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This graphic shows a molecular robot (automaton) in action. To tag cells (grey circle) that display the Mi, Mj, and Mk receptors, five different components of a molecular robot are deployed. Each of the first three components consists of DNA and an antibody; one antibody binds to each receptor, bringing its DNA (represented by the colored lines) close together on the cell. The fourth DNA component, represented by the single red line, then initiates a chain reaction by pulling the red DNA strand away from the first antibody. That causes the blue DNA strand to change position, followed by the green DNA strand. In the final step, the last antibody pulls a fluorescent DNA strand (labeled F) from the fifth component, completing the action of the robot.

A star is born

A new ScienceCast video anticipates the reversal of the sun's global magnetic field.

http://science.nasa.gov/science-news/science-at-nasa/2013/05aug_fieldflip/

Gray Scale Mona Lisa

This graphic depicts a device created using "negatively refracting metamaterials" that could bring advances in applications including sensing, imaging, data storage, solar energy and optics. Purdue researchers are working on a range of options to overcome a fundamental obstacle in commercializing the materials. The small spheres at right represent a lattice of "meta-atoms" carefully designed and fabricated to produce a high-performance device.

The dye-sensitized solar cell (DSC) converts light to electricity. A coloured copper complex absorbs light and injects an electron into a semiconductor. This electron then passes around a circuit, does work, and is eventually returned to the copper to regenerate the dye by a transport system. In this new work, the cobalt complex acts as an electron transport agent between the cathode and the dye molecules allowing the photocurrent to flow.

Created with the help of supercomputers, this still from a simulation shows the formation of a massive galaxy during the first 2 billion years of the universe. Hydrogen gas is gray, young stars appear blue, and older stars are red. The simulation reveals that gas flows into galaxies along filaments akin to cosmic bendy, or swirly, straws.

Shown is an experimental photodetector made out of amorphous silicon and molybdenum disulfide (MoS2). The two semiconductors together form a high speed photodetector.