Like soap bubbles, bubbles blown in gum are ephemeral, lasting only seconds. Their break-up mechanism is quite different, though. Where surface tension rips a bubble apart once it is pierced, bubblegum instead deflates and wrinkles around a hole that does not grow, thanks to the elasticity of the gum. This photographic series by Suzanne Saroff features a rainbow of gum sculptures, all frozen in the moments of their disintegration. (Image credit: S. Saroff; via Colossal)
Venus flower basket sponges have an elaborate, vase-like skeleton pocked with holes that allow water to pass through the organism. A recent numerical study looked at how the sponge’s shape deflects incoming (horizontal) ocean currents into a vertical flow the sponge can use to filter out food.
The sponges’ structure is porous and lined with helical structures. In their simulation, researchers reproduced a version of this structure (shown below) that used none of the real sponge’s active pumping mechanisms. The digital sponge was, instead, purely passive. Nevertheless, the simulation showed that, by their skeletal structure alone, sponges could redirect a significant fraction of incoming flow toward its filtering surfaces. Interestingly, the highest deflection fraction occurred at relatively low flow speeds, showing that the sponges are set up so that their structure is especially helpful for scavenging nutrients from nearly-still waters.
In the real world, these sponges use a combination of passive filtering and active pumping to capture their food, but this study shows that the sponge’s clever structure helps it save energy, especially in tough flow conditions. (Image credit: sponges – NOAA, simulation – G. Falcucci et al.; research credit: G. Falcucci et al.; via APS Physics)
Active nematic fluids borrow their ingredients from biology. Using long, rigid microtubules and kinesin motor proteins capable of cross-linking between and “walking” along tubules, researchers create these complex flow patterns. Here, a team took the system a step further by seeding the flow with a hydrogel that turns into a polymer when exposed to light. Then, by shining light patterns on the flow, the scientists can create rigid or flexible structures inside the active fluid. In this case, they show off some of the neat flow patterns they can create. (Video and image credit: G. Pau et al.)
Home to a sub-surface ocean, Saturn‘s moon Enceladus is a fascinating candidate for life in our solar system. As it orbits Saturn, plumes periodically shoot out long surface features known as tiger stripes that sit near the icy moon’s southern pole. A recent study, based on numerical simulation, suggests a geophysical mechanism that could account for the plumes.
The team suggests that, like the San Andreas Fault, the tiger stripes are a fault subject to strike-slip motion. In this type of fault, the ice on either side meets along a vertical face and the two sides will slide past one another in opposite directions. As Enceladus orbits, its proximity to Saturn causes tidal compression across the fault that modulates how much slip motion occurs. In their model, the authors found that strike-slip motion would intermittently open gaps in the fault that would allow water from the subsurface ocean to create plumes at intervals consistent with those observed. (Image credit: top – NASA/JPL-Caltech/Space Science Institute, illustration – A. Berne et al.; research credit: A. Berne et al.; via Gizmodo)
Here, a Soyuz rocket takes off in 2023, carrying three of the Expedition 70 crew to the International Space Station. This initial stage of the Soyuz launch vehicle uses four identical rocket boosters lashed around the second stage core. Each of the boosters has a rocket engine with four combustion chambers (and thus four exhaust nozzles) of its own. That creates the fiery flurry of engine plumes seen here. Most of the exhaust plumes are directed downward to provide the thrust needed to lift the rocket, but you can see a few angled slightly to either side to help stabilize the launch vehicle as it rises. (Image credit: NASA)
Streams of blue and yellow braid across Iceland’s volcanic landscape in this award-winning photo from Miki Spitzer. Glacial water shows an icy blue and sediments glisten in gold. Together, their interplay creates an arresting delta viewed from above. (Image credit: M. Spitzer; via WNPA)
Spiking natural gas power plants with hydrogen could help them burn cleaner as we transition away from carbon power. But burners in power plants and jet engines can be extremely finicky, thanks to thermoacoustic instabilities. As a flame burns, it can sputter and fluctuate in its heat output. That creates pressure oscillations (which we sometimes hear as sound waves) that reflect off the burner’s walls and return toward the flame, causing further fluctuations. This feedback loop can be destructive enough to explode combustion chambers.
Adding hydrogen to a burner designed purely for natural gas can trigger these instabilities (above image), but researchers hope that by exploring fuel-mixtures and their effect at lab-scale, they can help designers find safe ways to adapt industrial burners for the cleaner fuel mixture. (Image and research credit: B. Ahn et al.; via APS Physics)
The ESA’s Solar Orbiter captured this beautifully detailed video of our sun‘s corona last September. The Solar Orbiter took this footage from about 43 million kilometers away, a third of the distance between the sun and the Earth. Scattered across the visible surface are fluffy, lace-like features known as coronal moss. Along the curving horizon, gas spires called spicules stretch up to heights of 10,000 kilometers. The video also highlights a “small” eruption of plasma that is nevertheless larger than the entire Earth. We can even see evidence of coronal rain, denser and darker clumps of plasma that gravity pulls back toward the sun. (Video and image credit: ESA; via Colossal)
Microfluidic circuits are key to “labs on a chip” used in medical diagnostics, inkjet printing, and basic research. Typically, channels in these circuits are printed or etched onto solid surfaces, making it difficult to reconfigure them. A group in China developed an alternative design, inspired by reconfigurable toys like Lego blocks. Their set-up, shown above, uses a pillared surface immersed in oil. To create the channels, they pipette water — one droplet at a time — into the space between pillars. The combination of oil and pillars traps the drop. With multiple drops linked together, they get channels, like the ones above that mix two fluids. When the time comes to reconfigure the channels, they just pipette the water out and cut the channel with a sheet of coated paper. (Image and research credit: Y. Zeng et al.; via Physics Today)
Ferrofluids are a great platform for exploring liquids and magnetism. Here, researchers trap ferrofluid droplets along an oil-water meniscus and then apply a magnetic field that makes the drops repel one another. The results are crystalline patterns formed from magnetic droplets. For a given patch of drops, increasing the magnetic field’s strength pushes drops further apart. But changing the drops’ size and levels of self-attraction also shifts the patterns. Check out the video to see the crystals in action. (Video and image credit: H. Khattak et al.)