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Ricerca e Sviluppo (R&D)
Dan Cooper Offline
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#1
Ricerca e Sviluppo (R&D)
Penn Engineer’s ‘Metallic Wood’ Has the Strength of Titanium and the Density of Water

Citazione:...In a new study published in Nature Scientific Reports, researchers at the University of Pennsylvania’s School of Engineering and Applied Science, the University of Illinois at Urbana–Champaign, and the University of Cambridge have done just that. They have built a sheet of nickel with nanoscale pores that make it as strong as titanium but four to five times lighter.
The empty space of the pores, and the self-assembly process in which they’re made, make the porous metal akin to a natural material, such as wood...

Even the best natural metals have defects in their atomic arrangement that limit their strength. A block of titanium where every atom was perfectly aligned with its neighbors would be ten times stronger than what can currently be produced. Materials researchers have been trying to exploit this phenomenon by taking an architectural approach, designing structures with the geometric control necessary to unlock the mechanical properties that arise at the nanoscale, where defects have reduced impact.
Pikul and his colleagues owe their success to taking a cue from the natural world.
“The reason we call it metallic wood is not just its density, which is about that of wood, but its cellular nature,” Pikul says. “Cellular materials are porous; if you look at wood grain, that’s what you’re seeing — parts that are thick and dense and made to hold the structure, and parts that are porous and made to support biological functions, like transport to and from cells.”
“Our structure is similar,” he says. “We have areas that are thick and dense with strong metal struts, and areas that are porous with air gaps. We’re just operating at the length scales where the strength of struts approaches the theoretical maximum”...

[Immagine: 1*Dv0IDYWFrEJ1z5w188DC3A.jpeg]   PER INGRANDIRE
01-02-2019, 11:50 AM
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Dan Cooper Offline
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Messaggi: 5.155
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#2
RE: Ricerca e Sviluppo (R&D)
Unlocking Graphene’s Superconducting Powers with a Twist and a Squeeze

Citazione:Graphene has been heralded as a wonder material.
Not only is it the strongest, thinnest material ever discovered, its exceptional ability to conduct heat and electricity paves the way for innovation in areas ranging from electronics to energy to medicine
.
Now, a Columbia University-led team has developed a new method to finely tune adjacent layers of graphene—lacy, honeycomb-like sheets of carbon atoms—to induce superconductivity. Their research provides new insights into the physics underlying this two-dimensional material’s intriguing characteristics.
The team’s study is published in the Jan. 24 issue of Science.
“Our work demonstrates new ways to induce superconductivity in twisted bilayer graphene, in particular, achieved by applying pressure,” said Cory Dean, assistant professor of physics at Columbia and the study’s principal investigator. “It also provides critical first confirmation of last year’s MIT results—that bilayer graphene can exhibit electronic properties when twisted at an angle—and furthers our understanding of the system, which is extremely important for this new field of research”...

[Immagine: grapheneTH.jpg?itok=yVIw8543]
01-02-2019, 11:59 AM
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