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From the Trenches

From Egyptian Blue to Infrared


Monday, April 08, 2013

EgyptBlueEgyptian blue is known as the world’s oldest artificial pigment, first used more than 4,500 years ago, found on wall paintings at Luxor and sculptures recovered from the Parthenon. The hue comes from a compound called calcium copper tetrasilicate. Over the past decade, museum conservators and archaeologists have taken advantage of its properties to spot the presence of Egyptian blue on antiquities: When red light is shone on the pigment, it reflects infrared light, which can be detected via night-vision goggles or cameras.


Chemists at the University of Georgia (UGA) have now determined that the luminescent quality of calcium copper tetrasilicate is retained even when the compound is reduced to what are termed “nanosheets,” a thousand times thinner than a human hair. “Even if you have a single layer, the thinnest possible, you still get the effect,” explains UGA’s Tina Salguero. At that scale, she believes, you can start thinking about modern applications.


Salguero says that Egyptian blue’s primary molecule could be incorporated into a dye to improve medical imaging, since the infrared radiation it would reflect can pass through human tissue. The pigment’s luminescent quality could also be effective for developing new types of security ink, typically used to secure currencies and other official documents from forgery. Further, the possibilities for a second act for the long-out-of-use coloring extend to devices such as light-emitting diodes and optical fibers, both of which transmit signals using the relatively long wavelength of infrared light.


The UGA team is now looking at another compound, barium copper tetrasilicate, which was also used as an ancient pigment, in this case by the Chinese.

Oops! Down the Drain


Monday, April 08, 2013

Augusta-Raurica-ObjectsThe next time you lose something valuable down the drain, don’t feel too bad—it’s been happening for 2,000 years. In a recent study, Alissa Whitmore of the University of Iowa examined the broad range of activities that took place in Roman public baths. According to Whitmore, the ancient Romans lost all sorts of precious items, including jewelry, hairpins, and pendants, while bathing. But she also found that they deliberately discarded other things in the baths, such as broken ceramics and glass. Many of the artifacts that have been discovered in bath drains, such as perfume jars, oil flasks, nail cleaners, and tweezers, were related to hygienic behaviors. However, other artifacts indicate that less hygienic activities also took place there. Cups, seashells, animal bones, dice, gaming pieces, and needles suggest that feasting, gambling, and sewing occurred in some baths. The discovery of human teeth and a scalpel also imply that dental and medical procedures may have taken place in some facilities. “The wide variety of finds really drives home that the baths weren’t just for bathing,” says Whitmore, “but a major social center, in which people performed a number of different activities while spending time with friends.

Bad Monks at St. Stephen's


Monday, April 08, 2013

StStephenThe path to God often comes through self-denial, but sometimes temptation is too great to overcome. St. Stephen’s, a fifth-century monastery in Jerusalem, was home to Byzantine monks who purported to practice an ascetic lifestyle, including the consumption of little more than bread and water (with some fruits and vegetables). Unlike other monasteries of the period, which were often remote desert enclaves, St. Stephen’s was an urban monastery. An isotopic analysis of bone collagen from 54 skeletons at the monastery conducted by Lesley Gregoricka of Ohio State University reveals that 16 of the individuals regularly consumed animal protein, perhaps from eggs, cheese, milk, fish, meat, and perhaps even garum (fermented fish sauce). The city monastery was famously affluent, says Gregoricka, so perhaps higher status monks had access to luxury, taboo, decidedly non-monastic food items.

Hail to the Bождь (Chieftain)


Monday, April 08, 2013

chieftan-battle-axRussian archaeologists excavating a third-century B.C. necropolis on the slopes of the Central Caucasus Mountains have unearthed a spectacular warrior’s burial. Along with a dozen gold artifacts, including a brooch that holds a small crystal, the warrior went to the afterlife dressed in iron chain mail and armed with two iron swords and a battle-ax. One of the swords measured three feet long and was discovered between the warrior’s legs, its tip pointed toward his pelvis. “The burial goods are exceptionally rich,” says archaeologist Valentina Mordvintseva of the National Academy of Sciences of Ukraine, who helped analyze the unprecedented trove.chieftan-brooch “He belonged to the upper class of the society and was possibly a chieftain.” The burial of three horses and a cow nearby indicate that his people held the warrior in unusually high esteem.

A Killer Bacterium Expands Its Legacy


Monday, April 08, 2013

Yersinia pestisFrom the sixth through eighth century A.D., a terrifying illness called the Plague of Justinian gripped the Eastern Roman Empire. Like the Black Death pandemic that decimated Europe seven centuries later, this plague often caused death within a matter of days. New work by paleogeneticists at the University of Tübingen in Germany provides empirical evidence for an old historical theory: that the two pandemics were caused by the same pathogen. By comparing the genome of ancient Yersinia pestis, the bacterium responsible for the Black Death, with genetic data from hundreds of less virulent modern strains, the team reconstructed the pathogen’s genetic history, and found evidence suggestive of a significant Y. pestis outbreak corresponding to the Justinian plague. “Our results suggest that Y. pestis may have affected human populations several centuries before the Black Death,” says Kirsten Bos, the study’s lead author. “The Plague of Justinian seems like the best candidate for an earlier pandemic.”




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