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Category: materials – Page 288

“Extreme Relic”–Merging Black Holes Illuminated

In the nearby Whirlpool galaxy and its companion galaxy, M51b, two supermassive black holes heat up and devour surrounding material. These two monsters should be the most luminous X-ray sources in sight, but a new study using observations from NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission shows that a much smaller object is competing with the two behemoths.

The most stunning features of the Whirlpool galaxy – officially known as M51a – are the two long, star-filled “arms” curling around the galactic center like ribbons. The much smaller M51b clings like a barnacle to the edge of the Whirlpool. Collectively known as M51, the two galaxies are merging.

At the center of each galaxy is a supermassive black hole millions of times more massive than the Sun. The galactic merger should push huge amounts of gas and dust into those black holes and into orbit around them. In turn, the intense gravity of the black holes should cause that orbiting material to heat up and radiate, forming bright disks around each that can outshine all the stars in their galaxies.

Self-healing, flexible electronic material restores functions after many breaks

Circa 2016

UNIVERSITY PARK, Pa. — Electronic materials have been a major stumbling block for the advance of flexible electronics because existing materials do not function well after breaking and healing. A new electronic material created by an international team, however, can heal all its functions automatically even after breaking multiple times. This material could improve the durability of wearable electronics.

“Wearable and bendable electronics are subject to mechanical deformation over time, which could destroy or break them,” said Qing Wang, professor of materials science and engineering, Penn State. “We wanted to find an electronic material that would repair itself to restore all of its functionality, and do so after multiple breaks.”

Self-healable materials are those that, after withstanding physical deformation such as being cut in half, naturally repair themselves with little to no external influence.

Talga reports positive test results on its graphene silicon Li-ion battery anode project

Talga Resources has revealed new test results on the ongoing optimization of its graphene silicon Li-ion battery anode product, Talnode™- Si. According to Talga, the battery anode product returns further performance gains, now delivering ~70% more energy density than commercial graphite-only anodes.

The product reportedly provides a “drop in” solution for improving current Li-ion battery performance. Commercial samples under confidentiality and material transfer agreements are scheduled to commence delivery around the end of February 2019 — recipients are said to include some of the world’s largest electronic corporations.

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Engineered metasurfaces reflect waves in unusual directions

In our daily lives, we can find many examples of manipulation of reflected waves such as mirrors to see our reflections or reflective surfaces for sound that improve auditorium acoustics. When a wave impinges on a reflective surface with a certain angle of incidence and the energy is sent back, the angle of reflection is equal to the angle of incidence. This classical reflection law is valid for any homogenous surface. Researchers at Aalto University have developed new metasurfaces for the arbitrary manipulation of reflected waves, essentially breaking the law to engineer the reflection of a surface at will.

Metasurfaces are artificial structures, composed of periodic arranged of meta-atoms at subwavelength scale. Meta-atoms are made of traditional materials but, if they are placed in a periodic manner, the surface can show many unusual effects that cannot be realized by the materials in nature. In their article published 15 February 2019 in Science Advances, the researchers use power-flow conformal metasurfaces to engineer the direction of reflected waves.

‘Existing solutions for controlling reflection of waves have low efficiency or difficult implementation,’ says Ana Díaz-Rubio, postdoctoral researcher at Aalto University. ‘We solved both of those problems. Not only did we figure out a way to design high efficient metasurfaces, we can also adapt the design for different functionalities. These metasurfaces are a versatile platform for arbitrary control of reflection.’

3D Printed Graphene Aerogel Enhances Supercapacitor Ability

Researchers are using 3D printing to develop electrodes with the highest electric charge store per unit of surface area ever reported for a supercapacitor.

A research collaboration from the University of California Santa Cruz and the U.S. Department of Energy’s Lawrence Livermore National Laboratory have 3D printed a graphene aerogel that enabled them to develop a porous three-dimensional scaffold loaded with manganese oxide that yields better supercapacitor electrodes. The recently published their findings in Joule. Yat Li, a professor of chemistry and biochemistry at UC Santa Cruz, explained the breakthrough in an interview with R&D Magazine.

“So what we’re trying to address in this paper is really the loading of the materials and the amount of energy we can store,” Li said. “What we are trying to do is use a printing method to print where we can control the thickness and volume.

3D Printed Graphene Aerogel Offers Highest-Ever Capacitance for a Supercapacitor

After what has seemed a bit of a lapse in the timeline of their development, graphene-enabled supercapacitors may be poised to make a significant advance. Researchers at the University of California, Santa Cruz, and Lawrence Livermore Laboratory (LLNL) have developed an electrode for supercapacitors made from a graphene-based aerogel. The new supercapacitor component has the highest areal capacitance (electric charge stored per unit of surface area) ever reported for a supercapacitor.

The 3D-printing technique they leveraged to make the graphene electrode may have finally addressed the trade-offs between the gravimetric (weight), areal (surface area), and volumetric (total volume) capacitance of supercapacitor electrodes that were previously thought to be unavoidable.

In previous uses of pure graphene aerogel electrodes with high surface area, volumetric capacitance always suffered. This issue has typically been exacerbated with 3D-printed graphene aerogel electrodes; volumetric capacitance was reduced even further because of the periodic large pores between the printed filaments.