Science

Ketchup, Quicksand and Slime

Want to get that ketchup out of its bottle, survive a plunge into quicksand, or make some really cool slime?

Then it's helpful to understand non-Newtonian fluids. Which means first understanding what Newtonian fluids are.

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Sir Isaac Newton (1642-1727) was one of the greats when it comes to science. Classical mechanics, laws of motion, gravity, calculus, reflecting telescopes… Newton discovered and defined a lot.

He also observed fluids and found that when fluids are heated, they’re easier to pour (aka, less viscous), and that when they’re cooled, they’re harder to pour (aka, more viscous). Most fluids – water, oil, alcohol – follow this trend. Their viscosity is impacted by temperature.

But for some fluids, viscosity is impacted by other factors besides temperature, such as squeezing and stirring. Those are non-Newtonian fluids.

Ketchup, for example, gets thinner or less viscous when stress is applied. That’s why if it’s stuck in a bottle, you hit the bottle to get it moving. Eventually, after you’ve shaken it up, it will return to its more viscose state.

Quicksand is another example, but of a different nature: it gets thicker or more viscous when stress is applied. Struggle in quicksand and it strengthens its hold on you, making escape more difficult. But if you find yourself in quicksand and relax, your body (which is less dense) will float.

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If you want to experience the properties of quicksand without any danger of being trapped, mix up some cornstarch and water. It looks like a liquid, but when you squeeze it, it turns to solid. Stop squeezing (remove the stress), and it becomes a liquid again. Another example is silly putty: hit it with a hammer, and the hammer bounces off, but push it slowly and you can flatten it with your hands.

You can also play around with non-Newtonian fluids by making slime. Start with glue, a polymer (which is made of very long chains of repeating molecules), then add borax. The protein molecules in the glue and the borate ions cross-link, preventing the long chains of glue from sliding past each other.

Playing with slime, you can observe its liquid properties (it stretches easily and will drip off the counter), and its more solid-like properties when stress is applied (pull it hard, and a piece will snap in two).

Observe long enough, and you just might feel a bit like Newton himself.

 

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Portrait of Newton by Godfrey Kneller | This story references information from "The Science of Slime" at www.acs.org

 

 

 

 

Lose it all, try again. Repeat.

That's how I'd sum up the story of John James Audubon's life. 

It sounds less like a scientist's life, and more like the saga of an artist. Which maybe all scientists are. Afterall, they go after that great unknown, with no idea of what they'll find, if anything.

Audubon is known for his work with birds: he discovered new species, studied their behavior (he completed the first known "bird banding" experiment in the United States, learning that certain birds return to the same nesting spots each year), and created the massive The Birds of America, known as one of the finest ornithological works ever made. 

But his fame and fortune were never guaranteed. Audubon's birth mother died a few months after he was born. When he first arrived in the U.S., he came down with yellow fever. After a visit back to his father in France, an English privateer overtook his ship (Audubon survived, somehow keeping his gold safe). Rats ate his collection of sketches (more than 200), but after weeks of depression, he decided to make the sketches again, this time even better. He went bankrupt in 1819 and was thrown into jail for debt. He made portraits and taught drawing to make ends meet. His wife taught school in order to support their two sons.

About those years when success was nothing more than a dream, he wrote, '[M]y heart was sorely heavy, for scarcely had I enough keep my dear ones alive; and yet through these dark days I was being led to the development of the talents I loved."

Somehow, Audubon stayed focused on his goal: to find and paint all the birds of North America. He attempted to paint one page each day. He was always working to improve: when he discovered one new painting technique, he decided to redo his earlier works. 

Then finally in 1826, at the age of 41, Audubon headed for England to show others his paintings. His work was extremely well received and he raised enough money to begin publishing his book.

Per one reviewer: "All anxieties and fears which overshadowed his work in its beginning had passed away. The prophecies of kind but overprudent friends, who did not understand his self-sustaining energy, had proved untrue; the malicious hope of his enemies, for even the gentle lover of nature has enemies, had been disappointed; he had secured a commanding place in the respect and gratitude of men."

Success - finally!

Stories like Audubon's are always stirring. Because they remind us that it takes courage to venture into the unknown. To sacrifice for a dream when the results are not guaranteed. To listen to that small yet insistent voice that tells you to keep working, keep improving, keep trying.

Maybe it's birds. Maybe it's a book. But it's brave to follow those dreams. And see where they take us.

 

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American Crow | Audubon by James Syme, 1826 | Barn Swallow

 

 

 

Near famous: ornithologist Alexander Wilson

For the past few weeks, my morning drive to work has taken me right by a Wilson's Snipe. The small shore bird, with its pebbly tan body and white chest and incredibly long beak, is always perched on a fence rail overlooking a damp field.

The beak makes the bird.

The beak makes the bird.

I looked the bird up and learned that these birds are shy, nest in well-hidden spots, use their long beak to probe soft earth for insects and worms, and have a special courtship flight that involves flying high in circles then making shallow dives to produce a distinctive noise. And, I learned they were named for Alexander Wilson, a man who's considered the greatest American ornithologist after John James Audubon, but who is definitely not a household name.

Wilson was born in 1766 in Scotland and started off on a weaving apprenticeship, though soon turned to writing poetry (some that was politically charged, most that was not good) and walking the countryside. After failing in writing and in love, he journeyed to America in 1794, settling near Philadelphia.

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He began working as a schoolteacher, then in 1801, left his job over a second love affair gone wrong - this time with a married woman. He started teaching again in Gray's Ferry, Penn., and lived down the street from naturalist William Bartram. 

At Bartram's urging, Wilson decided to produce a collection of drawings of birds. He spent much time outside, alone, once journeying from Gray's Ferry to Niagara Falls. In 1806, he took a job at Roe's Cyclopedia and studied and drew birds in his spare time. He continued with his journeys through the forests, and in 1808, he published his first volume of ornithology, which included his drawings and notes on the behaviors and habitats of the birds.

He continued to travel, trying to garner subscribers for his volumes on ornithology, hitting towns from Maine to Georgia. At one point in February, he decided to take a small skiff down the Ohio River for 720 miles, floating to Cincinnati. By the end, his hands were stiff and unfeeling. He later rode through the thick swamps from Lexington to Nashville, battling dysentery and forests so thick there was barely the light of day.

He went on to publish his volumes, gaining national and international recognition. He took a final long journey north in late 1812, saying he was devoted to finishing his work, even if it killed him, which seemed to be prophetic as he died of dysenterry in 1813.

I love these stories of American naturalists. I'm not exactly sure why. Maybe because I enjoy the outdoors, and like to imagine what it would've been like to walk through a land where much of what you saw was still unnamed. Maybe because they're the ultimate adventurers, risking their lives and forgoing a comfortable existence in the effort of identifying the plants and animals around them. 

Maybe because, in a very small way, it reminds me a bit of writing. Setting off into the unknown. Not exactly sure of what you'll find. Going along for the journey anyway.

Hopefully writing won't kill me. Sometimes, especially in the middle of first drafts or tenth revisions, I wonder. But I do it anyway. And I know I'll discover something along the way.

 

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resources: wilsonsociety.org | xroads.virginia.edu

American Ornithology by Alexander Wilson | portrait of Alexander Wilson attributed to Thomas Sully

Gambel's Oak

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You’ve likely walked by these scraggly trees, lichen nestled in the knobs and ridges of their dark bark. They’re the last trees to sprout green leaves in spring, forming a low, tight canopy overhead. By autumn, their leaves turn orange, complementing the golden aspens. And finally, as winter settles in, tangles of black branches are exposed, giving our woods an otherworldly feel. 

They go by many names: scrub oak, oak brush, white oak. Quercus gambelii, formally. Which in turn is shortened into their common name: Gambel oaks. 

That is the name that caught my attention, for it points back to a budding naturalist whose own life was cut short by a twist of ill fate. A twist not unlike the turning branches of the tree itself.

William Gambel was born near Philadelphia in 1823 to an impoverished Irish family; his father died when he was nine. At age 16, he joined naturalist Thomas Nuttall on a collecting trip in North Carolina. The trip sparked an interest in the world around him, and a few years later, Gambel set off for California, crossing the country by foot and observing plants and birds and other animals along the way. He was 18 years old.

He collected along the California coast and eventually returned to the east coast, became a physician and married, then decided to head back to California to begin his medical career – after all, it was 1849 and the Gold Rush was on. He made a plan with his wife: he’d establish his practice, then she would travel out to meet him. And finally, he began the long journey west with a small group of settlers for company.

But their pace was a bit quick for his liking: after all, there were so many species to observe and record. So Gambel made a fateful decision to join a slower-moving group. It would give him more time to collect samples. It would also turn out to be his demise.

The group was excruciatingly slow.  They didn’t make it to Nevada until the end of fall, and worry built as they realized winter was at hand. They were in bad shape.  The long autumn months had been dry.  Most of their cattle and horses had been lost.  But with no motel to check into, they pushed forward. They hit the eastern edge of the Sierras after the first snowfall and were certain they could make it no further. But onward they went. 

Somehow Gambel and a few others survived the treacherous mountains, reaching a gold-mining camp on the Yuba River.  But this was not the end to their struggles. For a typhoid epidemic had taken hold, working its way through the miners. Gambel, the good doctor that he was, stopped to help the sick. But his efforts were for naught as he soon caught typhoid himself and died. He was 26 years old.

His name lives on, in the scrub oak as well as Gambel’s Quail, mountain chickadee and a genus of lizard. It’s no wonder that, on early morning or late evening walks through stands of these low, twisted trees, I can’t help but imagine what it was like so many years ago, when so much land had yet to be explored, when every journey carried immense risk, and when so-called "small" decisions had the power to lead to life or to death. 

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Richard G. Beidleman | California’s Frontier Naturalists

Life that glows

As a child, I loved watching fireflies light up the dark corners of our backyard. But I never thought to ask how a little bug could make it's very own light. 

Photo by  Smoken Mirror  on  Foter.com

It turns out that making light all comes down to energy and some special molecules (luciferin, and the enzyme luciferase). Those words both come from the Latin "lucifer" or "lightbringer." You might recognize "Lucifer" from the Bible - he was the angel who wanted to be more powerful than God and ended up falling from heaven to hell.

But back to glowing things (which also include certain mushrooms and marine creatures): the luciferin molecule uses energy to react with oxygen, and the luciferase enzyme speeds it all up. Through the reaction, electrons in the luciferin molecule are excited, or have a little more energy than normal. When the electrons relax and go back to their normal state, that extra energy is released as light.

Amazingly, this whole process of bioluminescence is super efficient: most of the energy (up to 80 or 90 percent) is transformed into light. An incandescent lightbulb, by comparison, transforms less than 5 percent of the energy it receives into light (90 percent turns into heat), while LEDs come in at 20 percent. So while a lightbulb gets warm when it glows, fireflies and mushrooms do not.

For fireflies, the light can help attract mates and show predators they don't taste good. For mushrooms, a recent experiment showed the light may help attract insects, which then help spread the mushroom's spores.

Unfortunately for me, there's nothing glowing in the high rockies - I'll just have to Youtube glowing creatures to get my bioluminescence fix. Unless I can grow these myself...

 

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image credits: Photo by Smoken Mirror on Foter.com