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MessagePosté le: Dim 30 Sep - 10:02 (2018)    Sujet du message: www.teamnuggetsshop.com Répondre en citant

by Zou Huitong, Chen Yanbei

LOS ANGELES, Nov. 2 (Xinhua) -- Almost all materials expand as temperature increases. A new lightweight metamaterial may provide a new way to construct sustained infrastructures and improve our lives, a materials scientist told Xinhua on Monday.

Common materials have the property of "positive thermal expansion," meaning when heated, they expand. In the past, railway tracks are built with separate parts. There are "thermal gaps" between neighboring components. The gap serves as a buffer zone, so that the components would not squeeze into each other and make the whole construction deformed. Although the welded tracks we see now have been stretched in advance before being installed, they are still under the risk of buckling.

A new 3D-printed lightweight material may provide a solution: engineers from USC, MIT, UCLA and Lawrence Livermore National Laboratory (LLNL) successfully made it shrink when heated. The result was recently published in the journal Physical Review Letters.

This new material is what scientists call a "metamaterial," a composite material with custom-designed structure not normally found in nature. It is made from a lattice with star-shaped structures, and incorporates two separate materials with different, but positive, thermal expansion coefficients and elastic properties. One is a stiff, slow-to-expand copper-containing material, the other a more elastic, fast-expanding polymer substance.

Although proposed theoretically in the mid-1990s, these structures have only been produced now using 3D printing technology, in particular a new technique, named "microstereolithography," by the Fang Lab at MIT. Researchers plan to explore new 3D printing technologies so that they can create structures with more than two materials.

Ultimately, the limitations of the current 3D printing technology would be the biggest challenge facing scientists to further exploration. As the printer requires the material to be in certain forms (e.g. liquefied, powdered, etc.), how to synthesize new materials that can be used in 3D printing technology is the first problem to tackle. "This is the part where we need the help from chemists." Wang said.

For application that requires materials to resist thermal expansion rather than shrink with increasing temperature, scientist have two approaches. "One is to combine this material with negative thermal expansion with those with positive thermal expansion, while the other is to improve the design of the currently shrinking structure," Qiming Wang, an assistant professor at the University of Southern California, told Xinhua.

Zero expansion materials can improve our lives. Traveling by railways will be safer, bridges and other infrastructures will be more sustained, computers will perform better with more stable microchips as those are in use today whose performance are currently hampered by rising temperatures during long-time use.

"In terms of dental filling," Dr. Wang said, "optimally put, if we manage to find biocompatible material, which means that it would not cause conflicts with human bodies, consumers can expect to witness those materials being put in practical use in the near future and the new material will be affordable to ordinary people."
Niu Ben Lei Kesheng (left) and Kenneth Tsang Chin Han
The popularity and commercial success of the first season of Where Are We Going Authentic Scott Darling Jersey , Dad? last year proved that the conflicts and interesting stories arising from sending people of different generations on a trip could make for a successful reality series. As usual in the entertainment industry, after the success of this show a number of similar shows began to be produced by TV stations around the country, not only about parents traveling around with their children Authentic Elias Lindholm Jersey , but also middle-aged women traveling with young idols in this spring's Divas Hit the Road, and the current summer show Grandpas over Flowers.

Broadcasting every Sunday since June 15 on Shanghai Media Group's Dragon TV, Grandpas over Flowers is the Chinese version of the hit South Korean show that features aging stars traveling around with a younger star as their guide to different countries on a shoestring budget.

The first season of the show covers a 16-day trip to France and Switzerland and features actors Chin Han (6Cool from Taiwan Authentic Brock McGinn Jersey , Kenneth Tsang (79) from Hong Kong, Lei Kesheng (7Cool from Shandong Province, Niu Ben (79) from Tianjin and Liu Ye (36) as their guide.

While a trip to these countries sounds wonderful Authentic Sebastian Aho Jersey , unlike other travel shows, the four seniors have to face harsh challenges due to a tight budget and multiple language barriers, which lead to numerous surprises and even some accidents. However Authentic Justin Williams Jersey , this just makes the program even more tense and interesting, making it the center of hot discussion on the Internet.

For instance, in the episode broadcast on July 27 Authentic Jordan Staal Jersey , the four seniors ran into a bit of danger when they became stuck in an elevator. For over 30 minutes, the entire shooting staff did nothing to aid the men, only informing them that the elevator had run into trouble. This incident led to huge discussions online about whether the crew was acting responsibly by just sitting there and watching the four aging men suffer from oxygen deprivation.

Despite the occasional controversy ratings for the show have been good. The first episode received a 0.9 in viewership ratings Authentic Noah Hanifin Jersey , while episode 6 earned the highest rating of 1.1 against other TV programs shown during the same period.

Just what is the appeal of this show featuring four old men, three of whom are nearly 80? Although they were once the Prince Charmings of their age, they have now become white-haired and wrinkled old men.

In an article on 52hbtv Teuvo Teravainen Jersey , a new media website run by Hubei TV, critic Huang Xinliang wrote that although the show features aging actors, it doesn't give a feeling o. Cheap Jerseys China   Cheap Jerseys   MLB Jerseys China   Cheap Jerseys   Football Jerseys Wholesale   Soccer Jerseys Wholesale   New NHL Jerseys Wholesale   Wholesale Soccer Jerseys   Wholesale NHL Jerseys Cheap   Wholesale New NFL Jerseys 


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