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In a new study an international research team led by the University of Vienna has shown that structures built around a single layer of graphene allow for strong optical nonlinearities that can convert light. The team achieved this by using nanometer-sized gold ribbons to squeeze light, in the form of plasmons, into atomically-thin graphene. The results, which are published in Nature Nanotechnology are promising for a new family of ultra-small tunable nonlinear devices.

In the last years, a concerted effort has been made to develop plasmonic devices to manipulate and transmit light through nanometer-sized devices. At the same time, it has been shown that nonlinear interactions can be greatly enhanced by using plasmons, which can arise when light interacts with electrons in a material. In a plasmon, light is bound to electrons on the surface of a conducting material, allowing plasmons to be much smaller than the light that originally created them. This can lead to extremely strong nonlinear interactions. However, plasmons are typically created on the surface of metals, which causes them to decay very quickly, limiting both the plasmon propagation length and nonlinear interactions. In this new work, the researchers show that the long lifetime of plasmons in graphene and the strong nonlinearity of this material can overcome these challenges.

In their experiment, the research team led by Philip Walther at the University of Vienna (Austria), in collaboration with researchers from the Barcelona Institute of Photonic Sciences (Spain), the University of Southern Denmark, the University of Montpellier, and the Massachusetts Institute of Technology (USA) used stacks of two-dimensional materials, called heterostructures, to build up a nonlinear plasmonic device. They took a single atomic layer of graphene and deposited an array of metallic nanoribbons onto it. The metal ribbons magnified the incoming light in the graphene layer, converting it into graphene plasmons. These plasmons were then trapped under the gold nanoribbons, and produced light of different colors through a process known as harmonic generation. The scientists studied the generated light, and showed that, the nonlinear interaction between the graphene plasmons was crucial to describe the harmonic generation.

Mushroom buildings! 😃

Using mycelium, Bay-area designer Phil Ross creates an 6X6 arch out of mushroom roots turned into bricks, and he wants to build a house next.

We are doubling the mass of the human-made, ‘anthropogenic’ part of the world every 20 years. The entire planet Earth could be converted to human uses within the next several centuries if this trend continues.

Researchers have observed three-dimensional magnetic vortex rings in a real-world magnetic material for the first time. Contrary to theoretical predictions, these rings – which are spin configurations within the material’s bulk – are remarkably stable and could move through the material like smoke rings move through air. If such movement can be controlled, they might have applications in energy-efficient 3D data storage and processing.

In a ferromagnetic material, the spatial distribution of the local magnetization is responsible for the material’s magnetic properties. These spatial distributions can be very complex, and intricate magnetic “textures” are behind many modern technologies, including hard disk drives. A vortex is one such distribution, and it forms when the material’s magnetization circulates around a central core.

Vortex rings are more sophisticated still, and occur naturally in physical systems such as fluids, plasmas and turbulent gases in the Earth’s atmosphere. However, while they have long been predicted to exist in ferromagnets, they have never been observed there until now.

It seems even curtains are getting an upgrade. 😃

These intelligent curtains are printed with a material called PCM (Phase Changing Material) that absorbs heat and releases it when needed.

Potholes may soon reach the end of the road, as an Oxfordshire village hosts the first UK trial of a graphene-based wonder material designed to prevent cracks forming.

Graphene is a super-strong material made of specially-structured carbon.

Continue reading “Graphene is being used to surface a road in Oxfordshire” »

Thin glass-polymer sheet increases passive radiative cooling.

A new metamaterial film provides cooling without needing a power input. Made out of glass microspher.

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It’s the two highly problematic trends, that the study relates here, that are important: The comparatively slow, but long-term, continuous human-induced reduction of the global biomass stock vis-à-vis the exponentially growing anthropogenic (human-made) mass,” Krausmann said by email. “Better knowledge about the dynamics and patterns of anthropogenic mass, and how it is linked to service provision and resource flows is key for sustainable development. The big question is how much anthropogenic mass do we need for a good life.

The year 2020 could be the year when human-made mass surpasses the overall weight of biomass — estimated to be roughly 1,100,000,000,000 tons, or 1.1 teratons — a milestone scientists say speaks to the enormous impact that humans have had on the planet.

The analysis was published Wednesday in the scientific journal Nature, and was conducted by a group of researchers from Israel’s Weizmann Institute of Science.

Continue reading “Human-made materials may now outweigh all living things on Earth, report finds” »