Tag: Science

Swans: How do they stay so white? Spit & Sparkle…

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Swans are the gentle giants of my local waterways: floating paragons of snowy serenity that cruise peacefully through muddy brown water amid the rowdy confusion of their smaller brethren.

And they present a puzzle. Around them, mallards, Egyptian geese and Mandarin ducks have plumage so varied that it seems like any little speck of dirt or grime would disappear into the design. But the swans, paddling around in water so opaque that their feet can’t be seen, tip their tail feathers high in the air to forage underwater for the deepest plants—yet they re-emerge an unreasonably pure white. How do they stay so clean?

[…]

Just as a swan uses an oily coating to repel water, to get rid of oil it needs a watery coating. And the answer—discovered only three years ago in a paper published in the journal Advanced Functional Materials—is saliva. A swan’s spit is full of proteins that have a water-loving end and an oil-loving end. Once in a while, the bird distributes saliva on its feathers instead of preen oil, and the oil-loving ends stick to the feathers, leaving the water-loving ends exposed.

This makes the feathers attractive to water, and so allows the watery saliva to penetrate deep into the feathers. Once it’s there, it finds channels lined with tiny wedges. The wedge shapes help surface tension push the water from the center of the feather to the edges, sweeping along and clearing out any tiny droplets of oil or fat on the way.

The feathers get a watery deep cleaning as the tiniest oily contaminants are carried away. After a while, air dries the saliva out, and the surface returns to its normal water-hating state while the swan is restored to its pristine purity.

It’s a fascinating system, and scientists and engineers are now trying to replicate it to make self-cleaning fabrics that we could use. But kudos to the swan, for having evolved the perfect spit-and-sparkle system for keeping itself clean.

Read full article here.

— Helen Czerski, from “How Swans Stay White in Muddy Waters” (Wall Street Journal, June 6, 2024)

DK Photo: May 31, 2023. 4:30 am. Cove Island Park, Stamford, CT. More photos of the swans from that morning here.

Moments snap together like magnets, forging a chain of shackles. Why?

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There’s a famous play, Equus, about a troubled boy with a blinding love of horses. The boy sees a psychiatrist named Martin Dysart, who tries to understand him by trying to understand his love. Dysart is confounded by it:

A child is born into a world of phenomena all equal in their power to enslave. It sniffs—it sucks—it strokes its eyes over the whole uncountable range. Suddenly one strikes. Why? Moments snap together like magnets, forging a chain of shackles. Why? I can trace them. I can even, with time, pull them apart again. But why at the start they were ever magnetized at all—just those particular moments of experience and no others—I don’t know. 

I can trace my love, too. Why stars instead of horses, or boys, or hockey? I don’t know. I don’t know. Maybe it’s because the stars are the antithesis of darkness, of abusive stepfathers and imperiled little sisters. Stars are light. Stars are possibility. They are the places where science and magic meet, windows to worlds greater than my own. Stars gave me the hope that I might one day find the right answers.

But there’s more to my love than that. When I think of the stars I feel an almost physical pull. I don’t just want to look at them. I want to know them, every last one of them, a star for every grain of sand on Earth. I want to bask in the hundreds of millions of suns that shine in the thousands of billions of skies in our galaxy alone. Stars represent more than possibility to me; they are probability. On Earth the odds could seem stacked against me—but where you are changes everything. Each star was, and still is, another chance for me to find myself somewhere else. Somewhere new.

— Sara Seager, The Smallest Lights in the Universe: A Memoir (Crown, August 18, 2020)

Notes:

Cute (very), but…

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Cloned monkeys sit with a toy in an undated photo provided by the Chinese Academy of Sciences. The cloning method that produced Dolly the sheep was used to create two healthy monkeys for the first time.

Cloned monkeys sit with a toy in a photo provided by the Chinese Academy of Sciences. The cloning method that produced Dolly the sheep was used to create two healthy monkeys for the first time.

Source: Sun Qiang and Poo Muming, Chinese Academy of Sciences: Photos of the Day: Jan. 24.)

Miracle. All of it.

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duck-cold-winter

A small child next to us looked down at her snow-covered boots, then pointed to a duck that stood on the ice on the bank and asked her mother an extremely good question: “Why don’t his feet get cold?”…

It’s this: The bigger the temperature difference between two objects when they touch, the faster heat will flow from one to the other. Another way of putting that is to say that the more similar the temperatures of the two objects are, the more slowly heat will flow from one to the other. And that’s what really helps the ducks. As all that frantic paddling was going on, warm blood was flowing down the arteries of each duck’s legs. But those arteries were right next to the veins carrying blood back from the feet. The blood in the veins was cool. So the molecules in the warm blood jostled the blood vessel walls, which then jostled the cooler blood. The warm blood going to the feet got a bit cooler, and the blood going back into the body was warmed up a bit. Slightly farther down the duck’s leg, the arteries and the veins are both cooler overall, but the arteries are still warmer. So heat flows across from the arteries to the veins. All the way down the duck’s legs, heat that came from the duck’s body is being transferred to the blood that’s going back the other way, without going near the duck’s feet. But the blood itself goes all the way around. By the time the duck’s blood reaches its webbed feet, it’s pretty much the same temperature as the water. Because its feet aren’t much hotter than the water, they lose very little heat. And then as the blood travels back up toward the middle of the duck, it gets heated up by the blood coming down. This is called a countercurrent heat exchanger, and it’s a fantastically ingenious way of avoiding heat loss. If the duck can make sure that the heat doesn’t get to its feet, it has almost eliminated the possibility of losing energy that way.

So ducks can happily stand on the ice precisely because their feet are cold. And they don’t care.

~ Helen Czerski, from “Why Ducks Don’t Get Cold Feet” in  Storm in a Teacup: The Physics of Everyday Life

 

Notes:

  • Image Credit: wsj.com – Agence France Presse / Getty Images
  • Inspired by Albert Einstein’s quote: “There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.”
  • Related Posts: Miracle. All of it.

Miracle. All of it.

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comet-45p-honda-mrkos-pajdusakova

“Comet 45P/Honda–Mrkos–Pajdušáková was first discovered 13 orbits ago in 1948 and has returned to the inner Solar System. It is physically ancient. It spends most of its time near the orbit of Jupiter and last neared the Sun in 2011. Over the past few months, Comet 45P’s new sunward plummet has brightened it considerably. The comet is currently visible with binoculars over the western horizon just after sunset, not far from the much brighter planet Venus. Comet 45P was captured last week sporting a long ion tailwith impressive structure. It will pass relatively close to the Earth early next month.”

Notes: