Category: 7. Science

A glowing hand stretches across the cosmos, with its palm and fingers sculpted from the wreckage of a massive stellar explosion.

The eerie structure is part of the nebula MSH 15-52, powered by pulsar B1509-58 — a rapidly spinning neutron star that is only about 12 miles (20 kilometers) in diameter. By combining radio data from the Australia Telescope Compact Array (ATCA) with X-rays from NASA’s Chandra X-ray Observatory, astronomers created a new view of the nebula, which spans over 150 light-years and resembles a human hand reaching toward the remains of the supernova — formally known as RCW 89 — that formed the pulsar at the heart of the image.

“MSH 15–52 and RCW 89 show many unique features not found in other young sources,” according to a statement from the Chandra X-ray Observatory, releasing the new composite image. “There are, however, still many open questions regarding the formation and evolution of these structures.”

The central object, pulsar B1509-58, formed when a massive star ran out of fuel and collapsed before exploding as a supernova. The pulsar spins nearly seven times per second and has a magnetic field some 15 trillion times stronger than Earth’s. Despite its small size, it acts like a cosmic dynamo, accelerating particles to extreme energies and driving winds that carve the nebula into its hand-like form.

Researchers in McGill’s Department of Mechanical Engineering have discovered a safe and low-cost method of engineering living materials such as tissues, organs and blood clots. By simply vibrating these materials as they form, scientists can dramatically influence how strong or, weak they become.

The findings, published in the journal Advanced Functional Materials, could have a range of innovative applications, including in organ transplants, wound healing and regenerative medicine.

Good vibrations

The researchers used a speaker to apply controlled vibration, gently agitating the living materials during formation. By doing so, they found they could influence how cells organized and how strong or weak the final material became.

The technique works across a range of soft cellular materials, including blood clots made from real blood and other human tissues.

Aram Bahmani, study co-author and Yale postdoctoral fellow, conducted the research at McGill as a PhD student with Associate Professor Jianyu Li’s Biomaterials Engineering lab. Bahmani explained that strong, fast-forming blood clots are vital for use in emergencies like traumatic injuries. They’re also useful for people with clotting disorders.

“On the other hand, the same approach could help design clots that break down more easily as necessary, helping to prevent dangerous conditions like stroke or deep vein thrombosis,” he added. “Mechanical nudging allows us to make the material up to four times stronger or weaker, depending on what we need it to do.”

Why previous methods fell short

Earlier approaches to shaping living tissues relied on physical forces like magnets or ultrasound waves. While promising, these methods often fail to replicate the complexity of real tissues, which contain billions of cells and have thick, three-dimensional structures. In addition, they are often limited to specific materials, can damage healthy tissues and sometimes trigger immune responses.

The researchers’ study is the first to show that mechanical agitation, a very simple and widely accessible tool, can control the inner structure and performance of living materials in a “safe, scalable and highly tunable way.”

From the lab bench to living systems

To validate their findings, the team ran a series of tests to measure how vibration affected various cell-laden materials such as blood-based gels, plasma and seaweed-derived alginate. Using imaging and mechanical analysis, they assessed how broadly the method could be applied. Next, they tested the technique in animals.

The results showed that the technique works when applied inside the body, without harming surrounding healthy tissues.

Toward advanced medical technology

Bahmani said he believes the simple method could one day be integrated into advanced medical devices or wound-healing techniques.

“What makes this especially exciting is that our method is non-invasive, low-cost and easy to implement,” he said. “It does not rely on expensive machines or complex chemicals, meaning it could one day be built into portable medical devices, like a hand-held tool to stop bleeding, or a smart bandage that speeds up healing.”

He noted that the method requires further testing, such as in irregular wounds or in combination with certain medications, before it can be used in real-life medical settings.

“Moving toward clinical use will require miniaturizing the devices, optimizing settings for different medical scenarios and completing regulatory testing to ensure safety and effectiveness in humans,” he said.

About this study

“Engineering Highly Cellularized Living Materials via Mechanical Agitation” by Aram Bahmani, Jianyu Li et al was published in Advanced Functional Materials.

The research was funded by the Canadian Institutes of Health Research, the NSERC/FRQNT NOVA Program, the Fonds de Recherche du Québec-Nature et Technologies Doctoral Scholarship, the Canada Research Chairs Program, the Centre de Recherche sur les Systèmes Polymères et Composites à Haute Performance and the McGill Faculty of Engineering.

Likun Zhang, senior scientist at the National Center for Physical Acoustics and associate professor in the Department of Physics and Astronomy, led a research team studying how liquid waves move through barriers in low-gravity environments. Their results were published in Physical Review Letters.  

“In low-gravity cases like the space station, surface tension dominates everything,” said Zhengwu Wang, a fourth-year Ole Miss doctoral student in physics and co-author of the study. “The curvature of the water – the meniscus – is going to appear around structures, and we wanted to know how that meniscus would affect how waves move across barriers.” 

When water meets a partially submerged barrier – think of a leaf on a pond – the surface tension of the liquid causes the liquid to curve upward where it meets the barrier; in this case, the leaf. Zhang and Wang’s research shows that this curve, called the meniscus, can be manipulated to reduce or increase the amount of energy that passes through that barrier.  

If the meniscus’ curve is slight, more energy passes through. But as the meniscus curves more steeply, it reduces the energy conveyed by the fluid.  

“Our common sense tells us a barrier should block waves, but here we found certain meniscus shapes can make waves pass through more easily,” Zhang said. “Only a tiny, 1.5-millimeter change in the meniscus shape caused the transmission to drop from about 60% to just a few percent. Tiny meniscus, huge impact.” 

Space travelers use liquids for all manner of applications: from fuel and water-recycling systems to life support and cooling systems. Being able to better control the fluid in these systems can make them more efficient and lighter – a key for space travel. 

“These are really tiny effects in daily life, but they can have a huge impact in microgravity environments,” Wang said.  

To conduct the experiment, the researchers simulated low gravity by generating small, frequent surface waves. Then, they placed a partial barrier in the path of those waves and used acoustics to measure the meniscus’ movement.  

By changing the barrier’s height and using a surface coating to make it water-attracting or water-repelling, the researchers controlled the meniscus – and how much energy passed through the barrier.  

“As physicists, we are looking at very fundamental problems: the like problem of wave dynamics and barriers,“ Zhang said. “But being able to control fluid behavior in low gravity is crucial – whether you‘re talking about water recycling systems or fuel tanks – because you can‘t rely on gravity to separate liquids and gases.“ 

The applications could prove useful in earthbound manufacturing and biomedical engineering, too, where microfluidic devices move fluids through channels just millimeters wide, Zhang said. These devices range from printers to DNA chips to lab-on-a-chip technology.  

“This is the first experiment studying this behavior in fluid, but it opens the door to new phenomena and new physics,” he said. “This work is valuable because it shows a new way to control fluid for the first time.”  

This material is based on work supported by the National Science Foundation grant no. 2306106. 

Researchers in McGill’s Department of Mechanical Engineering have discovered a safe and low-cost method of engineering living materials such as tissues, organs and blood clots. By simply vibrating these materials as they form, scientists can dramatically influence how strong or, weak they become.

The findings, published in the journal Advanced Functional Materials, could have a range of innovative applications, including in organ transplants, wound healing and regenerative medicine.

Good vibrations

The researchers used a speaker to apply controlled vibration, gently agitating the living materials during formation. By doing so, they found they could influence how cells organized and how strong or weak the final material became.

The technique works across a range of soft cellular materials, including blood clots made from real blood and other human tissues.

Aram Bahmani, study co-author and Yale postdoctoral fellow, conducted the research at McGill as a PhD student with Associate Professor Jianyu Li’s Biomaterials Engineering lab. Bahmani explained that strong, fast-forming blood clots are vital for use in emergencies like traumatic injuries. They’re also useful for people with clotting disorders.

“On the other hand, the same approach could help design clots that break down more easily as necessary, helping to prevent dangerous conditions like stroke or deep vein thrombosis,” he added. “Mechanical nudging allows us to make the material up to four times stronger or weaker, depending on what we need it to do.”

Why previous methods fell short

Earlier approaches to shaping living tissues relied on physical forces like magnets or ultrasound waves. While promising, these methods often fail to replicate the complexity of real tissues, which contain billions of cells and have thick, three-dimensional structures. In addition, they are often limited to specific materials, can damage healthy tissues and sometimes trigger immune responses.

The researchers’ study is the first to show that mechanical agitation, a very simple and widely accessible tool, can control the inner structure and performance of living materials in a “safe, scalable and highly tunable way.”

From the lab bench to living systems

To validate their findings, the team ran a series of tests to measure how vibration affected various cell-laden materials such as blood-based gels, plasma and seaweed-derived alginate. Using imaging and mechanical analysis, they assessed how broadly the method could be applied. Next, they tested the technique in animals.

The results showed that the technique works when applied inside the body, without harming surrounding healthy tissues.

Toward advanced medical technology

Bahmani said he believes the simple method could one day be integrated into advanced medical devices or wound-healing techniques.

“What makes this especially exciting is that our method is non-invasive, low-cost and easy to implement,” he said. “It does not rely on expensive machines or complex chemicals, meaning it could one day be built into portable medical devices, like a hand-held tool to stop bleeding, or a smart bandage that speeds up healing.” 

He noted that the method requires further testing, such as in irregular wounds or in combination with certain medications, before it can be used in real-life medical settings.

“Moving toward clinical use will require miniaturizing the devices, optimizing settings for different medical scenarios and completing regulatory testing to ensure safety and effectiveness in humans,” he said.

About this study

“Engineering Highly Cellularized Living Materials via Mechanical Agitation” by Aram Bahmani, Jianyu Li et al was published in Advanced Functional Materials.

The research was funded by the Canadian Institutes of Health Research, the NSERC/FRQNT NOVA Program, the Fonds de Recherche du Québec–Nature et Technologies Doctoral Scholarship, the Canada Research Chairs Program, the Centre de Recherche sur les Systèmes Polymères et Composites à Haute Performance and the McGill Faculty of Engineering.

Presenting their work at the American Geophysical Union’s annual meeting in 2018, the researchers calculated the size of this mysterious treasure trove of life for the first time – and it was a lot bigger than they expected.

They reported that approximately 70 percent of the total number of microbes on the planet live underground. In total, these microbes represent around 15 to 23 billion tonnes of carbon – hundreds of times greater than the carbon mass of all humans on the surface.

Scientists have barely scratched the surface when it comes to describing these microorganisms. However, first glances suggest that the genetic diversity of life below the surface might be comparable to, or perhaps even exceed, life above the surface. This is why nicknamed the ecosystem the “subterranean Galapagos.”

However, don’t expect any giant tortoises down there. Bacteria and their evolutionary cousins – archaea – seem to dominate beneath the surface, although the researchers also noted a fair number of eukarya down there too. For example, researchers described an unidentified nematode over 1.4 kilometers (0.8 miles) deep in a South African gold mine. 

“Ten years ago, we had sampled only a few sites – the kinds of places we’d expect to find life,” Karen Lloyd, study author and Associate Professor of microbiology at the University of Tennessee, said in a statement in 2018.

“Thanks to ultra-deep sampling, we know we can find them pretty much everywhere, albeit the sampling has obviously reached only an infinitesimally tiny part of the deep biosphere,” added Professor Lloyd.

To reach the findings, the team brought together dozens of studies that looked at samples brought up from drilling between 2.5 and 5 kilometers (1.55 to 3.1 miles) into the Earth’s crust, both in the seafloor and the inland continents. Also, to their surprise, they discovered that the subsurface deep biosphere is almost twice the volume of all oceans.

Subjected to intense heat, crushing pressures, no light, and scarcely any nutrients, this is hardly where you would expect to find a diverse bank of life. Nevertheless, the researchers said that this ecosystem could answer many questions about the limits of life on Earth – and beyond.

“Our studies of deep biosphere microbes have produced much new knowledge, but also a realization and far greater appreciation of how much we have yet to learn about subsurface life,” added Rick Colwell, microbial ecologist at Oregon State University.

“For example, scientists do not yet know all the ways in which deep subsurface life affects surface life and vice versa. And, for now, we can only marvel at the nature of the metabolisms that allow life to survive under the extremely impoverished and forbidding conditions for life in deep Earth.”

An earlier version of this article was published in December 2018.