Despite the scale, no known human witnessed the cataclysm. As far as we know, early humans had not yet reached the continent. Across oceans, perhaps early humans did wonder at the hazier skies and unusually vivid sunsets. Volcanic particles circulating in the sky cooled their climate and likely affected their weather patterns and lives. Whether they noted these changes – or connected them to any distant event – is unknowable.

Today, humanity would certainly notice. We already know that a super-eruption on this scale would be a threat civilization as we know it. So what exactly would we experience if Yellowstone erupted? We are experts in disasters and volcanoes and what follows is a thought experiment into what might happen in the worst case scenario. We’ve based our hypothesis on research and by examining how countries have dealt with disasters in recent years.

T-2 months

Shortly after 6am, an analyst at the University of Utah Seismograph Stations sees a series of sharp spikes interrupting the usually quiet wavy lines recorded by Yellowstone’s earthquake monitors. The measurements represent earthquakes detected beneath Yellowstone overnight. The scientist raises an eyebrow and takes a deep breath – these observations don’t fit with Yellowstone’s usual behavior.

People often imagine Yellowstone as a sleeping “supervolcano.” It may sleep, but its geological processes never do. An array of instruments monitors its activity – and any changes in it. A dense network of seismometers records earthquakes in the region. Around the clock, data feeds in from GPS stations, strainmeters (instruments which measure deformations and changes in the shape of the Earth’s crust) and sensors positioned within its active geyser areas. Satellite observations, gas sampling and field surveys add plenty more information.

Scientists look at the number of earthquakes along with their location, depth and size. Earthquake “swarms” warrant particular attention, especially when they appear to be migrating through the crust (Earth’s solid, outermost rocky shell) or becoming progressively shallower. Such patterns can indicate that magma or pressurized hydrothermal fluids (hot, mineral-rich water) is moving upwards.

Our scientist is relieved to discover that most of the unusual tremors are tiny — too weak to have been felt. But together, they form an unusually concentrated swarm. The analyst checks the signals against neighboring seismometers and, more out of curiosity than concern, contacts colleagues at several partner organizations comprising the Yellowstone Volcano Observatory (YVO) in order to follow YVO’s response plan.

They deduce that, overnight, instruments have recorded a tightening cluster of earthquakes beneath Yellowstone’s vast caldera, which is roughly 55–70 kilometers across. Yellowstone experiences thousands of earthquakes each year, and swarms are not unusual. But this one appears to be migrating ever so slightly upwards. Still, an earthquake swarm by itself doesn’t mean Yellowstone is preparing to erupt, nor does ground deformation, changing temperatures or gas emissions. Scientists are more concerned about several such changes happening together.

The team of scientists decides to wait and see what happens next.

T−1 month

Four weeks later, the swarm has continued to migrate upwards. New events are also appearing along a narrow zone beneath the caldera, notes the analyst, who has now lost their appetite for both food and caution and is writing reports designed to be alarming. GPS stations above the swarm have begun moving apart. Measurements of strain have increased and satellite radar reveals the cause: there’s a broad area of accelerating uplift of the ground.

Together, the observations are consistent with magma forcing its way into the crust – as seen in places like Hawai’i prior to eruptions. Reassuringly for YVO staff, Yellowstone has produced similarly alarming combinations of signals before with no subsequent eruptions. Between 2013 and 2014, parts of the caldera began rising at rates of more than 15 centimeters a year and earthquake activity increased.

This culminated in a magnitude 4.8 earthquake, the largest recorded at Yellowstone since 1975. Shortly after, the uplift changed to subsidence (the ground moving downward) and scientists concluded that the episode was associated with hydrothermal fluid movements rather than magma.

Mindful of the need to keep the public informed without causing unnecessary alarm, YVO responds cautiously. A duty scientist assumes responsibility for assessing the incoming data. Additional, temporary seismometers and GPS units are deployed to provide more precise data, and gas and water are sampled more frequently.

YVO begins closer coordination with the National Park Service and emergency management authorities, reviewing road closures, public communications and evacuation plans. Perhaps ominously, but to err on the side of caution, Yellowstone’s Volcano Alert Level is raised from “normal” to “advisory,” indicating that unrest is above its established background level.

These developments are worrisome enough that scientists start speculating about a major eruption’s impacts. The media take an interest, but the volcanologists have learned how damaging it can be when volcanic uncertainties morph into a full-blown dispute, played out in public.

Scientists privately discuss differences in interpretations, agreeing on regular updates for the public via media briefings and social media postings. As the volcano’s activity continues to ramp up, high-level decision-makers are alerted that this situation could become a major catastrophe. The probability of it happening within three months increases from 6-9% to 21-27%.

Due to the uncertainties, the politicians make no specific declaration. The US’s Federal Emergency Management Agency nevertheless starts drawing up plans for a large-scale evacuation. They express confidence in public while perhaps fearing in private that a worst-case scenario could make it hopeless to try to save everyone.

Over the following fortnight, the unrest escalates dramatically. Earthquakes become more frequent and shallower. Long-period seismicity (much gentler earthquakes, usually caused by fluid movement rather than faults shifting and known to occur at Yellowstone) and sustained volcanic tremors suggest magma and pressurized fluids are forcing open fractures in the ground.

The uplift accelerates and GPS stations move centimeters in days. Geyser activity becomes increasingly erratic. Even the Old Faithful geyser becomes less faithful: its usually regular eruptions become harder to predict. Meanwhile, gas measurements and changes in spring water chemistry indicate an increased input of carbon dioxide and sulfurous gases into Yellowstone’s hydrothermal system. Taken together with the shallow earthquakes and rapid uplift, the concern is that magma may be moving upwards.

T-2 weeks: ‘It’s gonna blow!’

These new observations lead to a press conference describing an 85-92% probability of a cataclysmic eruption within three weeks. At this point, the YVO raises Yellowstone warning to “watch,” and the USGS raises the Aviation Color Code to orange, with aircraft rerouted around the region.

An evacuation zone extending 100 kilometers beyond Yellowstone National Park is announced, affecting roughly 200,000 residents, as well as thousands of visitors in the region. The topic now dominates both traditional and social media. The attention likely spawns detractors as well as conspiracists. The former claim that nothing will happen. The latter spread the disinformation that YVO is being paid by foreign shadow billionaires to bring down the US so that other countries can control the world’s economy.

Now that a super-eruption appears imminent with high confidence, world leaders swing into action. They must make a choice: help each other as a global village or repeat COVID-19 style global shuttering.

If they choose collaboration, then they start evacuations, moving people as far as needed – including across international borders. This would involve supporting them with adequate homes, water, food, electricity and community through schools, jobs, transport and safety. Achieving all this seems unlikely, since most of the world’s population has always lacked it. Nonetheless, the US has the money, skills and goods to evacuate and resettle the huge numbers, if leaders cooperate and use everything available.

More likely, many countries could be reticent to accept “volcano refugees,” making excuses – perhaps legitimate ones – that they don’t have the money, resources or space to safely settle so many people so swiftly. They are further stretched by those who self-evacuate through having more than one passport, along with the wealth or the social network to start afresh.

Charities step in to help some people leave on chartered planes, as well as via long, excruciating journeys on overcrowded trains and buses. The most marginalized and poorest may have no option but to stay behind. Some might join the minorities who do not believe the eruption will happen, who think their well-stocked underground bunkers will protect them (an overly optimistic belief), or who would rather die at home than live in a foreign land with a devastated world.

T=0

In an instant, seismic instruments are overwhelmed by an intense burst of shallow earthquakes. Expanding clouds of steam rise from newly opened cracks. The YVO and USGS have no choice but to raise the warning level and Aviation Color Codes to red: a dangerous eruption is imminent.

The eruption does not begin with the entire caldera exploding at once. Instead, rising magma intrudes into Yellowstone’s shallow hydrothermal system, rapidly vaporising immense volumes of water. At atmospheric pressure, water can expand in volume around 1,700 times when converted to steam. Trapped beneath the surface, this rapid expansion triggers violent so-called phreatomagmatic explosions that send superheated steam, mud and shattered blocks of rock kilometers into the air.

There are no human casualties yet, thanks to the wide exclusion zones on land and in the air. Wildlife, livestock and vegetation are not as fortunate. Within roughly 4–6 kilometers of the initial eruption sites, the landscape is battered by falling rock, ash and mud. Beyond the exclusion zone, people watch an impressive two kilometer-high plume rise into the sky – but it rapidly grows larger, and any sense of relief is short-lived.

A few hours later, gas-rich magma, 650-800°C in temperature – well above the melting points of lead and zinc – breaks through the fractured surface. As the confining pressure falls, dissolved gases separate into distinct components from the melt and expand violently. The magma fragments into pumice (porous rock) and ash while tearing away huge fragments of the surrounding rock from the walls of the erupting vent.

Expanding gases and intense heat drive this material upwards, creating a vast eruption column rising 30–50 kilometers into the atmosphere – far above commercial passenger aircraft, which usually cruise at up to about 13 kilometers. On this clear morning, its upper reaches are visible from Denver, some 800 kilometers away.

As the eruption continues and the volume of material expelled mounts, scientists realize it might be the opening stages of a VEI 8 super-eruption (magnitude 8 or greater) – the highest formal notch on a scale used to measure the size of explosive volcanic eruptions. It was 74,000 years ago that humanity last witnessed this scale of eruption with Toba in Indonesia.

The immense umbrella cloud that forms does not behave like a normal ash plume that simply drifts with the prevailing wind. Its momentum initially drives ash outwards in every direction – spreading hundreds of kilometers before high-altitude winds take over and carry fine ash thousands of kilometers downwind within a day.

After a few hours of continuous eruption, parts of the column collapse, generating scorching pyroclastic density currents (extremely hot, fast-moving mixtures of gas, ash and rock fragments). These surge for tens of kilometers, splintering trees, igniting forests and burying the remnants beneath hot ash and pumice.

Anyone within this zone is pulverized by the blasts, crisped by the heat, or asphyxiated by the ash. There may be up to 1,000 immediate human deaths, including people who refused to move. It is too dangerous to recover most bodies. And even if it were possible, many bodies no longer exist to be recovered.

Outside the main pyroclastic density current zone, casualties mount from vehicle crashes as drivers lose visibility or skid due to ash, from heart and breathing difficulties and from suicide. Vegetation fires spreading beyond the immediate burn zone add perhaps hundreds of fatalities from burning, smoke inhalation and vehicle crashes.

As the magma continues to escape, sections of the unsupported ground subside, opening new fractures and vents while feeding further eruptive columns and pyroclastic density currents. Hundreds of kilometers away – in Denver and along the Canadian border – heavy ashfall darkens the sky, obstructs roads and disrupts power, water supplies and communications. This ash devastates farmland across at least eight states.

Further immediate deaths could result from loss of power disrupting traffic and street lights; curtailing health services including surgery and obtaining prescriptions; and electrocution, fire and carbon monoxide poisoning from trying to set up and operate home electricity generators. Looting and increasing crime during disasters is typically rare, but it could happen in a more desperate worst-case scenario, adding to the casualty toll.

Over the coming days, the eruption continues in pulses as sections of the caldera collapse and new vents open. Successive column collapses generate pyroclastic density currents with the resulting deposits reaching several hundred meters in thickness, as they did in the last super-eruption.

Nearby infrastructure is shattered and entombed beneath the deposits. Airports close because ash interferes with aircraft and other transport networks falter. Communities across all states bordering Wyoming face darkness, breathing difficulties and roofs collapsing under accumulated ash. As the eruption eventually begins to weaken, sulphur dioxide high in the atmosphere forms sunlight-reflecting sulfate aerosols that spread around the northern hemisphere to influence the world’s climate for several years.

T+3 days

Three days into the eruption, much of North America is living in the shadow of Yellowstone. Each successive powerful eruptive pulse sends another column tens of kilometers upwards, from where it spreads into a new umbrella cloud.

Within Wyoming and neighboring states, conditions are catastrophic. Billings, Montana, the nearest large city, is disappearing beneath what will eventually exceed a meter of ash (one published model of a Yellowstone supereruption predicts the city as receiving up to 1.8 meters of ash). Salt Lake City, Utah, and Boise, Idaho, receive tens of centimeters. For southern Canada, much of the US and northern Mexico, day becomes twilight and breathing outdoors without masks becomes increasingly difficult. People on other continents watch in trepidation under vivid, red-orange sunrises and sunsets.

Back in the US, electricity networks begin failing. Warnings had not been heeded that damp ash conducts electricity, short circuiting power lines and substations. Ash clogs machinery and generator intakes. Its weight damages cables and weaker structures.

As electricity fails, so do water pumps, sewage treatment, heating systems, fuel stations and mobile phone and internet networks. People are scared and supermarket shelves empty nationwide as regional and national supply chains begin to break down.

T+2 weeks

Over the following weeks, the crisis becomes one of survival. Repeated ashfall blocks roads, overwhelms drainage systems and damages roofs. During rain, dry ash turns into a dense slurry that makes clearance work harder. Airports remain closed or severely disrupted across much of North America, while railways, freight depots and farms struggle to operate. Livestock and crops die where pasture and water supplies are buried or contaminated by ash.

Large areas close to Yellowstone remain evacuated, while across the US, shelter, fuel, food and clean water become increasingly scarce. Some countries airlift or airdrop humanitarian relief supplies, but are also concerned about stockpiling for themselves. Losses to agriculture, transport and insurance – with many other businesses and services closed – could lead Canada, Mexico and most Caribbean and Central American countries to declare states of emergency. This is partly due to direct impacts on those countries and partly due disruption across the USA and people fleeing from it.

T+4 months

Several months later, eruptions have weakened to intermittent explosions, but the threat of renewed activity remains. For millions, the disaster is far from over. Dry, windy days lift ash back into the air, while rain and snow turn it into a heavy deposit blocking drains and damaging infrastructure. Eye and throat irritation are widespread. People with asthma and other respiratory conditions face serious health risks under reduced and overworked health services.

Water treatment and power plants struggle with ash contamination, equipment failures, lack of spare parts and overwhelming demand, disrupting essential medical and industrial processes. Crops across the most heavily affected regions have been buried. The loss of American and Canadian grain, maize and soya exports drives global food prices upwards.

Flights gradually resume in less affected areas, but airports across North America repeatedly close whenever winds remobilize the ash. The unreliable airspace and transport networks – coupled with agricultural losses, business disruption and reconstruction costs – trigger banking and insurance crises, producing a global recession.

Meanwhile, the atmospheric effects become global. Most volcanic ash has fallen out, but sulfur dioxide injected into the stratosphere produces sulfate aerosols which reflect a significant proportion of the Sun’s energy. Scientists call it a “volcanic cooling episode,” avoiding the term “a new ice age”. Modeling suggests it’s unlikely to cool the global average by more than about 1.5°C, although particular regions and seasons could experience much larger changes. Notably, central North America remains far cooler than before the eruption.

T+10 years

In the years following the eruption, the world moves into long-term recovery and rebuilding. People across the world adapt to a more agrarian lifestyle, learning to fill the land with root vegetables, grains and legumes. With far less leisure time and diminished income, recreational facilities are turned over to food production, notably small-scale greenhouses and vertical farming for producing varied fruits, vegetables, nuts and legumes.

Livestock decreases due to lack of land and feed, opening up more space for crops. People still eating meat typically either hunt big game or trap smaller birds and mammals. Insect farming tends to dominate the re-establishment of bird or mammal farms. People living near coasts, rivers and lakes ramp up fishing, depleting stocks rapidly until controls are enacted in some locations, along with increased farming for seaweed. Where rules are not agreed or enforced, starvation and migration are rampant.

Freshwater availability varies. The world’s climate has changed, providing ample rainfall in some places while drying out others. Large-scale water treatment technology remains known and used, but supply lines for chemicals and spare parts are unreliable. Many people develop local approaches and manage while others suffer contaminated water and disease, including cholera, dengue fever and malaria, just as billions did before the eruption.

Before the eruption, around 4.4 billion people from the world’s population of 8.3 billion lacked full, safe freshwater access. A decade after the eruption, it’s possible that 4.8 billion people lack such freshwater, while the world’s population may have declined to 7.9 billion due to spikes in elderly and infant mortality.

For the eruption’s survivors, disease and death are still rising. The eruption may well provide substantive, long-term evidence for the carcinogenic level of silica in the ash. A small but statistically significant increase in diagnoses of both silicosis (an irreversible lung disease) and lung cancer appears from exposure to ash, with similar results for cardiovascular disease in people breathing in ash particles.

Rates are likely higher than measured, because health systems across a continent were knocked out by the eruption and struggling to recover ten years later. The worst part is that the lack of health systems means that many who are diagnosed cannot be treated properly. Survivable diagnoses become lethal.

Inside the eruption zone, two decades follow of a grey landscape. It appears almost lifeless, with the ash transformed into raging mudflows called lahars in every storm. But vegetation, starting with grasslands and shifting to forests, creeps back into the swathes wiped out in the explosion and people follow. These new pioneers coax the landscape into fertile framing, helping to feed hungry populations.

The dispersed ash eventually settles out of the atmosphere, permitting the Sun’s rays to shine fully on the surface again – reviving agriculture and ecosystems. It also revives fears of human-caused climate change, despite the volcano-induced reduction in greenhouse gas emissions. Scientists work hard to determine whether the global climate has been knocked onto a new trajectory – which might be better or worse for human beings – or whether the heat stored in the atmosphere and oceans from humanity’s greenhouse gas burning will once again force a rapidly heating globe.

Additionally, scientists want to calculate deaths, injuries and loss to quality of life. Excess mortality analyses could suggest 0.7-1.3 billion premature deaths due to the eruption and its impacts. Perhaps double that number experienced temporary or permanent health effects but survived, although some will say that 100% of humanity was directly affected.

The good news, at least for our species, is that this unstoppable power of volcanism changed the planet, but did not end humanity – or come close to doing so.

T+1 million years

A creature descends to Earth from a sleek spacecraft, still humanoid but far removed from its ancestor species Homo sapiens sapiens. Tjjze (the pronoun used) has absorbed all the scant information available about ancient “Earth” and is curious to learn more.

The most notable material is the rise of its first technological civilization just over a million years ago. This was followed by the species abandoning the planet as it changed 140,000-160,000 years ago – becoming taller, sleeker, with longer limbs, and with larger hands, heads and brains – having already established itself around the galaxy. In the remaining lore, myths recur of episodes of runaway planetary temperature changes, hot and cold, as well as a series of volcanic blasts that changed the globe.

Tjjze observes that the vegetation is lush and the H₂O is plentiful, providing ample food and water for the bizarre animals and ecosystems. A rapid scan reveals much below the surface. In fact, a large roughly ellipse-shaped ridge made of rock appears prominently underneath the top layers. Yes, this particular region, about 24.3 cqurzots in radius, is definitely lower than the vast plains outside the depression. This seems to indicate an ancient volcanic eruption. And to leave a scar this big, it must have been gigantic.

Tjjze warps the equivalent of the face into the equivalent of a frown as more data are revealed. Indeed, this definitely looks like a caldera. And the age is coming in at around a million years (plus/minus).

Could it have erupted during the time of the technological civilization? Or were they lucky to have just missed it? It is impossible to really know.

Stroke is extremely common, affecting about one in four adults over a lifetime. Roughly half of those who experience one are left with lasting problems such as paralysis or difficulty speaking.

These disabilities can occur because a stroke deprives parts of the brain of oxygen or causes bleeding that destroys brain cells. Once those cells are lost, the damage has traditionally been considered permanent because there are currently no treatments capable of rebuilding the affected brain tissue.

“That’s why it is essential to pursue new therapeutic approaches to potential brain regeneration after diseases or accidents,” says Christian Tackenberg, the Scientific Head of Division in the Neurodegeneration Group at the University of Zurich (UZH) Institute for Regenerative Medicine.

Stem Cells Could Help Rebuild Brain Tissue

One possible approach involves neural stem cells, which can develop into multiple types of cells found in the nervous system.

A research team led by Tackenberg and postdoctoral researcher Rebecca Weber tested that idea in two studies carried out in collaboration with a group headed by Ruslan Rust from the University of Southern California.

The results suggest that the transplanted cells do more than simply replace neurons lost after a stroke.

“Our findings show that neural stem cells not only form new neurons, but also induce other regeneration processes,” Tackenberg says.

Human Stem Cells Become New Neurons

The researchers used human neural stem cells capable of producing different types of nervous system cells. These cells were created from induced pluripotent stem cells, which are made by reprogramming ordinary human somatic cells so that they regain the ability to develop into many different cell types.

The team then induced permanent strokes in mice. The resulting brain damage was designed to closely resemble important features of stroke in humans.

Because the transplanted cells came from humans, the mice were genetically modified so their immune systems would not reject them.

One week after the strokes were induced, the researchers transplanted the neural stem cells directly into damaged regions of the brain. They then tracked what happened using imaging techniques and biochemical analyses.

“We found that the stem cells survived for the full analysis period of five weeks and that most of them transformed into neurons, which actually even communicated with the already existing brain cells,” Tackenberg says.

That ability to connect with the brain’s existing cells is particularly important because simply producing new neurons would not necessarily restore function. The new cells must also become part of working neural networks.

The Brain Shows Multiple Signs of Repair

The researchers found evidence that the treatment triggered a much broader healing response.

New blood vessels formed in the damaged brain tissue, inflammatory processes became less intense, and the integrity of the blood-brain barrier improved.

The blood-brain barrier is a tightly controlled protective boundary that separates circulating blood from brain tissue. Damage to this barrier can contribute to inflammation and further injury following a stroke.

“Our analysis goes far beyond the scope of other studies, which focused on the immediate effects right after transplantation,” Tackenberg explains.

Most importantly, the biological changes were accompanied by improvements in how the animals moved.

Stem cell transplantation reversed motor impairments caused by the strokes in the mice. Researchers measured those improvements in part using AI-assisted analysis of the animals’ walking patterns.

Waiting a Week May Improve Stem Cell Therapy

The researchers designed the experiments with eventual human treatment in mind.

For example, the stem cells were produced without reagents derived from animals. Avoiding animal-derived materials can be important when developing therapies intended for human use because it may reduce potential safety and regulatory complications.

The University of Zurich team created a defined production protocol in collaboration with the Center for iPS Cell Research and Application (CiRA) at Kyoto University.

The second study also revealed an important insight about timing. The researchers found that stem cell transplantation worked better when it was performed one week after a stroke rather than immediately afterward.

That delay could make the approach considerably easier to use in a clinical setting. Doctors would have more time to prepare the treatment instead of needing to deliver it during the immediate emergency period following a stroke.

Researchers Work Toward Human Trials

Despite the encouraging findings, the researchers stress that several obstacles must still be addressed before the therapy could be tested widely in people.

“We need to minimize risks and simplify a potential application in humans,” he says.

One concern is uncontrolled stem cell growth inside the brain. Tackenberg’s group, again working with Ruslan Rust, is developing a type of safety switch intended to prevent that from happening.

The team is also exploring a less invasive way to deliver the cells.

Instead of transplanting stem cells directly into brain tissue, researchers are developing an endovascular injection approach. This would involve delivering the cells through blood vessels and could be much more practical than performing a brain graft.

There is already precedent for moving induced stem cell therapies into human testing. Initial clinical trials using induced stem cells to treat Parkinson’s disease are underway in Japan, according to Tackenberg.

“Stroke could be one of the next diseases for which a clinical trial becomes possible.”

Polyethylene is widely used in products such as shopping bags and white plastic cutting boards, and large amounts of it ultimately end up as waste. The ORNL team’s method combines the plastic with molten salts containing aluminum chloride. These salts perform two jobs at once, acting as both the reaction medium and the catalyst that drives the chemical conversion.

The researchers have applied for a patent for the technology, and the findings were published in the Journal of the American Chemical Society.

How Molten Salts Break Plastic Into Fuel

To understand why the process works, the scientists closely tracked the chemical reactions that convert the polymer into fuel molecules.

Using soft X-ray spectroscopy and nuclear magnetic resonance, the team found that charged aluminum atoms bind with three other atoms, creating highly acidic catalytic sites. These sites can attack the long molecular chains that make up polyethylene and split them into smaller hydrocarbon molecules.

Additional experiments using isotopic labeling and neutron scattering showed how the structure of the starting polymer influences the resulting fuel. Simpler polymer chains tended to produce gasoline-like compounds, while more complex chains generated diesel-like fuels.

If the method can eventually be scaled beyond laboratory experiments, the researchers say it could contribute to U.S. energy security and strengthen industrial competitiveness.

“We developed an efficient and selective polyethylene-to-gasoline conversion,” said Liqi Qiu, a postdoctoral researcher at the University of Tennessee, Knoxville, who performed most of the study’s experiments in the ORNL laboratory of Sheng Dai, of ORNL and UTK. Dai, an ORNL Corporate Fellow and section head for separations and polymer chemistry, is a co-corresponding author of the paper.

The experiments achieved a gasoline yield of about 60 percent under relatively mild reaction conditions.

Plastic-to-Gasoline Conversion Below 200 Degrees Celsius

One of the most notable features of the method is how little it requires compared with more conventional plastic-to-fuel technologies.

“We converted polymer waste to value-added fuels by using commercially available inorganic salts as the reaction media to provide the catalytic sites,” said Zhenzhen Yang, an ORNL staff scientist who was also a co-corresponding author of the paper. “Unlike traditional techniques for converting polymer to fuel, the new process did not require noble-metal catalysts, organic solvents or external hydrogen. This is the first time molten salts were used as media to produce high-value-added chemicals from waste without any catalytic initiator or solvent and at a temperature below 200 degrees Celsius.”

Temperatures below 200 degrees Celsius are comparable to those found inside a conventional kitchen oven. Earlier approaches for converting polyethylene into gasoline have typically relied on pyrolysis, a process that uses intense heat to break large polymer molecules into smaller hydrocarbons. Those methods have required temperatures of roughly 450 to 500 degrees Celsius.

The lower temperature, along with the absence of costly noble-metal catalysts, external hydrogen, organic solvents, and a chemical initiator, could simplify the process.

“The ORNL system solves two fundamental issues. One, for a stable system, the process can be radically easier to scale up. Two, the previous system needed an initiator to kick off catalytic reactions.”

• Sheng Dai, ORNL Corporate Fellow and section head for separations and polymer chemistry

Decades of Molten Salt Research

ORNL has been studying molten salts for decades. During the 1960s, its Molten Salt Reactor Experiment demonstrated that mixtures of molten salts could function as both nuclear fuel and reactor coolant.

Building on that long history, Dai proposed using molten salts for an entirely different purpose: converting discarded polymers into useful fuels.

Molten salts are inorganic compounds that can remain stable even under demanding chemical reaction conditions.

“The ORNL system solves two fundamental issues,” Dai said. “One, for a stable system, the process can be radically easier to scale up. Two, the previous system needed an initiator to kick off catalytic reactions. However, the ORNL system does not need one.”

ORNL’s Tomonori Saito managed the project and contributed expertise in polymer science.

“In this case we tackled polyethylene, a widely available commodity polymer, using molten salt,” he said. “We’re trying to understand fundamental science that will lead to discoveries and new economic opportunities.”

Understanding exactly what was happening during the reaction required researchers from several scientific disciplines and the use of multiple advanced analytical techniques.

Tracking the Chemistry Atom by Atom

At ORNL, Luke Daemen used neutron scattering to help identify the hydrocarbon products created when different polymer chains reacted. Felipe Polo-Garzon analyzed the products with gas chromatography-mass spectrometry, a technique used to separate and identify individual chemical compounds.

When polyethylene interacted with an aluminum catalytic site, the reaction produced a positively charged carbon ion. Qiu, Yang and Dai tagged that carbon ion with deuterium, an isotope of hydrogen, allowing them to follow what happened to it as the reaction progressed.

The team also used neutrons at ORNL’s Spallation Neutron Source to monitor hydrogen within the system.

“The polymer contains a lot of hydrogen,” Dai said. “Neutrons are ideal at discerning light elements including hydrogen and its isotopes, such as deuterium.”

Researchers also needed to determine how the aluminum sites themselves changed during the process.

Yang traveled to the Advanced Light Source at Lawrence Berkeley National Laboratory, where she worked with Min-Jae Kim and Jinhua Guo. Using soft X-rays, the researchers examined interactions between aluminum and polyethylene at both the atomic and electronic levels. Soft X-rays are especially useful for studying relatively lightweight elements such as aluminum.

“The aluminum edge shifted to the low-electron-density edge, which means some electron-rich intermediates formed,” Yang said. “We compared the findings with other techniques and confirmed an aromatic ring intermediate can coordinate with aluminum and cause a binding-energy change.”

That shift provided evidence that the aluminum sites were actively catalyzing the chemical reaction.

Simulations and Advanced Imaging Reveal the Mechanism

Back at ORNL, Bobby Sumpter of the Center for Nanophase Materials Sciences used computer simulations to study the energy changes taking place during the reaction, including how stable carbon ions formed and were transferred into hydrocarbon products.

At UTK, Michael Koehler used in situ X-ray diffraction to follow changes in the phases of the reaction mixture as the chemistry unfolded. Carlos Alberto Steren used nuclear magnetic resonance to investigate the aluminum catalytic sites.

ORNL’s Tao Wang contributed expertise in molten salt chemistry, while ORNL’s Logan Kearney supplied high-density polymers and provided expert guidance on possible routes for converting them into higher-value products.

A Remaining Challenge: Keeping the Salts Stable

Although the aluminum-based catalytic system is inexpensive and chemically active, it has an important limitation. The material is hygroscopic, meaning it readily absorbs water. That moisture can reduce its stability.

The researchers now want to investigate ways to confine the molten salts, potentially using halogens or carbon-based materials, which could make the salts easier to separate and process while improving their stability.

The work could ultimately expand the range of methods available for producing transportation and industrial fuels from waste materials.

“Polymer source material is abundantly available from consumer waste, and our catalyst system, aluminum molten salts, is very cheap,” Qiu said. “This advance may be promising for industry.”

The DOE Office of Science (Materials Sciences and Engineering Division) primarily supported the research as well as the gas chromatography-mass spectrometry work (Chemical Sciences, Geosciences and Biosciences Division, Catalysis Science program). The research employed DOE Office of Science user facilities at ORNL (the Spallation Neutron Source for neutron scattering at the VISION beamline and the Center for Nanophase Materials Sciences for quantum chemistry calculations) and Lawrence Berkeley National Laboratory (the Advanced Light Source for soft X-ray spectra).

Researchers from DTU, the University of Copenhagen, University College London, and other institutions have developed a long, needle-thin brain electrode equipped with microscopic channels. Known as the microfluidic Axialtrode (mAxialtrode), the device is designed to provide multiple functional points along the length of the implant. This allows researchers to record neural activity and deliver medication to specific locations across different parts of the brain.

The findings were published in the journal Advanced Science.

A Multifunction Tool for Brain Research

For now, the technology is primarily intended as a research tool. Scientists could use it to investigate how signals travel through different layers of the brain during processes involving epilepsy, memory, and decision-making.

Over the longer term, the researchers say the mAxialtrode could also have therapeutic applications. One possibility would be using the device to deliver drugs to precise locations while simultaneously applying electrical stimulation or light stimulation to selected areas of the brain.

Postdoc Kunyang Sui, who developed the mAxialtrode concept together with Associate Professor Christos Markos, says one of the main advantages is that several capabilities can be combined within a single implant. That could allow researchers to perform more precise experiments while reducing the need for multiple devices inserted into the brain.

“Most current brain implants are based on hard materials such as silicon, which can irritate the brain and trigger inflammatory reactions in the tissue. The new implant differs in that it is made of soft, plastic-like optical fibers and has a specially angled tip that makes it smaller and reduces the damage caused when it is placed in the brain,” says Kunyang Sui.

Sui cautions that the technology is still far from routine clinical use. Extensive testing, additional development, and regulatory approvals would be required before it could be used to treat patients.

Moving Beyond Conventional Optical Fibers

Brain researchers currently use flat-ended optical fibers in many experiments. These thin fibers, made from glass or plastic, can carry light into deep regions of the brain. They are frequently used in optogenetics, a technique in which specific nerve cells are activated using light.

Conventional fibers, however, have an important limitation. They typically interact with brain tissue only at the end of the fiber, meaning researchers can stimulate or monitor just one location at a time.

The outermost end is called the distal tip, or the “nose” of the fiber. Light is emitted and contact with brain tissue occurs only at this point. As a result, scientists may be limited to measuring or stimulating one brain layer at a time, even though many brain functions depend on communication among several layers and deeper structures.

How the New Brain Implant Works

The needle-thin mAxialtrode begins as a much larger polymer rod. Researchers heat the material and draw it into an extremely thin fiber, somewhat like producing a very fine strand of sugar, but with far greater precision.

A light-conducting core runs through the center of the fiber. Surrounding it are eight microscopic channels that can transport liquids. Those channels can also hold extremely thin metal wires used to measure electrical activity in the brain.

The finished fiber measures less than half a millimeter across. It is also highly flexible, allowing it to move along with brain tissue rather than pressing rigidly through it. This difference in stiffness could be important because harder implants can trigger inflammatory responses when they remain in the brain for long periods.

Tested in Living Mice

The researchers tested the system not only in the laboratory but also “in vivo,” meaning in living mice. The electrode was implanted in the animals’ brains and connected to light sources, recording equipment, and small pumps used to deliver fluids.

The experiments showed that the device could stimulate nerve cells using both blue and red light. At the same time, researchers were able to record electrical activity from shallow and deeper brain regions, including the cerebral cortex and hippocampus.

They were also able to inject different substances at separate depths, with delivery points spaced almost three millimeters apart. All of these measurements and forms of stimulation were carried out using a single lightweight fiber, which the mice were able to carry without any obvious signs of discomfort.

Potential Applications in Epilepsy and Neuroscience

The in vivo experiments and neurophysiological validation were performed in close collaboration with Associate Professor Rune W. Berg of the University of Copenhagen and Associate Professor Rob C. Wykes from University College London. Their contributions included expertise in analyzing neural circuits and models relevant to epilepsy.

The research team is now working to patent the technology behind the brain electrode. The scientists are also exploring what would be required to begin testing the device in patients within a clinical setting.

Roman’s planet-imaging system, the Coronagraph Instrument, has also completed an early checkout of its digital, electronic, and mechanical systems after waking up earlier this month.

The tests are part of a months-long commissioning process that will continue as Roman travels roughly one million miles toward its destination at the second Lagrange point, L2.

Roman’s 300-Megapixel Camera Comes Online

The Wide Field Instrument, or WFI, is designed to combine an unusually broad view of the sky with the kind of sharp detail associated with space telescopes such as NASA’s Hubble. A single WFI image will cover an area of sky larger than the apparent size of a full moon.

That combination of wide coverage and high resolution will allow Roman to carry out enormous surveys of the cosmos. Scientists plan to use those observations to learn more about planets beyond our solar system, investigate mysteries such as dark energy, and study how matter is arranged throughout the universe. Roman’s expansive and detailed observations are also expected to create a valuable dataset for many additional scientific studies.

“After years of effort to build and test the instrument on the ground, we now have confirmation that it is operational in space. This is a huge milestone for the team at Goddard, our industry teams at BAE Systems, Inc. and Teledyne, and our science centers,” said Josh Schlieder, the Wide Field Instrument scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “There is much to do, but we are on our way to groundbreaking science.”

Cooling Roman’s Infrared Detectors

Before engineers could switch on the WFI, the instrument spent 10 days drying out and undergoing decontamination. During that period, its detectors were kept at a relatively warm (compared to their final operating temperature) minus 85 degrees Fahrenheit, or minus 65 Celsius.

On the morning of Sep. 11, the team shut off the instrument heater and allowed the WFI to cool to minus 225 degrees Fahrenheit (minus 143 degrees Celsius). At that temperature, engineers were able to activate Roman’s 18 infrared detectors. Together, those detectors have a light-sensitive area approximately the size of a laptop screen.

Later that evening, the team turned on the instrument’s calibration system. The following morning, engineers began sending test data through the WFI and transmitting it back to teams on Earth.

Testing Roman’s Filters and Focus

On Saturday evening, engineers turned their attention to the element wheel, which contains filters, prisms, and other optical components. The system controls which wavelengths of light reach the detectors and can separate light from cosmic objects into individual colors. This marked the first time the mechanism had been tested without gravity.

By Sunday morning, the team was testing the WFI’s focusing mechanism. That system will be critical for keeping the hundreds of thousands of images Roman is expected to capture properly focused.

Throughout these tests, the detectors continued cooling toward their final operating temperature of about minus 300 Fahrenheit (minus 183 Celsius).

The results showed that the Wide Field Instrument is functioning as expected. Roman remains on schedule to release its first science images by early 2027.

Roman’s Coronagraph Passes Early Checks

Roman’s Coronagraph Instrument is built to demonstrate some of the most advanced technology ever sent into space for directly imaging planets orbiting other stars.

The instrument combines optics, masks, self-flexing mirrors, and sensors that are designed to suppress the overwhelming glare of a star. By blocking that light, the coronagraph could allow scientists to detect the much fainter light reflected by planets orbiting nearby.

Scientists and engineers working at the Coronagraph Commanding Center at Caltech/IPAC in Pasadena, California, verified that they can communicate with every major part of the instrument. Those systems include its software, thermal controls, mechanisms, cameras, and the avionics that operate them.

In practical terms, the test confirmed that ground teams can remotely control the instrument’s various systems, including movable mechanisms that position its masks, color filters, lenses, and prisms.

Preparing the Coronagraph for Science

Engineers also verified that the coronagraph’s thermal system is functioning properly and can warm the hardware to its operating temperature, a relatively comfortable 72 degrees Fahrenheit (22 Celsius).

With the exception of its detectors, the coronagraph is intended to operate near room temperature. That design makes the system easier to test while also helping preserve the material properties required by its deformable mirrors.

“Now that this test is complete, we’ve been decontaminating: sitting idle with our detectors warm so anything that’s stuck to the surface, such as water or trace chemicals, will tend to leave it,” said Eric Cady, an optical engineer leading commissioning efforts for the Roman Coronagraph at NASA’s Jet Propulsion Laboratory in Southern California. “This will continue for 30 days, with occasional stops to do other early calibration activities.”