Yet a hummingbird is able to extract nectar from a flower by wrapping its tongue into a hummingbird-size straw. How? The answer is that the hummingbird is taking advantage of the forces of surface tension, the same forces that cause water to bead into droplets instead of spreading outward when sitting on a hard surface. “I’ve been looking at the big picture of drinking strategies in nature,” said John W M Bush, a professor of applied mathematics at the Massachusetts Institute of Technology. “This is a big theme of mine now.”
Last year, he showed how some shorebirds used surface tension to draw water droplets up their long, thin beaks into their mouths. For the latest research, Bush and his co-workers found that when a hummingbird stuck its tongue into a flower, the tongue, about three-quarters of an inch long, curled up into a cylinder just one twenty-fifth of an inch in diameter because of surface tension. “The hummingbird’s tongue looks like a straw with a slot cut in it,” Bush said.
Also because of the surface tension, the slot in the cylindrical tongue zips closed, beginning from the tip. The nectar is drawn upward, and the cylinder fills. The hummingbird then scrapes its tongue clean and swallows. Amazingly, it repeats this process 20 times a second as it feeds. The hummingbird tongue research, which Bush presented recently at a meeting of the American Physical Society’s Division of Fluid Dynamics, is not just a biological curiosity. The findings could be useful to researchers building miniature chemistry laboratories, so-called labs on a chip, that have to move tiny droplets of chemicals around. “Nature has already solved these problems,” Bush said.

By happy accident, a new kind of blue
Blue is sometimes not an easy colour to make. Blue pigments of the past have often been expensive (ultramarine blue was made from the gemstone lapis lazuli, ground up), poisonous (cobalt blue is a possible carcinogen and Prussian blue, another well-known pigment, can leach cyanide) or apt to fade (many of the organic ones fall apart when exposed to acid or heat).
So it was a pleasant surprise to chemists at Oregon State University when they created a new, durable and brilliantly blue pigment by accident.
The researchers were trying to make compounds with novel electronic properties, mixing manganese oxide, which is black, with other chemicals and heating them to high temperatures. Then Mas Subramanian, a professor of material sciences, noticed that one of the samples that a graduate student had just taken out of the furnace was blue.
“I was shocked, actually,” Subramanian said. In the intense heat, almost 2,000 degrees Fahrenheit, the ingredients formed a crystal structure in which the manganese ions absorbed red and green wavelengths of light and reflected only blue.
When cooled, the manganese-containing oxide remained in this alternate structure. The other ingredients, white yttrium oxide and pale yellow indium oxide, are also required to stabilise the blue crystal. When one was left out, no blue colour appeared.
The pigments have proven safe and durable, Subramanian said, although not cheap because of the cost of the indium.
Kenneth Chang
NYT News Service

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