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Category: materials

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 printer with all the advantages of previous technologies while eliminating known drawbacks such as expensive lasers, slow 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.

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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 .

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A Monash University study revealing new spin textures in pyrite could unlock these materials’ potential in future spintronics devices.

The study of pyrite-type provides new insights and opportunities for selective spin control in topological spintronics devices.

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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.

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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.

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Superhydrophobic materials, which are excellent at repelling water, can be extremely useful for a whole range of reasons, both obvious and not-so-obvious. They can prevent ice from building up on surfaces, make electronics waterproof, make ships more efficient or keep people from peeing in public. Now engineers have found a quirky new use for superhydrophobic materials – making “unsinkable” metals that stay floating even when punctured.

Superhydrophobic materials get their water-repelling properties by trapping air in complex surfaces. These air bubbles make it hard for water to stick, so droplets instead bounce or roll right off. But, of course, air also makes things buoyant, so the team set out to test how superhydrophobic materials could be used to make objects that float better.

The researchers used ultra-fast laser pulses to etch microscale and nanoscale patterns onto the surfaces. That traps large volumes of air, making the metals both superhydrophobic and buoyant. But the problem was that these complex surfaces would eventually wear away due to friction in the water, reducing the effectiveness of both of those properties.

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Trillions of plastic fragments are afloat at sea, which cause large “garbage patches” to form in rotating ocean currents called subtropical gyres. As a result, impacts on ocean life are increasing and affecting organisms from large mammals to bacteria at the base of the ocean food web. Despite this immense accumulation of plastics at sea, it only accounts for 1 to 2 percent of plastic debris inputs to the ocean. The fate of this missing plastic and its impact on marine life remains largely unknown.

It appears that sunlight-driven photoreactions could be an important sink of buoyant plastics at sea. Sunlight also may have a role in reducing plastics to sizes below those captured by oceanic studies. This theory could partly explain how more than 98 percent of the plastics entering the oceans go missing every year. However, direct, experimental evidence for the photochemical degradation of marine plastics remains rare.

A team of scientists from Florida Atlantic University’s Harbor Branch Oceanographic Institute, East China Normal University and Northeastern University conducted a unique study to help elucidate the mystery of missing plastic fragments at sea. Their work provides novel insight regarding the removal mechanisms and potential lifetimes of a select few microplastics.

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