Molecules/Matter & Energy

Sticky graphene, dried-up coffee, a panda pregnancy test and more in this week's news

Graphene glue
Graphene, a sheet of carbon only one atom thick, is unusually sticky. The energy required to peel it from a surface is 10,000 times that of a typical micromechanical structure, a new study finds. Steven Koenig and colleagues at the University of Colorado Boulder calculated carbon’s ability to adhere by covering holes in a piece of silicon oxide with graphene patches, using gas to increase the pressure inside the holes and measuring the shape of the patches blistering outward. The stickiness may be due to graphene’s remarkable flexibility, which allows it to behave much like a liquid coating a surface, the researchers report in an upcoming Nature Nanotechnology. —Devin Powell

Coffee-cup Tetris
Rings of coffee on tabletops are even messier than you think. Particles in drying java compete in a microscopic game of Tetris, now revealed by high-speed footage of plastic particles in an evaporating drop. At first, an outward flow carries the particles slowly, stacking them neatly like bricks. But as more liquid evaporates, the flow speeds up. Eventually, the particles rush to the edge too quickly to arrange themselves, forming a second chaotic ring inside the first. The results could explain why thin films are often difficult to grow by evaporation, researchers at the University of Twente in the Netherlands report in an upcoming Physical Review Letters. —Devin Powell

Panda pregnancy test
A pee-on-a-stick pregnancy test may soon be available for giant pandas. Conservation scientists have found that levels of the protein ceruloplasmin rise in the urine of pregnant pandas and stay high until a few weeks before birth. Until now, a noninvasive technique for discerning true panda pregnancies from pseudopregnancies, which are common in pandas, has eluded scientists, but ceruloplasmin levels reliably distinguish between pandas that are pregnant, not pregnant or have miscarried, researchers report online July 13 in PLoS ONE. The new data, gathered from pandas at zoos in Memphis, Atlanta, San Diego and Washington, D.C., could also aid reproduction efforts for other endangered captive bears, such as polar bears. —Rachel Ehrenberg

Sniffing out sea lampreys
The come-hither perfume released by male sea lampreys could help researchers track the invasive fish, which threaten native fish populations throughout the Great Lakes. Even with suction cup mouths, saw-like teeth and a proclivity for blood sucking, sea lampreys still manage to get some action: Female lampreys can’t resist the compound known as 3kPZS, which males release when they are ready to mate. Minute quantities of 3kPZS are detectable in water of infested streams during spawning season, scientists report in an upcoming Environmental Science & Technology. The find suggests that the scent may be useful for conservation management, say the Michigan State University researchers. —Rachel Ehrenberg

Motorized minihairs
Just four ingredients and a bit of mixing is enough to generate tiny motorized hairs that build themselves and beat in sync. The engineered hairs mimic cilia, hairlike structures that clear goop from the body’s airways and help single-celled critters move. While it takes more than 600 proteins to build life’s version of cilia, mixing together some minimotors, stringy proteins and a dash of polyethylene glycol prompts self-assembly of the motorized hairs, researchers from Brandeis University in Waltham, Mass., report in the July 22 Science. Bundles of the hairs spontaneously get their beat on, oscillating together just like native cilia. —Rachel Ehrenberg

Go, go magnet sponge
A new metal sponge contracts in the presence of a magnetic field, squeezing out molecules absorbed when the magnetic field was absent. Scientists in Japan and Singapore embedded nanoparticles of cobalt and palladium in a carbon-sulfur skeleton. This airy structure soaked up loads of nearby goodies (in this case nitrogen), until the team exposed the sponge to a magnetic field. Then the metal nanoparticles became irresistibly attracted to each other and the sponge contracted, expelling its contents, the team reports in an upcoming Journal of the American Chemical Society.Rachel Ehrenberg

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