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Science News April 26
🕑 Added 2023-04-26 15:00:06 +0000 UTC[This is a transcript with references.]
Welcome everyone to this week’s science news. Today we’ll talk about magnetic resonance imaging at record resolution, why the sun’s corona is so hot, nanoscale devices that can be reconfigured, an artificial tree that produces hydrogen from sunlight, a quantum light source on a chip, a sensor for plant health, aliens, quantum standards, and of course the telephone will ring.
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A team of American radiologists and computer scientists based at Duke University has taken a magnetic resonance image at record resolution.
Magnetic Resonance Imaging, MRI for short, was invented about 50 years ago. It works by applying a strong magnetic field to a sample. This aligns the magnetic moments of atomic nuclei. Then one uses a second, oscillating, field to look for resonances among the nuclei. These resonances can tell you what type of atomic nuclei are present at which location. The most common nuclei you look for in living tissue are hydrogen and oxygen.
The new device has now captured an image of a mouse brain at a resolution more than 1000 times better than previously. They did it by using an amazingly powerful magnet. It has a field strength of a whopping 9 point 4 Tesla rather than the typical 1 point 5 that most hospitalsuse. On top of that, they used advanced image processing on supercomputers to squeeze info out of their data. You can see the difference to the old imaging method here in these images of mouse brains. The old is on the left. New on the right. Both are thinking about cheese, I assume.
If you think that was impressive, look at this. This is track-density image of a mouse brain. It’s a 3D-reconstruction of MRI images that basically shows where water molecules flow. They make it down to a resolution of 5 microns, whereas typical MRIs have a resolution of a few hundred microns. So that’s an improvement by more than a factor 20 in each direction of space. It won’t be long, and they can tell whether the mouse is thinking about Cheddar or Parmesan.
An international team of astronomers has observed a small-scale reconnection of magnetic field lines on the sun. They say that these reconnections, if they are common enough, could explain why the sun’s corona is so much hotter than expected.
The reconnection happened on March third 2022 and took about an hour. It was captured by the Solar Orbiter, that’s a satellite from the European Space Agency which, as the name says, orbits the sun. They used data from an instrument that measures electromagnetic radiation in the extreme ultraviolet. The researchers then combined the Orbiter’s data with spectrographic measurements from NASA’s Solar Dynamics Observatory, that’s a satellite which orbits Earth but looks at the sun.
Scientists have seen *large magnetic reconnections before, like this one in 2015. They usually happen after violent coronal mass ejections when the sun spits out loads of energetic particles and radiation. But they haven’t been able to see much smaller, more leisurely, eruptions. This only became possible with the high-resolution measurements from the solar orbiter.
The new analysis found that the reconnection happened at what’s called a null-point on the surface of the sun. That’s a location where the magnetic field’s intensity vanishes. It basically means that positive and negative field values cancel each other out.
Let’s look at what they saw. This is the big picture, focusing in toward the null point and a small explosion of energy. In this case, the null point appeared above a small island of positive polarity, that was embedded within a region of dominant negative polarity near a sunspot. A fan of magnetic field lines spreads out from the null point, which is at the intersection of a spine-like field line above and one below. It looks sort of like a mop handle to me.
The heat at the null point remains at nearly 10 million degrees Kelvin. To give you some context, that’s pretty darn hot. Blobs of super-heated plasma are continuously tossed out from that place and propagate along the fan. They move about 80 kilometres a second. The researchers suggest that if these small-scale magnetic reconnections are sufficiently frequent, they could be an efficient way to transport heat into the corona, and thereby explain why it’s so hot.
Physicists at the University of California, Irvine have developed nanoscale devices that can be reconfigured after production.
Their discovery came about by accident. They printed nanoscale gold wires onto a type of crystal. When they tried to make a measurement on the wire, they accidentally bumped into it and saw that it moved around. This was quite unexpected. Most nanoparticles stay put on their surfaces because they’re strongly bound to it by van der Waals forces. Van der Waals force are caused by the distribution of electrons around atoms and molecules and are named after the Dutch theoretical physicist who won the Nobel Prize for discovering them in 1910.
Some materials, however, have weak van der Waals forces. In their experiment, the researchers used hexagonal boron nitride and it just turned out the friction from the force was so small that the golden nanowires on top could be moved around. This is super interesting because gold conducts electricity very well and is used in a lot of electronics.
The finding opens up entirely new ways to work with electronic devices because you could produce them so that they can perform different functions, depending on how you move the wires around. Maybe I shouldn’t have given up experimental physics, I am actually quite good with accidentally bumping into things.
A group of Swiss engineers has built a demonstration device for the production of hydrogen from sunlight and water. They had done that previously on a small scale in the laboratory, but they have now made the technology ready for application.
Their device is a shiny parabolic disk that tracks the sun through the day and concentrates its light almost 1,000 times. At the focus of the disk there’s a photoelectrochemical reactor. It’s supplied with water and the concentrated sunlight then splits the water into hydrogen and oxygen. They report a conversion efficiency of solar to hydrogen of more than 20 percent with a power output of more than 2 kilowatts.
In this diagram you see where the losses are. You also see that they don’t just capture the hydrogen, which is green in the diagram, but some of the heat, that’s the purple part . In principle the heat could be used for other purposes, such as, err, I guess heating?
The engineers are now working with a Swiss metal production facility to build a demonstration plant with many of these disks. They hope it will generate several hundreds of kilowatts of power, plus hydrogen and oxygen. They’ve called their device an artificial tree which makes me think the Swiss should let their engineers out a bit more often.
A group of researchers from several universities and the start-up QuiX Quantum has produced a chip that contains multiple sources for entangled light. It’s basically a microscopic version of an optical table.
The researchers effectively shrunk waveguides and non-linear optical crystals by a factor of more than 1,000. They also added a cavity where photons can interact. In the end, their device is barely the size of a one-Euro coin.
This chip works by shining laser light on it. The non-linear optical crystals on the chip then spontaneously create pairs of entangled photons which one can then perform further operations on. This artist’s illustration gives you an idea of what they’re talking about. The innovation here is that the creation of the entanglement is on the chip which shrinks down the amount of necessary external equipment.
The nice thing about quantum computing with photons is that you can use them at room temperature. That’s unlike, say IBM’s approach, which uses qubits made of superconducting circuits that need to be cooled to almost absolute zero, which is why IBM is now building the largest ever cryogenic tank.
A team of researchers at North Carolina State University has developed a sensor that monitors plant health. The small electronic patch is just three centimetres across, and you attachit to the underside of a leaf.
Its contains electrodes of silver nanowire that monitor temperature, humidity, the moisture exhaled by the plant, as well as the organic compounds the plant is shedding. These compounds can signal that the plant is under stress or battling infection. A machine-learning program then processes the data from the patch.
The team tested the sensor on tomatoes because they are one of the most widely consumed crops but unfortunately susceptible to many diseases. The sensor picked up wilt virus on the plant just four days after infection. This is long before the plant would show visible symptoms, which usually takes 10 to 14 days. This sensor could be a good method to limit the spread of crop diseases and overall make agriculture more efficient.
Scientists also recently found that plants make sounds when they are stressed. Or, if you’re the New York Times, you might say they heard plants “cry”. So maybe in the future the sensor should have a microphone, too.
But first the researchers want to make the sensor wireless and test it in the field, rather than in a greenhouse. They’ll not rest until every plant has its own fitbit.
The Harvard astronomer Avi Loeb, who claimed that the interstellar object ‘Oumuamua was alien technology is at it again. He has now produced a draft, together with Sean Kirkpatrick, head of the Pentagon’s All-domain Anomaly Resolution Office that’s tasked with figuring out what the Unidentified Aerial Phenomena are they’ve been seeing.
In their draft they elaborate on the possibility that aliens have sent probes which might land on our planet, or maybe already did. They call these probes ‘dandelion seeds and explain:
“In analogy with actual dandelion seeds, the probes could propagate the blueprint of their senders. As with biological seeds, the raw materials on the planet’s surface could also be used by them as nutrients for self-replication or simply scientific exploration.”
The draft also entertains the idea that a meteor which struck earth around the time that ‘Oumuamua passed by was such a probe, sent by its parent craft. I like the way this is going; alien stories are so much better than dark matter stories.
Hello?
Luke from Andromeda! Hey, haven’t heard from you in a while.
Your brother Mark, well, he’s still sorting out his metaverse business.
Yes, when he’s done, we’ll send him back right away, no worries. But remember, we get to keep Elon.
Thanks for checking in.
A European task force has published a roadmap to establish standards for quantum devices. The initiative is part of the European Commission’s push for quantum technology.
Yes, standards sound like the most boring thing ever, and very European indeed, but they’re actually super important. Imagine we had no standards for wall sockets, cables, or pipes. It’d be a mess. Or imagine there was no standard for what it means for something to be a “toothpaste”. You could sell mustard and call it toothpaste and there wouldn’t be anything wrong with it.
Trouble is, if you currently buy quantum technologies you don’t really know whether you’re getting mustard or toothpaste. At the moment, quantum devices with the same name may have different properties in different labs. And the properties of the devices aren’t the only problem. The units of measurement used for the specification also must be the same. That’s why we use the SI system. Most of us, anyway.
Quantum technology is new and its many components were invented without much coordination, or even common definitions. But if you want to one day sell those devices to other labs or companies, they must know exactly what they get before they notice it doesn’t fit to their other equipment.
Take the example of an ion trap. It’s a versatile component in quantum technology that’s used to store, cool, and manipulate charged atoms. But there are no technical norms that specify properties such as the geometry of electrodes or how well the confinement works. This means a trap from one lab may not fit to that of another lab and you can’t be sure if they’re even fit for your purposes.
So a roadmap for quantum standards may sound as boring as technology can get, but it’s an important step towards commercialization. You can’t count on the European Union for much, but you can count on them for standards.
Comments
Happy Tuesday Eric! I'd like to see field biologists develop humane processes that would end their killing of wildlife to become specimens, such as in taking genetic samples and using smaller, portable field technology for imaging internal structures to replace the physical need. So, do you feel that MRI machines can be reduced in size for field use? I've never worked on MRIs and so would like the opinion of someone who has.
We can keep Die Deutsche Physikerin, though? https://youtu.be/NrswlFxEiV4
Choices, choices ^^
Thanks, I very much appreciate the additional context. Please allow me to clarify that what I said was that they did it by using a strong magnet plus advanced data processing. At least that was my, admittedly rather limited, understanding of the paper.
Hi Sabine, medical physicist here. I'd like to offer you some constructive criticism on the mouse brain story you reported. The first is your comparison of the 9.4T mouse brain scans with the typical 1.5T scanners found in hospitals. Mice are going to be scanned with what is called a preclinical scanner, a much smaller device that has been able to reach those tesla levels and higher for decades. The second is your statement that the Tesla of the scanner is driving the resolution improvements. Not exactly. What higher Tesla scanners enable is better resolution over time, which is indeed the medically important parameter. However the resolution is really limited by the range of the gradient coils, which limits the bandwidth of the Fourier-transformed image the MRI machine produces. The issue that higher Tesla helps to solve is that, if the gradient coils are cranked too hard at a lower Tesla the image will be overwhelmingly noise. However the noise is white and can be removed over extended period s of time by averaging. So very high resolution images of a cadaver can indeed be obtained in a 1.5T scanner if it is left to run for a few days, although at some point the gradient coils reach their limits. There are in fact 9+T scanners for humans but they have not contributed much to science. This is because physiological tremor is wider than the resolution advantages so in the images with living people, the potential resolution advantage is blurred out, and with a corpse they can just use a lower Tesla scanner and average the images overnight.
Fair call.
If I had to keep one, at this point I'd keep Mark and definitely send Elon back instead.
The Duke 9.4 Tesla MRI is pretty impressive. I know the University of Minnesota does that sort of research, too. I see that they are using a 10.5 Tesla magnet: https://med.umn.edu/radiology/research/center-magnetic-resonance. No mice brain images, though.
No but can Luke and his mates take Elon back too, PLEASE!?
I love these science news updates.
