Category Archives: Science Magazine

Multifaceted Menace

Mosquitoes can walk on water as well as any waterbug, or stick to a wall like Spiderman. Now Chinese bioengineers are figuring out what makes them such versatile pests.

A team led by C. W. Wu at the Dalian University of Technology in China mounted a mosquito‘s leg on a needle and pushed it down onto a tub of water on a digital balance. By varying the angle, they found that a single leg could hold 23 times a mosquito‘s weight before becoming submerged, they report in July’s Physical Review Letters.

Scanning electron microscope images revealed that the insect’s legs are equipped with tiny scales, each with up to a dozen longitudinal ridges connected by fine transverse ribs. The scientists speculated that air trapped between the ribs may form “nanocushions” that contribute to buoyancy, but their experiments also indicated the importance of the angle of the leg in not breaking through the surface. As the authors note, mosquitoes are equally at home on dry land. It turns out that their feet are equipped with tiny hooks and covered in adhesive hairs similar to those on a fly.

Mathematician David Hu of New York University notes that understanding water-repellent nanostructures will be useful for anyone who wants to make an all-terrain robotic insect. “If it’s ever going to fly in the rain, water repellency is going to be important.”

Originally appeared in Science Magazine as a Random Sample: [html] [pdf]

Work Out, Chow Down

Heavy snacking after exercise may have little to do with hunger or appetite hormones. In a new study, people who rode a bike for an hour ate more for lunch than those who just sat around ate, despite similar levels of hunger and short-term appetite-suppressing hormones. The urge to gobble after exercise, it turns out, may be a more complicated mixture of psychology and body chemistry. Continue reading

Country Cooking

A wood-burning stove that uses sound to generate electricity and refrigeration could one day make waves in developing countries. That’s the hope of an international team headed by engineer Paul Riley of the University of Nottingham in the United Kingdom. This month, the U.K. government and the U.S.’s Los Alamos National Laboratory in New Mexico awarded the team almost $4 million to develop a Stove for Cooking, Refrigeration, and Electricity (SCORE). The appliance would rely on external combustion, such as a wood fire, to heat one end of a tube of compressed gas, inducing sound waves that can be harnessed to generate enough electricity to power a light bulb and a small refrigeration unit.

The principle isn’t new, but the technology has been too expensive for general use, says thermoacoustician Steven Garrett of Pennsylvania State University in State College. The SCORE team hopes to make it cost-effective with cheaper materials: Compressed air could replace high-pressure helium, for example. “If anybody can pull this off, it’s got to be these guys,” says Garrett. The device may not cut down on wood consumption, but tests suggest that it will make use of up to 30% of a wood fire’s energy, much more than a typical stove’s 7% efficiency.

Originally appeared in Science Magazine as a Random Sample: [html] [pdf]

A Swift Understanding of Flight

Robotic aircraft of the future, used for reconnaissance or communication, may need to rely on wing morphing, a trick mastered ages ago by birds for long flights. By measuring how ultraversatile swifts morph their wings to double their gliding time or triple their turn rate, researchers have given both biologists and engineers a greater understanding of the secrets of efficient flight.

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