Science

1236 Articles

Measuring Nanometers At Home

March 11, 2024 by 10 Comments

If someone asked you to measure a change in distance at about one ten thousandths of the diameter of a proton, you’d probably assume you would need access a high-tech lab. The job is certainly too tight for your cheap Harbor Freight calipers. [Opticsfan], though, has a way to help. You might not be able to get quite that close, but the techniques will allow you to measure a surprisingly small distance.

The technique requires a Fabry Perot cavity, an inexpensive spectrometer, and an online calculator to interpret the data. This type of cavity is two parallel mirrors facing each other with a slight gap between them. Light can only pass through the cavity when it is in resonance with the cavity. These have been around since 1899, so they aren’t that exotic. In fact, they are often used in laser communication systems, according to the post.

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Team members Madeleine Laitz, left, and lead author Dane deQuilettes stand in front of a tidy lab bench equipped with oscilloscopes and computers. Laitz has a snazzy yellow jacket that pops compared to the neutrals and blues of the rest of the picture.

More Progress On Perovskite Solar Cells

March 8, 2024 by 20 Comments

Perovskites hold enormous promise for generating solar energy, with the potential to provide lighter and cheaper cells than those made from silicon. Unfortunately, the material breaks down too rapidly to be practical for most applications. But thanks to some recent research, we now have a better understanding of the nanoscale changes that happen during this breakdown, and how to combat it.

The research is focused on the topic of passivation, which seeks to increase the useful lifespan of perovskites by studying the surface interface where they meet other materials. Most of the perovskite material is a perfect latticework of atoms, but this structure is broken at the surface. This atomically “jagged” interface introduces losses which only get worse over time. Currently, the best way to address this issue is to essentially seal the surface with a very thin layer of hexylammonium bromide.

While this technique significantly simplified the passivation process when it was discovered, the effect had yet to be adequately characterized to further advance the field. According to lead author, [Dane deQuilettes], “This is the first paper that demonstrates how to systematically control and engineer surface fields in perovskites.”

Prefer to roll your own cells? How about a DIY dye sensitized cell or this thermionic converter model?

Avi Loeb And The Interstellar Lottery

March 4, 2024 by 94 Comments

Except for rare occasions, I don’t play the lottery. Like many of you, I consider state-run lotteries to be a tax paid only by people who can’t do math. That’s kind of arrogant coming from a guy who chose to go into biology rather than engineering specifically because he’s bad at math, but I know enough to know that the odds are never in your favor, and that I’d rather spend my money on just about anything else.

But I’m beginning to get the feeling that, unlike myself and many others, Harvard professor Avi Loeb just might be a fan of playing the lottery. That’s not meant as a dig. Far from it. In fact, I readily concede that a physicist with an endowed chair at Harvard working in astrophysics knows a lot more about math than I do. But given his recent news splashes where he waxes on about the possibility that Earth has been treated to both near misses and direct hits from interstellar visitors, I’m beginning to think that maybe I’m looking at the lottery backward.

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DIY Geophone Build Performs Well

March 2, 2024 by 14 Comments

If you want to know what’s going on with the ground, geologically speaking, a geophone is a great tool to have. It lets you listen in on the rumbles and grumbles beneath your feet, and can give you great insight into matters of seismic importance. [mircemk] has designed a very capable geophone that’s simple enough for you to build at home.

The geophone relies on a mass suspended upon a spring inside a chamber, which as you might imagine, will move when shaken by seismic vibrations. The mass is in fact a plastic rod, fitted with an iron nut and a magnet on the end.

This is mounted above a coil, which is fixed to the base of the chamber. Thus, when the chamber is shaken by seismic activity, the mass moves relative to the coil, with the coil picking up the varying magnetic field as it dances around.

The YouTube video does a great job of explaining the concepts involved and how to practically build the device. [mircemk] has also had some other great projects featured on Hackaday before, too.

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An illustration of jellyfish swimming in the ocean by Rebecca Konte. The jellyfish are wearing cones on their "heads" to streamline their swimming that contain some sort of electronics inside.

The Six Million Dollar Jellyfish

March 1, 2024 by 14 Comments

What if you could rebuild a jellyfish: better, stronger, faster than it was before? Caltech now has the technology to build bionic jellyfish.

Studying the ocean given its influence on the rest of the climate is an important scientific task, but the wild pressure differences as you descend into the eternal darkness make it a non-trivial engineering problem. While we’ve sent people to the the deepest parts of the ocean, submersibles are much too expensive and risky to use for widespread data acquisition.

The researchers found in previous work that making a cyborg jellyfish was more effective than biomimetic jellyfish robots, and have now given the “biohybrid robotic jellyfish” a 3D-printed, neutrally buoyant, swimming cap. In combination with the previously-developed “pacemaker,” these cyborg jellyfish can explore the ocean (in a straight line) at 4.5x the speed of a conventional moon jelly while carrying a scientific payload. Future work hopes to make them steerable like the well-known robo-cockroaches.

If you’re interested in some other attempts to explore Earth’s oceans, how about drift buoys, an Open CTD, or an Open ROV? Just don’t forget to keep the noise down!

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NASA Found Another Super Earth With Tantalizing Possibilities

February 29, 2024 by 57 Comments

Earth is a rather special place, quite unlike the other planets in the solar system. It’s nestled at the perfect distance from the sun to allow our water to remain liquid and for life to flourish in turn. It’s a rare thing; most planets are either too close and scorching hot, or too far and freezing cold.

NASA is always on the hunt for planets like our own, and recently found a new super-Earth by the name of TOI-715b. The planet is larger than our own, but it’s position and makeup mean that it’s a prime candidate for further study. Let’s take a look at how NASA discovered this planet, and why it’s special.

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The Strange Metal Phase And Its Implications For Superconductivity

February 28, 2024 by 1 Comment

The behavior of electrons and the exact fundamentals underlying the phenomenon we call ‘electricity’ are still the subject of many competing theories and heated debates. This is most apparent in the area of superconducting research, where the Fermi liquid theory — which has has formed the foundation of much of what we thought we knew about interacting fermions and by extension electrons in a metal — was found to break down in cuprates as well as in other metals which feature a state that is a non-Fermi liquid, also called a ‘strange metal phase’.

This phase was the subject of a 2023 research article by [Liyang Chen] and colleagues in Science titled Shot Noise in a Strange Metal. As summarized in a Quanta Magazine article, the term ‘shot noise’ refers hereby to the quasiparticles that are postulated by the Fermi liquid theory to form part of the electrical current as electrons interact and ‘clump’ together, creating discrete ‘particles’ that can be measured like rain drops falling on a roof. [Liyang Chen] and colleagues created a 200 nm thin nanowire (pictured, top) out of ytterbium, rhodium and silicon, followed by cooling it down to a few Kelvin and measuring the current.

What the team found was no sign of these discrete quasiparticles, but rather non-Fermi liquid continuous current. Yet what is exactly the nature of this measured current? Quite a few attempts at explaining this phenomenon have been undertaken, e.g. Jianfan Wang et al. (2022) in rare-earth intermetallic compounds. More recently [Riccardo Arpaia] and colleagues explore charge density fluctuations (CDF) as a signature of the quantum critical point (QCP), which is a point in the phase diagram where a continuous phase transition takes place at absolute zero.

They studied the CDF using X-ray scattering in cuprate superconductors with a wide doping range, using the measured CDF as an indication of the QCP, indicating that the former may be a result of the latter. With these results mostly inspiring more discussion and research, it’ll probably be a while still before we risk replacing the Fermi liquid theory, or apply strange metal findings to produce high-temperature superconductors.