Molecules/Matter & Energy

How to fold a paper bag, plus good apples and designer silk in this week’s news

Shopping bag origami
Folding a tall paper bag to lie perfectly flat is a problem that seems easy, but has only just been solved by a pair of engineers at Oxford University. Weina Wu and Zhong You’s shopping bag origami, tested in simulations and on actual physical bags, uses a special crease pattern to collapse such a container in a T shape that folds flat. In a paper appearing in the March 30 Proceedings of the Royal Society A: Mathematical and Physical Sciences, they write that assembly line robots should be able to handle the technique, which could be useful for shipping large quantities of packed bags or boxes. —Devin Powell

FLATTER Tall shopping bags and boxes can now be folded perfectly flat for packing, thanks to a new origami-like crease pattern shown above. Zhong You


Designer silks
All silks are not created equal — the fiber can be especially stretchy, strong or have different optical properties depending on what fraction of its protein chains are in a twisted, pleated conformation. Now researchers have developed a simple, environmentally friendly technique to control the amount of pleated protein within silkworm silk, making it possible to spin fibers with specific properties that might be used to engineer tissues or make biomedical devices. Tweaking the temperature of water vapor used to anneal the silky fibers regulates the amount of pleated proteins, David Kaplan of Tufts University in Medford, Mass., and colleagues report online March 22 in Biomacromolecules. —Rachel Ehrenberg

Apples are good for you
Everyone knows that an apple a day keeps the doctor away; but scientists are still exploring how the fruit works its wonders. In mice infected with H1N1 virus, extracts from red Fuji apples boosted the number of immune system cells and improved survival rates, a team of Chinese scientists has found. Apples are chock-full of polyphenols, friendly compounds known for scavenging damaging molecules that roam the body. Mice that were fed the apple extract seemed to clear out the damaging molecules better than mice who didn’t get the apple elixir, the research teams reports in an upcoming Journal of Agricultural and Food Chemistry. —Rachel Ehrenberg

Hope for the sweets addict
Ghrelin, a hormone that contributes to strong feelings of hunger, can foster intense cravings for sweets, leading to overconsumption of them — at least in rats, a Scandinavian study shows. When the researchers administered a drug to block the cellular protein into which the hormone normally docks, the rodents cut their intake of sugar and saccharin. The finding confirms suspicions that ghrelin activates reward sensors in the brain, something that could foster an unhealthy desire for sweets, the scientists report online March 23 in PLoS One. Their data also point to a new target for drugs to treat addictive eating. —Janet Raloff

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