29 Jun 2012

No Ocean Necessary: Hands-on Science Activities for Beach Lovers

I grew up on the Eastern seaboard, so for me, summer means sand, surf, and soggy french fries from a red-striped paper box. It also means a long walk along the shore, picking up this and that, discovering something new every time. Last week, on New York's fabulous Jones Beach (an my old stomping grounds), we came across some sea lice on the beach - something I'd never seen in countless visits there.

Sea louse

Seeing this critter made me think about how you believe you know something, and then, much much later on, discover that what you thought you knew, about a person, a place, a fact, is incomplete or just plain wrong. Up until last week, my mental picture of Jones Beach did not include sea lice.  I now have had to modify that inner vision to include this new piece of data.

This is of course not the first time in my life I've had to revise my thinking on a subject. This past winter, while researching The Big Green Book of the Big Blue Sea,  I discovered that everything I thought I knew about pearls was wrong. No, they are not made by oysters when a bit of grit gets into their shell and irritates the lining.


You, like me, probably learned this fact aeons ago. How could it - we -  be wrong?

Even worse, the true cause of pearl formation has been known since 1856. People have been repeating incorrect information and spreading it for well over a hundred years. Jeesh.

So what does cause a pearl to form, if not a bit of grit? "The most beautiful pearl is only the brilliant sarcophagus of a worm," said Raphael Dubois in 1901. And in fact, the pearl is a method for entombing a parasite that has invaded the mollusk's shell. Slap it with a liquidy goo that soon hardens, and voila, the pest is neutralized.

One of the fun hands-on activities in The Big Green Book of the Big Blue Sea is making a real pearl of your own. Since finding and working with parasites is kind of yucky, I suggest you start the pearl the way I did - with a fake parasite/piece of grit. I used a tiny balled-up wad of paper. Over a period of several weeks, I coated the wad with layers of pearly white nail polish, letting the pearl dry between coats. Turn it over and repeat until you have a pearl like this one - pretty enough to wear, and not at all yukky.

22 Jun 2012

Lightning Under the Hood: Part Three - From Cell Phones to Sports Cars

by L E Carmichael

The Chevy Volt - a plug-in hybrid electric vehicle

Remember those brick-sized cell phones from movies in the 1980s? Lithium batteries are the reason we're no longer carrying them. They're also what make laptops, iPads, and MP3 players possible.

Lithium is the first metal on the periodic table, and it's 30 times lighter than lead. That also makes it a good candidate for electric car batteries, which have to pack maximum power into the lightest possible package.

As far as we know, lithium was first used in a battery in 1907, by Thomas Edison. His patent application claimed that 2 grams of lithium hydroxide in every 100 mL of electrolyte improved battery capacity by 10% and dramatically extended battery life.

It was a long time, however, before lithium batteries - Li-ION as they are usually known - could be used to power something as big and demanding as a vehicle. One of the reasons was safety. If the batteries overheat, elemental lithium can combine with water and oxygen in a reaction called "thermal runaway." This causes the battery to burst into flames.

The problem's been recognized since the 1970s, when researchers at Exxon were developing watch batteries using lithium chemistry. Their experiments were so dangerous, the fire department eventually threatened to bill the scientists for the costs involved in putting out the fires! Thermal runaway was vividly illustrated in 2011, when a plug-in hybrid electric vehicle – the Chevy Volt – caught fire several days after crash testing. As Chevy officials correctly pointed out, however, proper battery-handling protocols were ignored following the tests; in the real world, there's far less risk involved with a car powered by lithium batteries than “in carting around 15 gallons of highly flammable [gasoline].” 
An all-electric Tesla plugged in to recharge

Although scientists are still working towards newer and better variations in lithium battery chemistry, there's no denying their amazing energy potential. Martin Eberhard, cofounder of the electric sports-car company Tesla, says that for him there was never any doubt. “Lithium-ion batteries were at the top of my mind,” Eberhard says, “because in my rough calculations, you could actually fit enough batteries into a car to make a meaningful car.”

The battery pack in a Tesla Roadster contains 6,831 individual battery cells and weighs 990 pounds. That's about 200 pounds more than the lead-acid batteries in Riker's 1896 Electric Trap.  Riker's car, however, had a top speed of around 24 miles per hour, and a maximum range of around 40 miles. The Roadster's maximum speed is 125 miles per hour (artificially restricted for legal reasons), and it can travel 245 miles before it has to be recharged. Those results could never have been achieved without lithium batteries, which, by the way, are non-toxic and 60% recyclable.

They might not run on Mr. Fusion, but the cars of the future are definitely here.  Andrew Riker would probably wonder why the heck the future took so long.


Check out the Chevy Volt, the Nissan Leaf, and Tesla Motors for more information on electric cars available for purchase today.