Enlarge / Part of the system of reticulated tunnels (egress complex) of a mound of Macrotermes michaelseni termites from Namibia. (credit: D. Andréen)

The mounds that certain species of termites build above their nests have long been considered to be a kind of built-in natural climate control—an approach that has intrigued architects and engineers keen to design greener, more energy-efficient buildings mimicking those principles. There have been decades of research devoted to modeling just how these nests function. A new paper published in the journal Frontiers in Materials offers new evidence favoring an integrated-system model in which the mound, the nest, and its tunnels function together much like a lung.

Perhaps the most famous example of the influence of termite mounds in architecture is the Eastgate Building in Harare, Zimbabwe. It is the country’s largest commercial and shopping complex, and yet it uses less than 10 percent of the energy consumed by a conventional building of its size because there is no central air conditioning and only a minimal heating system. Architect Mick Pearce famously based his design in the 1990s on the cooling and heating principles used in the region’s termite mounds, which serve as fungus farms for the termites. Fungus is their primary food source.

Conditions have to be just right for the fungus to flourish. So the termites must maintain a constant temperature of 87° F in an environment where the outdoor temperatures range from 35° F at night to 104° F during the day. Biologists have long suggested that they do this by constructing a series of heating and cooling vents throughout their mounds, which can be opened and closed during the day to keep the temperature inside constant. The Eastgate Building relies on a similar system of well-placed vents and solar panels.

Enlarge / Materials in a butterfly's wing create color by altering the paths taken by some wavelengths of light. This was the inspiration for a new form of paint. (credit: Getty Images )

Do you know more than 50 percent of microplastic pollution in our oceans comes from color paints? Almost every object that people throw into the ocean, whether it be a broken toy, a small bottle cap, or a shoe, has some sort of color coating. While you might try to collect all the plastic objects that are thrown into the oceans, there is no way to gather the microplastics that have already mixed into the water.

Particles derived from paint aren’t only a problem in the ocean; they also mix into the air that you breathe. In 2010, scientists studied the effect of chemicals that are used in commercial wall paint on children’s health. They found that kids who sleep in rooms with walls coated with paint having high levels of volatile organic compounds (VOCs) are more likely to develop medical conditions like eczema and asthma.

So does that mean commercial paint materials will continue to degrade our environment and our health? Well, there is a new ray of hope. Researchers from the University of Central Florida (UCF) recently published a study that describes “plasmonic paint,” a lightweight, eco-friendly material that has the potential to replace most colored coatings. They claim that their plasmonic paint is also the lightest paint in the world because it avoids the use of pigments and all the materials needed to hold the pigments in place.

Enlarge (credit: Renphoto )

Government building rules and regulations can be outdated and misguided, insisting upon conventional building materials with prices that aren’t compatible with building affordable housing. The building codes suggested by the United Nations decades ago often preclude using local, lower-cost, and environmentally friendly materials.

Of late, certain researchers have speculated that they might be able to solve two problems plaguing burgeoning cities—a glut of non-degradable waste and dearth of building materials—by folding the former into the latter. Now, a team in Japan reports that used, sanitized disposable diapers can be incorporated into concrete and mortar, which would still meet Indonesian building standards. Low-cost housing is desperately needed there as the urban population continues to bloom and housing is scarce. Obviously, all of the people moving to the cities bring more waste there, as well.

Diapers are substituted for the fine aggregates that are normally used in making concrete. The team determined that mortar for structural components, like load-bearing walls and public road pavement, could only tolerate a maximum of 10 percent added diaper material. But mortar and concrete for nonstructural components, like non-load-bearing wall partitions and low-impact floor pavers, could tolerate having up to 40 percent of their aggregates swapped for diaper material.

Enlarge (credit: Istituto Italiano di Tecnologia )

Can you tell me how many batteries you use in a year? A report from the University of Illinois reveals that Americans buy about 3 billion dry-cell batteries annually, which means that an average American ends up using nearly 10 batteries a year. Of course, this shouldn’t come as a surprise given that almost everything we use runs on batteries. What’s shocking is that out of these billions of batteries, about 2,500 end up in the stomachs of kids.

Almost every day, there are numerous cases of kids swallowing batteries that power their toys, watches, or gadgets; this results in many cases of internal injuries or stomach infections.

A team of researchers at the Italian Institute of Technology (IIT) in Milan recently created a fully rechargeable battery using nontoxic edible components. This is probably the world’s first battery that is safe to ingest and entirely made of food-grade materials. “Given the level of safety of these batteries, they could be used in children's toys, where there is a high risk of ingestion,” said Mario Caironi, a senior researcher at IIT. However, this isn’t the only solution the edible battery could provide.

Enlarge / Archaeologists analyzed samples of Maya plasters collected from the Copan archaeological site in Honduras. (credit: Rodriguez-Navarro et al., 2023)

There is a rich body of scientific research investigating the secrets behind the remarkable durability of ancient Roman concrete. But ancient Maya masons had their own secrets when it came to making the lime plasters, mortars, and stuccos used to build their magnificent structures, many of which still stand today. A team of Spanish scientists has analyzed samples of Maya plasters from Honduras and confirmed that the Maya added plant extracts to improve the plasters' performance, according to a new paper published in the journal Science Advances.

As we've reported previously , like today's Portland cement (a basic ingredient of modern concrete), ancient Roman concrete was basically a mix of a semi-liquid mortar and aggregate. Portland cement is typically made by heating limestone and clay (as well as sandstone, ash, chalk, and iron) in a kiln. The resulting clinker is then ground into a fine powder, with just a touch of added gypsum—the better to achieve a smooth, flat surface. But the aggregate used to make Roman concrete was made up of fist-sized pieces of stone or bricks.

Mayan lime plaster draws on similar ancient knowledge, according to Carlos Rodriguez-Navarro and his colleagues at the University of Granada. The use of lime plaster dates back to around 10,000 to 12,000 BCE, and the manufacturing process typically involved the calcination of carbonate rocks like limestone to produce quicklime, which was then slaked to create portlandite. It seems the Maya independently developed their own lime pyrotechnology around 1100 BCE, and the plasters, mortars, and stuccos they produced exhibit impressive resistance to granular disintegration, fracturing, or scaling, despite more than 1,200 years of exposure in a hot and humid tropical environment.

Enlarge / The much-larger-than-2D form of molybdenum disulfide. (credit: RHJ / Getty Images )

Atomically thin materials like graphene are single molecules in which all the chemical bonds are oriented so that the resulting molecule forms a sheet. These often have distinctive electronic properties that can potentially enable the production of electronics with incredibly small features only a couple of atoms thick. And there have been a number of examples of functional hardware being built from these two-dimensional materials.

But almost all the examples so far have used bespoke construction, sometimes involving researchers manipulating individual flakes of material by hand. So we're not at the point where we can mass-manufacture complicated electronics out of these materials. But a paper released today describes a method of doing wafer-scale production of transistors based on two-dimensional materials. And the resulting transistors perform more consistently than those made with more traditional manufacturing approaches.

Better manufacturing

Most of the efforts made toward easing the production of electronics based on atomically thin materials have involved integrating these materials into traditional semiconductor manufacturing techniques. That makes sense because these techniques allow us to perform incredibly fine-scale manipulations of materials at high volumes. Typically, this has meant that much of the metal wiring needed for the electronics is put in place by traditional manufacturing. The 2D material is then layered on top of the metal, and additional processing is done to form functional transistors.

Enlarge / Brown University scientists used two 3D-printed plastic disks to explore the Cheerios effect. (credit: A. Hooshanginejad et al., 2023)

Scientific research often produces striking visuals, and this year's winners of the Gallery of Soft Matter Physics are no exception. Selected during the American Physical Society March Meeting last week in Las Vegas, Nevada, the winning video entries featured the Cheerios effect, the physics of clogs, and exploiting the physics behind wine tears to make bubbles last longer. Submissions were judged on the basis of both striking visual qualities and scientific interest. The gallery contest was first established last year, inspired in part by the society's hugely successful annual Gallery of Fluid Motion . All five of this year's winners will have the chance to present their work at next year's March meeting in Minneapolis, Minnesota.

Mermaid Cereal

As we've previously reported , the " Cheerios effect " describes the physics behind why those last few tasty little "O"s of cereal tend to clump together in the bowl: either drifting to the center or to the outer edge. The effect can also be found in grains of pollen (or mosquito eggs) floating on top of a pond or small coins floating in a bowl of water. The culprit is a combination of buoyancy, surface tension, and the so-called " meniscus effect." It all adds up to a type of capillary action . Basically, the mass of the Cheerios is insufficient to break the milk's surface tension. But it's enough to put a tiny dent in the surface of the milk in the bowl, such that if two Cheerios are sufficiently close, they will naturally drift toward each other. The "dents" merge and the "O"s clump together. Add another Cheerio into the mix, and it, too, will follow the curvature in the milk to drift toward its fellow "O"s.

Measuring the actual forces at play on such a small scale is daunting, since they're on about the same scale as the weight of a mosquito. Typically, this is done by placing sensors on objects and setting them afloat in a container, using the sensors to deflect the natural motion. But Cheerios are small enough that this was not a feasible approach. So Brown University postdoc Alireza Hooshanginejad and cohorts used two 3D-printed plastic disks , roughly the size of a Cheerio, and placed a small magnet in one of them. Then they set the disks afloat in a small tub of water, surrounded by electric coils, and let them drift together (attraction). The coils in turn produced magnetic fields, pulling the magnetized disk away from its non-magnetized partner (repulsion).

Enlarge (credit: Stefania Pelfini, La Waziya Photography )

Superhumans don't exist in the real world, but someday you might see super robots. Obviously, robots can be made that are stronger, faster, and better than humans, but do you think there is a limit to how much better we can make them?

Thanks to the ongoing developments in material science and soft robotics, scientists are now developing new technologies that could allow future robots to push the limits of non-human biology. For instance, a team of researchers at the University of Colorado Boulder recently developed a material that could give rise to soft robots capable of jumping 200 times above their own thickness. Grasshoppers, one of the most astonishing leapers on Earth, can leap into the air only up to 20 times their body lengths.

Despite outperforming the insects, the researchers behind the rubber-like jumping material say they took their inspiration from grasshoppers. Similar to the insect, the material stores large amounts of energy in the area and then releases it all at once while making a jump .

Enlarge / Brewing kombucha tea. Note the trademark gel-like layer of SCOBY (symbiotic culture of bacteria and yeast). (credit: Olga Pankova/Getty Images)

Cheap, light, flexible, yet robust circuit boards are critical for wearable electronics, among other applications. In the future, those electronics might be printed on flexible circuits made out of bacterial cultures used to make the popular fermented black tea drink called kombucha, according to a recent paper posted to the arXiv preprint server.

As we've reported previously , making kombucha merely requires combining tea and sugar with a kombucha culture known as a SCOBY (symbiotic culture of bacteria and yeast), aka the "mother"—also known as a tea mushroom, tea fungus, or a Manchurian mushroom. It's akin to a sourdough starter. A SCOBY is a firm, gel-like collection of cellulose fiber (biofilm), courtesy of the active bacteria in the culture creating the perfect breeding ground for the yeast and bacteria to flourish. Dissolve the sugar in non-chlorinated boiling water, then steep some tea leaves of your choice in the hot sugar-water before discarding them.

Once the tea cools, add the SCOBY and pour the whole thing into a sterilized beaker or jar. Then cover the beaker or jar with a paper towel or cheesecloth to keep out insects, let it sit for two to three weeks, and voila! You've got your own home-brewed kombucha. A new "daughter" SCOBY will be floating right at the top of the liquid (technically known in this form as a pellicle).