FYFD

Tag: chemistry

  • Melted Polymers

    Melted Polymers

    What you see here, despite appearances, is not a soap film. On the contrary, this is a thin vertical film made up of melted polymers. Like a soap film, it is extremely thin, varying from a few nanometers at its thinnest to several hundred nanometers at the thickest point. But unlike a freestanding soap film, this polymer film can last for more than a day before the film breaks. Researchers attribute the long life of the films to structural forces inside the fluid.

    They observed that the films remain highly stratified, varying smoothly in thickness from their thinnest point at the top to the thickest point at the bottom. They hypothesize that the geometry of the film preferentially traps the polymer’s molecules in preferred orientations, which reinforces the stratification and helps stabilize the film. For more, check out the research paper. (Image credit: T. Gaillard et. al., source; via KeSimpulan)

  • “Aurora”

    “Aurora”

    This bulbous, ethereal shape is a spreading flame front captured by artist Fabian Oefner in his new “Aurora” series. Oefner used a few alcohol droplets in a glass vessel and ignited the volatile vapors, capturing the propagating flame. Take a look at it in action. Because the air inside the vessel is mostly still, the chemical reactions in the combustion occur much faster than the air’s motion. As a result, the flame spreads as a thin sheet instead of a uniform, widespread flame. The wrinkled and corrugated look of the flame front is due local turbulence distorting the flame. (Photo credit: F. Oefner)

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    Inksplosion

    Chemical Bouillon are a trio of artists who use the chemistry of surface reactions to create abstract videos full of exploding and imploding droplets and colors. As chemicals react, local concentrations at the interface vary, which changes the local surface tension. These gradients drive flow from areas of low surface tension to those of higher surface tension. This is called the Marangoni effect – the same behavior that drives tears in a glass of wine. Chemical Bouillon have a whole YouTube channel dedicated to these kinds of videos, with everything from inks to ferrofluids. Be sure to take a look at some of their other videos and, if you like them, subscribe. (Video credit: Chemical Bouillon)

  • Fluids Round-up – 24 August 2013

    Fluids Round-up – 24 August 2013

    Fluids round-up time! Here are your latest fluids links to check out:

    (Photo credit: G. Pretor-Pinney)

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    Levitation By Sound

    Levitation is an effect usually associated with electromagnetic forces, but it’s possible with sound as well. This acoustic levitation is achieved by using the pressure from sound waves to balance gravity’s effect. By manipulating the sound, it’s possible to bring separate objects together while continuing to levitate them. The behavior is demonstrated in the video above by combining solid sodium with a drop of water for what any high school chemist will tell you is a spectacular reaction. (Though, if that’s too small-scale for you, there’s also this video.) (Video credit: D. Foresti et al; via SciAm)

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    Dribbling Droplets

    Ethanol droplets on a hot copper plate bounce under the influence of electrostatic forces from a charged rod. The temperature of the plate is high enough that the droplet is supported by a thin vapor film, which is what keeps it from wetting the plate.  Ethanol does not have the strong polarity that water does, but the hydroxyl group on one end does make it susceptible to the electrostatic charge built up on the teflon rod.  As a result, the droplets oscillate under electrostatic and gravitational forces, resulting in a dribbling effect. (Video credit: S. Wildeman et al.)

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    Turing Patterns

    Turing patterns form as a result of a particular kind of chemical reaction: a reaction-diffusion system. It consists of an activator chemical capable of making more of itself, and an inhibitor chemical which slows the production of the activator as well as a mechanism for diffusing the chemicals. Although Turing’s original work was theoretical in nature, scientists have since proven that Turing patterns do occur in nature, both in petri dishes and in the markings of animals. Here artist Jonathan McCabe explores multi-scale Turing patterns in a fluid-like environment. (Video credit: Jonathan McCabe and Jason Forrest; submitted by Stuart R)

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    Moving Droplets with Electric Fields

    Many microfluidic devices employ techniques that manipulate droplet motion for applications like sorting, manufacturing, or precisely controlling chemical reactions at a small scale. The video above shows the oscillations of a droplet on an inclined surface as it is perturbed with an electric field. (Video credit and submission: K. Nichols)

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    Supercritical Fluids

    A supercritical fluid exists without a distinct liquid or gas phase and forms when temperatures and pressures exceed the substance’s critical point. Here supercritical transition is demonstrated with an ampule of liquid chlorine. When immersed in a hot bath, the temperature and pressure inside the ampule rises until around 0:20 when the meniscus marking the interface between liquid and gas disappears. The chlorine is now in its supercritical state. Around 0:43 the hot bath is removed and the chlorine begins to cool, reverting to distinct phases of matter around 0:55.

  • Feynman: The Universe in a Glass of Wine

    Some wisdom for you this Friday from the incomparable Richard Feynman:

    A poet I think it is who once said the whole universe is in a glass of wine. I don’t think we’ll ever know in what sense he meant that for the poets don’t write to be understood. But it is true that if you look at a glass of wine closely enough, you’ll see the entire universe.

    There are the things of physics: the twisting liquid, the reflections in the glass, and our imagination adds the atoms. It evaporates, depending on the wind and weather. The glass is a distillation of the earth’s rocks and in its composition, as we’ve seen, the secret of the universe’s age and the evolution of the stars. What strange array of chemicals are in a wine? How did they come to be? There are the ferments, the enzymes, the substrates and the products, and there in wine was found great generalization: all life is fermentation. Nor can you discover the chemistry of wine without discovering, as did Pasteur, the cause of much disease. How vivid is the claret, pressing its existence into the consciousness that watches it?

    And if our small minds for some convenience divides this glass of wine, this universe, into parts: to physics, biology, geology, astronomy, psychology and all, remember that nature doesn’t know it. So we should put it all back together and not forget at last what it’s for. Let it give us one final pleasure more: drink it up and forget about it all.

    (submitted by @jerrodh)