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Slippery when wet: Fish, seaweed to help cargo ships reduce fluid friction

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Sept. 15 (UPI) — Shipping engineers are looking to fish and seaweed for new strategies to reduce fluid friction and help cargo ships slide through the ocean water.

To reduce drag, fish and seaweed secrete lubricants that form a slippery layer, helping their bodies move efficiently through the ocean.

Researchers suggest cargo ships could use a similar strategy by deploying lubricant-infused surfaces marked with cavities. By continuously filling the cavities with lubricant, a slippery layer is formed over the surface of the ship’s hull.

The strategy has been tested before, with success, but until now, researchers had not characterized the physics that make the fluid friction-reduction strategy work.

For the new study, published Tuesday in the journal Physics of Fluids, developed a model to simulate performance of different materials, lubricants and cavity designs.

The simulations showed lubricants spread more quickly when the open area of the cavities are larger. Simulations also showed the thickness of the cavity lids had little effect on the formation of the lubricant layer.

“Our investigation of the hydrodynamics of a lubricant layer and how it results in drag reduction with a slippery surface in a basic configuration has provided significant insight into the benefits of a lubricant-infused surface,” senior study author Hyung Jin Sung, mechanical engineer at the Korea Advanced Institute of Science and Technology, said in a news release.

In followup studies, researchers plan to test different lubricant setups on real life marine vessels.

“If the present design parameters are adopted, the drag reduction rate will increase significantly,” Sung said.

By reducing drag, ships could reduce fuel consumption and speed up shipping times.



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Rising atmospheric dust across the Great Plains recalls lead up to the Dust Bowl

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Oct. 13 (UPI) — Atmospheric dust levels are rising 5 percent per year across the Great Plains, according to a new survey by scientists at the University of Utah.

The research, published this week in the journal Geophysical Research Letters, increased cropland conversion and expanded growing seasons are exposing more and more soil and wind erosion.

Authors of the new study suggest the phenomenon, if combined with drier climate conditions as a result of climate change, could yield conditions comparable to the Dust Bowl, the series of droughts and dust storms that devastated the Midwest during the 1930s.

“We can’t make changes to the earth surface without some kind of consequence just as we can’t burn fossil fuels without consequences,” lead study author Andy Lambert said in a news release.

“So while the agriculture industry is absolutely important, we need to think more carefully about where and how we plant,” said Lambert, a recent graduate of the University of Utah.

In the 1920s, farmers across the Great Plains converted massive amounts of grassland to farm tracts. When drought hit in the 1930s, extensive crop failures left newly plowed fields exposed to the wind, yielding waves of dust storms.

“These dust storms removed nutrients from the soil, making it more difficult for crops to grow and more likely for wind erosion to occur,” Lambert said.

Soaking rains eventually brought an end to the Dust Bowl, but much of the damage caused by erosion was permanent. Soils in some parts of the Great Plains have never recovered.

Three-quarters of a century later, around 2000, as demand for biofuels increased, farmers started clearing additional grassland to biofuel feedstocks.

Between 2006 and 2011, nearly 2,050 square miles of grassland across five Midwestern states was converted to farmland. Meanwhile, droughts have become longer and more across the Great Plains.

To gauge the risk of dust storms in the region, researchers amassed data from a variety of instruments designed to measure atmospheric haziness from both the ground up and space down. The data, from NASA satellites and two federally managed ground monitoring systems, showed the amount of dust in the atmosphere above the Great Plains has steadily increased over the last 20 years.

“The amount of increase is really the story here,” said study co-author Gannet Hallar, associate professor of atmospheric sciences. “That 5 percent a year over two decades, of course, is a hundred percent increase in dust loading. This is not a small signal to find.”

Scientists were also able to link rises in dust levels with crop expansion. Across Iowa, atmospheric dust increased predominantly in June and October, the planting and harvesting months for soybeans, the dominant crop. Across the southern Great Plains, where corn is more popular, the dust increases appeared in March and October.

“I think it’s fair to say that what’s happening with dust trends in the Midwest and the Great Plains is an indicator that the threat is real if crop land expansion continues to occur at this rate and drought risk does increase because of climate change,” Lambert says. “Those would be the ingredients for another Dust Bowl.”

Authors of the new study said their findings should serve as a warning to farmers and policy makers across the Midwest that proactive measures are needed to ensure history doesn’t repeat itself.



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NASA’s Kate Rubins, 2 cosmonauts dock with International Space Station

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Tracy Caldwell Dyson pauses for a portrait in her spacesuit before going underwater in the Neutral Buoyancy Lab at NASA’s Johnson Space Center in Houston on July 8, 2019. Photo by Bill Ingalls/UPI



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Layered hybrid fibers could be used to build anti-viral masks, researchers say

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Oct. 14 (UPI) — Hybrid polymer fibers, featuring layers with different qualities, can be used for an array of biomedical applications, according to a new study in the journal Applied Physics Reviews.

Instead of searching for a single material that meets all the requirements of biomedical processes like tissue scaffolding, drug delivery and cardiac patching, authors of the new study suggest medical researchers utilize core-sheath polymer fibers — hybrid fibers featuring a strong core surrounded by a biologically applicable sheath layer.

“You want strength, but you also want bioactivity,” study co-author Mohan Edirisinghe said in a news release.

“So, if you align them in a core-sheath polymer, you have the strength of the core material, but the functionality comes from a bioactive polymer or ingredient that is in the sheath. That is a big advantage,” said Edirisinghe, a material scientist at University College London.

Because researchers can select from an array of materials to create the core-sheath fibers, the layered fibers could be used to meet a variety of biomedical applications, including the creation of antiviral mask materials.

“If you want to make a fibrous mask from a textile, you really need to have the strength, because you’re going to wash it and use it,” Edirisinghe said. “But on the other hand, you need an active material.”

Researchers suggest virus-fighting drugs or proteins could even be embedded in the fiber’s sheath layer during the manufacturing process.

Scientists have already augmented several fiber fabrication processes to create prototype core-sheath fibers.

One of the most promising methods involves embedding a vessel with a reservoir of the core material inside another vessel with a reservoir of sheath material. The reservoirs are released simultaneously through the vessel orifices, creating a bi-layered core-sheath fiber.

“This is just the tip of the iceberg, because this is just two reservoirs with two materials, which become the sheath and core layers of the fibers, but you can extend this to three or four,” Edirisinghe said. “In each layer, you can have a different drug that satisfies a different purpose.”



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