This environmentally friendly quantum sensor runs on sunlight

A new take on highly sensitive magnetic field sensors ditches the power-hungry lasers that previous devices have relied on to make their measurements and replaces them with sunlight. Lasers can gobble 100 watts or so of power — like keeping a bright lightbulb burning. The innovation potentially untethers quantum sensors from that energy need. The result is an environmentally friendly prototype on the forefront of technology, researchers report in an upcoming issue of Physical Review X Energy.
The big twist is in how the device uses sunlight. It doesn’t use solar cells to convert light into electricity. Instead, the sunlight does the job of the laser’s light, says Jiangfeng Du, a physicist at the University of Science and Technology of China in Hefei.

Quantum magnetometers often include a powerful green laser to measure magnetic fields. The laser shines on a diamond that contains atomic defects (SN: 2/26/08). The defects result when nitrogen atoms replace some of the carbon atoms that pure diamonds are made of. The green laser causes the nitrogen defects to fluoresce, emitting red light with an intensity that depends on the strength of the surrounding magnetic fields.

The new quantum sensor needs green light too. There’s plenty of that in sunlight, as seen in the green wavelengths reflected from tree leaves and grass. To collect enough of it to run their magnetometer, Du and colleagues replaced the laser with a lens 15 centimeters across to gather sunlight. They then filtered the light to remove all colors but green and focused it on a diamond with nitrogen atom defects. The result is red fluorescence that reveals magnetic field strengths just as laser-equipped magnetometers do.
Changing energy from one type to another, as happens when solar cells collect light and produce electricity, is an inherently inefficient process (SN: 7/26/17). The researchers claim that avoiding the conversion of sunlight to electricity to run lasers makes their approach three times more efficient than would be possible with solar cells powering lasers.

“I’ve never seen any other reports that connect solar research to quantum technologies,” says Yen-Hung Lin, a physicist at the University of Oxford who was not involved with the study. “It might well ignite a spark of interest in this unexplored direction, and we could see more interdisciplinary research in the field of energy.”

Quantum devices sensitive to other things, like electric fields or pressure, could also benefit from the sunlight-driven approach, the researchers say. In particular, space-based quantum technology might use the intense sunlight available outside Earth’s atmosphere to provide light tailored for quantum sensors. The remaining light, in wavelengths that the quantum sensors don’t use, could be relegated to solar cells that power electronics to process the quantum signals.

The sunlight-driven magnetometer is just a first step in the melding of quantum and environmentally sustainable technology. “In the current state, this device is primarily for developmental purposes,” Du says. “We expect that the devices will be used for practical purposes. But there [is] lots of work to be done.”

Ancient ‘demon ducks’ may have been undone by their slow growth

Giant flightless birds called mihirungs were the biggest birds to ever stride across what is now Australia. The animals, which weighed up to hundreds of kilograms, died out about 40,000 years ago. Now researchers might have a better idea why.

The birds may have grown and reproduced too slowly to withstand pressures from humans’ arrival on the continent, researchers report August 17 in the Anatomical Record.

Mihirungs are sometimes called “demon ducks” because of their great size and close evolutionary relationship with present-day waterfowl and game birds. The flightless, plant-eating birds lived for more than 20 million years.
Over that time, some species evolved into titans. Take Stirton’s thunderbird (Dromornis stirtoni). It lived about 7 million years ago, stood 3 meters tall and could exceed 500 kilograms in weight, making it the largest-known mihirung and a contender for the largest bird ever to live.

Most research on mihirungs has been on their anatomy and evolutionary relationships with living birds. Little is known about the animals’ biology, such as how long they took to grow and mature, says Anusuya Chinsamy-Turan, a paleobiologist at the University of Cape Town in South Africa.

So Chinsamy-Turan and colleagues at Flinders University in Adelaide, Australia took samples from 20 fossilized leg bones of D. stirtoni, from animals of varying life stages.
“Even after millions of years of fossilization, the microscopic structure of fossil bones generally remains intact,” and it can be used to decipher important clues about extinct animals’ biology, Chinsamy-Turan says.

The team examined the thin bone slices under a microscope, detailing the presence or absence of growth marks. These marks provide information on how fast the bone grew while the birds were alive.

D. stirtoni took 15 years or more to reach full size, the team found. It probably became sexually mature a few years before that, based on the timing of a shift from rapidly growing bone to a slower-growing form that’s thought to be associated with reaching reproductive age.

These results differ from the team’s earlier analysis of the bones of another mihirung, Genyornis newtoni. That species — the last-known mihirung — was less than half the size of D. stirtoni. It lived as recently as about 40,000 years ago and was a contemporary of the continent’s earliest human inhabitants. G. newtoni grew up much faster than its giant relative, reaching adult size in one to two years and growing a bit more in the following years and possibly reproducing then.

This difference in how fast mihirung species that were separated by millions of years developed may have been an evolved response to Australia developing a drier, more variable climate over the last few million years, the researchers say. When resources are unpredictable, growing and reproducing quickly can be advantageous.

Even so, that seeming pep in the developmental step of more recent mihirungs was still slower than that of the emus they lived alongside. Emus grow up quickly, reaching adult size in less than a year and reproducing not long after, laying large numbers of eggs.

This difference may explain why G. newtoni went extinct shortly after hungry humans arrived in Australia, yet emus continue to thrive today, the team says. Even though over millions of years, mihirungs as a group seem to have adapted to growing and reproducing quicker than they used to, it wasn’t enough to survive the arrival of humans, who probably ate the birds and their eggs, the researchers conclude.

“Slowly growing animals face dire consequences in terms of their reduced ability to recover from threats in their environments,” Chinsamy-Turan says.

The scientists’ research on other giant, extinct, flightless birds thought to have met their end thanks to humans — such as the dodos of Mauritius (Raphus cucullatus) and the largest of Madagascar’s elephant birds (Vorombe titan) — shows that they too grew relatively slowly (SN: 8/29/17).

“It is very interesting to see this pattern repeating again and again with many large, flightless bird groups,” says Thomas Cullen, a paleoecologist at Carleton University in Ottawa who was not involved with the new study.

Modern ratite birds seem to be the exception in their ability to handle similar pressures, he says. Other ratites besides emus that have survived until the present day — such as cassowaries and ostriches — also grow and reproduce quickly (SN: 4/25/14).

Physicists dispute a claim of detecting a black hole’s ‘photon ring’

The first image of a black hole may conceal treasure — but physicists disagree about whether it’s been found.

A team of scientists say they’ve unearthed a photon ring, a thin halo of light around the supermassive black hole in the galaxy M87. If real, the photon ring would provide a new probe of the black hole’s intense gravity. But other scientists dispute the claim. Despite multiple news headlines suggesting the photon ring has been found, many physicists remain unconvinced.
Unveiled in 2019 by scientists with the Event Horizon Telescope, or EHT, the first image of a black hole revealed a doughnut-shaped glow from hot matter swirling around the black hole’s dark silhouette (SN: 4/10/19). But according to Einstein’s general theory of relativity, a thinner ring should be superimposed on that thick doughnut. This ring is produced by photons, or particles of light, that orbit close to the black hole, slung around by the behemoth’s gravity before escaping and zinging toward Earth.

Thanks to this circumnavigation, the photons should provide “a fingerprint of gravity,” more clearly revealing the black hole’s properties, says astrophysicist Avery Broderick of the University of Waterloo and the Perimeter Institute for Theoretical Physics in Canada. He and his colleagues, a subset of scientists from the EHT collaboration, used a new method to tease out that fingerprint, they report in the Aug. 10 Astrophysical Journal.

Creating images with EHT isn’t a simple point-and-shoot affair (SN: 4/10/19). Researchers stitch together data from EHT’s squad of observatories scattered across the globe, using various computational techniques to reconstruct an image. Broderick and colleagues created a new black hole image assuming it featured both a diffuse emission and a thin ring. On three out of four days of observations, the data better matched an image with the added thin ring than one without the ring.

But that method has drawn harsh criticism. “The claim of a photon ring detection is preposterous,” says physicist Sam Gralla of the University of Arizona in Tucson.

A main point of contention: The photon ring is brighter than expected, emitting around 60 percent of the light in the image. According to predictions, it should be more like 20 percent. “That’s a giant red flag,” says physicist Alex Lupsasca of Vanderbilt University in Nashville. More light should come from the black hole’s main glowing doughnut than from the thin photon ring.

This unexpected brightness, Broderick and colleagues say, occurs because some of the light from the main glow gets lumped in with the photon ring. So the ring’s apparent brightness doesn’t depend only on the light coming from the ring. The researchers note that the same effect appeared when testing the method on simulated data.

But that mishmash of purported photon ring light with other light doesn’t make for a very convincing detection, critics say. “If you want to claim that you’ve seen a photon ring, I think you have to do a better job than this,” says astrophysicist Dan Marrone of the University of Arizona, a member of the EHT collaboration who was not a coauthor on the new paper.

The new result suggests only that an added thin ring gives a better match to the data, Marrone says, not whether that shape is associated with the photon ring. So it raises the question of whether scientists are seeing a photon ring at all, or just picking out an unrelated structure in the image.

But Broderick argues that the features of the ring — the fact that its size and location are as expected and are consistent day-to-day — support the photon ring interpretation.

Meanwhile, in a similar, independent analysis, Gralla and physicist Will Lockhart, also of the University of Arizona, find no evidence for a photon ring, they report in a paper submitted August 22 at arXiv.org. Their analysis differed from Broderick and colleagues’ in part because it limited how bright the photon ring could be.

To convincingly detect the photon ring, some scientists propose adding telescopes in space to the EHT’s crew of observatories (SN: 3/18/20). The farther apart the telescopes in the network are, the finer details they may be able to pick out — potentially including the photon ring.

“If there were a photon ring detection,” Lupsasca says, “that would be the best thing in physics this year, if not for many years.”

The curious case of the 471-day coronavirus infection

As omicron subvariant BA.5 continues to drive the coronavirus’ spread in the United States, I’ve been thinking about what could come next. Omicron and its offshoots have been topping the variant charts since last winter. Before that, delta reigned.

Scientists have a few ideas for how new variants emerge. One involves people with persistent infections — people who test positive for the virus over a prolonged period of time. I’m going to tell you about the curious case of a person infected with SARS-CoV-2 for at least 471 days and what can happen when infections roil away uncontrolled.
That lengthy infection first came onto epidemiologist Nathan Grubaugh’s radar in the summer of 2021. His team had been analyzing coronavirus strains in patient samples from Yale New Haven Hospital when Grubaugh spotted something he had seen before. Known only as B.1.517, this version of the virus never got a name like delta or omicron, nor rampaged through communities quite like its infamous relatives.

Instead, after springing up somewhere in North America in early 2020, B.1.517 tooled around in a handful of regions around the world, even sparking an outbreak in Australia. But after April 2021, B.1.517 seemed to sputter, one of the who-knows-how-many viral lineages that flare up and then eventually fizzle.

B.1.517 might have been long forgotten, shouldered aside by the latest variant to stake a claim in local communities. “And yet we were still seeing it,” Grubaugh says. Even after B.1.517 had petered out across the country, his team noticed it cropping up in patient samples. The same lineage, every few weeks, like clockwork, for months.

One clue was the samples’ specimen ID. The code on the B.1.517 samples was always the same, Grubaugh’s team noticed. They had all come from a single patient.

That patient, a person in their 60s with a history of cancer, relapsed in November of 2020. That was right around when they first tested positive for SARS-CoV-2. After seeing B.1.517 show up again and again in their samples, Grubaugh worked with a clinician to get the patient’s permission to analyze their data.
Ultimately, the patient has remained infected for 471 days (and counting), Grubaugh, Yale postdoctoral researcher Chrispin Chaguza and their team reported last month in a preliminary study posted at medRxiv.org. Because of deteriorating health and a desire to maintain their anonymity, the patient was not willing to be interviewed, and Grubaugh has no direct contact with them.

But all those samples collected over all those days told an incredible tale of viral evolution. Over about 15 months, at least three genetically distinct versions of the virus had rapidly evolved inside the patient, the team’s analyses suggested.

Each version had dozens of mutations and seemed to coexist in the patient’s body. “Honestly, if any one of these were to emerge in a population and begin transmitting, we would be calling it a new variant,” Grubaugh says.

That scenario is probably rare, he says. After all, lots of prolonged infections have likely occurred during the pandemic, and only a handful of concerning variants have emerged. But the work does suggest that persistent viral infections can provide a playground for speedy evolutionary experimentation — perhaps taking advantage of weakened immune systems.

Grubaugh’s work is “probably the most detailed look we’ve had at a single, persistent infection with SARS-CoV-2 so far,” says Tom Friedrich, a virologist at the University of Wisconsin–Madison, who was not involved with the work.
The study supports an earlier finding about a different immunocompromised patient — one with a persistent omicron infection. In that work, researchers documented the evolution of the virus over 12 weeks and showed that its descendant infected at least five other people.

Together, the studies lay out how such infections could potentially drive the emergence of the next omicron.

“I am pretty well convinced that people with persistent infection are important sources of new variants,” Friedrich says.

Who exactly develops these infections remains mysterious. Yes, the virus can pummel people with weakened immune systems, but “not every immunocompromised person develops a persistent infection,” says Viviana Simon, a virologist at the Icahn School of Medicine at Mount Sinai who worked on the omicron infection study.

In fact, doctors and scientists have no idea how common these infections are. “We just don’t really have the numbers,” Simon says. That’s a huge gap for researchers, and something Mount Sinai’s Pathogen Surveillance Program is trying to address by analyzing real-time infection data.

Studying patients with prolonged infections could also tell scientists where SARS-CoV-2 evolution is heading, Friedrich says. Just because the virus evolves within a person doesn’t mean it will spread to other people. But if certain viral mutations tend to arise in multiple people with persistent infections, that could hint that the next big variant might evolve in a similar way. Knowing more about these mutation patterns could help researchers forecast what’s to come, an important step in designing future coronavirus vaccine boosters.
Beyond viral forecasting, Grubaugh says identifying people with prolonged infections is important so doctors can provide care. “We need to give them access to vaccines, monoclonal antibodies and antiviral drugs,” he says. Those treatments could help patients clear their infections.

But identifying persistent infections is easier said than done, he points out. Many places in the world aren’t set up to spot these infections and don’t have access to vaccines or treatments. And even when these are available, some patients opt out. The patient in Grubaugh’s study received a monoclonal antibody infusion about 100 days into their infection, then refused all other treatments. They have not been vaccinated.

Though the patient remained infectious over the course of the study, their variants never spread to the community, as far as Grubaugh knows.

And while untreated chronic infections might spawn new variants, they could emerge in other ways, too, like from animals infected with the virus, from person-to-person transmission in groups of people scientists haven’t been monitoring, or from “something else that maybe none of us has thought of yet,” he says. “SARS-CoV-2 has continued to surprise us with its evolution.”

How to make recyclable plastics out of CO2 to slow climate change

It’s morning and you wake on a comfortable foam mattress made partly from greenhouse gas. You pull on a T-shirt and sneakers containing carbon dioxide pulled from factory emissions. After a good run, you stop for a cup of joe and guiltlessly toss the plastic cup in the trash, confident it will fully biodegrade into harmless organic materials. At home, you squeeze shampoo from a bottle that has lived many lifetimes, then slip into a dress fashioned from smokestack emissions. You head to work with a smile, knowing your morning routine has made Earth’s atmosphere a teeny bit carbon cleaner.

Sound like a dream? Hardly. These products are already sold around the world. And others are being developed. They’re part of a growing effort by academia and industry to reduce the damage caused by centuries of human activity that has sent CO2 and other heat-trapping gases into the atmosphere .
The need for action is urgent. In its 2022 report, the United Nations Intergovernmental Panel on Climate Change, or IPCC, stated that rising temperatures have already caused irreversible damage to the planet and increased human death and disease (SN: 5/7/22 & 5/21/22, p. 8). Meanwhile, the amount of CO2 emitted continues to rise. The U.S. Energy Information Administration predicted last year that if current policy and growth trends continue, annual global CO2 emissions could rise from about 34 billion metric tons in 2020 to almost 43 billion by 2050.

Carbon capture and storage, or CCS, is one strategy for mitigating climate change long noted by the IPCC as having “considerable” potential. A technology that has existed since the 1970s, CCS traps CO2 from smokestacks or ambient air and pumps it underground for permanent sequestration. Today, 27 CCS facilities operate around the world — 12 in the United States — storing an estimated 36 million tons of carbon per year, according to the Global CCS Institute. The 2021 Infrastructure Investment and Jobs Act includes $3.5 billion in funding for four additional U.S. direct capture facilities.

But rather than just storing it, the captured carbon could be used to make things. This year for the first time, the IPCC added carbon capture and utilization, or CCU, to its list of options for drawing down atmospheric carbon. CCU captures CO2 and incorporates it into carbon-containing products like cement, jet fuel and the raw materials for making plastics. Still in early stages of development and commercialization, CCU could reduce annual greenhouse gas emissions by 20 billion tons in 2050 — more than half of the world’s global emissions today, the IPCC estimates.

Such recognition was a big victory for a movement that has struggled to emerge from the shadow of its more established cousin, CCS, says chemist and global CCU expert Peter Styring of the University of Sheffield in England. Many CCU-related companies are springing up and collaborating with each other and with governments around the world, he adds.

The potential of CCU is “enormous,” both in terms of its volume and monetary potential, said mechanical engineer Volker Sick at a CCU conference in Brussels in April. Sick, of the University of Michigan in Ann Arbor, directs the Global CO2 Initiative, which promotes CCU as a mainstream climate solution. “We’re not talking about something that’s nice to do but doesn’t move the needle,” he added. “It moves the needle in many, many aspects.”
The plastics paradox
The use of carbon dioxide in products is not new. CO2 is used to make soda fizzy, keep foods frozen (as dry ice) and convert ammonia to urea for fertilizer. What’s new is the focus on making products with CO2 as a strategy to slow climate change. Today’s CCU market, estimated at $2 billion, could mushroom to $550 billion by 2040, according to Lux Research, a Boston-based market research firm. Much of this market is driven by adding CO2 to cement — which can improve its properties as well as reduce atmospheric carbon — and to jet fuel, which can lower the industry’s large carbon footprint. CO2-to-plastics is a niche market today, but the field aims to battle two crises at once: climate change and plastic pollution.

Plastics are made from fossil fuels, a mix of hydrocarbons formed by the remains of ancient organisms. Most plastics are produced by refining crude oil, which is then broken down into smaller molecules through a process called cracking. These smaller molecules, known as monomers, are the building blocks of polymers. Monomers such as ethylene, propylene, styrene and others are linked together to form plastics such as polyethylene (detergent bottles, toys, rigid pipes), polypropylene (water bottles, luggage, car parts) and polystyrene (plastic cutlery, CD cases, Styrofoam).
But making plastics from fossil fuels is a carbon catastrophe. Each step in the plastics life cycle — extraction, transport, manufacture and disposal — emits massive amounts of greenhouse gases, mostly CO2, according to the Center for International Environmental Law, a nonprofit law firm based in Geneva and Washington, D.C. These emissions alone — more than 850 million tons of greenhouse gases in 2019 — are enough to threaten global climate targets.

And the numbers are about to get much worse. A 2018 report by the Paris-based intergovernmental International Energy Agency projected that global demand for plastics will increase from about 400 million tons in 2020 to nearly 600 million by 2050. Future demand is expected to be concentrated in developing countries and will vastly outstrip global recycling efforts.

Plastics are a serious crisis for the environment, from fossil fuel use to their buildup in landfills and oceans (SN: 1/16/21, p. 4). But we’re a society addicted to plastic and all it gives us — cell phones, computers, comfy Crocs. Is there a way to have our (plastic-wrapped) cake and eat it too?

Yes, says Sick. First, he argues, cap the oil wells. Next, make plastics from aboveground carbon. Today, there are products made of 20 to over 40 percent CO2. Finally, he says, build a circular economy, one that reduces resource use, reuses products, then recycles them into other new products.

“Not only can we eliminate the fossil carbon as a source so that we don’t add to the aboveground carbon budget, but in the process we can also rethink how we make plastics,” Sick says. He suggests they be specifically designed “to live very, very long so that they don’t have to be replaced … or that they decompose in a benign manner.”

But creating plastics from thin air is not easy. CO2 needs to be extracted, from the atmosphere or smokestacks, for example, using specialized equipment. It often needs to be compressed into liquid form and transported, generally through pipelines. Finally, to meet the overall goal of reducing the amount of carbon in the air, the chemical reaction that turns CO2 into the building blocks of plastics must be run with as little extra energy as possible. Keeping energy use low is a special challenge when dealing with the carbon dioxide molecule.

A bond that’s hard to break
There’s a reason that carbon dioxide is such a potent greenhouse gas. It is incredibly stable and can linger in the atmosphere for 300 to 1,000 years. That stability makes CO2 hard to break apart and add to other chemicals. Lots of energy is typically needed for the reaction.

“This is the fundamental energy problem of CO2,” says chemist Ian Tonks of the University of Minnesota in Minneapolis. “Energy is necessary to fix CO2 to plastics. We’re trying to find that energy in creative ways.”

Catalysts offer a possible answer. These substances can increase the rate of a chemical reaction, and thus reduce the need for energy. Scientists in the CO2-to-plastics field have spent more than a decade searching for catalysts that can work at close to room temperature and pressure, and coax CO2 to form a new chemical identity. These efforts fall into two broad categories: chemical and biological conversion.

First attempts
Early experiments focused on adding CO2 to highly reactive monomers like epoxides to facilitate the reaction. Epoxides are three-membered rings composed of one oxygen atom and two carbon atoms. Like a spring under tension, they can easily pop open. In the early 2000s, industrial chemist Christoph Gürtler and chemist Walter Leitner of Aachen University in Germany found a zinc catalyst that allowed them to break open the epoxide ring of polypropylene oxide and combine it with CO2. Following the reaction, the CO2 was joined permanently to the polypropylene molecule and was no longer in gas form — something that is true of all CO2-to-plastic reactions. Their work resulted in one of the first commercial CO2 products — a polyurethane foam containing 20 percent captured CO2. Today, the German company Covestro, where Gürtler now works, sells 5,000 tons of the product annually in mattresses, car interiors, building insulation and sports flooring.

More recent research has focused on other monomers to expand the variety of CO2-based plastics. Butadiene is a hydrocarbon monomer that can be used to make polyester for clothing, carpets, adhesives and other products.

In 2020, chemist James Eagan at the University of Akron in Ohio mixed butadiene and CO2 with a series of catalysts developed at Stanford University. Eagan hoped to create a polyester that is carbon negative, meaning it has a net effect of removing CO2 from the atmosphere, rather than adding it. When he analyzed the contents of one vial, he discovered he had created something even better: a polyester made with 29 percent CO2 that degrades in high pH water into organic materials.
“Chemistry is like cooking,” Eagan says. “We took chocolate chips, flour, eggs, butter, mixed them up, and instead of getting cookies we opened the oven and found a chicken potpie.”

Eagan’s invention has immediate applications in the recycling industry, where machines can often get gummed up from the nondegradable adhesives used in packaging, soda bottle labels and other products. An adhesive that easily breaks down may improve the efficiency of recycling facilities.

Tonks, described by Eagan as a friendly competitor, took Eagan’s patented process a step further. By putting Eagan’s product through one more reaction, Tonks made the polymer fully degradable back to reusable CO2 — a circular carbon economy goal. Tonks created a start-up this year called LoopCO2 to produce a variety of biodegradable plastics.

Microbial help
Researchers have also harnessed microbes to help turn carbon dioxide into useful materials including dress fabric. Some of the planet’s oldest-living microbes emerged at a time when Earth’s atmosphere was rich in carbon dioxide. Known as acetogens and methanogens, the microbes developed simple metabolic pathways that use enzyme catalysts to convert CO2 and carbon monoxide into organic molecules. In the atmosphere, CO will react with oxygen to form CO2. In the last decade, researchers have studied the microbes’ potential to remove these gases from the atmosphere and turn them into useful products.

LanzaTech, based in Skokie, Ill., uses the acetogenic bacterium Clostridium autoethanogenum to metabolize CO2and CO emissions into a variety of industrial chemicals, including ethanol. Last year, the clothing company Zara began using LanzaTech’s polyester fabric for a line of dresses.

The ethanol used to create these products comes from LanzaTech’s two commercial facilities in China, the first to transform waste CO, a main emission from steel plants, into ethanol. The ethanol goes through two more steps to become polyester. LanzaTech partnered with steel mills near Beijing and in north-central China, feeding carbon monoxide into LanzaTech’s microbe-filled bioreactor.

Steel production emits almost two tons of CO2 for every ton of steel made. By contrast, a life cycle assessment study found that LanzaTech’s ethanol production process lowered greenhouse gas emissions by approximately 80 percent compared with ethanol made from fossil fuels.

In February, researchers from LanzaTech, Northwestern University in Evanston, Ill., and others reported in Nature Biotechnology that they had genetically modified the Clostridium bacterium to produce acetone and isopropanol, two other fossil fuel–based industrial chemicals. Company CEO Jennifer Holmgren says the only waste product is dead bacteria, which can be used as compost or animal feed.

Other researchers are skipping the living microbes and just using their catalysts. More than a decade ago, chemist Charles Dismukes of Rutgers University in Piscataway, N.J., began looking at acetogens and methanogens as a way to use atmospheric carbon. He was intrigued by their ability to release energy when making carbon building blocks from CO2, a reaction that usually requires energy. He and his team focused on the bacteria’s nickel phosphide catalysts, which are responsible for the energy-releasing carbon reaction.

Dismukes and colleagues developed six electrocatalysts that are able to make monomers at room temperature and pressure using only CO2, water and electricity. The energy­-releasing pathway of the nickel phosphide catalysts “lowers the required voltage to run the reaction, which lowers the energy consumption of the process and improves the carbon footprint,” says Karin Calvinho, a former student of Dismukes who is now chief technical officer at RenewCO2, the start-up Dismukes’ team formed in 2018.

RenewCO2 plans to sell its monomers, including monoethylene glycol, to companies that want to reduce their carbon footprint. The group proved its concept works using CO2 brought into the lab. In the future, the company intends to obtain CO2 from biomass, industrial emissions or direct air capture.
Barriers to change
Yet researchers and companies face challenges in scaling up carbon capture and reuse. Some barriers lurk in the language of regulations written before CCU existed. An example is the U.S. Environmental Protection Agency’s program to provide tax credits to companies that make biofuels. The program is geared toward plant-based fuels like corn and sugar­cane. LanzaTech’s approach for making jet fuel doesn’t qualify for credits because bacteria are not plants.

Other barriers are more fundamental. Styring points to the long-standing practice of fossil fuel subsidies, which in 2021 topped $440 billion worldwide. Global government subsidies to the oil and gas industry keep fossil fuel prices artificially low, making it hard for renewables to compete, according to the International Energy Agency. Styring advocates shifting those subsidies toward renewables.

“We try to work on the principle that we recycle carbon and create a circular economy,” he says. “But current legislation is set up to perpetuate a linear economy.”
The happy morning routine that makes the world carbon cleaner is theoretically possible. It’s just not the way the world works yet. Getting to that circular economy, where the amount of carbon above ground is finite and controlled in a never-ending loop of use and reuse will require change on multiple fronts. Government policy and investment, corporate practices, technological development and human behavior would need to align perfectly and quickly in the interests of the planet.

In the meantime, researchers continue their work on the carbon dioxide molecule.

“I try to plan for the worst-case scenario,” says Eagan, the chemist in Akron. “If legislation is never in place to curb emissions, how do we operate within our capitalist system to generate value in a renewable and responsible way? At the end of the day, we will need new chemistry.”

An AI can decode speech from brain activity with surprising accuracy

An artificial intelligence can decode words and sentences from brain activity with surprising — but still limited — accuracy. Using only a few seconds of brain activity data, the AI guesses what a person has heard. It lists the correct answer in its top 10 possibilities up to 73 percent of the time, researchers found in a preliminary study.

The AI’s “performance was above what many people thought was possible at this stage,” says Giovanni Di Liberto, a computer scientist at Trinity College Dublin who was not involved in the research.
Developed at the parent company of Facebook, Meta, the AI could eventually be used to help thousands of people around the world unable to communicate through speech, typing or gestures, researchers report August 25 at arXiv.org. That includes many patients in minimally conscious, locked-in or “vegetative states” — what’s now generally known as unresponsive wakefulness syndrome (SN: 2/8/19).

Most existing technologies to help such patients communicate require risky brain surgeries to implant electrodes. This new approach “could provide a viable path to help patients with communication deficits … without the use of invasive methods,” says neuroscientist Jean-Rémi King, a Meta AI researcher currently at the École Normale Supérieure in Paris.

King and his colleagues trained a computational tool to detect words and sentences on 56,000 hours of speech recordings from 53 languages. The tool, also known as a language model, learned how to recognize specific features of language both at a fine-grained level — think letters or syllables — and at a broader level, such as a word or sentence.

The team applied an AI with this language model to databases from four institutions that included brain activity from 169 volunteers. In these databases, participants listened to various stories and sentences from, for example, Ernest Hemingway’s The Old Man and the Sea and Lewis Carroll’s Alice’s Adventures in Wonderland while the people’s brains were scanned using either magnetoencephalography or electroencephalography. Those techniques measure the magnetic or electrical component of brain signals.

Then with the help of a computational method that helps account for physical differences among actual brains, the team tried to decode what participants had heard using just three seconds of brain activity data from each person. The team instructed the AI to align the speech sounds from the story recordings to patterns of brain activity that the AI computed as corresponding to what people were hearing. It then made predictions about what the person might have been hearing during that short time, given more than 1,000 possibilities.

Using magnetoencephalography, or MEG, the correct answer was in the AI’s top 10 guesses up to 73 percent of the time, the researchers found. With electroencephalography, that value dropped to no more than 30 percent. “[That MEG] performance is very good,” Di Liberto says, but he’s less optimistic about its practical use. “What can we do with it? Nothing. Absolutely nothing.”

The reason, he says, is that MEG requires a bulky and expensive machine. Bringing this technology to clinics will require scientific innovations that make the machines cheaper and easier to use.

It’s also important to understand what “decoding” really means in this study, says Jonathan Brennan, a linguist at the University of Michigan in Ann Arbor. The word is often used to describe the process of deciphering information directly from a source — in this case, speech from brain activity. But the AI could do this only because it was provided a finite list of possible correct answers to make its guesses.

“With language, that’s not going to cut it if we want to scale to practical use, because language is infinite,” Brennan says.

What’s more, Di Liberto says, the AI decoded information of participants passively listening to audio, which is not directly relevant to nonverbal patients. For it to become a meaningful communication tool, scientists will need to learn how to decrypt from brain activity what these patients intend on saying, including expressions of hunger, discomfort or a simple “yes” or “no.”

The new study is “decoding of speech perception, not production,” King agrees. Though speech production is the ultimate goal, for now, “we’re quite a long way away.”

Readers discuss big bacteria, gravitational radar and more

Biggest bacteria?
A newfound species of bacteria, Thiomargarita magnifica, averages 1 centimeter long and can be seen by the naked eye, making it the largest bacteria yet discovered, Erin Garcia de Jesús reported in “Newfound bacteria make a big splash” (SN: 7/16/22 & 7/30/22, p. 17).

Reader J.C. Smith pointed out that another article in the magazine seems to contradict the findings in this story. In “Live wires,” Nikk Ogasa reported that cable bacteria, which channel electricity, can grow up to 5 centimeters long (SN: 7/16/22 & 7/30/22, p. 24).

This is no contradiction, Garcia de Jesús says. T. magnifica is a single-celled species of bacteria, which means all of the cellular functions necessary for the organism’s survival happen within its one cell. Cable bacteria, on the other hand, are multicellular, with different cells performing different functions. “T. magnifica is the largest single-celled bacterium ever found,” Garcia de Jesús says.

Given that bacteria are typically defined as single-celled organisms, reader Barry Maletzky wondered how multicellular cable bacteria can be considered part of the group.

Most bacteria are single-celled, Ogasa says, but several multicellular species do exist. “For instance, some cyanobacteria, sometimes called blue-green algae, are also multicellular. That allows the organisms to split the jobs of photosynthesis and nitrogen absorption between cells.”

Mapping out space
Massive objects that warp spacetime can redirect gravitational waves. Researchers might someday leverage those waves as a kind of gravity “radar” to peer inside stars and find globs of dark matter, Asa Stahl reported in “Gravitational wave ‘radar’ could map the universe” (SN: 7/16/22 & 7/30/22, p. 12).

Reader Neil Kaminar wondered if changes in the frequency of light coming from massive objects could be used to detect the distortion of spacetime.

In theory, yes, says Glenn Starkman, a physicist at Case Western Reserve University in Cleveland. When light travels through spacetime toward or away from a massive object, gravity changes the frequency of the light, he says. Scientists have witnessed one form of this process, called gravitational redshift, in action on Earth.

But this effect would probably not be very useful when it comes to gravitational radar, Starkman says. After light moves toward a massive object, changing its frequency, it would then move away from the object. That process would shift the light’s frequency toward what it was before the encounter, mostly canceling out the effect, Starkman says.

Science and society
In “We won’t shy away from covering politicized science,” editor in chief Nancy Shute reflected on Science News’ history of reporting on the science of politically contentious issues and asserted our commitment to continue that coverage (SN: 7/16/22 & 7/30/22, p. 2).

Brigitte Dempsey was glad to read Shute’s editor’s note in the wake of the U.S. Supreme Court striking down Roe v. Wade, the landmark decision that had protected a person’s right to an abortion. Since then, debates around abortion and pregnancy biology have become more heated, and accurate science is often missing from the discussions (SN: 7/16/22 & 7/30/22, p. 6). “Bravo for meeting the issue square on,” Dempsey wrote. “Our only hope to bring reason to bear … is to let science speak.”

NASA’s Artemis I mission sets the stage for our return to the moon

When Artemis I blasts off into the early morning sky over Florida, it may launch a new era of lunar science and exploration with it.

The NASA mission, scheduled to launch in the next two weeks, is the first of three planned flights aimed at landing humans on the moon for the first time since 1972. No astronauts will fly on the upcoming mission. But the flight marks the first test of the technology — the rocket, the spacesuits, the watery return to Earth — that will ultimately take people, including the first woman and the first astronaut of color, to the lunar surface.
The test includes the first flight of NASA’s Space Launch System, or SLS, and its Orion spacecraft, a rocket and crew capsule that have been decades in the making. These craft have been delayed, blown through their budgets and been threatened with cancellation more than once. Even within the spaceflight community, a lot of people feared they would never fly.

To see a human-capable moon rocket finally on the launchpad is “pretty astonishing,” says Casey Dreier, a Seattle-based space policy expert at the Planetary Society. “This is a reality that most of us alive on Earth today have never experienced.”

And if the Artemis program works, opportunities for science will follow.

“Because humans have to come back, alive, you have a huge opportunity to bring samples back with you,” Dreier says. Sending human astronauts may be a wedge to open the door for pure learning.

The launch
Artemis I is slated to lift off on August 29 at 8:33 a.m. EDT. The SLS rocket will lift Orion into space, where the crew capsule will separate from the rocket and continue to an orbit around the moon. After circling the moon for about two weeks, Orion will slingshot back to Earth and splash down in the Pacific Ocean off the coast of San Diego. The whole mission will last about 42 days.

Orion will stay in space longer than any other human-rated spacecraft has without docking to another spaceship, like the International Space Station. At its closest approach, the spacecraft will fly about 100 kilometers above the lunar surface. It will also go up to 64,000 kilometers past the moon, farther from Earth than any spacecraft built for humans. The previous record, set by Apollo 13 in 1970, was 16,000 kilometers beyond the far side of the moon.
The main goal of the mission is to prove that everything works. That includes Orion’s heat shield, which will need to protect astronauts as the capsule comes screaming through Earth’s atmosphere at 40,000 kilometers per hour and heats up to more than 2700° Celsius on its return trip. It also includes the procedure for retrieving the capsule and its crew and cargo after splashdown.

Even though it has no astronauts, the mission won’t be flying empty. Just beneath the Orion capsule are 10 CubeSats, small, simple spacecraft each about the size of a shoebox. After Orion separates from the SLS rocket, those CubeSats will go their separate ways to study the moon, the radiation environment in space and the effects of that radiation on organisms like yeast. One CubeSat will unfurl a solar sail and take off to explore a near-Earth asteroid (SN: 8/26/11).

The “crew”
Inside the Orion capsule ride three humanoid passengers. In the commander’s seat is faux astronaut Moonikin Campos, named for Arturo Campos, a NASA engineer who played a key role in returning the Apollo 13 moon mission safely to Earth after its in-flight disaster in 1970. The “moonikin” — a mashup of moon and manikin — is based on a firefighter training rescue manikin, says NASA engineer Dustin Gohmert. Moonikin Campos will be wearing the new flight suit that was designed for the Artemis missions.
The spacesuit is like a personalized spacecraft, says Gohmert, of the Johnson Space Center in Houston, Texas. It’s meant to be worn during takeoff, landing and any time there is an emergency in the cabin. The suit may look familiar to anyone who watched space shuttle launches, Gohmert says, because it does a very similar job: “It’s an orange suit that acts like a balloon that’s shaped like your body.”

The main difference is that the Orion suit, plus the accompanying helmet, seat and connection to the Orion spacecraft itself, are designed to keep a crew member alive for up to six days, the time it could take to get back to Earth if something goes wrong in deep space. Astronauts visiting the International Space Station, by contrast, were never more than a few hours from Earth.

To help make that week tolerable, each suit will be custom fit to the astronaut. “I’d like to say the word ‘comfort,’ but that’s a difficult word to use,” Gohmert says. “Nothing will be comfortable about six days in a spacesuit, no matter what you do.”

The suit and spacecraft will provide the astronauts with oxygen and scrub the astronauts’ air of carbon dioxide. The suit will also have a tube for the astronauts to eat liquid food and a way for them to collect urine and feces, although Moonikin Campos won’t test those aspects. He will be equipped with radiation sensors, while his seat will have sensors to detect acceleration and vibration throughout the mission.
The suit, helmet and seat all take safety lessons from the space shuttle Columbia disaster, Gohmert says (SN: 9/22/2003). A junior engineer at the time, Gohmert worked on the suits the Columbia astronauts wore and saw the seven-member crew off to the launchpad. “It was a pivotal point for all of us, of course, who were there at the time,” he says. “If we didn’t take lessons from that, we wouldn’t be doing them justice.”

Moonikin Campos will be accompanied by a pair of mockup female torsos named Helga and Zohar. Their mission is to report back on space risks that are unique to female bodies, which have never been near the moon. NASA plans to send a woman on the first crewed Artemis flight, and women have different cancer risks from space radiation than men.
The two torsos are figures used in medicine called anthropomorphic phantoms, which are made from materials that simulate human bone, tissue and organs. “They are in principle identical twins,” said physicist Thomas Berger of the German Aerospace Center in Cologne in a briefing on August 17. But Zohar — whose name means “light” or “radiance” in Hebrew — will wear a radiation protection vest provided by the Israel Space Agency and the private company StemRad, based in Tampa, Fla.

The vest is made of a polymer designed to deflect protons that the sun releases during solar storms and has more shielding over radiation-sensitive organs like breasts and ovaries. Each phantom will also carry more than 6,000 small radiation detectors to build a 3-D picture of the dose of charged particles a female astronaut might receive on a trip to the moon and back. Comparing the radiation levels each phantom receives will help refine the vest’s design for future astronauts.

Orion will also carry two other nonhuman passengers — the British stop motion television character Shaun the sheep and Snoopy, who will serve as an indicator of zero gravity.

The past and the future
SLS and Orion have had a checkered history. The program goes back to 2004, when President George W. Bush proposed sending astronauts to the moon and then to Mars. In 2010, President Barack Obama canceled that plan, and then in 2017 President Donald Trump directed NASA to retrain its sights on the moon.

All the while, Congress continued to fund the development of the SLS rocket. Originally, SLS was supposed to cost $6 billion and fly in 2016. It has so far cost $23 billion on the eve of its launch in 2022.

“The rhetoric has flip-flopped a bunch,” Dreier says, as political leaders kept changing their vision for NASA’s direction. “But if you look at the actual programs, very little changed. … The whole time, the money was going to a moon rocket and a moon capsule.”

The next Artemis mission, Artemis II, is scheduled to launch in 2024 and take astronauts — real, live, human astronauts — around the moon but not to its surface.

Artemis III will be the moon landing mission. On August 19, NASA announced 13 candidate landing regions, all near the moon’s south pole, an intriguing spot that has never been visited by humans (SN: 11/11/18). That mission is scheduled to launch in 2025, but there are still a lot of untested elements. Those include the actual lander, which will be built by SpaceX.

There are still a lot of things that can go wrong and a long way to go. But the Artemis I launch is an optimistic dawn for lunar science nevertheless. “The whole [human spaceflight] system has all been shifting to point at the moon,” Dreier says. “I think that’s profoundly exciting. There’s going to be really interesting lessons that happen no matter what comes out of this.”

‘Chameleon’ forces remain elusive in a new dark energy experiment

A chameleon-like force that shifts its nature based on its environment could explain a major physics quandary: how the mysterious substance called dark energy is compelling the cosmos to expand faster and faster. But a new experiment casts doubt on some chameleon theories, researchers report August 25 in Nature Physics.

The chameleon force would be a fifth type of force beyond the basic four: gravitational, strong, weak and electromagnetic. And like a chameleon changing its colors, the hypothetical fifth force would morph depending on the density of its surroundings. In dense environments like Earth, this fifth force would be feeble, camouflaging its effects. In the sparseness of space, the force would be stronger and long-ranged.
This force would result from a chameleon field — an addition to the known fields in physics, such as electric, magnetic and gravitational fields. A chameleon field with these morphing properties could drive the accelerating expansion of the universe without disagreeing with measurements on Earth.

But it’s a challenge to suss out such a changeling force. On Earth, says astrophysicist Jianhua He of Nanjing University in China, “it’s very, very tiny. That’s the most difficult part.”

So He and colleagues designed a detector to search for a subtle fifth force. A wheel with plastic films attached spins past another film sitting on a magnetically levitated piece of graphite. If a chameleon force really exists, the films spinning by would cause a periodic force on the levitating plastic, pulling it up and down. (Gravity also acts this way, but thanks to the device’s design, it should be much weaker than a chameleon force.)

The team was able to rule out a category of chameleon theories. In the future, the researchers hope to improve their results by chilling their device to allow for more sensitive measurements.

7-million-year-old limb fossils may be from the earliest known hominid

In 2001, researchers unearthed a partial fossil leg bone and two forearm bones in the central African nation of Chad. Those fossils come from the earliest known hominid, which lived around 7 million years ago, and reveal that the creature walked upright both on the ground and in the trees, a new study proposes.

But a lively debate surrounds the fossils, concerning whether they actually belong to the hominid species, known as Sahelanthropus tchadensis, or to an ancient ape, and to what extent either species could have adopted a two-legged gait. These have become vexing questions as scientists increasingly suspect that ape and hominid species evolved a variety of ways to walk upright, some more efficient than others, around 7 million years ago.
Since its discovery, the leg bone has also triggered competing accusations of scientific misconduct and an official investigation by the French government–funded research organization CNRS in Paris.

Previously, skull, jaw and tooth finds uncovered at the Chad site in 2001 and 2004 were classified as remnants of S. tchadensis (SN: 4/6/05). The finds are the only other fossils attributed to the species, though some researchers have also since suggested that those fossils represent an ancient ape instead.

Analyses of the three limb bones show that they belong to the previously identified Sahelanthropus species, say paleontologists Guillaume Daver and Franck Guy, both of the University of Poitiers in France, and their colleagues. And internal and external features of the leg bone indicate that Sahelanthropus walked upright, the scientists report August 24 in Nature. Shapes and structures of the two forearm bones suggest that the hominid moved on two legs through trees while grasping branches with its hands, the team says.

“The Chadian species has a set of anatomical features that clearly indicate that our oldest known [hominid] representative [walked] on the ground and in the trees,” Guy says. It’s hard to tell how efficiently or how fast Sahelanthropus moved on two legs, he adds.

Guy’s team studied 3-D digital models of the fossils derived from CT scans. The leg bone was compared with fossils of ancient apes and other hominids and with modern apes and humans. Traits including thickening of the leg bone’s tough outer layer at key points and the presence of an internal bony projection near the hip joint signal an upright stance, the scientists say.

Fossils from the African site, including the three limb bones, suggest that Sahelanthropus was the earliest known hominid, agrees paleoanthropologist Kristian Carlson of the University of Southern California in Los Angeles, who did not participate in the new study. But exactly how it moved while upright remains unknown, he says. Sahelanthropus exhibits a mix of upper leg and forearm traits that differs from those of living apes and humans, suggesting it adopted a novel posture and limb movements while walking.

Whatever stance Sahelanthropus assumed, it probably resembled that of two other early hominids, roughly 6-million-year-old Orrorin tugenensis and more than 5-million-year-old Ardipithecus kadabba, says paleoanthropologist Yohannes Haile-Selassie, director of the Institute of Human Origins at Arizona State University in Tempe (SN: 9/11/04; SN: 3/3/04). Walking abilities of those hominids remain poorly understood due to limited fossils — a partial leg bone for O. tugenensis and a toe bone for the Ardipithecus species.

Haile-Selassie regards all three hominids as part of a single genus that evolved from around 7 million to 5 million years ago. On that issue, “the debate is open, even between members of our team,” Guy says.

Another debate concerns the upper leg’s internal bony projection that the researchers cite as crucial for standing upright. That trait sometimes appears in modern African apes and occasionally is absent in humans, paleoanthropologist Marine Cazenave of the American Museum of Natural History in New York City and colleagues report in the June Journal of Human Evolution. The presence of this bony growth does not definitively show that Sahelanthropus walked upright, Cazenave says.

Other researchers contend that the leg bone most likely comes from an ancient ape — not a hominid — that may have occasionally walked upright. Shape measurements, including curvature of the fossil’s shaft, closely resemble those of modern chimps’ upper leg bones, University of Poitiers paleoanthropologist Roberto Macchiarelli and colleagues reported in December 2020 in the Journal of Human Evolution.

“There may have been ancient apes that had distinctive types of [upright movement] unlike any living apes, including humans,” says paleoanthropologist Bernard Wood of George Washington University in Washington, D.C., who was a coauthor of the 2020 study.

Here is where charges of scientific misconduct come into play. The 2020 study was based on measurements of the Sahelanthropus leg fossil taken in 2004 by a University of Poitiers graduate student conducting a project on how fossilization affects bones.

That student, Aude Bergeret-Medina, was given access to fossils from the Sahelanthropus site that Daver and Guy’s team had tagged as neither hominid nor, more generally, as primate. She noted that one specimen — the leg bone — looked like it belonged to a primate, possibly an ape. Macchiarelli confirmed her observation. Plans for Bergeret-Medina to cut open the bone to study its mineral content were halted.

Macchiarelli informed his university and CNRS of the fossil’s identity. He spent the next 16 years, he says, sending repeated complaints to those institutions that the Sahelanthropus discoverers were violating codes of scientific conduct by not providing information about the leg bone in scientific papers or talks.

Then, CNRS launched an investigation of possible misconduct by Macchiarelli himself when the 2020 study appeared before the Sahelanthropus team published findings on the leg bone in its possession. No ruling has been made yet.

In supplementary information published with the new study, Guy and colleagues write that they identified the forearm bones among stored fossils after Macchiarelli brought the leg bone’s identity to their attention. Further excavations in Chad were conducted before launching a detailed study of the three limb fossils in 2017, the team says.

But the Sahelanthropus team does not cite Bergeret-Medina — now the curator of the Muséum d’Histoire Naturelle Jacques de La Comble in Autun, France — by name for her role in the leg bone’s identification. The investigators write that “a master’s student in taphonomy” received various fossils for a research internship in early 2004 before those finds had been carefully examined by senior scientists. The student, “seeking expertise,” gave the leg fossil to Macchiarelli who identified it as a hominid, Daver and colleagues say.

That’s incorrect, Macchiarelli contends. Bergeret-Medina initially identified the fossil as a primate’s upper leg bone followed by his confirmation of her observation. No claim was made that the fossil came from a hominid, he says. But without Bergeret-Medina’s insightful fossil observation, the new study would never have happened, Macchiarelli asserts.