Issue Date: April 12, 2004
White House gets six nanoflags, Greenbacks tested for quality
On March 30, Cornell University presented to the White House a Lucite paperweight containing a nanofabrication. The fabrication included six full-color U.S. flags and 15 White Houses. All are etched on a silicon chip the size of a postage stamp.
The chip carries 15 monochrome images of the White House, flanked by six full-color U.S. flags. The flags are embedded with microscopic features that reflect the colors of the stars and stripes. Three White House images are visible; a dozen nanosize images (500 mm wide and 225 mm high) appear as dots if not magnified. Each of the White House images flies a U.S. flag. The nanofabrication was made at the Cornell Nanoscale Facility, which is supported by the National Science Foundation.
The chip was made to recognize the 21st Century Nanotechnology Research & Development Act. The act was introduced by Rep. Boehlert and authorizes four-year funding for nanotechnology research, starting in 2005. It creates programs supported by the National Nanotechnology Initiative.
Greenbacks tested for quality
The U.S. Bureau of Engraving & Printing, it turns out, tests thousands of greenbacks weekly to be sure they meet its specifications for the nation's paper currency, or bank notes. Jeannine Aversa of the Associated Press reports on the bureau's tests in the March 30 Washington Post.
For testing, Aversa writes, the bureau picks bank notes at random from freshly printed batches. The notes never make it into the normal system, however. Each is submitted to only one of the procedures that compose the "torture tests," whose dates of origin are obscure. Each bill tested is discarded when the test is completed. Bills of all denominations are subjected to the same tests. Each test has pass-fail criteria.
The tests are designed to simulate real-life scenarios, according to chemist Goutam Gupta, who heads the bureau's Office of Technical Support. One example is the crumple test, which recognizes people's tendency to fold bank notes and stuff them into their pockets, purses, etcetera. Although all the tests are important, it is most troubling if a bill flunks the crumple test, says Gupta, because crumpling is the most likely scenario in actual use.
For the crumple test, Aversa spoke with physicist Virgil Huber. Huber cuts a fresh $20 bill into three parts, rolls the three like cigarettes, and stuffs them into a metal device that crushes them into pellets. The pellets are then unfolded and examined. Bills are tested seven to 10 days after they are printed, according to chemist Valentino DeVito, manager of technical services, to be sure the ink is cured. The bills generally hold up well, he says, because inks these days are very good.
A second example is the laundry test, which recognizes our tendency to launder our currency along with our clothing. The laundry test involves 25 bills, eight all-cotton terry towels, and standard laundry detergent. The mixture goes through a regular wash cycle, Aversa was told by chemist Andrew Wilson, in about 14 gal of water at about 142 °F. Once the wash is completed, the money is air-dried and examined. In another test, bills are soaked for 24 hours in one of nine chemicals or solvents, such as gasoline, bleach, or sulfuric acid. There are other tests, but most bills pass.
In the worst case, Gupta says, "the production may have to be destroyed." The bureau takes only small samples for testing, he notes, but if it finds something awry with a batch of paper money, the batch "will be put on hold until a determination can be made as to what to do with that." Aversa writes, however, that bureau officials "cannot think of a time in recent memory when that has happened."
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