An der TU Wien wurde ein neuartiges Material entwickelt, das aus Temperaturunterschieden sehr effizient elektrischen Strom erzeugt.
Category: materials – Page 262
For years, physicists have assumed that Cooper pairs, the electron duos that enable superconductors to conduct electricity without resistance, were two-trick ponies. The pairs either glide freely, creating a superconducting state, or create an insulating state by jamming up within a material, unable to move at all.
But in a new paper published in Science, a team of researchers has shown that Cooper pairs can also conduct electricity with some amount of resistance, like regular metals do. The findings describe an entirely new state of matter, the researchers say, that will require a new theoretical explanation.
“There had been evidence that this metallic state would arise in thin film superconductors as they were cooled down toward their superconducting temperature, but whether or not that state involved Cooper pairs was an open question,” said Jim Valles, a professor of physics at Brown University and the study’s corresponding author. “We’ve developed a technique that enables us to test that question and we showed that, indeed, Cooper pairs are responsible for transporting charge in this metallic state. What’s interesting is that no one is quite sure at a fundamental level how they do that, so this finding will require some more theoretical and experimental work to understand exactly what’s happening.”
Researchers have developed a new printer that produces digital 3D holograms with an unprecedented level of detail and realistic color. The new printer could be used to make high-resolution color recreations of objects or scenes for museum displays, architectural models, fine art or advertisements that do not require glasses or special viewing aids.
“Our 15-year research project aimed to build a hologram printer with all the advantages of previous technologies while eliminating known drawbacks such as expensive lasers, slow printing speed, limited field of view and unsaturated colors,” said research team leader Yves Gentet from Ultimate Holography in France. “We accomplished this by creating the CHIMERA printer, which uses low-cost commercial lasers and high-speed printing to produce holograms with high-quality color that spans a large dynamic range.”
In The Optical Society (OSA) journal Applied Optics, the researchers describe the new printer, which creates holograms with wide fields of view and full parallax on a special photographic material they designed. Full parallax holograms reconstruct an object so that it is viewable in all directions, in this case with a field of view spanning 120 degrees.
A combined team of researchers from Lawrence Livermore National Laboratory in the U.S. and Atomic Weapons Establishment in the U.K. has found that rapidly compressing lead to planetary-core type pressures makes it stronger than steel. In their paper published in the journal Physical Review Letters, the group describes how they managed to compress the metal so strongly without melting it.
Defining strength in a material is difficult. Strength can refer to a material’s ability withstand bending or breaking under certain conditions. Making things even more complicated is that the strength of any given material can change under varying conditions—such as when heat or compression are applied. In this new effort, the researchers showed just how difficult it can be to nail down how strong a material is—in this case, lead.
Lead is not very strong. Pressing a fingernail against a car’s battery terminal is enough to create indentations, for example. But the researchers with this new effort report that the metal can be strengthened considerably by exerting extreme pressure.
A Monash University study revealing new spin textures in pyrite could unlock these materials’ potential in future spintronics devices.
The study of pyrite-type materials provides new insights and opportunities for selective spin control in topological spintronics devices.
Graphene, the super-strong, super-light and super-conductive material that was discovered in 2004 is often described as the material of the future. But it might be just the beginning.
In the Marshall Islands, locals have a nickname for the Runit Dome nuclear-waste site: They call it ‘The Tomb’.
The sealed pit contains more than 3.1 million cubic feet (87,800 cubic meters) of radioactive waste, which workers buried there as part of efforts to clean hazardous debris left behind after the US military detonated nuclear bombs on the land.
From 1977 to 1980, around 4,000 US servicemen were tasked with cleaning up the former nuclear testing site of Enewetak Atoll. They scooped up the contaminated soil, along with other radioactive waste materials such as military equipment, concrete, and scrap metal.
Not an endorsement of this; But interesting concept and claims for a graphene coat.
An all-around graphene-based 3-layer jacket: Breathable, Waterproof, Ultralight & Durable + state-of-the-art technology.
We could essentially control water at the coast lines with magnetism keeping it from eroding things.
Fuel-efficient ships that produce no wakes could soon be a reality thanks to computer simulations of “water cloaks” done by two researchers in the US. Yaroslav Urzhumov and Dean Culver of Duke University have shown that ions present in ocean water can be accelerated by electromagnetic waves in such a way that any turbulence created by sea-going vessels is cancelled out. Their work offers new opportunities for creating ships with greater propulsion efficiency – and could also be used to make vessels that are harder to detect.
“This cloaking idea opens a new dimension to create forces around an underwater vessel or object, which is absolutely required to achieve full wake cancellation,” says Urzhumov.
Guiding waves
Initial ideas for a water cloak were based on developing a specially designed metamaterial to coat the hulls of ships. Metamaterials are more common in optics and acoustics and comprise structures that can bend light or sound waves in ways not possible with conventional materials. In 2011, Urzhumov and colleagues hoped to develop a porous material interspersed with a complex network of miniscule pumps, to act as a metamaterial for guiding water waves. It was hoped that the system could cancel-out any turbulence caused by a moving vessel.
Innovative nanosheets made from equal parts of hydrogen and boron have a greater capacity to store and release hydrogen compared with conventional metal-based materials.