3D Printing Livers

February 21, 2022 by Al Williams 1 Comment

The University of Utrecht has a team that is successfully bioprinting “liver units” that are able to do some of the functions of a human liver and may open the door to new medical treatments. This isn’t simply printing a fake liver in a jar though, instead the technique uses optical tomography to rapidly create small structures of about 1 cc of volume in less than 20 seconds.

Apparently, one problem with printing hydrogels full of biological structures is that passing them through a nozzle tends to disturb the delicate structures. This technique uses no nozzle or layers, which makes it useful in this situation.

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The Electrifying Debate Around Where Lightning Comes From

February 17, 2022 by Maya Posch 26 Comments

Along with many other natural phenomena, lightning is probably familiar to most. Between its intense noise and visuals, there is also very little disagreement that getting hit by a lightning strike is a bad thing, regardless of whether you’re a fleshy human, moisture-filled plant, or conductive machine. So it’s more than a little bit strange that the underlying cause of lightning, and what makes certain clouds produce these intense voltages along ionized air molecules, is still an open scientific question.

Many of us have probably learned at some point the most popular theory about how lightning forms, namely that lightning is caused by ice particles in clouds. These ice particles interact to build up a charge, much like in a capacitor. The only issue with this theory is that this process alone will not build up a potential large enough to ionize the air between said clouds and the ground and cause the lightning strike, leaving this theory in tatters.

A recent study, using data from Earth-based radio telescopes, may now have provided fascinating details on lightning formation, and how the charge may build up sufficiently to make us Earth-based critters scurry away to safety when dark clouds draw near.

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Martian Wheel Control Algorithms Gain Traction

February 15, 2022 by Ryan Flowers 13 Comments

Imagine the scene: You’re puttering along in your vehicle when, at least an hour from the nearest help, one of your tires starts losing air. Not to worry! You’ve got a spare tire along with the tools and knowhow to change it. And if that fails, you can call roadside assistance. But what if your car isn’t a car, has metal wheels for which no spares are available, and the nearest help is 200 million miles away? You just might be a Jet Propulsion Laboratory Engineer on the Curiosity Mars Rover mission, who in 2017 was charged with creating a new driving algorithm designed to extend the life of the wheels.

High Performance Rock Crawler, Courtesy Spidertrax.com License: CC BY 3.0

You could say that the Curiosity Mars rover is the ultimate off-road vehicle, and as such it has to deal with conditions that are in some ways not that different from some locations here on Earth. Earth bound rock crawlers use long travel suspensions, specialized drivetrains, and locking differentials to keep the tires on the ground and prevent a loss of traction.

On Mars, sand and rocks dominate the landscape, and a rover must navigate around the worst of it. It’s inevitable that, just like a terrestrial off-roader, the Mars rovers will spin a tire now and then when a wheel loses traction. The Mars rovers also have a specialized drivetrain and long travel suspensions. They don’t employ differentials, though, so how are they to prevent a loss of traction and the damaging wheel spin that ensues? This where the aforementioned traction control algorithm comes in.

By controlling the rotation of the wheels with less traction, they can still contribute to the motion of the vehicle while avoiding rock rash. Be sure to check out the excellent article at JPL’s website for a full explanation of their methodology and the added benefits of uploading new traction control algorithms from 200 million miles away! No doubt the Perseverance Mars rover has also benefited from this research.

But why should NASA get to have all the fun? You can join them by 3d printing your own Mars rover and just maybe some Power Wheels derived traction control. What fun!

“So Long,” Said All The Tank-Driving Fish

February 15, 2022 by Kristina Panos 19 Comments

Though some of us are heavily assisted by smart phone apps and delivery, humans don’t need GPS to find food. We know where the fridge is. The grocery store. The drive-thru. And we don’t really need a map to find shelter, in the sense that shelter is easily identifiable in a storm. You might say that our most important navigation skills are innate, at least when we’re within our normal environment. Drop us in another city and we can probably still identify viable overhangs, cafes, and food stalls.

The question is, do these navigational skills vary by species or environment? Or are the tools necessary to forage for food, meet mates, and seek shelter more universal? To test the waters of this question, Israeli researchers built a robot car and taught six fish to navigate successfully toward a target with a food reward. This experiment is one of domain transfer methodology, which is the exploration of whether a species can perform tasks outside its natural environment. Think of all the preparation that went into Vostok and Project Mercury.

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Making Light Of Superconductors

February 10, 2022 by Al Williams 3 Comments

Once upon a time, making a superconductor required extremely cold temperatures. Scientists understood why superconducting materials could move electrons without loss, but the super cold temperatures were a problem. Then in 1986, a high-temperature superconductor was found. High temperature, of course, is a relative term. The new material works when cooled to a frosty temperature, just not a few degrees off of absolute zero like a conventional superconductor. Since then, the race has been on to find a room-temperature superconductor that doesn’t require other exotic conditions, such as extreme pressure. Department of Energy scientists may have found a different path to get there: X-ray light.

The problem is that scientists don’t fully understand why these high-temperature superconductors work. To study the material, YBCO, scientists chill a sample to it superconducting state and then use a magnetic field to disrupt the superconductivity to study the material’s normal state. The new research has shown that a pulse of light can also disrupt the superconductivty, although the resulting state is unstable.

The research shows that charge density waves, which can serve as markers for superconductivity, occur when the samples are exposed to a magnetic field or to high-energy light pulses. While this is a far cry from creating room temperature superconductors, further study of the mechanism that allows light and magnetic fields to cause similar changes in the material could lead to a better understanding of the physics and maybe — one day — room-temperature superconductors.

Want to make your own YBCO? Go for it! Of course, you can already get room-temperature superconductors if you can stand the pressure.

As Light As Plastic; As Strong As Steel

February 7, 2022 by Al Williams 38 Comments

Chemical engineers at MIT have pulled off something that was once thought impossible. By polymerizing material in two different directions at once, they have created a polymer that is very strong. You can read a pre-print version of the paper over on Arxiv.

Polymers owe many of their useful properties to the fact that they make long chains. Molecules known as monomers join together in strings held together by covalent bonds. Polymer chains may be cross-linked which changes its properties, but it has long been thought that material that had chains going through the X and Y axis would have desirable properties, but making these reliably is a challenge.

Part of the problem is that it is hard to line up molecules, even large monomers. If one monomer in the chain rotates a bit, it will create a defect in the 2D structure and that defect will grow rapidly as you add more monomers. The new technique is relatively easy to do and is irreversible which is good because reversible chains tend to have undesirable characteristics like low chemical stability. Synthesis does require a few chemicals like melamine, calcium chloride, pyridine, and trimesic acid. Along with N-Methyl-2-pyrrolidone, the mixture eventually forms a gel. The team took pieces of gel and soaked it in ethanol. With some filtering, ultrasonics, centrifuging, and washing with water and acetone, the material was ready for vacuum drying and was made into a powder.

The powder is dissolved in acid and placed on a spinning silicon wafer to form a polymerized nanofilm. Other 2D films have been produced, of course, such as graphene, but polymer films may have a number of applications. In particular, in contrast to conventional polymers, sheets of this material are impermeable to gas and liquid, which could make it very useful as a coating.

According to the MIT press release, the film’s elastic modulus is about four and six times greater than that of bulletproof glass. The amount of force required to break the material is about twice that of steel. It doesn’t sound like this material will be oozing out of our 3D printers anytime soon. But maybe one day you’ll be able to get 2D super-strong resin.

For all their faults, conventional polymers changed the world as we know it. Some polymers occur naturally, and some use natural ingredients, too.