaks more than 75 percent of the time. Five of nine found leaks 90 percent of the time, even when leaks were especially small. One of the drone-based gas detection technologies found 100 percent of leaks with no false positives.
"This is only the first step to demonstrating that these technologies could help reduce emissions on a level equivalent to existing approaches," Brandt said. "The tests were run in the spring of 2018, and I'm sure most -- if not all -- of these technologies have been improved since then."
Previous studies have suggested methane leaks at natural gas wells are underestimated. The natural gas is to blame for as much as 25 percent of global warming. In 2016, the U.S. Environmental Protection Agency took steps to ramp up natural gas monitoring efforts and reduce methane emissions. Last month, the agency reversed course, rolling back regulations for methane emissions.
"The recent U.S. EPA announcement about rolling back methane regulations is not just bad for the environment, but also deprives oil and gas communities of high-paying, local jobs that these innovative technology companies could create," said Arvind Ravikumar, lead study author. "Rolling back the regulations could stifle development of these technologies."
While some of the technologies produced by challenge participants focused on pinpointing small leaks, two teams of researchers developed technologies designed to find big leaks quickly. Research suggests just a handful of "super emitters" are responsible for majority of methane emissions in the United States.
*-- New color-changing smart skin inspired by chameleons --*
Scientists have managed to create new "smart skin" that changes color but doesn't change size, just like a chameleon.
Researchers have previously created color-changing smart skin, but scientists have struggled to develop smart materials that stay the same size. The new smart skin reacts to heat and light, changing color, without altering its volume.
"Watching a chameleon change colors gave me the idea for the breakthrough," study author Yixiao Dong, a doctoral candidate in chemistry at Emory University, said in a news release. "We've developed a new concept for a color-changing smart skin, based on observations of how nature does it."
Photonic crystals in a chameleon's skin help the lizard change its appearance to better blend in with its surroundings. For some time, scientists have been trying to create similar photonic crystals.
"Scientists in the field of photonic crystals have been working for a long time to try to create color-changing smart skins for a range of potential applications, such as camouflage, chemical sensing and anti-counterfeiting tags," said Khalid Salaita, senior study author and a professor of chemistry at Emory. "While our work is still in the fundamental stages, we've established the principles for a new approach to explore and build upon."
Some fish species use similar crystals to change their appearance. The crystals are not pigment filled, but they are patterned in a way that allows some wavelengths of light to pass through and become absorbed, while causing others to be reflected. Changes in the spacing of the crystals or in lighting conditions can alter which wavelengths are absorbed and which are reflected.
Traditionally, scientists have embedded various photonic crystal arrays into flexible, water-containing polymers, or hydrogels, to create smart skin. When the polymer expands or contracts, the pattern of crystals changes, altering the material's appearance. But constant expansion and contraction can lead to structural instabilities.
"I wanted to understand why a chameleon doesn't get bigger or smaller as it changes color, but remains its original size," Dong said.
While watching videos of chameleons changing colors, Dong noticed that only parts of the lizard's skin are covered by patterns of photonic crystals. The patterns are interspersed with patches of dark skin. Dong realized the dark matrix adjust to compensate for changes in the patterns of crystals, helping the chameleon's skin maintain its size.
"I wondered if we could design something similar -- a composite structure of photonic crystal arrays embedded into a strain-accommodating matrix," Dong said.
In the lab, researchers used magnets to arrange iron oxide-based photonic crystals in a layer of hydrogel. Next, scientists embedded the arrays into a second non-color-changing hydrogel. Scientists designed the second hydrogel to accommodate the movement of the crystal arrays.
In lab tests, the skin successfully changed color in response to heat without altering its size. The smart skin, which scientists cut into the shapes of fish and leaves and took outside, also changed from orange-to-green in reaction to sunlight -- and without changing size.
The research team described their breakthrough this week in the journal ACS Nano.
"We've provided a general framework to guide the future design of artificial smart skins," Dong said. "There is still a long way to go for real-life applications, but it's exciting to push the field another step further."
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