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World’s most sensitive strain sensor can detect the weight of a feather

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June 4 (UPI) — Scientists have unveiled the world’s most sensitive strain sensor, capable of detecting the weight of a single feather.

The sensor is significantly more stretchable, capable of enduring 80 times greater strain than current commercial sensors, and is able to register resistance changes with 100 times the precision of current sensors, researchers said.

The new strain sensor — described Thursday in the journal Advanced Functional Materials — could be used to improve the sensitivity of a variety of medical and wearable devices.

“The next wave of strain sensing technology uses elastic materials like rubber imbued with conductive materials such as graphene or silver nanoparticles, and has been in development for over a decade now,” lead study author Marcus O’Mara, researcher at the University of Sussex, said in a news release.

“We believe these sensors are a big step forward,” O’Mara said. “When compared to both linear and non-linear strain sensors referenced in the scientific literature, our sensors exhibit the largest absolute change in resistance ever reported.”

According to Alan Dalton, study co-author and professor of experimental physics at Sussex, the device could be used to measure joint movements of an athlete or the vital signs of a hospital patient.

“Multiple devices could be used across the body of a patient, connected wirelessly and communicating together to provide a live, mobile health diagnostics at a fraction of the current cost,” Dalton said.

Researchers created the new strain sensor by carefully incorporating large amounts of graphene nanosheets into a matrix composed of the composite material polydimethylsiloxane, or PDMS.

According to the new study, PDMS is “biocompatible, elastic, transparent, durable, and has very minimal shrinkage on curing.”

PDMS is normally resistant to mixing, but researchers developed a novel process for incorporating graphene into the composite material — methods that researchers suggest could be used to develop other kinds of two-dimensional layered materials and polymer matrices.

Most strain sensors are limited in either their range or their sensitivity, but the latest strain sensor material is able to take on large amounts of strain while also registering tiny changes in strain.

“Nanocomposites are attractive candidates for next generation strain sensors due to their elasticity, but widespread adoption by industry has been hampered by non-linear effects such as hysteresis and creep due to the liquid like nature of polymers at the nanoscale which makes accurate, repeatable strain readouts an ongoing challenge,” said Sean Ogilvie, researcher fellow at Sussex.

“Our sensors settle into a repeated, predictable pattern which means that we can still extract an accurate read-out of strain despite these effects,” Ogilvie said.



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Ryugu’s rubble suggests its short life has been rather turbulent

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Sept. 21 (UPI) — The asteroid Ryugu is a loose assemblage of fragments from a collision between two asteroids, according to new research published Monday in the journal Nature Astronomy.

Some asteroids are composed of large, solid pieces of rock, but Ryugu is more like a rubble pile than a rock. It is too small and fragile to have remained intact for very long — scientists estimate Ryugu formed between 10 million to 20 million years ago.

“Ryugu is too small to have survived the whole 4.6 billion years of solar system history,” Seiji Sugita, professor of planetary sciences at the University of Tokyo in Japan, said in a news release. “Ryugu-sized objects would be disrupted by other asteroids within several hundred million years on average.”

“We think Ryugu spent most of its life as part of a larger, more solid parent body,” Sugita said. “This is based on observations by Hayabusa-2 which show Ryugu is very loose and porous. Such bodies are likely formed from reaccumulations of collision debris.”

For the latest study, scientists used images collected by Hayabusa-2 to identify the different types of rock on Ryugu. Researchers were able to uncover clues to the asteroid’s violent past by analyzing the ratios of different rock types.

“Ryugu is considered a C-type, or carbonaceous, asteroid, meaning it’s primarily composed of rock that contains a lot of carbon and water,” said postdoctoral researcher Eri Tatsumi. “As expected, most of the surface boulders are also C-type; however, there are a large number of S-type, or siliceous, rocks as well. These are silicate-rich, lack water-rich minerals and are more often found in the inner, rather than outer, solar system.”

The presence of siliceous rocks suggests Ryugu was formed from the rubble created by a collision between between a small S-type asteroid and a larger C-type asteroid.

“We used the optical navigation camera on Hayabusa2 to observe Ryugu’s surface in different wavelengths of light, and this is how we discovered the variation in rock types. Among the bright boulders, C and S types have different albedos, or reflective properties,” said Tatsumi.

Once Hayabusa-2 returns rock samples to Earth, scientists plan to compare the asteroids geochemical composition to meteorites samples found on Earth.

“This could in turn tell us something new about the history of Earth and the solar system as a whole,” Tatsumi said.



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Study highlights carbon sequestration services provided by U.S. forests

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Sept. 21 (UPI) — Forests in the United States currently sequester approximately three decades worth of carbon dioxide emitted by the American fossil fuel industry, according to a new a study.

What’s more, forests and harvested wood products uptake approximately 14 percent of economy-wide CO2 emissions in the United States annually.

Despite declining carbon emissions in the United States, the contribution of forests to emissions offsets has remained stable. This, researchers say, suggests the ability of U.S. forests to absorb new carbon — an ability driven largely by forest regrowth — is slowly declining.

To better understand the ability of afforestation and reforestation activities to improve carbon sequestration capabilities, researchers analyzed data from more than 130,000 national forest inventory plots.

The findings — published Monday in the journal Proceedings of the National Academy of Sciences — confirmed that there is potential for U.S. forests to capture and store more carbon.

Researchers used forest inventory plots to estimate the total carbon storage capabilities provided by forests in the United States. Their analysis showed each acre of forest in the United States stores nearly 700 metric tons of CO2. But the data also showed forests are underperforming.

“There are opportunities on existing forestland to increase the contribution of forests to climate change mitigation,” researchers wrote in their paper.

Researchers found nearly 82 million acres of productive forestland in the U.S. are understocked with trees, characterized by tree coverage of less than 35 percent.

“Currently, there is federal infrastructure to produce and plant approximately 65 million seedlings per year, and state and private capacity is approximately 1.1 billion tree seedlings per year,” researchers wrote.

These efforts sequester between 16 and 28 million metric tons of CO2 annually.

According to the study’s authors, concentrating tree-planting efforts on understocked forest acreage could significantly increase carbon sequestration capacity in the United States.



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Bobcat fire threatens historic Mount Wilson Observatory

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Sept. 21 (UPI) — Days after officials declared the historic Mount Wilson Observatory in Los Angeles County safe from an aggressive fast-moving blaze, firefighters on Monday were attempting to beat back the Bobcat fire as it attempted to work its way up the mountain.

The Angeles National Forest said Sunday that the fire, which has grown to be one of the largest in the county’s history, was “threatening all of the values” on Mount Wilson. Officials had said Friday said it was safe after crews deployed strategic firing to protect the iconic observatory in the San Gabriel Mountains.

Strong winds and low humidity overnight helped the blaze to grow a few thousand acres to 105,345 acres as of 8 a.m. Monday, the Angeles National Forest said in a statement. It was 15% contained.

Engines, hand crews and aircraft on Monday were deployed to the north side of Mount Wilson to extinguish spot fires, the service said.

“Bobcat fire is making a hard push at Mount Wilson,” the Angeles National Forest said on Twitter. “Defensive strategic operations are beginning from Mount Wilson to the west.”

Thomas Meneghi, the observatory’s executive director, told the Los Angeles Times, that on Sunday eight additional strike units were seen being dispatched to the area after it was deemed safe two days prior.

“Just when I thought the danger was over — it wasn’t,” he said.

The observatory said on its Facebook Page Monday evening that the fire has picked up and is making its way toward the Mount Wilson drainage on the northwestern slope.

The Times reported that it’s the second time the observatory, historic for its role in space exploration, has been under threat of fire with crews protecting it from the Station fire of 2009, which holds the title for the county’s largest blaze at some 160,000 acres.

Due to the Bobcat fire encroaching on communities, the Los Angeles County Sheriff’s Office issued evacuations orders Monday for those who live in south and west of Upper Big Tujunga and east and north of Angeles Forest Highway, while the Los Angeles County Office of Emergency Management ordered residents of Camp Colby to leave the area immediately.

“This warning has been upgraded to an evacuation ordered,” the service announced via Twitter. “If you are in the identified area GO NOW! EVACUATE.”

Los Angeles County Fire Chief Daryl Osby told reporters and residents during a virtual press conference Monday evening that firefighters “scratch and claw” to protect every property they can.

Osby said this year has been a record fire season for California, with thousands of firefighters battling some 27 blazes, but added “the scary thing about all this” is that the fire season for Southern California wasn’t near finished.

Cal Fire said more than 3.6 million acres have been burned in nearly 8,000 fires, resulting in 7,097 structures impacted and at least 26 deaths.

Gov. Gavin Newsom called the wildfire season “historic” in a press conference on Monday, stating that last year, there were only 5,316 fires burning some 157,000 acres.

The Democratic governor said evictions have forced 23,154 people from their homes, adding that more than 6,400 structures have been wholly destroyed.

Six major fires continue to burn in the state, he said, including the August fire, the largest in the state’s history at 846,000 acres, which was at 34% contained.

In Plumas and Lassen counties, the North Complex fire, the fifth-largest ever in the state at 294,000 acres was at 64% contained, compared to 36% on Wednesday.

The Creek fire, in Fresno and Madera counties, was the seventh-largest fire in state history, and was at 278,000 acres and contained at 27%.

Concerning the Bobcat fire, he said they were deploying as many resources as possible to battle the blaze.

“We’re putting all the resources we possibly can on all these complexes but focusing, as we should, on that Bobcat fire,” he said.

Nationally, 78 large fires have consumed some 3.9 million acres this season, according to the national interagency Fire Center.

In Oregon, the Department of Forestry said some 7,500 personnel have been assigned to 10 major fires in the state.

The state’s Office of Emergency Management has confirmed nine people have died in the fires and five people were missing as of Monday.

Some 1 million acres have been burned statewide, destroying 2,268 residences and an additional 1,556 instructions, it said in a statement.

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