Wednesday 30 March 2016

Trigger for Milky Way's youngest supernova identified

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Scientists have determined the likely trigger for the most recent supernova in the Milky Way. They applied a new technique that could have implications for understanding other Type Ia supernovas, a class of stellar explosions that scientists use to determine the expansion rate of the Universe.
via Science Daily
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How supermassive black holes and galaxies formed from collapsing gas clouds in the early universe

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Simulations have revealed for the first time exactly how these black holes formed 700 million years after the Big Bang.
via Science Daily
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Titan's tallest peaks: Towering mountain discovered on Saturn's largest moon

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In a nod to extraterrestrial mountaineers of the future, scientists have identified the highest point on Saturn's largest moon, Titan.
via Science Daily
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Map of rocky exoplanet reveals a lava world

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The most detailed map of a small, rocky 'super Earth' to date reveals a planet almost completely covered by lava, with a molten 'hot' side and solid 'cool' side.
via Science Daily
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Integral sets limits on gamma rays from merging black holes

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Following the discovery of gravitational waves from the merging of two black holes, ESA’s Integral satellite has revealed no simultaneous gamma rays, just as models predict.


via ESA Space Science
http://www.esa.int/Our_Activities/Space_Science/Integral_sets_limits_on_gamma_rays_from_merging_black_holes

NGC 6188 and NGC 6164

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Graphene wrinkles weakest point

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Graphene is hailed as a top material for technology due to its electrical, optical, and mechanical properties. Its high carrier mobility, optical transparency and tensile strength yield an unprecedented combination of properties favorable for applications ranging from high-speed electronics to construction. However, even with its high durability and flexibility, graphene can break when pulled at large forces, or due to friction when rubbed against. It is important to know the limits of wear resistivity when considering applications of this material. Now researchers from Graphenea and the Institute of Physics in Belgrade have shown that wear and breaking of graphene always start from wrinkles formed naturally during fabrication. The results were published in the journal Carbon.

Using atomic force microscopy (AFM), researchers scanned a very sharp needle probe across the surface of graphene. By gradually increasing the contact force that the probe exerts on graphene, effectively increasing friction until the surface ripped, the scientists observed that tears always start from the wrinkles. Wrinkles are out-of-plane deformations of graphene that probably occur during the transfer of graphene from its growth substrate to a practical substrate such as SiO2. The experiments were performed with CVD graphene.

Aside from wrinkles, CVD graphene contains naturally occurring terraces, which form because graphene conforms to the terraces of the copper substrate during CVD growth. It was shown that terraces have no effect on wear resistance.

Image: Graphene topography and local current flow. Current is reduced at the position of wrinkles.

Electric measurements with nanometer-scale resolution, using the same AFM method, further showed that no current is conducted through wrinkles, and that islands enclosed by wrinkles have different electrical potential compared to the surrounding area, indicating that wrinkles impede electrical conductance in graphene. This is an important finding, because technological applications in electronics require efficient transport of carriers across graphene devices.

This careful study of electrical and mechanical effects of wrinkles in graphene is expected to lead to new experiments on improving graphene uniformity and flatness, helping to speed up the adoption of graphene technology.


via Graphenea

Return of the LHC – season 2 continues