A Cracked Piece of Metal Healed Itself in Experiment That Stunned Scientists

Physics02 September 2024

ByDavid Nield

(Luis Diaz Devesa/Moment/Getty Images)

File this under 'That's not supposed to happen!'. In an experiment, scientists observed a metal healing itself. If this process can be fully understood and controlled, we could be at the start of a whole new era of engineering.

In a study published last year, a team from Sandia National Laboratories and Texas A&M University was testing the resilience of the metal, using a specialized transmission electron microscope technique to pull the ends of the metal 200 times every second.

They then observed the self-healing at ultra-small scales in a 40-nanometer-thick piece of platinum suspended in a vacuum.

Cracks caused by the kind of strain described above are known as fatigue damage: repeated stress and motion that causes microscopic breaks, eventually causing machines or structures to break.

Amazingly, after about 40 minutes of observation, the crack in the platinum started to fuse back together and mend itself before starting again in a different direction.

Pulling forces (red arrows) created a crack that healed (green) in platinum metal. (Dan Thompson/Sandia National Laboratories)

"This was absolutely stunning to watch first-hand," said materials scientist Brad Boyce from Sandia National Laboratories when the results were announced.

"We certainly weren't looking for it. What we have confirmed is that metals have their own intrinsic, natural ability to heal themselves, at least in the case of fatigue damage at the nanoscale."

These are exact conditions, and we don't know yet exactly how this is happening or how we can use it. However, if you think about the costs and effort required for repairing everything from bridges to engines to phones, there's no telling how much difference self-healing metals could make.

While the observation is unprecedented, it's not wholly unexpected. In 2013, Texas A&M University materials scientist Michael Demkowicz worked on a study predicting that this kind of nanocrack healing could happen, driven by the tiny crystalline grains inside metals essentially shifting their boundaries in response to stress.

Demkowicz also worked on this study, using updated computer models to show that his decade-old theories about metal's self-healing behavior at the nanoscale matched what was happening here.

That the automatic mending process happened at room temperature is another promising aspect of the research. Metal usually requires lots of heat to shift its form, but the experiment was carried out in a vacuum; it remains to be seen whether the same process will happen in conventional metals in a typical environment.

A possible explanation involves a process known as cold welding, which occurs under ambient temperatures whenever metal surfaces come close enough together for their respective atoms to tangle together.

Typically, thin layers of air or contaminants interfere with the process; in environments like the vacuum of space, pure metals can be forced close enough together to literally stick.

"My hope is that this finding will encourage materials researchers to consider that, under the right circumstances, materials can do things we never expected," said Demkowicz.

The research was published in Nature.

An earlier version of this article was published in July 2023.

 

Mongolia’s ‘Eternal Ice’ Is Melting, 

Revealing Ancient Artifacts

 www.vice.com

Precious artifacts have been tumbling out of melting ice patches and glaciers in Mongolia: an arrow, painted red at the tip, that may date back thousands of years to the Bronze Age; a mass animal graveyard containing the remains of dozens of bighorn sheep; remnants of a beautiful rope braided from horsehair.

These ice patches, known as Mongolia’s “eternal ice” because they normally stay intact even in summer, are melting at an accelerated rate due to climate change.

As piles of ice and snow recede, ancient objects from many periods of Mongolian history are spilling from their frozen prisons to be glimpsed for the first time by modern eyes, according to a study published on Wednesday in the open-access journal PLOS ONE.

But even as this rapid ice melt opens a window into Mongolia’s past, it also threatens the future of the traditions and lifeways practiced by the people who live there today.

“Folks in essentially every corner of Mongolia that we’ve worked in don’t have the luxury of climate denial, because their day-to-day life is drastically impacted by these changes,” said lead author William Taylor, an archeologist at the Max Planck Institute for the Science of Human History and the University of Colorado-Boulder, in a call.

“People within the last decade have seen a number of important patches that were a big focus of their livelihoods melt completely,” he noted.

While important artifacts are being recovered from some of the ice patches, Taylor emphasized that troves of archeological objects may be destroyed by the melt before people can collect them. Even if ice patches that fully melted in one season return in colder weather, for instance, the degradation of archeological materials that were preserved inside them could never be reversed.

“The vast majority of the artifacts that we recovered were actually from a patch which was in its absolute dying throes when we visited,” he explained. “So, that’s really sad and it suggests that we probably have already lost a lot of the important clues to this particular part of Mongolia.”

During research trips to Mongolia last year, reported in the new study, the team quickly realized the troubling implications of climate change for the region’s extraordinary heritage and cultural practices, such as reindeer pastoralism.

At one of the ice patches, Taylor and his colleagues discovered wooden artifacts that had melted out of the snowpack. Interviews with the Tsaatan people, who are domestic reindeer herders in northern Mongolia, suggest that one of the items was a fishing pole made of willow wood. Radiocarbon-dating of these specimens revealed that they were likely fashioned in modern times, around the 1960s and 70s.

Galvanized by the ticking clock of the ice melt, the team organized another expedition to survey ice patches and glaciers in Western Mongolia this year. The researchers relied on the knowledge of locals to guide them to sites that they suspected might be hemorrhaging artifacts during the summer melt.

A man named Bekbolat Bugibay, who runs a tour company, showed them an arrow shaft he had discovered that appeared to date from “the time of Genghis Khan,” according to Taylor.

Bugibay directed to them to the glacial site where he retrieved it, on the slopes of a 4,000-meter-high mountain. The team was able to reach the glacier, even after a storm destroyed three of their tents during the trek.

Toward the end of an exhausting day, Taylor and his colleague Nick Jarman spotted an arrow emerging from the ice at the bottom of the glacier. Upon closer examination, they realized it was made of bronze, and probably dated back to the Bronze Age some 3,000 years ago.

“When we actually spotted that glint of green of the bronze melting, poking through the ice, the first reaction was genuinely a loss of breath,” Taylor recalled.

“The next thing that settles in is the enormity of what you’re looking at,” he said. “You’re looking at something that has literally been preserved almost exactly as it entered this ice millennia ago.”

This arrowhead is the team’s “star find,” Taylor said, though its age has not yet been verified with radiocarbon dating.

The 2019 expedition also uncovered the horsehair rope, numerous animal skeletons that were likely hunted and deposited by humans, and wooden artifacts that may be spear shafts that predate the Bronze Age, though it will take radiocarbon-dating to be sure.

As thrilling as these finds have been for Taylor and his colleagues, the team is mindful of the bigger picture. The new study focuses on the Tsaatan herders who rely on ice patches as a source of water for themselves and their reindeer, as well as a place to retreat from irritating bugs and summer heat.

In interviews with Tsaatan families, the researchers learned what an enormous toll climate change has been exacting on their economic stability and cultural traditions. Despite the fact that these remote populations are essentially blameless for the climate crisis, which is primarily caused by fossil fuel emissions from wealthy nations, they are facing disproportionate disruptions as they lose a crucial source of freshwater.

“If you read a story like this and you’re not just outraged at the injustice of it, then there’s something wrong,” Taylor said. “The issue here is that we not only have folks who have done very little to contribute to the problem, but we see that climate change is undercutting the viability of their way of making a living and erasing the clues we have to their past and their cultural heritage.”

“This example should be really troubling especially because this is just one corner of Eurasia, and this kind of research has not really been done in vast swaths of the globe,” he added. “This same story may be playing out in other places and we really don’t know the scope of the problem.”

Science is rewriting the history of horse domestication

As they spread, horses reshaped ecology, social structures and economies at a never-before-seen scale.

Perspective by William Taylor
September 1, 2024 

THE CONVERSATION

Across human history, no animal has had a deeper impact on human societies than the horse. But when and how people domesticated horses have posed an ongoing scientific mystery.

Half a million years ago or more, early human ancestors hunted horses with wooden spears, the very first weapons, and used their bones for early tools. During the late Paleolithic era, as far back as 30,000 years ago or more, ancient artists chose wild horses as their muse: Horses are the most commonly depicted animal in Eurasian cave art.

Following their first domestication, horses became the foundation of herding life in the grasslands of Inner Asia, and key leaps forward in technology such as the chariot, saddle and stirrup helped make horses the primary means of locomotion for travel, communication, agriculture and warfare across much of the ancient world. With the aid of ocean voyages, these animals eventually reached the shores of every major landmass — even Antarctica, briefly.

Archaeologists William Taylor (left), and Aidan Marler (right) investigate an ancient horse jaw bone in western Mongolia. (Yancen Diemberger)

As they spread, horses reshaped ecology, social structures and economies at a never-before-seen scale. Ultimately, only industrial mechanization supplanted their near-universal role in society.

Because of their tremendous impact in shaping our collective human story, figuring out when, why and how horses became domesticated is a key step toward understanding the world we live in now.

Doing so has proved to be surprisingly challenging. In my new book, “Hoof Beats: How Horses Shaped Human History,” I draw together new archaeological evidence that is revising what scientists like me thought we knew about this story.

A domestication hypothesis

Over the years, almost every time and place on Earth has been suggested as a possible origin point for horse domestication, from Europe tens of thousands of years ago to places such as Saudi Arabia, Anatolia, China or even the Americas.

By far the most dominant model for horse domestication, though, has been the Indo-European hypothesis, also known as the “Kurgan hypothesis.” It argues that, sometime in the fourth millennium B.C. or before, residents of the steppes of western Asia and the Black Sea known as the Yamnaya, who built large burial mounds called kurgans, hopped astride horses. The newfound mobility of these early riders, the story goes, helped catalyze huge migrations across the continent, distributing ancestral Indo-European languages and cultures across Eurasia.

But what’s the actual evidence supporting the Kurgan hypothesis for the first horse domestication? Many of the most important clues come from the bones and teeth of ancient animals, via a discipline known as archaeozoology. Over the past 20 years, archaeozoological data seemed to converge on the idea that horses were first domesticated in sites of the Botai culture in Kazakhstan, where scientists found large quantities of horse bones at sites dating to the fourth millennium B.C.

Other kinds of circumstantial evidence had already started to pile up. Archaeologists discovered evidence of what looked like fence post holes that could have been part of ancient corrals. They also found ceramic fragments with fatty horse residues that, based on isotope measurements, seem to have been deposited in the summer months, a time when milk could be collected from domestic horses.

The scientific smoking gun for early horse domestication, though, was a set of changes found on some Botai horse teeth and jawbones. Like the teeth of many modern and ancient ridden horses, the Botai horse teeth appeared to have been worn down by a bridle mouthpiece, or bit.

Together, the data pointed strongly to the idea of horse domestication in northern Kazakhstan around 3500 B.C. — not quite the Yamnaya homeland, but close enough geographically to keep the basic Kurgan hypothesis intact.

There were some aspects of the Botai story, though, that never quite lined up.

From the outset, several studies showed that the mix of horse remains found at Botai was unlike that found in most later pastoral cultures: Botai is evenly split between male and female horses, mostly of a healthy reproductive age. Killing off healthy, breeding-age animals like this on a regular basis would devastate a breeding herd. But this demographic blend is common among animals that have been hunted. Some Botai horses even have projectile points embedded in their ribs, showing they died through hunting rather than a controlled slaughter.

These unresolved loose ends loomed over a basic consensus linking the Botai culture to horse domestication.

New tools, new questions

In recent years, as archaeological and scientific tools have rapidly improved, key assumptions about the cultures of Botai, Yamnaya and the early chapters of the human-horse story have been overturned.

In 2018, nuclear genomic sequencing revealed that Botai horses were not the ancestors of domestic horses but of Przewalski’s horse, a wild relative and denizen of the steppe that has never been domesticated, at least not in recorded history.

Next, when my colleagues and I reconsidered skeletal features linked to horse riding at Botai, we saw that similar issues are also visible in ice age wild horses from North America, which had certainly never been ridden. Even though horse riding can cause recognizable changes to the teeth and bones of the jaw, we argued that the small issues seen on Botai horses can reasonably be linked to natural variation or life history

This finding reopened the question: Was there horse transport at Botai at all?

Leaving the Kurgan hypothesis in the past

Over the past few years, trying to make sense of the archaeological record around horse domestication has become an ever more contradictory affair.

For example, in 2023, archaeologists noted that human hip and leg skeletal problems found in Yamnaya and early Eastern European burials looked like problems found in mounted riders, consistent with the Kurgan hypothesis. But such problems can also be caused by other kinds of animal transport, including the cattle carts found in Yamnaya-era sites.

So how should archaeologists make sense of these conflicting signals?

A clearer picture may be closer than we think. A detailed genomic study of early Eurasian horses, published in June in the journal Nature, shows that Yamnaya horses were not ancestors of the first clearly domestic horses, known as the DOM2 lineage. And Yamnaya horses showed no genetic evidence of close control over reproduction, such as changes linked with inbreeding.

Instead, the first DOM2 horses appear just before 2000 B.C., long after the Yamnaya migrations and just before the first burials of horses and chariots also show up in the archaeological record.

For now, all lines of evidence seem to converge on the idea that horse domestication probably took place in the Black Sea steppes, but much later than the Kurgan hypothesis requires. Instead, human control of horses took off just before the explosive spread of horses and chariots across Eurasia during the early second millennium B.C.

There’s still more to be settled, of course. In the latest study, the authors point to funny patterns in the Botai data, especially fluctuations in genetic estimates for generation time — essentially, how long it takes on average for a population of animals to produce offspring. Might these suggest that Botai people still raised those wild Przewalski’s horses in captivity, but only for meat, without a role in transportation? Perhaps. Future research will let us know for sure.

Either way, out of these conflicting signals, one consideration has become clear: The earliest chapters of the human-horse story are ready for a retelling.

The writer is an assistant professor and curator of archaeology at the University of Colorado at Boulder. This article was produced in collaboration with theconversation.com.

Why biologists are listening to soil — and what it’s telling them

Researchers searched for sounds produced by ants, worms and other creatures underground, soundscapes studied in the emerging field of ecoacoustics.


By Erin Blakemore
September 1, 2024 


Healthy soil is surprisingly noisy, a new analysis suggests — and researchers are listening for clues on the cacophony’s link to biodiversity.

To better assess the links between soil sounds and biodiversity, researchers looked at — and listened to — a variety of landscapes in South Australia. They were searching for sounds produced by ants, worms and other creatures underground, soundscapes studied in the emerging field of ecoacoustics.

Writing in the Journal of Applied Ecology, researchers describe experiments with three different types of temperate forest sites: two deforested plots of land maintained by regular mowing, two woodland plots that had been restored in recent years and two mostly undisturbed plots of land.

The researchers recorded soil sounds during daytime hours at all six sites, supplementing the data with recordings of soil samples taken in a soundproofed chamber. They counted the number of invertebrates in each soil sample to determine how much diversity could be found beneath each site.

The analysis showed more diversity in both the untouched and restored plots — and both had more complex acoustics. Recordings of the soils on those plots featured clicks, bubbling and a range of other sounds — evidence of the variety and health of life beneath the Earth’s surface. The deforested plot was quieter and had less abundant life inside than the more vegetated land.

Listening to the soil could one day help identify areas in need of restoration or protection, or even warn of environmental disturbances, the researchers write, adding that the technology could be used to identify invasive species and biosecurity risks like fire ants.


“All living organisms produce sounds, and our preliminary results suggest different soil organisms make different sound profiles depending on their activity, shape, appendages and size,” Jake M. Robinson, an ecologist and researcher at Flinders University in Australia and the study’s first author, said in a news release.

Nuke Em

Michigan Plotting to Re-Open Shuttered 1970s Nuclear Plant

Calling Homer Simpson!

FUTURISM
Sep 1, 2024
bySharon Adarlo  

Getty / Futurism

Power Hour

After shutting it down in 2022, Michigan is making an abrupt u-turn and is now planning to reopen an old 1970s nuclear power, according to The Wall Street Journal.

When it starts operating again in about a year, the Palisades plant would become the first decommissioned nuclear power plant in the world that would go back online, the WSJ reports, a feat that bucks the trend in old nuclear power plants going permanently dark, such as in Germany.

And there's serious money behind this: the federal government and the state are pouring $2 billion into the plant's refurbishment and reopening, a move that seeks to address AI data centers' hunger for ever more electricity, according to the WSJ's reporting.

Coupled with this is the federal government's push for nuclear power as a green, sustainable energy source, which goes against lingering public distrust and fear of nuclear power due to the Chernobyl disaster, the Three Mile Island accident in New York, and most recently the meltdown of the Japanese Fukushima nuclear power plant in 2011.

There are of course naysayers such as from the Sierra Club, but restarting this plant and building news ones seems like a smart move as we contend with the impact of climate change and energy-hungry data centers.

Nuclear Option

Many have pushed renewable energy sources such as solar and wind to take the place of nuclear power, such as proponents in Germany.

But these sources are intermittent, because wind always doesn't blow and the Sun doesn't shine all the time. Crucially, solar power is subjected to the infamous duck curve, which shows a mismatch between supply and demand that's shaped like the back of a duck.

Basically, the mismatch is that when solar generation is at its peak during the day, people aren't using as much electricity. But at night when people are home and using all sorts of appliances, the demand is high but supply is down.

To address renewable sources' intermittent issues, Germany has fired up an increasing amount of gas-fired power plants, which goes against its plan to cut down carbon emissions from fossil fuels.

That's why some are getting back on the nuclear power bandwagon. It's stable base load energy that can step up when solar, wind and other renewables are not generating power.

And it's green because it doesn't release any direct carbon emissions (though mining and disposing of radioactive fuel does, to some degree.)

Basically, if we want to sustain an advanced civilization while minimizing the impact of climate change, we're almost certainly gonna have to split some atoms.

More on nuclear power: AI Data Centers Need So Much Power They May Need Built-in Nuclear Reactors

Mpox in the Democratic Republic of Congo: Children are at high risk—health expert explains why

by Nadia Adjoa Sam-Agudu, The Conversation

 SEPTEMBER 1, 2024

A one-month-old baby at an mpox isolation unit in South Kivu province, DRC. 

Credit: UNICEF

The World Health Organization (WHO) has warned that children, pregnant women and people with weak immune systems are at higher risk from the mpox outbreak in the Democratic Republic of Congo. Reports confirm that children under 5 account for 39% of all cases in the country, and babies as young as 2 weeks are being diagnosed with this viral illness.

Nadia Adjoa Sam-Agudu, an expert in pediatric infectious diseases, explains how mpox can be dangerous for children and what must be done to protect them.

Why is the DRC outbreak affecting children so badly?

Because of conflict, political instability and insecurity, large parts of the DRC have not had stable, consistent, sustained health responses or health prevention. As a result, it's hard to control infectious diseases like mpox.

In addition, children in any outbreak setting are already vulnerable given their immature and still-developing immune systems, especially under the age of 5.

In a paper on pediatric mpox, my colleagues and I reported that children in Africa were much more vulnerable to monkeypox virus infection than children elsewhere. About 2% of those infected globally were under the age of 18 years, while children in Africa constituted nearly 40% of cases.

These statistics are due to a combination of things: living in a country where mpox is consistently present (endemic), exposure through contact with animals, and not having the benefit of a vaccine. Smallpox vaccine is effective against mpox, but this was discontinued in 1980 after smallpox was eradicated, so anyone born after that in DRC or other African countries has not been vaccinated against mpox. This is still true, even after the global outbreak.

The new variant circulating in the DRC—Clade Ib—has genetic changes that have been linked to sustained human-to-human transmission, which is thought to be driving the current outbreaks in the DRC and east Africa. Furthermore, current WHO reports indicate that Clade Ib is also linked to sexual contact and is affecting mostly adults, especially men who have sex with men and sex workers.

It is Clade Ia, the previously known circulating virus, which is significantly affecting children. Of course, adolescents (those between 10 and 19 years) may be caught in the middle and represented in the case numbers for both Clade Ia and Ib.

But it's important to note that children have been susceptible to mpox since the first ever reported case in the DRC in 1970. That particular case was a 9-month-old boy.

In those days, animal-to-human contact was a more common means of mpox transmission—after all, it is a zoonotic disease. Studies and reports suggest that, historically, children were more susceptible to mpox because of higher exposure to wild animals, for example, different species of monkeys and rodents in rural and forest areas.

Is this unusual? Are there other diseases that children are more susceptible to?

No, it's not unusual.

Children are born with immune systems that are still developing.

It's when they get to around five years of age that they have had enough time and disease exposure (or vaccines) to make their immune systems more robust and build adequate immune protection.

Children in the DRC are particularly vulnerable to vaccine-preventable diseases because the country has quite low child vaccination rates. In 2021, approximately 19.1% of children in the DRC between 12 and 23 months had never been vaccinated for diseases such as pertussis (whooping cough); the ideal vaccine coverage is 95%.

This also means that children in the DRC are more susceptible to highly contagious and dangerous diseases, like measles. An outbreak or rise in cases of measles infection is an early indicator that a health system is broken. This is because measles control needs a very high level of herd immunity—when enough people in a population are immune to a disease, making it harder for the disease to spread to those who aren't immune. Once immunization levels drop—like in the setting of conflict or other humanitarian emergency—measles infections start popping up. Containing them requires immense catch-up vaccination efforts.

Chickenpox and malaria are other diseases that children are more susceptible to on account of their immature and still-developing immune systems.

What are the priorities to protect children in this outbreak?

First, children must be specifically targeted for protection. This is because they are a primary population of concern that can develop severe and fatal disease.

Second, the health system and health care workers must make it as easy as possible to get parents or caregivers to bring children in. This includes addressing the inconveniences of leaving their communities to seek care.

Third, the stigma connected to mpox must be addressed. Parents and caregivers may be reluctant to seek care because of the stigma and negative treatment they may receive. The skin lesions are quite noticeable for mpox and unfortunately draw negative attention and treatment by society and health workers. The media, including international media, have been feeding into this—especially for African people with mpox—and it needs to stop.

Finally, a vaccination program focused on children needs to be rolled out to stem transmission. But there are major challenges.

First, the mpox vaccine approved for use by the WHO and in most countries with access during the global 2022 outbreak and to date is the MVA-BN vaccine (Jynneos), which is not approved for children under 18 years. MVA-BN makes up the vast majority of ongoing vaccine donations to African countries. Japan's LC16 vaccine has been used for children as young as 1–7 years, but it may require approvals for use or trials among children outside Japan.

In addition, children urgently need routine vaccines to protect them from other diseases such as measles, chickenpox, meningitis or polio. This will ensure that they aren't struck by multiple illnesses while they are still highly vulnerable. It gives their immune system a better chance at fighting mpox.

What steps should be taken if a child is infected with mpox?

This may be hard to do, especially in the home, but the child should be isolated to minimize human to human transmission. There has been some promise of drugs that directly treat mpox infection, but recent results from tecovirimat and Clade I mpox have been disappointing.

The next step is to treat the symptoms and prevent complications. The most common manifestations in pediatric mpox are rash, fever and enlarged lymph nodes, and the most common cause of complications is secondary bacterial infection.

It's particularly important that skin lesions are managed to prevent secondary infection. The danger is in mpox lesion infection. If left unmanaged, the infection can develop into sepsis. This is a potentially fatal bloodstream infection that can affect the function of one or more organs. The reports of mortality among children in the DRC are usually sepsis. Proper wound care and antibiotics are important preventive tools.

In parallel to this, steps must be taken to help improve the overall health and well-being of the child. For instance, if the child is malnourished, they need age-appropriate therapeutic nutrition so that they are better able to fight mpox and other infections.

Children in mpox-endemic African countries are facing outbreaks with little to no access to pediatric vaccines and effective antiviral treatments. In this context, the most important things are nutrition, completion of routine immunizations, and prevention of secondary infection. This requires convenient access to stigma-free, evidence-based care and support for children and their parents or caregivers.

Provided by The Conversation 

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Congo says it will receive its first mpox vaccines next week to address new global emergency