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Monitoring heavy metal contaminants-such as lead, mercury and cadmium-in rivers and wells requires multiple trips to the lab for analysis with expensive and bulky equipment. A team of chemists headed by Joseph T. Hupp at Northwestern University has a more efficient method that could be adapted to make a portable device for testing samples in the field. Hupp’s group starts with nanoscale-sized particles of gold, each smaller than a virus. They then coat the particles with molecules that are able to bind with the heavy metals. Water containing the particles naturally assumes a deep shade of red. But if, for example, lead ions are present, they attach to the receptors, causing the gold particles to aggregate and turn the water blue. The greater the lead concentration, the more dramatic the color change. Then, to determine the exact quantity of heavy metal in the water, the Northwestern researchers measure its absorption of ultraviolet light. While not as sensitive as standard tests, the nano method’s speed and low cost make it an attractive alternative.

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Five poems about the mind

DREAM VENDING MACHINE I feed it coins and watch the spring coil back,the clunk of a vacuum-packed, foil-wrappeddream dropping into the tray. It dispenses all kinds of dreams—bad dreams, good dreams,short nightmares to stave off worse ones, recurring dreams with a teacake marshmallow center.Hardboiled caramel dreams to tuck in your cheek,a bag of orange dreams…

Work reinvented: Tech will drive the office evolution

As organizations navigate a new world of hybrid work, tech innovation will be crucial for employee connection and collaboration.

lucid dreaming concept
lucid dreaming concept

I taught myself to lucid dream. You can too.

We still don’t know much about the experience of being aware that you’re dreaming—but a few researchers think it could help us find out more about how the brain works.

panpsychism concept
panpsychism concept

Is everything in the world a little bit conscious?

The idea that consciousness is widespread is attractive to many for intellectual and, perhaps, also emotional
reasons. But can it be tested? Surprisingly, perhaps it can.

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Illustration by Rose WongIllustration by Rose Wong

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