Category: 7. Science

Genomes contain the complete library of information required to build and maintain a living organism — the figurative blueprints of life. In eukaryotes, genomes are stored in the nuclei, where they are organized into chromosomes. A eukaryote is an organism whose cells have a nucleus surrounded by a membrane: plants, animals, fungi and many microbes are eukaryotes.

The human genome, for example, is organized in 23 chromosomes, each containing a portion of the complete genetic code. Until recently, it has always been assumed that each nucleus contains at least a complete set of chromosomes, and thus the “one nucleus, one full genome” rule.

However, our research has revealed that in two species of fungi, their genomes can be split across multiple nuclei, with each nucleus receiving only part of the total chromosomes.

A surprising discovery

Our laboratory at the University of British Columbia studies the fungus Sclerotinia sclerotiorum, which is a soil-borne pathogen causing stem rot or white mold in various crop plants, including canola, soybean and sunflower.

Despite its impact on cash crops, S. sclerotiorum‘s genetics and cell biology are not well understood.

While trying to better understand the biology of this fungus, our laboratory made a startling discovery about the organization of S. sclerotiorum’s 16 chromosomes during cell division and reproduction.

Most eukaryotic cells are diploid, meaning the nucleus contains two copies of each different chromosome. In many fungi, such as baker’s yeast, reproduction begins with a parent diploid cell dividing to form haploid spore cells with one nucleus housing one copy of each chromosome.

However, S. sclerotiorum spores, known as ascospores, each contain two separate nuclei. Previously, it was assumed that each nucleus was haploid, containing the full suite of 16 chromosomes. This would mean that each ascospore contains a total of 32 chromosomes, similar to a diploid cell.

Using fluorescent microscopy, we were able to directly count the number of chromosomes present in a single ascospore. Remarkably, we consistently observed only 16 chromosomes per ascospore, in conflict with the 32 predicted by the current “one nucleus, one full genome” theory.

Additionally, we used fluorescent probes to label specific chromosomes, and found that the two nuclei in an ascospore contain distinct chromosomes. Ascospores contain one set of 16 chromosomes divided across two nuclei, rather than each nucleus containing a complete set of chromosomes.

An irregular manner

The next question we asked was whether the 16 chromosomes are randomly assorted between the two nuclei, or whether this genomic division follows a regular pattern.

To answer this, we separated individual nuclei and determined which chromosomes were present through polymerase chain reaction (PCR) analysis. We found that chromosome composition varies among nuclei, suggesting the division of chromosomes between nuclei is in an irregular manner.

Intrigued, we sought to investigate whether similar phenomenon occurs in other fungi. Botrytis cinerea is another species of plant pathogenic fungi in the same family as S. sclerotiorum.

B. cinerea produces conidial spores typically with four to six nuclei, rather than the two regularly observed in ascospores of S. sclerotiorum. Using similar methods, we found that the 18 chromosomes in the B. cinerea genome are similarly split across nuclei, with each nucleus generally carrying three to eight chromosomes.

This observation showed that haploid genome “splitting” across nuclei occurs in multiple plant pathogenic fungi. However, whether this phenomenon is wider spread across fungal families, or even other eukaryotes, requires further study.

An unknown mechanism

The observation that the S. sclerotiorum and B. cinerea haploid genomes are divided across nuclei raises questions about how this separation plays a role in the rest of the fungal life cycle.

In order to produce the next generation, these fungi need to reform a diploid cell with the full suite of chromosomes, from which new ascospores can be produced. Presumably, this requires the fusion of nuclei with complementary chromosomes to reunite the genome. So how do these fungi ensure that the correct nuclei fuse?

Perhaps the simplest explanation would be one of viability selection: nuclei may fuse randomly, but only those with a complete genome would produce viable ascospores. This seems inefficient, and a more attractive scenario would involve some structure or mechanism to keep complementary nuclei together after the initial division, allowing them to easily reassemble later in the fungal life cycle.

We hope our future work will provide answers to these fascinating questions, and help broaden our understanding of the fundamental dynamics of nuclei and their genomes. This improved understanding will enable dramatic revolutions in gene editing, allowing researchers to manipulate chromosomes and nuclei at will.

In a rocky outcrop on Mount Carmel, in what is now Israel, a group of ancient humans buried their dead about 140,000 years ago. Scientists uncovered the site, called Skhul Cave, in 1928, and about three years later they found the remains of more than a dozen individuals.

The site is one of the oldest examples of burial practices among ancient humans, but researchers were puzzled by the excavated hominins’ anatomy. Some of their skeletal features resembled those of Homo sapiens, while others were more Neanderthal-like, making the species difficult to classify.

The first skeleton discovered at the Skhul burial site belonged to a child between 3 and 5 years old, most likely a girl. Using high-resolution scans of the child’s cranium and jaw, scientists now propose that the individual possessed anatomical traits of both Homo neanderthalensis and Homo sapiens. If that finding is the case, the skull — and other remains at Skhul Cave — represents the earliest known example of interbreeding between Neanderthals and our own species, researchers reported in the July-August issue of the journal L’Anthropologie.

Earlier analysis of DNA in the modern human and Neanderthal genomes suggested that the two species interbred between 50,500 and 43,500 years ago. The new findings could push back this genetic mingling by nearly 100,000 years, said senior study author Dr. Israel Hershkovitz, a professor in the Gray Faculty of Medical and Health Sciences at Tel Aviv University.

They also indicate an extended period of peaceful coexistence between modern humans and Neanderthals in the Levant, a region bordering the eastern Mediterranean Sea, Hershkovitz told CNN.

“What we bring to the story of human evolution is not a short overlap with our relatives, the Neanderthals, but a very long overlap in time and space,” Hershkovitz said. “You would think that those are two Homo groups that are considered to be competing populations. Suddenly, you see that they managed to live together side by side.”

This interpretation of Neanderthal-Homo sapiens hybridization requires caution, however, as anatomical features can be more ambiguous than genetic data, and factors such as an individual’s life history can affect the expression of anatomical traits, said William Harcourt-Smith, a resident research associate at the American Museum of Natural History in New York City and an adjunct professor at the museum’s Richard Gilder Graduate School.

The young age of the individual in the study must also be considered, as childhood growth can affect anatomical variations, added Harcourt-Smith, who was not involved in the new research.

“Most species comparison studies tend to focus on adult individuals only, to minimize this problem,” he said. Scientists therefore need to be careful when using only skeletal data as proof that a fossil represents a hybrid species.

Certain features can also be retained from ancestors and do not necessarily represent hybridization, said Dr. Zeresenay Alemseged, a Donald N. Pritzker Professor in the University of Chicago’s department of organismal biology and anatomy who was also not involved in the new study. Still, this hypothesis that the child’s ancestry included interbreeding “is not farfetched,” Alemseged, who was not involved in the new research, told CNN in an email.

“Previous DNA studies show that the two (species) interbred, and fossil evidence shows that they geographically overlapped in the Levant before 100,000 years ago, when H. sapiens first attempted to leave Africa,” he added. “But the ultimate arbiter is DNA or another biochemical marker.”

Mingling and interbreeding

Modern humans and Neanderthals share an ancestor that originated in Africa, but the two lineages diverged at least 500,000 years ago. The first Neanderthals appeared in Asia and Europe about 400,000 years ago, while H. sapiens evolved in Africa about 300,000 years ago and later migrated to the Asian and European continents.

Outside Africa, populations of Neanderthals and H. sapiens mingled and interbred until Neanderthals went extinct about 40,000 years ago. Today, the genomes of most modern humans whose ancestors migrated to Europe and Asia contain about 1% to 4% of Neanderthal DNA.

When scientists discovered the Skhul fossils nearly a century ago, they suggested that hybridization between the two species could explain the hominins’ unusual anatomy. Tools available at the time were unable to investigate the bones at high resolution, of course.

In the new study, however, researchers from France and Israel used micro-CT scans to capture images of structures of the Skhul child’s skull and jaw in unprecedented detail and then digitally modeled the bones in 3D.

In its overall shape, especially in the curve of the skull vault around the brain, the cranium looked like a H. sapiens skull. But the structure of the bony labyrinth — a rigid area surrounding the inner ear, too small to see except with micro-CT — was a closer match to the anatomy of Neanderthals. The shape of the lower jaw, the inner structure of the teeth and the underdeveloped blood vessel network inside the skull were also more Neanderthal-like.

Skeletons of seven adults and three children who were intentionally buried, as well as isolated bones from 16 other individuals, have been uncovered in the Skhul Cave. Of the 10 burials, each person possessed a different combination of H. sapiens and Neanderthal traits, Hershkovitz said. While the skull of the first child discovered was the only Skhul fossil examined for the study, “all of them manifest what we call ‘mosaic morphology,’ in the sense that they have both Neanderthal and Homo sapiens features.”

The burials at Skhul also call for a reevaluation of the development of culture in early humans, Hershkovitz said. By designating the rocky outcrop as a cemetery, the people who buried their dead there were demonstrating territoriality, a type of social behavior typically associated with the start of agriculture nearly 12,000 years ago.

“And here we see that 140,000 years ago, people were already some kind of territorial group,” Hershkovitz said. “We have to go back and redo our studies of human behavior, not just biology.”

Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine. She is the author of “Rise of the Zombie Bugs: The Surprising Science of Parasitic Mind-Control” (Hopkins Press).

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.

For more CNN news and newsletters create an account at CNN.com

Aug. 28 (UPI) — Ecologists saw nocturnal spiders attracting prey with their web by using fireflies as bait, according to a new study.

Tunghai University researchers observed Psechrus Clavis a sheet web spider capturing fireflies using their bioluminescent light to catch prey. The spiders also went back from time to time to check on the captured fireflies.

Researchers set up a test using LED lights resembling fireflies to see if the newly found strategy increased spider hunting success.

The findings published in the Journal of Animal Ecology have found that three times the amount of prey was attracted to webs with LED webs and the LED webs grabbed 10 times more fireflies than the non-LED webs.

“Our findings highlight a previously undocumented interaction where firefly signals, intended for sexual communication, are also beneficial to spiders. This study sheds new light on the ways that nocturnal sit-and-wait predators can rise to the challenges of attracting prey and provides a unique perspective on the complexity of predator-prey interactions,” said Dr. I-Min Tso, the lead author of the study.

The researchers think the spiders have developed their own bioluminescence as sheet web spiders normally wait for prey in the dark.

“Handling prey in different ways suggests that the spider can use some kind of cue to distinguish between the prey species they capture and determine an appropriate response,” Tso said. “We speculate that it is probably the bioluminescent signals of the fireflies that are used to identify fireflies enabling spiders to adjust their prey handling behavior accordingly.”

As SpaceX’s Starship vehicle gathered all of the attention this week, the company’s workhorse Falcon 9 rocket continued to hit some impressive milestones.

Both occurred during relatively anonymous launches of the company’s Starlink satellites but are nonetheless notable because they underscore the value of first-stage reuse, which SpaceX has pioneered over the last decade.

The first milestone occurred on Wednesday morning with the launch of the Starlink 10-56 mission from Cape Canaveral, Florida. The first stage that launched these satellites, Booster 1096, was making its second launch and successfully landed on the Just Read the Instructions drone ship. Strikingly, this was the 400th time SpaceX has executed a drone ship landing.

Then, less than 24 hours later, another Falcon 9 rocket launched the Starlink 10-11 mission from a nearby launch pad at Kennedy Space Center. This first stage, Booster 1067, subsequently returned and landed on another drone ship, A Shortfall of Gravitas.

This is a special booster, having made its debut in June 2021 and launching a wide variety of missions, including two Crew Dragon vehicles to the International Space Station and some Galileo satellites for the European Union. On Thursday, the rocket made its 30th flight, the first time a Falcon 9 booster has hit that level of experience.

A decade in the making

These milestones came about one decade after SpaceX began to have some success with first-stage reuse.

The company first made a controlled entry of the Falcon 9 rocket’s first stage in September 2013, during the first flight of version 1.1 of the vehicle. This proved the viability of the concept of supersonic retropropulsion, which was, until that time, just theoretical.

This involves igniting the rocket’s nine Merlin engines while the vehicle is traveling faster than the speed of sound through the upper atmosphere, with external temperatures exceeding 1,000 degrees Fahrenheit. Due to the blunt force of this reentry, the engines in the outer ring of the rocket wanted to get splayed out, the company’s chief of propulsion at the time, Tom Mueller, told me for the book Reentry. Success on the first try seemed improbable.

He recalled watching this launch from Vandenberg Space Force Base in California and observing reentry as a camera aboard SpaceX founder Elon Musk’s private jet tracked the rocket. The first stage made it all the way down, intact.

Scientists discovered that communities of microbes living beneath the seafloor are able to survive in rock sediments for over 100 million years with desperately little nutrients. After being coaxed under the right conditions in a lab, the ancient microbes are even able to snap out of their “hibernation” to metabolize and multiply once again.

Reported in the journal Nature Communications back in July 2020, researchers from Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and the University of Rhode Island got their hands on these microbes by gathering sediment samples from 75 meters (246 feet) below the seafloor in the South Pacific Ocean, nearly 5,700 meters (18,700 feet) below sea level. 

The microbial life was capable of being revived through finely tuned techniques in a laboratory. Incubated with isotope-labeled carbon and nitrogen-laced nutrients, within 10 weeks the isotopes showed up in the microbes, demonstrating they were in a metabolically active state, even capable of feeding and dividing.

“These are the oldest microbes revived from a marine environment,” Steven D’Hondt, study author and Professor of Oceanography at the University of Rhode Island, told IFLScience in 2020.

“Even after 100 million years of starvation, some microbes can grow, reproduce, and engage in a wide variety of metabolic activities when they’re returned to the surface world,” he added.

The microbe communities became trapped beneath the seafloor long ago after being buried by layers of sediment made up of “marine snow,” debris, dust, and other particles. This layer of sediment from the study was deposited over a period from 13 to 101.5 million years ago. 

If the sediment is formed under the right circumstances, oxygen is still just about able to penetrate to these depths, but little else can migrate, suggesting the microbial communities have stayed put for all these years. While the layer does contain oxygen, it has very limited amounts of organic material, such as carbon, and is an unbelievably harsh environment for life. 

In the incubated lab conditions, some of the microbes responded rapidly, increasing in number by more than four orders of magnitude over the 68 days of incubation. Even in the oldest 101.5-million-year-old sediment, they observed the microbes uptaking the isotopes and increasing in cell numbers.

Most of the microbes appear to be aerobic bacteria, meaning they are microbes that need oxygen to survive and grow. Given the scarcity of nutrients that far down, it’s likely these microbes have slowed down their “body clocks” to live an extremely sluggish life, complete with a slow metabolism and very slow evolutionary speed. 

“We believe the community has remained there for 100 million years, with an unknown number of generations. Since the calculated energy flux for subseafloor sedimentary microbes is barely sufficient for molecular repair, the number of generations could be inconceivably low,” Professor D’Hondt explained to IFLScience.

It was once assumed that life could only survive just a few meters beneath the seabed, namely near continental edges where lots of organic matter can be found. However, as this study affirms, researchers are now showing that life beneath the seafloor is much more diverse and fascinating than previously realized. In a separate study published in March 2020, scientists even discovered microbial communities living some 750 meters (2,500 feet) beneath the seabed.

An earlier version of this article was published in July 2020.

Amino acids are the building blocks of proteins, the “workhorses” of life essential to nearly every living process. But proteins cannot replicate or produce themselves — they require instructions. These instructions are provided by RNA, a close chemical cousin of DNA (deoxyribonucleic acid).

In a new study, published in Nature, researchers chemically linked life’s amino acids to RNA in conditions that could have occurred on the early Earth — an achievement that has eluded scientists since the early 1970s.

Senior author Professor Matthew Powner, based at UCL’s Department of Chemistry, said: “Life relies on the ability to synthesize proteins — they are life’s key functional molecules. Understanding the origin of protein synthesis is fundamental to understanding where life came from.

“Our study is a big step towards this goal, showing how RNA might have first come to control protein synthesis.

“Life today uses an immensely complex molecular machine, the ribosome, to synthesize proteins. This machine requires chemical instructions written in messenger RNA, which carries a gene’s sequence from a cell’s DNA to the ribosome. The ribosome then, like a factory assembly line, reads this RNA and links together amino acids, one by one, to create a protein.

“We have achieved the first part of that complex process, using very simple chemistry in water at neutral pH to link amino acids to RNA. The chemistry is spontaneous, selective and could have occurred on the early Earth.”

Previous attempts to attach amino acids to RNA used highly reactive molecules, but these broke down in water and caused the amino acids to react with each other, rather than become linked to RNA.

For the new study, the researchers took inspiration from biology, using a gentler method to convert life’s amino acids into a reactive form. This activation involved a thioester, a high-energy chemical compound important in many of life’s biochemical processes and that has already been theorized to play a role at the start of life*.

Professor Powner said: “Our study unites two prominent origin of life theories — the ‘RNA world’, where self-replicating RNA is proposed to be fundamental, and the ‘thioester world’, in which thioesters are seen as the energy source for the earliest forms of life.”

In order to form these thioesters, the amino acids react with a sulfur-bearing compound called pantetheine. Last year, the same team published a paper demonstrating pantetheine can be synthesized under early Earth-like conditions, suggesting it was likely to play a role in starting life.

The next step, the researchers said, was to establish how RNA sequences could bind preferentially to specific amino acids, so that RNA could begin to code instructions for protein synthesis — the origin of the genetic code.

“There are numerous problems to overcome before we can fully elucidate the origin of life, but the most challenging and exciting remains the origins of protein synthesis,” said Professor Powner.

Lead author Dr Jyoti Singh, from UCL Chemistry, said: “Imagine the day that chemists might take simple, small molecules, consisting of carbon, nitrogen, hydrogen, oxygen, and sulfur atoms, and from these LEGO pieces form molecules capable of self-replication. This would be a monumental step towards solving the question of life’s origin.

“Our study brings us closer to that goal by demonstrating how two primordial chemical LEGO pieces (activated amino acids and RNA) could have built peptides**, short chains of amino acids that are essential to life.

“What is particularly groundbreaking is that the activated amino acid used in this study is a thioester, a type of molecule made from Coenzyme A, a chemical found in all living cells. This discovery could potentially link metabolism, the genetic code and protein building.”

While the paper focuses solely on the chemistry, the research team said that the reactions they demonstrated could plausibly have taken place in pools or lakes of water on the early Earth (but not likely in the oceans as the concentrations of the chemicals would likely be too diluted).

The reactions are too small to see with a visible-light microscope and were tracked using a range of techniques that are used to probe the structure of molecules, including several types of magnetic resonance imaging (which shows how the atoms are arranged) and mass spectrometry (which shows the size of molecules).

Notes

*The Nobel laureate Christian de Duve proposed that life began with a “thioester world” — a metabolism-first theory that envisages life was started by chemical reactions powered by the energy in thioesters.

** Peptides typically consist of two to 50 amino acids, while proteins are larger, often containing hundreds or even thousands of amino acids, and are folded into a 3D shape. As part of their study, the research team showed how, once the amino acids were loaded on to the RNA, they could synthesize with other amino acids to form peptides.

The work was funded by the Engineering and Physical Sciences Research Council (EPSRC), the Simons Foundation and the Royal Society.

Researchers at McGill University report a simple way to steer the behavior of engineered living materials during formation. In a new paper, the team shows that gently vibrating cell-rich gels as they set can make the final material stronger or softer on demand.

The idea could help in emergency bleeding control, wound care, and future tissue implants. It also opens a practical route to tune materials without changing their chemistry or harming nearby tissue.

Testing vibrations on blood clots

The work was led by Aram Bahmani, a postdoctoral fellow at Yale University who completed this research in McGill University’s Department of Mechanical Engineering (MU). The team used a speaker-driven platform to apply controlled vibration while blood-based and other cell-laden gels solidified.

They tested the approach across several soft materials that clinicians and engineers already know. That list included whole-blood clots, plasma gels with added fibroblasts, and gels based on alginate, a common hydrogel used in wound dressings and tissue engineering.

Vibration settings mattered. Different combinations of amplitude and frequency subtly reorganized how cells sat in 3D space inside the forming gel, shifting them from clustered patterns to more dispersed arrangements.

The group then measured stiffness and fracture toughness to see how those micro-scale changes played out at the macro scale.

They also imaged fibrin fibers, tracked clot contraction, and ran a rat liver puncture model to check that the method worked inside a living body.

Gentle shaking, big changes

Earlier attempts to mold living tissues relied on magnets, acoustic fields, or ultrasound. These tools can be powerful, but at certain settings ultrasound can cause cavitation or heating that damages tissue.

The McGill method avoids those pitfalls by using mild mechanical agitation rather than intense energy. It gives researchers a dial to turn without adding chemicals or embedding foreign particles.

Cell placement shapes the material’s internal scaffold. That change spreads from cell placement to the fibrin network that bears load.

When cells clump, they leave larger pores and create weaker paths for cracks to grow. When cells stay dispersed, fibrin fibers build a denser, shorter linkage network that resists deformation and slows enzymatic breakdown.

Vibration changes clots

A blood clot that seals a wound must be tough enough to resist tearing. Clots that break can shed pieces that travel downstream, a risk highlighted by work from back in 2020.

The McGill team reports that certain vibration settings produced stiffer, tougher clots, while others made clots softer and easier to break down.

Those outcomes tracked with how cells organized and how the fibrin network took shape, not with any change in chemistry.

“Mechanical nudging allows us to make the material up to four times stronger or weaker, depending on what we need it to do,” said Bahmani. That flexibility points toward tailored materials for very different clinical jobs.

The in vivo tests echoed the lab data. In the rat liver model, optimized settings produced clots that were measurably stiffer than untreated controls, without hurting nearby tissue.

Applications in medicine

Emergency medicine often needs fast, firm sealing of bleeding surfaces. On the other hand, certain cases call for clots that break down more readily so that flow is restored, as when doctors use clot-busting therapy to treat an ischemic stroke.

This vibration method could one day be integrated into dressings or surgical tools that tune clot properties at the bedside.

It might also assist tissue engineers who need scaffold gels with specific stiffness profiles for different cell types.

“What makes this especially exciting is that our method is non-invasive, low-cost and easy to implement,” said Bahmani. The approach uses equipment that is widely available, which lowers the barrier to adoption outside specialized labs.

Beyond blood, the same concept worked in cell-laden gels that matter for regeneration. It also worked in materials built on alginate, suggesting a path to tune constructs in wound care and soft-tissue repair without exotic reagents.

Limits and next steps

Translating a benchtop platform to clinical tools takes careful engineering. Devices must be miniaturized, made portable, and calibrated so that settings match different tissues and clinical scenarios.

The animal results support safety at the tested settings, but human studies will need to confirm tissue tolerance and long-term outcomes.

Teams will also need to establish how vibration interacts with drugs that change clotting, such as anticoagulants or fibrinolytics.

Irregular wounds present another challenge because geometry and motion can vary from patient to patient. Real-world tools will likely need built-in feedback so that the delivered vibrations stay in a safe, effective window.

Finally, biology is not one-size-fits-all. What helps in hemostasis might hinder fibrinolysis, so clinicians will need clear guidance on when to stiffen a clot and when to soften it, and how to time those adjustments relative to other treatments.

The study is published in Advanced Functional Materials.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–

Images and video of woven structure experiments

Newswise — Drawing on the prehistoric art of basketweaving, engineers at the University of Michigan found that woven materials return to their original shape after repeated cycles of strong compression, while continuous sheets of the same material permanently deform. 

The modular platform to assemble woven corners presented in Physical Review Research could be used in any application where both resilience and stiffness are essential including soft robotics, car parts and architectural components.

After lead author Guowei (Wayne) Tu, U-M doctoral student of civil and environmental engineering, came across an article that dated woven baskets to around 7500 BCE, the researchers wondered if the ancient craft persists today for reasons beyond geometry and aesthetics.

“We knew weaving is an effective way of creating 3D shapes from ribbons like reed and bark, but we suspected there must also be underlying mechanical advantages,” said Evgueni Filipov, U-M associate professor of civil and environmental engineering and mechanical engineering and corresponding author of the study. 

The study, supported by the U.S. Air Force Office of Scientific Research, unearthed those mechanical advantages: high stiffness for load-bearing and resilience for long-term use. 

“I’m very excited about harnessing the benefits of ancient basket weaving for modern 21st century engineering applications,” Filipov said. “For instance, lightweight woven materials for robotics would also help humans stay safer in case of human-robot collisions.”

To test mechanical properties, the research team assembled structures by weaving together Mylar polyester ribbons, about the width of a pinky finger and the thickness of two sheets of copy paper, arranged perpendicularly to one another. They formed this 2D weave into a 3D metamaterial—meaning a synthetic composite material with a structure that creates physical properties not found in natural materials.

“While modern metamaterials are often designed for electromagnetic, optical or acoustic properties, people have been making mechanical metamaterials through weaving and other structural approaches for millenia,” Tu said.

The structures used four different corner arrangements that brought together three, four, five and six planes. For comparison, the team assembled the same structures with continuous, unwoven Mylar. They then tested both types by progressively crushing them.

One pair of rectangular boxes standing 17 centimeters tall, returned to their original shape after being compressed by one centimeter. When compressed more, the continuous structure was permanently damaged while the woven structure was unchanged even after being compressed by 14 centimeters, to less than 20% of its original height.

High resolution 3D scans identified points on the continuous structure where concentrated stress caused the material to buckle and deform. The woven structure instead redistributes the stress across a wider area, preventing permanent damage.

Next, the research team investigated stiffness, measured by how much force is needed to compress structures from the top or bend them with a push on the side. They tested all four corner structures against continuous structures of the same Myler polyester. Across all experiments, woven materials were 70% as stiff as their continuous counterparts—disproving the misconception that woven systems are inherently flexible. 

When testing more complex configurations, an L-shaped structure meant to resemble a robot arm supported 80 times its weight vertically—like holding a heavy bag at waist-level—and easily flexed upward, as a human arm would. A woven robot prototype with four legs that the researchers refer to as a dog held 25 times its weight and could still move its legs to walk. When overloaded, the woven dog robot returned to its original shape, able to hold the same weight again. 

“With these few fundamental corner-shaped modules, we can design and easily fabricate woven surfaces and structural systems that have complex spatial geometries and are both stiff and resilient,” Tu said. “There is just so much more potential for how we could use these corner-based woven structures for future engineering design.”

As one such application, the researchers designed a concept for a woven exoskeleton that adapts stiffness for different parts of the human body—allowing movement while providing reusable shock absorption.

“Going forward, we want to integrate active electronic materials into these woven structures so they can be ‘smart’ systems that can sense the external environment and morph their shapes in response to different application scenarios,” Filipov said.

The research was funded in part by the U.S. Air Force Office of Scientific Research (FA9550-22-1-0321).

Study: Corner topology makes woven baskets into stiff, yet resilient metamaterials (DOI: 10.1103/9srl-9gsc)