If you read from a backlit screen just before going to bed you may be harming your sleep. Researchers at Rensselaer Polytechnic Institute tested the effects of self-luminous tablets on melatonin suppression. Their study showed a connection between two hours of use of a backlit tablet before sleep and reduced melatonin. That could affect the quality of sleep. Melatonin's produced at night and in the dark, and its suppression has been implicated in sleep disturbances. The study suggests that reducing screen brightness can help avoid reduced melatonin.


MOLECULES AWEIGH: Scientists at the California Institute of Technology have created a mechanical device that can measure the mass of individual molecules one at a time. This ability could help doctors study viruses and diagnose diseases. The nanoscale device uses a tiny, vibrating bridge-like structure. When a molecule lands on the bridge, its mass changes the oscillating frequency in a way that reveals how much the particle weighs. The device uses standard, semiconductor fabrication techniques, so it's easy to mass-produce. Next goal: weighing atoms? California Institute of Technology details.


UNDERSEA MINING: One way to get the uranium needed for nuclear fuel plants is to dig it out of the ground. But it turns out the world's oceans are full of the stuff too — 4.5 billion tons of it. US researchers used mats of braided plastic fibres, embedded with uranium-absorbent amidoxime, to capture trace amounts of uranium from 200 metres down in the ocean. After the mats are drawn up they're washed in an acidic solution that captures the radioactive metal for refining. Extracting uranium from the ocean is five times as expensive as mining it from land. They should find a way to attach the material to shipping, or even fishing nets to get uranium as a sort of by-catch. New Scientist has further info.

SOFT LIKE A ROCK: DARPA's Maximum Mobility and Manipulation programme is working on a new low-cost silicone robot that can change its appearance to match the background, and hide in plain sight. The soft robot uses microfluidic channels for actuation, camouflage, display, fluid transport and temperature regulation. Air and various fluids allow it to change its colour, contrast, apparent shape and temperature to blend in with its environment. That means it can hide whether against a plain background or something like rocks. The robot currently needs 30 seconds to change colour. You'll never see it heading your way. DARPA elaborates. Check out the video.

STRAIGHT SHOOTING: Physicists at Harvard University have created a silicon and gold flat lens that's only 60 nanometres thick. Lenses are usually thicker in some parts than others, which can create distortion in a signal that passes through them. The flat lens scales from near-infrared to terahertz wavelengths, and is simple to manufacture. Precisely tuned V-shaped structures on the lens capture incoming light and hold onto it briefly before releasing it again. That changes the direction of the light, but without aberrations. That sounds like it could be handy in conjunction with lasers. Harvard University has the details.

Miraz Jordan,