Researchers open secret cave under Mexican pyramid
Archaeologists are opening a cave sealed for more than 30 years deep beneath a Mexican pyramid to look for clues about the mysterious collapse of one of ancient civilization’s largest cities. The soaring Teotihuacan stone pyramids, now a major tourist site about an hour outside Mexico City, were discovered by the ancient Aztecs around 1500 AD, not long before the arrival of Spanish explorers to Mexico. But little is known about the civilization that built the immense city, with its ceremonial architecture and geometric temples, and then torched and abandoned it around 700 AD. Archeologists are now revisiting a cave system that is buried 20 ft beneath the towering Pyramid of the Sun and extends into a tunnel stretching for some 295 ft with a height of 8 ft.They say new excavations begun this month could be the key to unlocking information about the sacred rituals of the people who inhabited the city, later dubbed “The Place Where Men Become Gods” by the Aztecs who believed it was a divine site.

A cloth to cut the mercury risk from light bulbs
Compact fluorescent lamps last longer and use much less electricity than conventional bulbs. But they contain small amounts of the neurotoxin mercury. Compact fluorescents are supposed to be recycled so that the mercury (which is in vapour form) can be dealt with properly. But the tubes do occasionally crack or break, and the recycling rate is currently low, so mercury could be released in homes or elsewhere, posing a small risk to children. Robert H. Hurt, an engineering professor at Brown University, along with a student, Natalie C. Johnson, and others, set out to see what could be done to reduce the risk. They experimented with tiny particles of sulfur, copper, nickel and other elements to see how well mercury was absorbed onto them. Selenium, in particular, has a well-known affinity for mercury, and the researchers found that particles of it with a size from about 10 to 600 nanometers were capable of binding with almost all of the mercury from a lamp. The researchers say this “nanoselenium,” impregnated in cloth, could be used in packaging for new lamps or for cleaning up a broken lamp in the home.

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