Tag Archives: materials

Scientists zoom in on snake skin to see how they navigate sandy surfaces

Despite having a similar body shape and structure, not all snakes move in the same way. Most, when they move from A to B, slither head-first. But a minority of them (especially desert snakes) do it differently: they slither with their mid-sections first, slithering sideways across the loose sand. Now, researchers know why.

At first glance, you’d think that snakes have a hard time moving around — after all, they have no legs. But here’s the thing: not only do snakes do just fine by slithering, they’re found in almost all environments on Earth, managing to thrive on a variety of surfaces, including sandy environments.

If you’ve ever tried jogging on a beach, you know how hard moving across loose sand is. Now imagine you’re a snake, and your whole body is essentially a sole, how would you even manage moving around?

Researchers have known for a while that snakes in sandy environments tend to move in a different way than others, and they suspected it has something to do with the sand itself. So they set out to investigate it.

“The specialized locomotion of sidewinders evolved independently in different species in different parts of the world, suggesting that sidewinding is a good solution to a problem,” says Jennifer Rieser, assistant professor of physics at Emory University and a first author of the study. “Understanding how and why this example of convergent evolution works may allow us to adapt it for our own needs, such as building robots that can move in challenging environments.”

Rieser’s work joins together biology and soft matter physics (flowable materials, like sand). She studies how animals move around on these surfaces, and how this could help us develop new technologies by adapting what we see in nature (something called biomimicry).

Snakes are particularly interesting because they move in such a peculiar way. Even though snakes “have a relatively simple body plan, they are able to navigate a variety of habitats successfully,” she says. What we’ve learned from snakes has already been applied in several fields. Their long flexible bodies have inspired robots used in surgical procedures or search missions in collapsed buildings, for instance.

The key to the movements of these sidewinder snakes lies in their bellies — in the tiny details of their bellies, to be precise. Rieser and colleagues analyzed three sidewinder snakes (all vipers). They gathered skin the snakes had shed and looked at it with an atomic microscope, zooming in to the atomic level. They also scanned skins shed by non-sidewinders for comparison.

A zoomed-in comparison between holes on a sidewinder snake skin (left) and a non-sidewinder snake skin (right). A mathematical model developed by the researchers shows that the lack of spikes allows sidewinder snakes to move on loose surfaces. Image credits: Tai-De Li.

The regular, non-sidewinder snakes had tiny spikes on their skin, invisible to the human eye. These spikes create friction between the snake and the surface, which acts as a grip allowing them to propel themselves forward headfirst. The sidewinders, however, didn’t have the spikes. Instead, they had tiny holes, because you can’t really create friction or a grip with a surface like sand (that’s also why it’s harder to run on sand than concrete or soil).

“You can think about it like the ridges on corduroy material,” Rieser says. “When you run your fingers along corduroy in the same direction as the ridges there is less friction than when you slide your fingers across the ridges.”

However, some snakes also seemed to have a few spikes, which researchers interpret as a sort of evolutionary “work in progress”. These snakes are younger in their evolutionary history, and haven’t yet had time to fully shed their spikes, the team explains.

“That may explain why the sidewinder rattlesnake still has a few micro spikes left on its belly,” Rieser says. “It has not had as much time to evolve specialized locomotion for a sandy environment as the two African species, that have already lost all of their spikes.”

As for biomimicry, it’s a good lesson: if you want to build a robot that can move on a sand or sand-like surface, you need to pay attention to the texture of its skin.

Journal Reference: Jennifer M. Rieser el al., “Functional consequences of convergently evolved microscopic skin features on snake locomotion,” PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.2018264118

Bioprinting as a matter of the heart

A cross-disciplinary team of scientists at Carnegie Mellon University College of Engineering have just brought an ambitious what-if plan to fruition. The team has created a full-size 3D bio-printed human heart model.

Yes, it is just a model but, but it realistically mimics the elasticity of cardiac tissue and could be useful for medical research.

Image credits: CMU Engineering.

Those behind this model at Carnegie Mellon University (CMU) are Adam Feinberg and his team in the Departments of Biomedical Engineering and Materials Science and Engineering.

They managed to print this artificial heart through special bioprinting with a 3D printer, using custom materials and a technique called FRESH, which stands for Freeform Reversible Embedding of Suspended Hydrogels. Their 3D printer was custom made to hold a gel support bath large enough to print at the desired size and some software changes served to maintain the speed and fidelity of the print.

“FRESH 3D printing uses a needle to inject bioink into a bath of soft hydrogel,” said the school’s news story about the heart model, “which supports the object as it prints. Once finished, a simple application of heat causes the hydrogel to melt away, leaving only the 3D bioprinted object,” the researchers explain.

Jumping the hurdles

The work is a culmination of several years of research. Machine Design talked about what was new and what was not new about the Carnegie Mellon marker: Full-size organ models have been replicated before, using 3D printing techniques, but the materials had a tendency of not being ideal for replicating the “feel” and mechanical properties of natural tissue.

Now, this team was focused on getting the right materials to get the artificial structure to behave just like the real thing. They were aware that soft, tissue-like materials, such as silicone rubbers, often collapsed when 3D printed in air, making it difficult to reproduce large, complex structures.

They used something called alginate, a naturally occurring polymer, as the alginate could mimic the elastic modulus of cardiac tissues. Alginate is a soft, natural polymer, with properties similar to real cardiac tissue. They placed sutures in a piece of alginate to hold even when stretched. This suggested how surgeons could practice procedures on a heart model made from the alginate material.

That is just one potential application. Although hospitals might have facilities for 3D printing models of a patient’s body, the tissues and organs can currently only be modeled in hard plastic or rubber. The Carnegie model would enable manipulation in ways similar to a real heart.

Crticial steps taken

Feinberg is interested in working with surgeons and clinicians to fine-tune the technique and ensure readiness for a hospital setting.

The paper discussing their work has been published in ACS Biomaterials Science and Engineering. Lead author Eman Mirdamadi recognized that major hurdles still exist in bioprinting a full-sized functional human heart, but this is a foundational groundwork—and showing immediate applications for realistic surgical simulation.

Feinberg concludes:

“While we have not yet achieved printing a whole adult-sized functional heart, what we have done is really taken critical steps along that path.”

Scientists look at ways to make cheap, eco-friendly leather alternatives from fungi

These renewable, sustainable materials hold great promise for the future, researchers conclude.

“Fungi-derived leather substitutes are an emerging class of ethically and environmentally responsible fabrics that are increasingly meeting consumer aesthetic and functional expectations and winning favour as an alternative to bovine and synthetic leathers.”

Leather-like products produced from fungal mycelium. Image credits: MycoTech/Bolt Threads/ Jones et al (2020).

Leather is one of the more common materials in the world. It’s used for anything from shoes and jackets to seat coverings — but it’s becoming somewhat less desirable in recent years. Leather, a co-product of meat production, is ethically questionable (as it involves the slaughtering of animals) and it’s bad for the environment: in addition to the deforestation and grazing required for livestock, there’s also the greenhouse gas emissions and the use of hazardous substances in the tanning process.

Meanwhile, traditional alternatives to leather, like polyvinyl chloride (PVC) or polyurethane (PU), are still based on fossil fuels.

“This is where leather-like materials from fungi come into play, which, in general, are CO2 neutral as well as biodegradable at the end of their life span,” says Alexander Bismarck from the Faculty of Chemistry at the University of Vienna.

Bismarck and his colleague Mitchell Jones from the University of Vienna reviewed several studies regarding the production of leather alternatives — specifically, those derived from fungi.

The first advantage of ‘fungi leather’ is that it is at least partially biodegradable. It’s also cheap to grow, making it cost-effective compared to leather. The fungi are basically grown using forestry byproducts such as sawdust, feeding growth for the fungal filaments (called the mycelium).

The literature already contains several studies involving various mushrooms such as the white button mushroom A. bisporus and the bracket fungus D. confragosa. They grow in only a few weeks, and they are then pressed and treated to mimic leather.

“As a result, these sheets of fungal biomass look like leather and exhibit comparable material and tactile properties,” says Alexander Bismarck.

In terms of physical parameters, the resulting material are comparable to leather. Already, several companies working on developing materials derived from fungi, with applications ranging from clothing to construction materials. The researchers also note that woven and felted fabrics are also
sometimes intertwined with mycelium to increase tensile and tear
strength.

The materials are also sustainable since the growth of fungi is effectively carbon neutral since it enables the capture and storage of carbon that would otherwise be emitted to or remain in the atmosphere.

However, there are also challenges, particularly with regard to uniformity. Achieving uniformity is challenging due to the inherent biological variation in fungal growth,

“In addition to being more environmentally sustainable to produce than leather and its synthetic alternatives, as they do not rely on livestock farming or the use of fossil resources, pure fungi-biomass-based leather substitutes are also biodegradable at the end of their service life and cheap to manufacture,” the researchers conclude.

Journal Reference: Nature Sustainability.

Sew face masks out of cotton and chiffon or natural silk to protect against COVID-19

A new study from the University of Chicago reports that a multi-layered mask made from cotton fabric and chiffon or natural silk can be just as effective as N95 masks against the coronavirus.

Image credits Alexandra Gerea.

There just aren’t enough masks to go around, and those that we do have should be earmarked for healthcare workers. How, then, are we to keep ourselves safe in the great (and pandemic) outdoors? Well, according to one new study, we should do like our forefathers before us — and sew!

The authors analyzed the filtration properties of fabrics against aerosols (the main method of transmission for the SARS-CoV-2 coronavirus) and reported on the types of materials to use in order to create an effective mask.

Cotton and chiffon

Although the U.S. Centers for Disease Control and Prevention recommends the use of face masks whenever going outside, the reality on the ground is that such equipment is often in short supply. Surgical masks are somewhat easier to come by, but they are much less effective than filtering masks such as the N95 model (although they’re still useful).

The real problem is that every mask we use is one that’s no longer available for the healthcare sector, and the medical personnel fighting to help the infected against the disease need such masks to be able to continue doing their jobs. So people have started making their own, which is awesome. Researchers are now pitching in, too, and are informing us of the best way, and the best materials, to use when making our masks.

Coronavirus is spread through saliva droplets that form aerosols when we breathe, talk, or cough. The heavier droplets fall to the floor, but the lighter ones remain in suspension around us and can travel (and infect) up to 4 meters away.

The team, led by Molecular Engineering Professor Supratik Guha, used an aerosol mixing chamber to produce particles ranging in diameter from 10 nm to 6 μm in diameter, roughly the same interval of the size seen in coronavirus-carrying aerosols. A fan was used to force them through various textile samples (the fan was set to generate airflow comparable to that of a person’s respiration at rest), and the team compared particle levels in the air before and after passing through the material. The study was carried out at the U.S. Department of Energy’s Center for Nanoscale Materials user facility at Argonne National Laboratory with funding from the U.S. Department of Defense’s Vannevar Bush Fellowship.

Their results show that one layer of “tightly-woven” cotton combined with two layers of polyester-spandex chiffon (a type of sheer fabric most commonly seen in evening gowns — can filter out between 80% to 99% of all aerosol particles in a sample (depending on their size). Such performance, they add, is close to that of an N95 respirator mask.

The chiffon can be swapped for natural silk or flannel without losing filtering ability, or the whole thing can be replaced with a cotton quilt with cotton-polyester batting. The combination of two materials is important, however. The team explains that the cotton creates a physical barrier to incoming aerosol particles, while materials such as chiffon and natural silk can become charged, and serve as an electrostatic barrier.

Another thing to keep in mind is that it’s essential for such masks to be perfectly fitted. Even the slightest gap between the mask’s edges and the user’s skin can reduce their filtering efficiency by 60%.

The paper “Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks” has been published in the journal ACS Nano.

Flash-baking waste could make for stronger concrete and protect the environment

New research at Rice University describes how bulk quantities of carbon-bearing material can be quickly and cheaply turned into graphene flakes. The secret? Intense bursts of heat.

The process in action.
Image credits Credit: Jeff Fitlow / Rice University.

Waste food, plastics, wood, paper, clothes — carbon is everywhere around us. The new technique developed at Rice aims to reduce the environmental impact related to the production of concrete and other building materials by creating a source of cheap graphene to reinforce these materials.

Cook at high temperature

“This is a big deal,” says James Tour, a chemist at Rice and the lead author of the paper. “The world throws out 30% to 40% of all food, because it goes bad, and plastic waste is of worldwide concern. We’ve already proven that any solid carbon-based matter, including mixed plastic waste and rubber tires, can be turned into graphene.”

“With the present commercial price of graphene being $67,000 to $200,000 per ton, the prospects for this process look superb.”

Tour says that the “flash graphene” method they developed can convert bulk material (such as coal, plastic waste, or discarded food) into graphene for a fraction of the cost of other comparable methods. It takes just 10 milliseconds of extreme heat — 3,000 Kelvin, about 5,000 °F or 2,800 °C — to turn the source material into graphene flakes.

The team christened its new method ‘Flash Joule heating’, and explained that it takes much less effort and costs to produce graphene than previous approaches. The whole process takes place in a custom-designed reactor that quickly heats up the material and removes all non-carbon elements like oxygen and nitrogen from the resulting gas. If applied on an industrial scale, these gases can be captured “because they have value,” Tour explains. He adds that the system produces very little waste heat (meaning it’s energy-efficient) despite the fact that “this is almost three times hotter than the furnaces we formerly used to make graphene”.

The whole process yields “turbostratic” graphene, which has misaligned layers that are easy to separate. This makes it much simpler to work with than stacked graphene layers, which are hard to pull apart. The team hopes that their method will be employed to create stronger building materials and help protect the environment.

“By strengthening concrete with graphene, we could use less concrete for building, and it would cost less to manufacture and less to transport,” Tour said. “Essentially, we’re trapping greenhouse gases like carbon dioxide and methane that waste food would have emitted in landfills.”

‘We are converting those carbons into graphene and adding that graphene to concrete, thereby lowering the amount of carbon dioxide generated in concrete manufacture. It’s a win-win environmental scenario using graphene.”

Tour explains that adding as little as 0.1% flash graphene in the cement used to bind concrete could lessen its massive environmental impact by a third. Production of cement reportedly emits as much as 8% of human-made carbon dioxide every year, the team notes.

“Turning trash to treasure is key to the circular economy,” said co-corresponding author Rouzbeh Shahsavari. “Here, graphene acts both as a 2D template and a reinforcing agent that controls cement hydration and subsequent strength development.”

The paper “Gram-scale bottom-up flash graphene synthesis” has been published in the journal Nature.

Oldest material on Earth is stardust found in meteorite

The oldest material known to exist on Earth was just discovered by a group of researchers, working on a meteorite that fell fifty years ago in Australia. The space object, which felt on Earth in the 1960s, had dust grains within that were formed 5 to 7 billion years ago, preceding the formation of the solar system.

Some of the pre-solar grains in the Murchison meteorite (inset) could have come from evolved stars similar to the Egg Nebula (pictured). Credit ESA/Hubble/NASA

Stars have life cycles, born when dust and gas floating through space find each other and then collapse in on each other and heat up. They continue to burn for billions of years until they die, setting off a supernova explosion. When that happens, they create particles known as stardust that are expelled into the universe eventually forming new stars.

Researchers from the Field Museum, the University of Chicago, ETH Zurich and other universities found presolar grains in the meteorite, which are minerals formed before the Sun was born. The stardust was trapped in the meteorites and remained unchanged for billions of years.

Presolar grains are usually hard to find as they are only found in about 5% of the meteorites that have fallen to Earth. The Murchinson meteorite, which fell in Australia in 1969, was filled with them. The study, published in the journal Proceedings of the National Academy of Sciences, now took a closer look at them.

“It starts with crushing fragments of the meteorite down into a powder,” said co-author Jennika Greer, from the Field Museum and the University of Chicago. “Once all the pieces are segregated, it’s a kind of paste, and it has a pungent characteristic – it smells like rotten peanut butter.”

The researchers worked to determine the age of the grains by measuring how long they had been exposed to cosmic rays in space. The rays are high-energy particles that travel through the galaxy and penetrate solid matter.

Some of the grains in the sample were the oldest ever discovered, the study found. Most of them were 4.6 to 4.9 billion years old, and some were even older than 5.5 billion years, something never seen before. For context, the Sun is 4.6 billion years old, and Earth is 4.5 billion.

Lead author Philipp Heck said: “Only 10% of the grains are older than 5.5 billion years, 60% of the grains are “young” (at) 4.6 to 4.9 billion years old, and the rest are in between the oldest and youngest ones. I am sure there are older pre-solar minerals in Murchison and other meteorites, we just haven’t found them yet.”

The findings revive the debate over whether or not new stars are formed at a steady rate or whether there are highs and lows in the number of new starts over time. Also, thanks to the findings, researchers now know that pre-solar grains float through space together in large clusters.

Metallic wood.

Researcher devise ‘metallic wood’ that’s stronger than titanium but could float on water

A team of US researchers has developed a light, but incredibly strong new material — they’re calling it metallic wood. This material, despite being a porous sheet of nickel, is as strong as titanium but four to five times lighter.

Metallic wood.

A microscopic sample of the researchers’ “metallic wood.”
Image credits University of Pennsylvania.

The way atoms stack in a lump of metal determines how strong that metal is — but we can’t (yet) produce such objects. For example, a sample of perfectly-stacked titanium would be ten times as strong as any titanium we can create today. This comes down to random defects that form in the manufacturing process, impacting the metal’s overall properties.  Materials researchers have been trying to exploit this phenomenon by taking an architectural approach, controlling the metal’s nanoscale layout to unlock the mechanical properties that arise at the nanoscale, where defects have reduced impact.

In a new study, researchers at the University of Pennsylvania’s School of Engineering and Applied Science, the University of Illinois at Urbana-Champaign, the Middle East Technical University in Turkey, and the University of Cambridge have designed a new material in which every atom is carefully laid out in its correct place, leading to a surprisingly high strength-to-weight ratio.

Woody metal

“The reason we call it metallic wood is not just its density, which is about that of wood, but its cellular nature,” says lead author James Pikul, Assistant Professor in the Department of Mechanical Engineering and Applied Mechanics at Penn Engineering.

“Cellular materials are porous; if you look at wood grain, that’s what you’re seeing — parts that are thick and dense and made to hold the structure, and parts that are porous and made to support biological functions, like transport to and from cells.”

The team writes that the material’s porous nature and the self-assembly process in which it’s created make it akin to wood and similar natural materials. Their metallic wood is made up of dense, strong metallic struts surrounding empty pores. The design operates “at the length scales where the strength of struts approaches the theoretical maximum,” Pikul explains.

Pikul’s team started with tiny plastic spheres of a few hundred nanometers in diameter, which they suspended in water. As the water slowly evaporated, the spheres stacked onto each other into an orderly, crystalline framework. The spheres were electroplated with nickel, then dissolved — leaving behind a network of metallic struts.

Material production process.

The fabrication process for a unit cell of the material. (b–g) Cross section SEM images of the (nickel inverse opal) material.

Each strut is around 10 nanometers wide, which is roughly the length of 100 nickel atoms, they explain. The team favored this production method over other techniques like 3D-printing as it’s easier to scale up.

“We’ve known that going smaller gets you stronger for some time,” Pikul says, “but people haven’t been able to make these structures with strong materials that are big enough that you’d be able to do something useful. Most examples made from strong materials have been about the size of a small flea, but with our approach, we can make metallic wood samples that are 400 times larger.”

“We’ve made foils of this metallic wood that are on the order of a square centimeter, or about the size of a playing die side,” he adds. “To give you a sense of scale, there are about 1 billion nickel struts in a piece that size.”

Because some 70% of the material is empty space, it has extremely low density in relation to its strength. It’s just a tad less dense than water, meaning a block of this material could float while still being stronger than most metal alloys today.

In a somewhat ironic twist, this process of creating metallic wood (which is metal in a wood-like configuration) is the opposite of how researchers at the University of Maryland created superdense wood (which is wood in a metal-like configuration).

The team is now focusing on expanding the production process to commercially relevant sizes. The materials used aren’t particularly rare or expensive on their own, but the infrastructure needed to carry out the production process is currently very limited. If that infrastructure is developed, however, the team is confident that their metallic wood can be produced more quickly and cheaply than their prototype sample.

A larger production base would also allow the team to further test their creation. Since they’ve only produced a tiny sample in the lab, the team is limited in what macroscale tests it can run on the material.

“We don’t know, for example, whether our metallic wood would dent like metal or shatter like glass.” Pikul says. “Just like the random defects in titanium limit its overall strength, we need to get a better understand of how the defects in the struts of metallic wood influence its overall properties.”

Another exciting possibility is merging the metallic wood with other materials to tailor it to a wide range of applications. Infusing it with anode and cathode materials, for example, would essentially turn the metallic wood into a very solid battery.

“The long-term interesting thing about this work is that we enable a material that has the same strength properties of other super high-strength materials but now it’s 70 percent empty space,” Pikul says.

“And you could one day fill that space with other things, like living organisms or materials that store energy.”

For example, the material could be used to produce smart prosthetics that store their own power — which would be pretty sweet.

The paper “High strength metallic wood from nanostructured nickel inverse opal materials” has been published in the journal Nature.

Smart clothes may be right around the corner, thanks to a new fabrication technique

Two seemingly incompatible worlds have been joined together thanks to a new technique which allows weaving sensors and semiconductors directly into clothes.

Knitted fabric illuminated by embedded light emitting fiber. Pictures taken by Greg Hren. Owner: Michael Rein and Yoel Fink.

Even before humans developed a true society, we were relying on textiles to cover our skin and insulate ourselves from the cold and rain. As technology progressed, we used textiles for a wide variety of purposes, from backpacks to packaging, and, of course, more clothing. Now, textiles might be getting a revamp and might go “smart”.

Everyday objects seem to get smarter and smarter by the day. We now have smartphones, smartwatches, even smart homes. But one commodity which has remained stubbornly non-smart are clothes. It’s not like clothes wouldn’t benefit from this — there’s a wide array of potential applications, from health sensors to cool, changing colors — but the fabrication process has remained cumbersome and difficult to effectively apply. Simply put, electrical circuits and textiles don’t normally mix well.

This is where Michael Rain, Yoel Fink, and colleagues, enter the stage. They started with a larger polymer mass containing the semiconductor devices alongside a hollow channel. This material is heated and drawn out, at the same time as wire is spooled into the channels.

“As the preform is heated and drawn into a fibre, the conducting wires approach the diodes until they make electrical contact, resulting in hundreds of diodes connected in parallel inside a single fibre,” the study authors explain.

Light emitting fibers woven into fabrics.Pictures taken by Greg Hren. Owner: Michael Rein and Yoel Fink.

Diodes (either LEDs or photodetecting diodes) are spaced out and once drawn, the resulting fibers can be easily woven into fabrics. The process is inherently scalable, allowing the creation of hundreds of meters of these smart fibers, thus overcoming one of the main problems associated with this type of process. The manufacturing process also provides a pattern to knit fabrics with even more advanced functions — opening up a whole new area of research for smart textiles of wearable technologies.

In an accompanying News & Views article, Walter Margulis, a guest professor at KTH Royal Institute of Technology with 30 years in photonics, explains an application demonstrated by the study authors.

“As a final application, Rein et al. show that, if a person presses a finger against a light-emitting fibre and a light-detecting fibre that are near each other, the intensity of the light collected by the light-detecting fibre varies according to the person’s heart rate. This physiological application of textiles could be used in primary-care settings.”

Essentially, this paves the way for integrating low-cost electronic components into fabrics. Whether or not this becomes common practice will presumably be controlled by economic rather than scientific factors, Margulis says, but it’s easy to envisage practical applications of this technology.

The study “Diode fibres for fabric-based optical communications” has been published in Nature.

Viral shell.

Boiling-acid-proof virus’ outer shell structure could inspire better medication, sturdier buildings

The shell of a virus which calls boiling acid pools of Yellowstone home could show us the way to more powerful drugs, stronger materials, and more resilient buildings.

Viral shell.

The virus’ unusual envelope structure, never before seen in nature.
Image credits Peter Kasson et al., 2017.

First isolated in 2002 by Pasteur Institute researchers, the virus known as Acidianus hospitalis Filamentous Virus 1 is scaringly hard to kill. This bug lives in the hot-springs of Yellowstone National Park, pools of acid bubbling to temperatures as high as 237 degrees Celsius (455-ish degrees Fahrenheit), which can dissolve people.

Naturally, anything that can live in such conditions is bound to have some pretty impressive tricks up their sleeves — or up their viral casing, as an international team of researchers reports. The finding could open up new avenues of research into material sciences, with applications from pinpoint drug delivery mechanisms to earthquake-resistant buildings.

“Anytime you find something that behaves really differently, especially something this stable, it’s interesting and potentially useful,” says first author Peter M. Kasson, MD, PhD, from the University of Virginia School of Medicine Department of Molecular Physiology and Biological Physics

“When you’re doing curiosity-driven science that finds something new, in the back of your mind, you think, ‘Hey, this is really different. What might it be good for?’ And this has many potential applications.”

Thick-skinned

The secret behind the virus’ extreme resilience lies in its membrane, the team reports. Although it’s outer shell is only half as thick as known cell membranes, it’s ridiculously stable. The molecules which make up the membrane are stacked up in a horseshoe-shaped arrangement, creating a very dense and durable structure.

The team had to rely on the UVA’s Titan Krios electron microscope to probe the virus’ secrets. This device is so sensitive, that it had to be installed underground to insulate it from vibrations — the slightest of which would be enough to throw off its calibrations. Armed with these readings, the team turned to computer modeling to tease out the structure of the membrane’s lipid molecules.

“Essentially, we encode everything we know about the physics of these molecules and then come up with models that are both consistent with the basic physics and consistent with the observations from the electron microscope,” Kasson explains.

Duplicating this structure might help scientists paste the virus’ defenses into other materials. These could have a dramatic impact in construction, material science, every field where a super-resilient material could come in handy.

Nanomedicine stands to benefit a whole lot if we manage to reverse-engineer the virus’ shell. We could use the structures to create microscopic particles to protect drugs from our body’s effort to metabolize them, allowing for pinpoint delivery of more efficient drug doses. For example, injecting drugs directly into tumors.

 

“It’s amazing how much we still don’t know about life as it exists on Earth — at the bottom of the ocean, in the deep sea vents, or places like Yellowstone or Iceland where you have these very strange environments we think of as inhospitable to life,” paper co-author Edward Egelman said.

“But the things that live there, they may look at our environment and think, ‘Strange.'”

The paper “Model for a novel membrane envelope in a filamentous hyperthermophilic virus” has been published in the journal eLife.

Even ubiquitous iron could run short.

We may face a huge shortage of essential raw materials stiffling green energy if governments don’t step up their game

An international team of researchers led by Saleem Ali, Blue and Gold Distinguished Professor of Energy and Environment at the University of Delaware, warns that greater international political and scientific cooperation is needed to secure the resources we’ll need in the future.

Even ubiquitous iron could run short.

Even ubiquitous iron could run short.
Image credits nightowl / Pixabay.

To say that humanity today faces some challenges would be an understatement. Political unrest, climate change, income inequality, drug resistance, they all add up. Still, as a species, we’ve shown a knack for eventually overcoming all the problems that’ve been thrown our way — be them by chance or our own hand. All we need is enough time to think about a solution and enough stuff to put it together and voila! Progress.

But we may be soon running short on the second part, the raw materials, an international team of researchers warns. They say that greater international transparency and a free exchange of geophysical data between countries is needed to secure the future’s supply of raw minerals.

What’s (low) on the menu

The team includes members from the academic, industrial, and government sectors in institutions throughout the U.S., South America, Europe, South Africa, and Australia. They are primarily concerned with future supply of a wide range of technology minerals, which are indispensable in all kinds of industries — from copper wiring in homes or laptop batteries all the way to solar panels and superdense batteries for electric cars. However, they say there’s also cause for concern regarding base metals such as copper or iron ore.

“There are treaties on climate change, biodiversity, migratory species and even waste management of organic chemicals, but there is no international mechanism to govern how mineral supply should be coordinated,” said Ali, who is the paper’s lead author.

They looked at demand records and forecasts, as well as estimates of the sustainability of mineral supplies in the coming decades. They write that current mining operations won’t be able to keep up with the rise in demand, especially considering the fact that “implementation of the Paris Agreement requires technologies that utilize a wide range of minerals in vast quantities.” When push comes to shove, no matter how green our policy and technology gets, if we can’t build it and field it, it won’t do us much good. So we need to up our extraction game.

“Metal recycling and technological change will contribute to sustaining supply, but mining must continue and grow for the foreseeable future to ensure that such minerals remain available to industry,” they conclude.

The materials required for the transition to a low-carbon economy, the stuff that goes into manufacturing clean tech, will be particularly tricky, the researchers say. While base materials are used extensively in current economies –so it’s only a matter of expanding on well-established methods and deposits –traditionally there hasn’t been a wide-scale demand of the more exotic minerals required for clean energy sources, leaving society ill-equipped to meet the extra demand for these materials.

Neodymium is used to make the strongest permanent magnets we know of.

Neodymium is used to make the strongest permanent magnets we know of.
Image credits Brett Jordan / Flickr.

We’ll have to both find suitable deposits and develop more efficient methods of extracting, refining, and handling these elements. Metals like neodymium, terbium, or iridium, although only needed in small quantities, can’t be substituted for anything else in certain clean energy applications and other advanced tech. So while they seem to only make up a tiny part of the overall requirements, they are vital for future applications. A bottleneck in terms of material production for these vital minerals would bottleneck development of the industry and ultimately energy production.

According to the team, the best way to prevent this is to work together. International coordination is needed to determine where to focus future exploration efforts, what areas are likely to be rich or poor in which resources and thus what kind of economic agreements are needed between different countries to make sure that there aren’t any deficiencies anywhere.

Supply and demand

Those of you who think laissez-faire systems are the bee’s knees are probably prickling in horror at the mere thought of international government meddling in the market. But the team points out that the forces which dictate the prices of major commodity minerals don’t (currently) apply to rare earths and other technology minerals.

For example, the largest percentage of exploration investment in a single mineral is in gold, which although highly profitable, is largely used for jewelry. It, along with other major commodity metals such as copper or iron ore are sold on a global market the same way grain or oil is, a market which fluctuates according to supply and demand. But rare earth metals and other technology minerals, however, are sold through individual dealers and prices can vary wildly between them.

Even more, the UN expects global population to reach about 8.5 billion by 2030, which means more demand for these substances in the next decade or so. For your run of the mill goods, take clothes or newspapers, a growth in demand (reflected in a greater price) is swiftly and easily followed by an increase in production. But mineral supply doesn’t follow that same relationship to demand, because of the huge spans of time required to get an exploitation up and running — the horizon for developing a rare earth mineral deposit, from exploration and subsequent discovery to actually mining the thing, is 10 to 15 years, the team says.

Rare earth elements are usually produced as oxides. Clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium, and gadolinium.

Rare earth elements are usually produced as oxides. Clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium, and gadolinium.
Image credits Peggy Greb, US department of agriculture / Wikimedia.

Considering that only about 10% or early exploration efforts result in a mineable deposit, the outlook is even bleaker. Most deposits prospectors find simply aren’t big enough or concentrated enough to be economically viable. Companies can also have a lot of trouble getting exploitation rights or run into zoning problems due to geopolitical factors.

“Countries where minerals are likely to be found may have poor governance, making it higher risk for supply. But production from these countries will be needed to meet global demand. We need to be thinking about this,” Ali said.

The authors also warn that for many of the minerals their paper calls into discussion, there aren’t any substitutes. With so few commercially viable alternatives even for the humble copper wire, it’s simply a matter of produce enough stuff or run short.

Ali and his team hope that the paper will form the foundation of an intergovernmental framework or another similar system which would allow countries to plan and prevent mineral scarcity in the future — as both private and public sectors are dependent on raw materials. They say that quick improvements can be made through expansion of developing organizations, such as the United Nation’s International Resource Panel or the Canadian-led Intergovernmental Panel on Mining Metals and Sustainable Development. Longer-term solutions will need greater international transparency and could include global sharing of geological data and the creation of mechanisms to protect mineral deposit ‘finds’ much like we protect intellectual property.

“It’s about managing the flow of resources from the ground to product to consumer to recycling,” Ali said.

“People have been so concerned about climate change that it’s created a real movement around it. We don’t see this around resource use and recovery, even though it is much closer to us on a daily basis.”

The full paper “Mineral supply for sustainable development requires resource governance” has been published in the journal Nature.

New engineered spider silk material could lead to better wound stitches

Scientists believe they have untangled the method of creating spider silk-like materials. This material could greatly help in controlling bleeding and repairing difficult wounds.

Image in Public Domain, via Pexels.

Spider silk is a protein fibre which spiders use to create webs or other structures, as well as for nests or coccons. Most silks, in particular dragline silk, have exceptional mechanical properties. The material is five times stronger than steel and three times tougher than Kevlar.

“Recently there has been a lot of interest in using spider silk for advanced textiles, but we are mainly interested in medical applications,” said Anna Rising, a researcher at Swedish University of Agricultural Sciences and one of the authors of the study.

The quest to create usable spider silk is not new, but harvesting it directly from the spiders is not really feasible (they get very aggressive and usually start eating or killing one another when housed together).

“Since spiders are territorial and produce small amounts of silk, any industrial application of spider silk requires production of recombinant spidroins and generation of artificial spider silk fibers,” the researchers wrote in a paper published Monday (Jan. 9) in the journal Nature Chemical Biology.

The idea of using such materials in medicine is also not new. There has been some success in stitching animal wounds with spider silk but generally, produced silks were in disappointingly small quantities at low concentrations and required intense processing even after production, to develop the desired properties. The problem lies in the structure. The bigger a protein is, the harder it is to produce – and silk is huge, “often in the range of 3,000 aminoacids,” Daniel Meyer, marketing executive at the biotech company Spiber Inc., told the Wall Street Journal.

This time, the team mimicked the conditions inside the spiders’ silk glands and produced significant quantities of the substance from a mixture of bacteria and bioengineered proteins, all of which are safe for living tissues, because no harmful chemical or additives were incorporated. Just one liter of it can generate a whole kilometer of spider silk.

But even though it looked and behaved similarly to the real deal, the engineered product still had lower toughness and tensile strength than its natural counterpart.

“The as-spun NT2RepCT fibers had a qualitatively similar stress-strain behavior to native spider silk in that they displayed an initial elastic phase up until a yielding point,” after which the silk began to deform, the researchers wrote in the paper.

“One possible way to increase the toughness could be to spin NT2RepCT fibers with diameters closer to that of native dragline silk, as this apparently has an impact on the mechanical properties of silk fibers,” the researchers wrote.

 

Stanford researchers develop the coolest clothes – literally

Stanford engineers have developed cheap, low-cost textiles that can cool your body much more efficiently than existing clothes.

The clothes can make you feel cooler than wearing nothing at all. Photo by AhmetSelcuk.

Naturally, a logical application for this technology would be in hot climates, especially where air conditioning is not available. But even when air conditioning is available, the cooling clothes could help save a lot of energy. Detailing their work in Science, the researchers explain:

“If you can cool the person rather than the building where they work or live, that will save energy,” said Yi Cui, an associate professor of materials science and engineering at Stanford and of photon science at SLAC National Accelerator Laboratory.

There are two mechanisms through which the material cools the body. The first one is not innovative, and is something that already exists in some fabrics: it lets perspiration evaporate through the material. But the second mechanism is indeed revolutionary: it allows heat that the body emits as infrared radiation to pass through the plastic textile. This means that the wearer feels almost 4 degrees Fahrenheit cooler than if they wore cotton clothing.

The anti-blanket

All existing bodies in the universe give off infrared radiation, which is invisible to the human eye. To easily visualize this, think of night-vision goggles – they see the heat given away by bodies. When you put a blanket on, it doesn’t heat you directly, but it traps the heat you radiate close to you. This material does kind of the opposite, allowing most of this energy to be released.

“Forty to 60 percent of our body heat is dissipated as infrared radiation when we are sitting in an office,” said Shanhui Fan, a professor of electrical engineering who specializes in photonics, which is the study of visible and invisible light.

“But until now there has been little or no research on designing the thermal radiation characteristics of textiles.”

Stanford researchers began with a sheet of polyethylene and modified it with a series of chemical treatments, resulting in a cooling fabric. (Image credit: L.A. Cicero)

While the idea sounds fairly simple, the technology behind it is anything but. The team implemented nanotechnology, photonics, and chemistry to give polyethylene – the common, transparent plastic often used as kitchen wrap – a number of desirable characteristics. For example, they made it allow thermal radiation to pass right through it. The same goes for air and water vapor. They also made it opaque (not transparent).

But people don’t wear plastic, so they had to change it once more. To make this thin material more fabric-like, they created a three-ply version: two sheets of treated polyethylene separated by a cotton mesh for strength and thickness.

Better than wearing nothing at all

The end result was that the clothes keep you cooler than your own skin, which is quite an achievement.

“Wearing anything traps some heat and makes the skin warmer,” Fan said. “If dissipating thermal radiation were our only concern, then it would be best to wear nothing.”

When they compared it with regular cotton, it made the skin surface 3.6 F colder. This might not seem like much, but it can make a huge difference – the difference between turning the air conditioning on or leaving it off, or the difference between making a person feel comfortable or uncomfortable.

The team is now working on making different textures and colors, making it suitable for mass production. The material and the thermal treatment is quite cheap, and it could be suitable for countries in hot climates.

“If you want to make a textile, you have to be able to make huge volumes inexpensively,” Cui concluded.

KTH researchers develop transparent wood for use in building and solar panels

Wood, one of the cheapest and most widely used construction materials humanity has ever employed,  just had its range of uses expanded: researchers at Stockholm’s KTH Royal Institute of Technology developed a method that makes wood transparent. The method is suitable for mass production, making it even more attractive.

A close-up look at the transparent wood created at KTH Royal Institute of Technology.
Image credits KTH Royal Institute of Technology.

Optically transparent wood is not a new thing, says Lars Berglund, professor at the Wallenberg Wood Science Center at KTH. But it’s usually only been done in microscopic samples intended for wood anatomy studies. Their new process would allow for transparent wood production and usage on a much larger scale than anything ever before attempted.

“Wood is by far the most used bio-based material in buildings. It’s attractive that the material comes from renewable sources. It also offers excellent mechanical properties, including strength, toughness, low density and low thermal conductivity,” Berglund says.

“Transparent wood is a good material for solar cells, since it’s a low-cost, readily available and renewable resource. This becomes particularly important in covering large surfaces with solar cells.”

These transparent panels can also be employed as windows, or used to create semitransparent facades to allow light in while also maintaining privacy.

Optically transparent wood is actually a type of wood veneer from which lignin, a structurally-important component in the cellular walls of trees, is chemically removed. The resulting porous veneer substrate is saturated with a transparent polymer and the optical properties of the two materials are then matched.

“When the lignin is removed, the wood becomes beautifully white. But because wood isn’t not naturally transparent, we achieve that effect with some nanoscale tailoring,” Berglund adds.

“No one has previously considered the possibility of creating larger transparent structures for use as solar cells and in buildings.”

Wood is a renewable resource, but that doesn’t mean we’re doing it substantially  — we have to grow and harvest it accordingly, not by logging away, chainsaws blazing, at the forests around us. The KTH team is now working on ways to improve the transparency of their material and on scaling-up their production method.

“We also intend to work further with different types of wood,” Berglund concludes.

The full paper, titled “Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance” was published online in the journal Biomacromolecules and can be read here.

Nano-enhanced textiles could lead us to a brighter future with no laundry

Tired of laundry day? Pioneering nano research into self-cleaning textiles could soon make cleaning your clothes as easy as hanging them out on a sunny day.

Cotton textile fibers and nanostructures. Image magnified 200 times.
Image credits RMIT University

A team from the Ian Potter NanoBioSensing Facility and NanoBiotechnology Research Lab at the RMIT University in Melbourne, Australia, have developed a cheap and efficient method of incorporating nanostructures which degrade organic when exposed to light directly into textile fibers. Thier new production technology could pave the way for clothes that can shrug off grime and slime when put under a light bulb or worn out in the sun.

When exposed to light, the nanostructures release so-called hot electrons — particles that gain very high kinetic energy after being accelerated by a strong, high intensity electrical field within a semiconductor. These electrons then consume their energy to degrade organic matter stuck in the weave around them. The researchers worked with copper and silver-based compounds to create their nanostructures, as these are known for their ability to absorb visible wavelength intervals of light.

The color red indicates the presence of silver nanoparticles. The image shows a full coverage of the material with nanostructures grown by the RMIT team. Image magnified 200 times.
Image credits RMIT University

Self-cleaning clothes aren’t a new concept. But the RMIT team aimed to develop a method that would allow active structures to be permanently attached to the fibers and be usable on an industrial scale at the same time. Their novel solution was to grow them directly onto the materials by dipping these into a series of chemical solutions. The whole process takes roughly 30 minutes and results in extremely stable nanostructures.

During laboratory tests, it took less than six minutes of light exposure for the nano-enhanced fabrics to spontaneously clean themselves.

Nanostructures grown on cotton textiles by RMIT University researchers. Image magnified 150,000 times.
Image credits RMIT University

“The advantage of textiles is they already have a 3D structure so they are great at absorbing light, which in turn speeds up the process of degrading organic matter,” said Lead researcher Dr Rajesh Ramanathan.

Dr Ramanathan says that the process has a variety of possible applications in catalysis-based industries such as agrochemicals, pharmaceuticals and natural products, and can be easily scaled up to industrial levels.

“Our next step will be to test our nano-enhanced textiles with organic compounds that could be more relevant to consumers, to see how quickly they can handle common stains like tomato sauce or wine.”

“There’s more work to do to before we can start throwing out our washing machines, but this advance lays a strong foundation for the future development of fully self-cleaning textiles,” Ramanathan concluded.

The full paper, titled “Robust Nanostructured Silver and Copper Fabrics with Localized Surface Plasmon Resonance Property for Effective Visible Light Induced Reductive Catalysis” has been published online in the journal Advanced Materials Interfaces and is available here.

 

New MIT material can soak up solar heat and release it on demand

A team of researchers from MIT created a material that can make use of solar energy in a novel way, absorbing heat and releasing it later, when needed. The researchers led by MIT Prof. Jeffrey Grossman published their results in the journal Advanced Energy Materials.

The layer-by-layer solar thermal fuel polymer film comprises three distinct layers (4 to 5 microns in thickness for each). Cross-linking after each layer enables building up films of tunable thickness. Image credits: Jeffrey Grossman

Heat will inevitably dissipate sooner or later, no matter how you try to store or insulate it. The key here is to store the energy in a chemical form instead of directly storing the heat; they used a molecule that can remain stable in two different configurations. When exposed to sunlight, the energy of the light kicks the molecules into their “charged” configuration, in which they can remain for several hours. After a certain stimulus, they can revert to their initial state, giving off the heat they stored in the process. Such chemical materials are called solar thermal fuels (STF) and have been developed in the past, but this materials seems to overcome some of the limitations of past achievements.

“This work presents an exciting avenue for simultaneous energy harvesting and storage within a single material,” says Ted Sargent, university professor at the University of Toronto, who was not involved in this research.

The manufacturing process is also simple and scalable, and the material they ended up is transparent, which means it can be used to defrost windshields or windows – something especially important as BMW is one of the sponsors for this research.

With such a window, energy would be stored and at a simple trigger, released to de-frost the windshield.

“We did tests to show you could get enough heat to drop ice off a windshield.”

He went on to explain that you don’t need to melt all the ice, just the ice that’s closes to the glass – the rest of the ice will simply slide on that layer. The technology could be extremely useful for electric cars, who lose much of their autonomy (up to 30%) in cold conditions.

“The approach is innovative and distinctive,” says Sargent, from the University of Toronto. “The research is a major advance towards the practical application of solid-state energy-storage/heat-release materials from both a scientific and engineering point of view.”

Self-repairing concrete might build the future

Tomorrow’s bridges, tunnels and other engineering structures might be built with a different material – a type of “smart” concrete. Belgian researchers at the University of Ghent have created two types of self-repairing concrete, using polymers and bacteria.

Image via Flickr.

 

“The concrete is filled with super-absorbent polymers. So when a crack appears, water comes in, and the super-absorbent polymers swell and they block the crack from further intake of water.”

The concrete was developed as part of a pioneering European project called healCON. The idea of developing self-repairing materials is not new, and it has been suggested in several materials, though it hasn’t been applied at a truly large scale. Bath University researchers have also suggested using self-repairing concrete last year, and the topic seems to be picking on a lot of steam.

Nele de Belie, Technical Director of the Magnel Laboratory for Concrete Research explains that impermeability is the key factor:

“You do not have healed concrete regain its strength completely. It’s strong enough as it is. What you do want to regain is the liquid tightness and impermeability, so that durability still remains fine”.

Basically, special polymers are added into the cement mix, and make it so that small cracks are healed. As scientists explain, small cracks aren’t a big problem in itself – it’s the fact that they tend to grow into bigger cracks.

“If a small crack starts healing immediately, then there is no risk that it grows bigger. So the total structure won’t run the risk of falling down. We want to stop the problem before it is big enough”.

In order to design the polymers, the team took inspiration from nature. Biological systems such as bones, skin or plants have the capacity to detect damage very quickly and repair it – they wanted to do the same for concrete. Needless to say, the potential of such a self-healing concrete are huge, in terms of stability and reducing maintenance and repair costs.

Image credits: healCON.

 

They also tried another approach – one which used a more organic approach to self-healing concrete – namely bacteria.

“These are bacteria that we have isolated from locations in our planet that have conditions which are similar to concrete,” says Henk Jonkers, a biologist at Delft University of Technology. “One condition is rock-like. The other condition is being very alkaline, so very high PH conditions. These bacteria like to grow under those conditions. These bacteria are not pathogenic, and are not harmful for human beings or for the environment”.

According to reports, both approaches passed initial lab tests. For example, with the bacteria solution, as soon as cracks appear, the bacteria starts to produce calcium carbonate and fill them up. It’s not clear at the moment exactly how impenetrable this filling is though. The next steps are to test the technology in big-scale real life conditions, test the impenetrability, and ultimately conduct a life-cycle assessment to see just how much money and effort it can save.

“The initial cost will increase. But then if you can reduce the maintenance costs and you increase the service life of the structures, then at the end, this self-healing concrete presents an economically positive picture”.

You can find out more about this project from their webpage, where you can also browse their publications.

 

 

Berkeley scientists create material that changes color when pulled or twisted

It’s awesome when engineers can take inspiration from nature and design something truly spectacular – and useful. Now, a Berkeley team has managed to create a material that can shift colors as easy as a chameleon’s skin when pulled or twisted. The material could be used for camouflage or for the next generation of display technologies.

Chameleon-like artificial skin changes colors by applying the slightest force.
The Optical Society

“This is the first time anybody has made a flexible chameleon-like skin that can change color simply by flexing it,” said Connie J. Chang-Hasnain, a member of the UC Berkeley team that published a paper on the technology this week in the journal Optica.

 

The approach they used was physical, as they didn’t tamper with the chemical make-up of the material. Instead of using chemical dyes or pigments to absorb and reflect light in a different way, thus changing colors, engineers manipulated the structure of a silicon film about a thousand times thinner than a human hair (120 nm). They carved rows of tiny ridges — each smaller than a wavelength of light — onto the film, at different wavelengths. Each color has its own specific wavelength, and each of the small carvings is designed to reflect a very specific wavelength, and therefore its corresponding color. The study leader explains:

“If you have a surface with very precise structures, spaced so they can interact with a specific wavelength of light, you can change its properties and how it interacts with light by changing its dimensions,” said Chang-Hasnain.

This is called structural color. Structural coloration is the production of colour by microscopically structured surfaces, also called schemochromes, fine enough to interfere with visible light without the need of pigments. This type of coloration is present in several types of birds and beetles. But rather than reflecting the entire rainbow, the researchers “tuned” the space between the bars to achieve specific colors.

The approach itself is not entirely new. In astronomy, for example, evenly spaced slits known as diffraction gratings are routinely used to direct light and spread it into its component colors. However, efforts to actually control this technique have remained futile and earlier efforts to develop a flexible, color shifting surface failed in a number of aspects. The Berkeley researchers were able to overcome these problems by using a semiconductor layer of silicon approximately 120 nanometers thick, embedding the silicon bars into a flexible layer of silicone. As the silicone was bent or flexed, the period of the grating spacings responded in kind.

The next step would be to create a proof-of-concept large enough for commercial applications.

“The next step is to make this larger-scale and there are facilities already that could do so,” said Chang-Hasnain. “At that point, we hope to be able to find applications in entertainment, security, and monitoring.”

Aside for being used for camouflage or display technologies, this could also be developed into a sensor that indicates structural fatigue and stress for buildings and bridges.

“This is the first time anyone has achieved such a broad range of color on a one-layer, thin and flexible surface,” concluded Change-Hasnain. “I think it’s extremely cool.”

Indeed it is, sir. Indeed it is.

Journal Reference: Li Zhu, Jonas Kapraun, James Ferrara, and Connie J. Chang-Hasnain. Flexible photonic metastructures for tunable coloration. http://dx.doi.org/10.1364/OPTICA.2.000255