One of the benefits of being on Physics World is that you get to meet some of the world’s best and brightest physicists – some of whom are Nobel laureates and some who could very well be among this year’s winners.
For years I attended the March Meeting of the American Physical Society – a gathering of upwards of 10,000 physicists where you are sure to bump into a Nobel laureate or two. At the 2011 meeting in Dallas I had the pleasure of interviewing MIT’s Frank Wilczek, who shared the 2004 prize with David Gross and David Politzer for their “for the discovery of asymptotic freedom in the theory of the strong interaction”.
But instead of looking back on his work on quarks and gluons, Wilczek was keen to chat about the physics of superconductivity and it’s wide-reaching influence on theoretical physics. You can watch a video of that interview above or here: “Superconductivity: a far-reaching theory”.
Amusing innuendo
Wilczek was a lovely guy and I was really pleased four years later when he recognized me at the Royal Society in London. We were both admiring portraits of fellows, and the amusing innuendo found in one of the picture captions. On a more serious note, we were both there for a celebration of Maxwell’s equations and you can read more about the event here: “A great day out in celebration of Maxwell’s equations”.
Also at that event in London were John Pendry of nearby Imperial College London and Harvard University’s Federico Capasso – who are both on our list of people who could win this year’s Nobel prize. Pendry is a pioneer in the mathematics that describes how metamaterials can be used to manipulate light in weird and wonderful ways – and Capasso has spent much of his career making such metamaterials in the lab, and commercially.
The Royal Society was also where I recorded a video interview with Albert Fert, who shared the 2007 prize with Peter Grünberg for their work on giant magnetoresistance (watch below). A decade or so earlier, I had completed a PhD on ultrathin magnetic materials, so I was very happy to hear that two pioneers of the field had been honoured.
In the interview, Fert looks to the future of spintronics. This is an emerging field in which the magnetic spin of materials is used to store and transport information – potentially using much less energy than conventional electronics.
I recorded a second video interview that day with David Awschalom, now at the University of Chicago. He is a pioneer in spintronics and much of his work is now focused on using spins for quantum computing. Another potential Nobel laureate perhaps?
We don’t do video interviews anymore – instead we chat with people on our podcasts. As you can see from our videos, I really struggled with the medium. The laureates, however, were real pros!
SmarAct proudly supports Physics World‘s Nobel Prize coverage, advancing breakthroughs in science and technology through high-precision positioning, metrology and automation. Discover how SmarAct shapes the future of innovation at smaract.com.
Amid the hype of Nobel Prize week, it’s important to remember that in many respects, Nobel laureates are just like the rest of us. They wake up and get dressed. They eat. They go about their daily lives. And when it’s time for bed, they lie down on mattresses that have been rotated scientifically, according to the principles of symmetry group theory.
In the early 1960s, Josephson – then a PhD student in theoretical condensed matter physics at the University of Cambridge, UK – predicted that a superconducting current should be able to tunnel through an insulating junction even when there is no voltage across it. He also predicted that if a voltage is applied, the current will oscillate at a well-defined frequency. These predictions were soon verified experimentally, and in 1973 he received a half share of the Nobel Prize for Physics (Ivar Giaever and Leo Esaki, who did experimental research on quantum tunnelling in superconductors and semiconductors respectively, got the other half).
Subsequent work has borne out the importance of Josephson’s discovery. “Josephson junctions” are integral to instruments called SQUIDs (superconducting quantum interference devices) that measure magnetic fields with exquisite sensitivity. More recently, they’ve become the foundation for superconducting qubits, which drive many of today’s quantum computers.
Josephson himself, however, lost interest in theoretical condensed-matter physics. Instead, he has devoted most of his post-PhD career to the physics of consciousness, researching topics such as telepathy and psychokinesis under the auspices of the Mind-Matter Unification Project he founded.
An unusual scientific paper
Josephson’s later work hasn’t attracted much support from his fellow physicists. Still, he remains an active member of the community and, incidentally, a semi-regular contributor to Physics World’s postbag. It was in this context that I learned of his work on the pressing domestic dilemma of mattress rotation.
In December 2014, Josephson responded to a call for submissions to Physics World’s Lateral Thoughts column of humorous essays with a brief but tantalizing message. “What a pity my ‘Group Theory and the Art of Mattress Turning’ is too short for this,” he wrote. This document, Josephson explained, describes “the order-4 symmetry group of a mattress, and how an alternating sequence of the two easiest non-trivial group operations…takes you in sequence through all four mattress orientations, thereby preserving as much as possible the symmetry of the mattress under perturbations by sleepers [and] enhancing its lifetime.”
At the time, I had only recently purchased my first mattress, and I was keen to avoid shelling out for another any time soon. I therefore asked for more details. Within days, Josephson kindly replied with a copy of his mock paper, in the form of a scanned “cribsheet” which, he explained, lives under the mattress in the home he shares with his wife.
An argument from symmetry
Like all good scientific papers, Josephson’s “Group Theory and the Art of Mattress Turning” begins with a summary of the problem. “A mattress may be laid down on a bed in four different orientations,” it states. “For maximum life it should be cycled regularly through these four orientations. How may a mattress user ensure that this be done?”
The paper goes on to observe that the symmetry group of a mattress (that is, the collection of all transformations under which it is mathematically invariant) contains four elements. The first element is the identity transformation, which leaves the mattress’ orientation unchanged. The other three elements are rotations about the mattress’ axes of symmetry. Listed “in order of increasing physical effort required to perform”, these rotations are:
V, rotation by π (180 degrees) about a vertical axis (that is, keeping the mattress flat and spinning it around so that the erstwhile head area is at the feet)
L, rotation by π about the longer axis of symmetry (that is, flipping the mattress from the side of the bed, such that the head and foot ends remain in the same position relative to the bed, but the mattress is now upside down)
S, rotation by π about the shorter axis of symmetry (that is, flipping the mattress from the end of the bed, such that the head and foot ends swap places while the mattress is simultaneously turned upside down)
“Ideally, S should be avoided in order to minimize effort”, the paper continues. Fortunately, there is a solution: “It is easily seen that alternate applications of V and L will cause the mattress to go through all ‘proper’ orientations relative to the bed, in a cycle of order 4. The following algorithm will achieve this in practice: Odd months, rotate about the lOng axis. eVen months, rotate about the Vertical axis.” In case this isn’t memorable enough, the paper advises that “potential users of this algorithm may find it helpful to write it down on a piece of paper which should be slipped under the mattress for retrieval later when it may have been forgotten”.
A challenging problem
The paper concludes, as per convention, with an acknowledgement section and a list of references. In the former, Josephson thanks “cj” – presumably his wife, Carol – “for bringing this challenging problem to my attention”. The latter contains a single citation, to a “Theory of Compliant Mattress Group lecture notes on applications of group theory” supposedly produced by Josephson’s office-mate Volker Heine.
The most endearing part of the paper, though, is the area below the references in the scanned cribsheet. This contains extensive handwritten notes on months and rotations, strongly suggesting that Josephson does, in fact, rotate his mattress according to the above-outlined principles. Indeed, in a postscript to his e-mail, Josephson noted that he and Carol recently had to modify the algorithm in response to a change in experimental conditions, namely the purchase of “a very flexible foam mattress”. This, he observed, “makes S rotations easier than L rotations, so we use that instead”.
I wish I could say that I adopted this method of mattress rotation in my own domestic life. Alas, my housekeeping is not up to Nobel laureate standards: I rotate my mattress approximately once a season, not once a month as the algorithm requires. However, whenever I do get round to it, I always think of Brian Josephson, the unconventional Nobel laureate whose tongue-in-cheek determination to apply physics to his daily life never fails to make me smile.
SmarAct proudly supports Physics World‘s Nobel Prize coverage, advancing breakthroughs in science and technology through high-precision positioning, metrology and automation. Discover how SmarAct shapes the future of innovation at smaract.com.
The European Space Agency (ESA) has launched a €360m mission to perform a close-up “crash-scene” investigation of the 150 m-diameter asteroid Dimorphos, which was purposely hit by a NASA probe in 2022. Hera took off aboard a SpaceX Falcon 9 rocket from Cape Canaveral at 10:52 local time. The mission should reach the asteroid in December 2026.
On 26 September 2022, NASA confirmed that its $330m Double Asteroid Redirection Test (DART) mission successfully demonstrated “kinetic impact” by hitting Dimorphos at a speed of 6.1 km/s. This resulted in the asteroid being put on a slightly different orbit around its companion body – a 780 m-diameter asteroid called “Didymos”.
A month later in October, NASA confirmed that DART had altered Dimorphos’ orbit by 33 minutes, shortening the 11 hour and 55-minute orbit to 11 hours and 23 minutes. This was some 25 times greater than the 73 seconds NASA had defined as a minimum successful orbit period change. Much of the momentum change came from the ejecta liberated by the impact including a plume of debris that extended more than 10 000 km into space.
Mars flyby
The Hera mission, which has 12 instruments including cameras and thermal-infrared imagers, will perform a detailed post-impact survey of Dimorphos. This will involve measuring its size, shape mass and orbit more precisely than has been carried out to date by follow-up measurements from ground- and space-based observatories including the Hubble Space Telescope.
It is hoped that Hera will be able to reach up to 200 m from the surface of Dimorphos to deliver 2 cm imaging resolution in certain sections.
Part of the Hera mission involves releasing two cubesats – each the size of a shoebox – that will also have imagers and radar onboard. They will examine Dimorphos’ internal structure to determine whether it is a rubble pile or has a solid core surrounding by layers of boulders.
The cubesats will also attempt to land on the asteroid with one measuring the asteroid’s gravitational field. The cubesats are also technology demonstrators, testing communication in deep space between them and Hera.
Once Hera’s mission is complete about six months after arrival at Dimorphos, it may also attempt to land on the asteroid, although a decision to do so has not yet been made.
On its way to Dimorphos, next year Hera will carry out a “swingby” of Mars and a flyby of the Martian moon Deimos.
Charting disciplines This infographic shows the fields of physics associated with successive Nobel Prizes for Physics. Click on the image to expand. (Courtesy: Alison Tovey/IOP Publishing)
Part of the fun of the run-up to the announcement of the Nobel Prize for Physics is the speculation – serious, silly or otherwise – of who will be this year’s winner(s). Here at Physics World, we don’t shy away from making predictions but our track record is not particularly good.
That’s not surprising, because the process of choosing Nobel winners is highly secretive and we know nothing about who has been nominated for this year’s prize. That’s thanks to the 50-year embargo on all information related to the decision.
Several years ago we created an infographic that charts the history of the Nobel Prize for Physics in terms of the discipline of the winning work (see figure). For example, last year the prize was shared by Pierre Agostini, Ferenc Krausz and Anne L’Huillier for their pioneering work using attosecond laser pulses to study the behaviour of electrons. We categorized this prize as “atomic, molecular and optical” and you can see that prize at the top of the infographic, connected to its category by a darkish blue line.
As well as revealing which disciplines of physics have received the most attention from successive Nobel committees, the infographic also shows that some disciplines fall in and out of favour, while others have produced a steady stream of winners over the past 12 decades. The infographic shows, for example, the return of quantum physics to the Nobel realm. The discipline was popular with the Nobel committee in the 1910s–1950s and then fell completely out of favour until 2012.
Another thing that is apparent from the infographic is that after about 1990 there tends to be well-defined gaps between disciplines. And for no good scientific reason, we have decided that we can analyse these gaps and use the results to make predictions!
Partially correct
Last year, we noticed that atomic, molecular and optical physics was due a prize. That observation, in part, led us to predict that Paul Corkum, Ferenc Krausz and Anne L’Huillier would win in 2023. This partially correct prediction has emboldened our faith in the mystical ability of our infographic to help predict winners.
So what does that mean for our predictions for this year?
The infographic makes it clear that we are overdue a prize in condensed-matter physics. Some possibilities that we have identified include magic-angle graphene and metamaterials.
So tune into Physics World tomorrow and find out if we are right.
SmarAct proudly supports Physics World‘s Nobel Prize coverage, advancing breakthroughs in science and technology through high-precision positioning, metrology and automation. Discover how SmarAct shapes the future of innovation at smaract.com.
The initial idea to build an online system that uses a micro-plasma to analyse metals in liquids came from Toni Laurila, who is now Sensmet’s co-founder and CEO. He got the idea during his post-doctoral studies at the University of Cambridge, UK, and after he returned to Finland, we started to develop an online instrument for industrial process and environmental applications.
Typically, if you need to measure metals in liquid – whether it’s wastewater, industrial process water or natural bodies like rivers and lakes – you collect a sample and send it to a laboratory for analysis. Depending on the lab, it might take up to several days to get the results. If you need to control a process based on such outdated data, it’s like trying to drive your car while solely relying on a rearview mirror where the image is 4‒10 hours old. By the time you see what’s happening, you’ve already veered off the road.
We saw that we can do for liquid monitoring what other companies did for online gas monitoring around 30 years ago, when the regulations started changing in a way that meant practically all gaseous emissions needed to be monitored in real time. We believe this will also be the future for liquids.
What kinds of liquids are you analysing?
Regulations on real-time monitoring of liquids are going to come at some point, and we believe that our technology will make that possible, but it has not happened yet. This means that for now, we are focusing on analysing liquids involved in industrial processes, because that is an area where we can give customers a return on their investment.
A good example is the battery industry, which is growing rapidly due to the popularity of electric cars. This is driving huge demand for lithium and other metals. If we want to produce enough electric cars to reduce emissions from petrol and diesel vehicles, we can’t do it just by mining new metals. The recycling rate for old batteries also needs to rise.
How does battery recycling work, and how do Sensmet’s analysers help?
Typically, you take the end-of-life battery from an electric car and shred it into very fine particles to create what’s known as the black mass. Separating the valuable metals from the black mass then involves a hydrometallurgical process, where the metals are converted into a liquid form, typically by dissolving or leaching them in acids. Once the valuable metals are dissolved, they are extracted from the black mass one by one through processes such as solvent extraction or ion exchange.
What makes our analyser particularly well-suited for monitoring this battery recycling process is that we can measure multiple metals simultaneously. This includes light elements such as lithium and sodium that cannot be measured using X-ray fluorescence, a commonly used technique for metals analysis.
Real-time measurement is essential for optimizing the battery metal recycling process. By continuously monitoring the concentrations of key metals such as lithium, manganese, cobalt, nickel, copper, aluminium and calcium, process operators can quickly detect anomalies, enhancing both quality and efficiency. The speed of the processes used to separate elements from the black mass is another critical factor. If you’re having to wait around for a laboratory analysis, you cannot optimize them very well. You’re not getting the rapid, real-time measurements you need to improve your yield, and that can mean increased waste.
Ready to go Based on spectrometers built by Avantes, Sensmet aims to sell its products to companies involved in the battery manufacturing and mining sectors. (Courtesy: Sensmet)
A clear example is ion exchange columns, which require periodic regeneration as they become saturated. Our analyser monitors the solution from these columns, and when it detects a rise in, say, nickel concentration, the customer knows it’s time to regenerate the column. In these situations, the speed of analysis is crucial for optimizing the production efficiency.
What challenges did you encounter in developing your analyser?
While proving a technology’s effectiveness in the lab is relatively straightforward, developing a product that performs reliably in real-world conditions is much more challenging. Our customers require an analyser that is both robust and reliable in demanding industrial environments, consistently delivering accurate results day after day, year after year.
We also conduct environmental online monitoring of industrial wastewater, which is challenging in Finland, where winter temperatures can drop to –35 °C. To address this, we can house our analyser in a container and use heated measurement lines to transfer the liquid samples, for example from a settling pond.
These harsh conditions and customer requirements are some of the reasons we chose to use a spectrometer from Avantes in our analyser. The way Avantes builds their spectrometers, they are quite robust. If you accidentally hit them a little bit, they maintain their calibration.
What are some other advantages of Avantes spectrometers?
We bought our first spectrometer from them before we spun out of the university in 2017. It was a high-resolution system for plasma research, and it allowed us to do very fast measurements and collect multiple spectra at high speeds. After that, it was easy to choose the next spectrometer from the same manufacturer because we’d already built the programs and controls for our prototype analyser based on it. And we’ve always had very good service from Avantes. When we have faced a problem, they’ve always helped us quickly. That’s very important, especially at the university stage when we were using the spectrometer beyond its regular scope.
What do you know now that you wish you’d known when Sensmet got started?
When we started building our analyser and realized what it could do, we felt like kids in a candy shop surrounded by a million treats. There is water everywhere, so we believed our technology had universal appeal and expected everyone to adopt it immediately.
As a start-up, focus is everything. You need to concentrate on a specific market and convince those customers that your product is the right fit for them. Only then can you expand to the next market. However, we were young with limited experience, so it took us some time to realize this.
What are you working on now?
Our first product is ready, so our focus is on pushing it to the market. We are working with multiple battery manufacturing companies and mining companies to make ourselves known as a reliable provider of analysers that can really bring significant added value to customer processes.
Kalle Blomberg is the chief technology officer at Sensmet
With the CERN particle-physics lab turning 70 this year, I’ve been thinking about the impact of big science on business. There are hundreds – if not thousands – of examples I could cite, the most famous being, of course, the World Wide Web. It was devised at CERN in 1989 by the British computer scientist Tim Berners-Lee, who was seeking a way to organize and share the huge amounts of data produced by the lab’s fundamental science experiments.
While the Web wasn’t a spin-off technology as such, it’s hard to think of anything developed with one purpose in mind that’s had such far-reaching applications across the whole of business and society. Indeed, CERN can lay claim to lots of spin-off firms that have pushed the boundaries of technology. Many of those firms specialize in detectors, imaging and sensors, but quite a few are involved in materials, coatings, healthcare and environmental applications.
It would be impossible for me to discuss them all in a short article, but there are lots – and CERN is rather good these days at knowledge transfer. So too are large national labs, such as Harwell and Daresbury in the UK, which have co-ordinated spin-out and knowledge transfer activities supported by UK Research and Innovation. A recent report from the UK government claims that firms spun out from the country’s public sector had raised a total of £5.1bn of investment and created more than 7000 new jobs over the last four decades.
One particularly exciting spin-off from big science is from the burgeoning fusion industry. There are currently about 40 different companies around the world trying to develop commercial fusion-power plants that can serve as a sustainable source of electricity in our quest for net zero. Whilst the sector is making steady progress towards that goal, the associated technology could have some other rather interesting applications too.
Fusion tech
Consider Tokamak Energy, which was founded in 2009 by a group of scientists and researchers at the UK Atomic Energy Authority, making it a spin-out of sorts. The company’s main aim is to build a tokamak fusion plant that could one day deliver electricity to the grid. But over the years it’s also become rather good at making high-temperature superconducting (HTS) magnets, with more than 200 patents to its name.
The company is, for example, working with the US Department of Energy, via the Defense Advanced Research Projects Agency (DARPA), to build a magnetohydrodynamic drive (MHD). Such a device, which provides propulsion without any moving parts, conjures up visions of the great 1990s movie The Hunt for Red October, where Sean Connery played a Soviet sailor captaining a submarine that can’t be detected by sonar.
One particularly exciting spin-off from big science is from the burgeoning fusion industry
In terms of physics, an MHD drive uses electric fields to accelerate an electrically conducting fluid. A magnetic field applied perpendicularly to the flow creates a thrust – the Lorenz force – at 90° to the electric and magnetic fields, in accordance with the right-hand rule. Back in the 1990s, the Japanese firm Mitsubishi did build a ship – Yamato 1 – powered by a prototype MHD thruster, but with the technology available at the time limiting magnetic fields to just 4 T, the boat only had a top speed of 15 km/h.
Since then, however, HTS magnet technology has markedly improved. In 2019, for example, Tokamak Energy announced it had built a magnet that produced a record-breaking 24 T field at 20 K. Based on superconducting barium-copper-oxide tape technology, the magnet is designed to be used in the poloidal field coils of a tokamak fusion device. The superconducting magnets at the Joint European Torus (JET) fusion facility in the UK, in contrast, produced fields of only 4 T.
For Tokamak Energy to create such a powerful magnet was quite an achievement, and you can imagine that it could improve MHD performance and open the door to many other applications too. In fact, the company has just launched a new business division called TE Magnetics, focusing on HTS magnet technology. It wants to tap into a market that a recent report from Future Market Insights reckons was worth an astonishing $3.3bn in 2023.
Aircraft advances
David Kingham, co-founder and executive vice-chair of Tokamak Energy, points to applications of HTS magnets in everything from space thrusters and proton-beam therapy to motors and generators for wind turbines and planes. That final application is perhaps the most intriguing as it’s very difficult for non-superconducting motors to achieve the huge power density needed for large aircraft to fly.
If you’re thinking an HTS-powered plane sounds far-fetched, it turns out that Airbus is already on the case, as are many other firms too. Over the last few years, Airbus has been developing prototype motors using this kind of technology that, to me, are a serious contender in the quest for low-carbon air travel. Through its ASCEND programme, the company has already built a 500 kW powertrain featuring an electric motor powered by the current from HTS tape.
Airbus thinks the cryogenics needed to cool the tape could be driven by the liquid hydrogen fuel that would generate the power in a fuel cell. The beauty of superconducting systems is that they’re much more efficient than conventional technology and can deliver huge power densities – pointing the way to lighter and more efficient planes.
If you think a plane powered by high-temperature superconductors sounds far-fetched, it turns out that Airbus is already on the case
There’s obviously a little more work to do before such technology can reach commercial reality. After all, getting today’s city-hopping turboprop planes off the ground using electric power alone would require around 8 MW of power. But what Airbus has done is a promising start – and reliable HTS magnets will be vital for this work to really succeed.
Another company working on the electrification of air transport is Evolito, which was spun out in 2021 by the UK firm YASA. Now owned by Mercedes-Benz, YASA is a pioneer of “axial-flux” electric motors, which have very high power densities yet don’t need to be cooled to cryogenic temperatures. YASA has already worked with Rolls-Royce to develop Spirit of Innovation, which in 2021 claimed the record for the world’s fastest electric plane, clocking a top speed of 623 km/h.
My message is simple: spin-offs and spin-outs are everywhere. So next time you have your head down and are working on something very specific, keep an open mind as to what else it could be used for – it may be more commercially relevant than you think. The applications could be even more than you ever imagined – and if you don’t believe me, just go and ask Tim Berners-Lee.
Astronauts spending time in the harsh environment of space often experience damaging effects on their health, including a deterioration in heart function. Indeed, the landmark NASA Twins Study found that an astronaut who spent a year on the International Space Station (ISS) had significantly increased cardiac output and reduced arterial pressure compared with his identical twin who remained on Earth. And with missions planned to Mars and beyond, there’s an urgent need to understand how long-duration spaceflight affects the cardiovascular system.
With this aim, a research team headed up at Johns Hopkins University has sent a heart-on-a-chip platform to the International Space Station and investigated the impact of 30 days in space on the cardiac cells within. The findings, reported in the Proceedings of the National Academy of Sciences, could also shed light on the changes in heart structure and function that occur naturally due to ageing.
“I began cardiac research after my own father died of heart disease when I was a senior college student, and my main motivation for studying the effects of spaceflight on cardiac cells stemmed from the striking resemblance between cardiac deterioration in microgravity and the ageing process on Earth,” project leader Deok-Ho Kim tells Physics World. “The ability to counteract the impacts of microgravity on cardiac function will be essential for prolonged duration human spaceflights, and may lead to therapies for ageing hearts on Earth.”
Compact housing Launch-ready tissue chamber containing six EHTs (top image) and four chambers loaded into a plate habitat (lower image). (Courtesy: Jonathan Tsui)
The heart-on-a-chip platform is based on engineered heart tissues (EHTs), in which heart muscle cells (cardiomyocytes) derived from human-induced pluripotent stem cells are cultured within a hydrogel scaffold. The key advantage of this design over previous studies using 2D cultured cells is its ability to more accurately replicate human cardiac muscle tissue.
“Cells cultured on traditional 2D petri dishes do not behave as they would in the body, whereas our platform provides a physiologically relevant 3D environment that mimics in vivo conditions,” Kim explains.
Inside the platform, the EHTs are mounted between two posts, one of which is flexible and contains a small magnet that moves as the tissue contracts. Small magnetic sensors measure the changes in magnetic flux to determine tissue contraction in real time.
Designed for space
To allow culture of the cardiac cells in microgravity, Kim’s team – primarily postdoctoral fellow Jonathan Tsui – developed custom sealed tissue chambers containing six EHTs. These chambers, along with the magnetic sensors and associated electronics, were housed within a compact plate habitat that required minimal handling to maintain cell viability. “The platform was designed to be easily maintained by astronauts aboard the ISS, an important consideration as crew time is a precious resource,” says Kim.
The tissue chambers were carefully transported by Tsui to the Kennedy Space Center, then launched to the ISS aboard the SpaceX CRS-20 mission in March 2020. The researchers then monitored the function of the cardiac tissues for 30 days in microgravity, using the sensors to automatically detect magnet motion as the cells beat. The raw data were transmitted down from the ISS and converted into force and frequency measurements that provided insight into the contraction strength and beating patterns, respectively.
Once the samples were back on Earth, the researchers examined the cardiac tissues during a nine-day recovery period. They compared their findings with results from an identical set of EHTs cultured on Earth for the same duration.
Cardiac impact
After 12 days on the ISS, the EHTs exhibited a significant decrease in contraction strength compared with both baseline values and the control EHTs on Earth. This reduction persisted throughout the experiment and during the recovery period on Earth. The cardiac tissues also exhibited increased incidences of arrhythmia (irregular heart rhythm) whilst on the ISS, although this resolved once back on Earth.
At the end of the experiment (day 39), Kim and colleagues examined the cardiac tissue using transmission electron microscopy. They found that spaceflight caused sarcomeres (protein bundles that help muscle cells contract) to become shorter and more disordered – a marker of human heart disease. The changes did not resolve after return to Earth and may be why the cardiac tissues did not regain contraction strength in the recovery period. The team also observed mitochondrial damage in the cells, including fragmentation, swelling and abnormal structural changes.
To further assess the impact of prolonged microgravity, the researchers performed RNA sequencing on the returned tissue samples. They observed up-regulation of genes associated with metabolic disorders, heart failure, oxidative stress and inflammation, as well as down-regulation of genes related to contractility and calcium signalling. Finally, they used in silico modelling to determine that spaceflight-induced oxidative stress and mitochondrial dysfunction were key to the tissue damage and cardiac dysfunction seen in space-flown EHTs.
“By conducting a detailed investigation into cellular changes under real microgravity conditions, we aimed to uncover the mechanisms behind these alterations, potentially leading to therapies that could benefit both astronauts and the ageing population,” says Kim.
Last year, the researchers sent a second batch of EHTs to the ISS to screen drugs that may protect against the effects of low gravity. They are currently analysing the data from these studies. “These results will help us refine the effectiveness of promising drug therapies for our upcoming third mission,” says Kim.
If you have ever experienced a preschool environment you will know how seemingly chaotic it can be. Now physicists in the US and Germany have examined the movement of preschool children in classroom and playground settings to determine if any rules can be gleaned from their dawdling.
To do so they put radio-frequency tags on the vests of more than 200 children aged between two and four and then monitored their position and trajectories via receivers placed around the environment.
The researchers found that the dynamics resembled two distinct phases. The first is a gas-like phase in which the children are moving freely while exploring their surroundings.
This was mostly seen in the playground where children could roam without restriction, with the researchers finding that toddlers’ movement is similar to that of pedestrian flow.
The second phase is a “liquid-vapour-like state”, in which the children act like molecules to form “droplets” of social groups. In other words, they coalesce into smaller, more clustered groups with some “free-moving” individuals entering and exiting these groups.
The team found that this phase was most evident in classrooms, in which the children are more constrained and social communication plays a bigger role. Indeed, this type of behaviour has not been observed in human movement before, with the findings offering new insights about the dynamics of low-speed movement.
Researchers have succeeded in growing a uniform 2D layer of silk protein fragments on a van der Waals substrate – in this case, graphene – for the first time. The feat should prove important for developing silk-based electronics, which have been limited until now because of the difficulty in controlling the inherent disorder of the fibrillar silk architecture.
Silk is a protein-based material that humans have been using for over 5000 years. In recent years, researchers have been looking to exploit one of its two main components, silk fibroin (which is made up of protein fragments), in electronic and bioelectronic applications. This is because it can self-assemble into a range of fibril-based architectures that boast excellent mechanical and optical properties. Indeed, devices in which silk fibroin films are interfaced with van der Waals solids, metals or oxides appear to be particularly promising for making next-generation thin-film transistors, memory transistors (or memristors), human–machine interfaces and sensors.
There is a problem, however, in that silk cannot be used in its natural form for such devices because its fibres are arranged in a disordered, tangled fashion. This means it cannot uniformly or accurately modulate electronic signals.
Controlling natural disorder
A team of researchers, led by materials scientist and engineer James De Yoreo of the PNNL and the University of Washington, has now found a way to control this disorder. In their work, the researchers grew highly organized 2D films of silk fibroins on graphene, a highly conducting sheet of carbon just one atom thick.
Using atomic force microscopy, nano-Fourier transform infrared spectroscopy and molecular dynamics calculations, the researchers observed that the films consist of stable lamellae of silk fibroin molecules that have the same structure as the nano-crystallites of natural silk. The fibroins pack in precise parallel beta-sheets – a common protein shape found in nature – on this substrate.
Thanks to scanning Kelvin probe measurements, De Yoreo and colleagues also found that the films modulate the electric potential of the graphene substrate’s surface.
The researchers say that they took advantage of the inherent interactions of the silk molecules with the substrate and its crystallinity to force the silk molecules to assemble into a crystalline layer at the interface between the two materials. They then regulated the concentration of the aqueous solution in which the silk proteins had been dissolved to limit the number of silk layers that form. In this way, they were able to assemble single monolayers, bilayers or much thicker multilayers.
Uniform properties
Since the material is highly ordered, its properties are uniform, says De Yereo. What’s more, because of the strong intermolecular interactions in the beta-sheet arrangement and the strong interactions with the substrate, it is highly stable. “In its pure state, it can regulate the surface potential of the underlying conductive substrate, but there are techniques for doping silk to introduce both optical and electronic properties that can greatly expand its useful properties,” he explains.
The researchers hope their results will help in the development of 2D bioelectronic devices that exploit natural silk-based layers chemically modified to provide different electronic functions. They also plan to use their starting material to create purely synthetic silk-like layers assembled out of artificial, sequence-defined polymers that mimic the amino acid sequence of the silk molecule. “In particular, we see potential for using these materials in memristors, for computing based on neural networks,” De Yereo tells Physics World. “These are networks that could allow computers to mimic how the brain functions.”
It is important to note that the system developed in this work is nontoxic and water-based, which is crucial for biocompatibility, adds the study’s lead author Chenyang Shi.
It was a once-in-a-lifetime moment during a meeting in 2011 when Juan Pedro Ochoa-Ricoux realized that new physics was emerging in front of his eyes. He was a postdoc at the Lawrence Berkeley National Laboratory in the US, working on the Daya Bay Reactor Neutrino Experiment in China. The team was looking at their first results when they realized that some of their antineutrinos were missing.
Ochoa-Ricoux has been searching for the secrets of neutrinos since he began his master’s degree at the California Institute of Technology (Caltech) in the US in 2003. He then completed his PhD, also at Caltech, in 2009, and is now a professor at the University of California Irvine, where neutrinos are still the focus of his research.
The neutrino’s non-zero mass directly conflicts with the Standard Model of particle physics, which is exciting news for particle physicists like Ochoa-Ricoux. “We actually like it when the theory doesn’t match the experiment,” he jokes, adding that his motivation for studying these elusive particles is for the new physics they could reveal. “We need to know how to extend [the Standard Model] and neutrinos are one area where we know it has to be extended.”
Because they rarely interact with matter, neutrinos are notoriously hard to study. Electron antineutrinos are however produced in measurable quantities by nuclear reactors and this is what Daya Bay was measuring. The experiment consisted of eight detectors measuring the electron antineutrino flux at different distances from six nuclear reactors. As the antineutrinos disperse, the detectors further away are expected to measure a smaller signal than those close by.
However, when Ochoa-Ricoux and his team analysed their results, they found “a deficit in the far location that could not only be explained by the fact that those detectors were farther away”. Neutrinos come in three types, or “flavours”, and it seemed that some of the electron antineutrinos produced in the power plants were changing into tau and muon antineutrinos, meaning the detector didn’t pick them up.
This transformation of neutrino type, also known as “oscillation”, occurs for both neutrinos and antineutrinos. It was first observed in 1998, with the discovery leading to the award of the 2015 Nobel Prize for Physics. However, physicists are still not sure if antineutrinos and neutrinos oscillate in the same way. If they don’t, that could explain why there is more matter than antimatter in the universe.
The mathematics of neutrino oscillation is complex. Among many parameters, physicists define an angle called θ13, which plays a role in determining the probability of certain flavour oscillations. For differences in oscillation probabilities between neutrinos and antineutrinos to be possible, this quantity must be non-zero. When Ochoa-Ricoux was working on the Main Injector Neutrino Oscillation Search (MINOS) at Fermilab in the US for his PhD, he had found tantalizing but inconclusive evidence that θ13 is different from zero.
Science at work Juan Pedro Ochoa-Ricoux at the Jiangmen Underground Neutrino Observatory (JUNO) during its construction. Ochoa-Ricoux stands in front of the detector, a 35.4 m diameter sphere filled with 20 kilotonnes of liquid scintillator that will study neutrinos from nuclear reactors. (Courtesy: JUNO/ Yuexiang Liu)
The memorable meeting Ochoa-Ricoux recalled at the start of this article was, however, the first moment he realized “Oh, this is real”. Their antineutrino deficit data eventually proved that the angle is about nine degrees. This discovery set the stage for Ochoa-Ricoux’s career, which, a little like the oscillating neutrino, he describes as a “mixture of everything”.
The asymmetry between antimatter and matter is one of the biggest mysteries in physics and in the next four years, two experiments – HyperKamiokande in Japan and the Deep Underground Neutrino Experiment (DUNE) in the US – will start looking for evidence of matter–antimatter asymmetry in neutrino oscillation (Ochoa-Ricoux is a member of DUNE). “Had θ13 been zero” he says, “my job and my life would have been very very different”.
All hands on deck
On the one hand you analyse the data, but before you can do that, you actually have to build the apparatus
Ochoa-Ricoux wasn’t just analysing the results from Daya Bay, he was also assembling and testing the experiment. This was sometimes frustrating work – he remembers having to painstakingly remeasure detector components because they wouldn’t fit inside the machine. But he emphasizes that this was an important part of the Daya Bay discovery. “On the one hand you analyse the data, but before you can do that, you actually have to build the apparatus,” he says.
While Ochoa-Ricoux now spends much less time climbing inside detector equipment, he is actively involved in designing the next generation of neutrino experiments. As well as DUNE, he works on Daya Bay’s successor, the Jiangmen Underground Neutrino Observatory (JUNO) in China, a nuclear reactor experiment that is projected to start taking data at the end of the year.
The first neutrino oscillation measurement was made in 1998 by the Japanese researcher Takaaki Kajita, who would later share the 2015 Nobel Prize for Physics for his work. However, the experiment where Kajita made this observation, called SuperKamiokande, was originally designed to search for proton decay.
Ochoa-Ricoux thinks that DUNE and JUNO need to be open to finding something equally unexpected. JUNO’s main aim is to determine which neutrino mass is the heaviest by measuring oscillating antineutrinos from nuclear power plants. It will also detect neutrinos coming from the Sun or the atmosphere, and Ochoa-Ricoux thinks this flexibility is vital.
“Sometimes nature will surprise us and we need to be ready for that,” he says, “I think we need to design our experiments in such a way that we can be sensitive to those surprises.”
Exploring the unknown
Experiments like DUNE and JUNO could change our understanding of the universe, but there is no guarantee that neutrinos hold the key to mysteries like matter–antimatter asymmetry. There’s therefore pressure to deliver results, but Ochoa-Ricoux is excited that the field is taking leaps into the unknown.
When you understand your world better, sometimes it’s impossible to predict what applications will come
He also argues that as well as advancing fundamental science, these projects could lead to new technologies. Medical imaging devices like MRI and PET scanners are offshoots of particle physics and he believes that “When you understand your world better, sometimes it’s impossible to predict what applications will come.”
However, at the heart of Ochoa-Ricoux’s mindset is the same fascination with the mysteries of the universe that motivated him to pursue neutrino physics as a student. For him, projects like JUNO and DUNE can justify themselves on those grounds alone. “We’re humans. We need to understand the world we live in. I think that’s highly valuable.”
