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The Moon is slated to be our next frontier. When Artemis 3 takes off (tentatively) near the end of 2025, it will be the first mission since the Apollo era to land humans on our satellite. By then, there might be a new way to get around on the Moon’s gray dust, which could at least mitigate damage from sharp particles of lunar regolith.

An international team of researchers with the ESA PAVER project has figured out a way to melt Moondust—or at least an ESA-developed stimulant for it—with lasers. The researchers fired laser beams at lunar soil to create interlocking pavers that could be used to construct paved roads and landing pads. The hardened molten regolith is tough enough to withstand the weight of rovers and other spacecraft with minimal dust kickup, and it could all be made right there on the Moon.

“This technology is envisioned to play a major role in the first phase (survivability) of lunar infrastructure and base development, and over time to contribute to all phases of lunar exploration,” the researchers said in a study recently published in Scientific Reports .

Imagine sitting down to a fine-dining meal in which droplets of sauce dynamically move basil leaves and other garnishes around the plate in preprogrammed patterns. Alternatively, you could choose to mix and match droplets to create your own flavor profile. That's the long-term goal of the so-called " Dancing Delicacies " computational food project, which brings together scientists from Monash University’s Exertion Games Lab, Carnegie Mellon University’s Morphing Matter Lab , and Gaudi Labs in Switzerland to explore innovative new ways to turn meals into interactive performance art. Their latest invention is a 3D-printed plate that uses electrical voltage to manipulate liquid droplets, according to a paper published as part of the 2023 Designing Interactive Systems Conference.

“Cooking and eating is more than simply producing a dish and then facilitating energy intake,” co-author Floyd Mueller of Monash told Forbes . “It is about sharing, caring, crafting, slowing down and self-expression, and Dancing Delicacies aims to highlight these virtues at a time when they are often forgotten. The integration of food and computing will transform how we understand both computing and food as not two very different things, but a new frontier that combines the best of both.”

Chefs have been working with this kind of innovation for years via the molecular gastronomy and molecular mixology movements, creating a "Flor de Caco" dessert in which a cocoa bean expands like a flower when exposed to hot chocolate sauce, for instance. Then there was that cocktail ( the "Disco Sour" ) that changed color when blended with citrus, thanks to the incorporation of butterfly pea flower tea, which is a pH-sensitive ingredient. On the technology side, in 2014, MIT's Media Matters Lab experimented with a shape-changing fork that inflated depending on how fast a person was eating. Another fork design was outfitted with electronics, in which an LED changed from red to green when users touched a food item with a conductive element, indicating how much water was in the food.

Enlarge / A pendant, espresso cups, and flower planters 3D-printed from used coffee grounds. (credit: Michael Rivera)

Most coffee lovers typically dump the used grounds from their morning cuppa straight into the trash; those more environmentally inclined might use them for composting. But if you're looking for a truly novel application for coffee grounds, consider using them as a sustainable material for 3D printing, as suggested by a recent paper published in DIS '23: Proceedings of the 2023 ACM Designing Interactive Systems Conference.

“You can make a lot of things with coffee grounds,” said co-author Michael Rivera of the University of Colorado, Boulder, and the ATLAS Institute, who specializes in digital fabrication and human-computer interactions. “And when you don’t want it anymore, you can throw it back into a coffee grinder and use the grounds to print again. Our vision is that you could just pick up a few things at a supermarket and online and get going.”

As 3D printers have moved into more widespread use, it has sparked concerns about environmental sustainability, from the high energy consumption to the thermoplastics used as a printing material—most commonly polylactic acid (PLA). PLA waste usually ends up in a landfill where it can take as long as 1,000 years to decompose, per Rivera. While there have been efforts to recycle PLA in the same way plastic (PET) soda bottles are typically recycled, it's an energy-intensive process that can't be done by the average user at home. Adding biomass fillers (bamboo or hemp fiber, oyster shells, and yes, spent coffee grounds) makes recycling even more labor and energy intensive.

Enlarge / Microscopic view of photonic crystals on the surface of ancient Roman glass. (credit: Giulia Guidetti)

Nature is the ultimate nanofabricator. The latest evidence of that is an unusual shard of ancient Roman glass (dubbed the "wow glass") that boasts a thin, golden-hued patina. Roman glass shards are noteworthy for their iridescent hues of blue, green, and orange—the result of the corrosion process slowly restructuring the glass to form photonic crystals —and this particular shard's shimmering mirror-like gold sheen is a rare example with unusual optical properties, according to a new paper published in the Proceedings of the National Academy of Sciences.

It's yet another example of naturally occurring structural coloration. As previously reported , the bright iridescent colors in butterfly wings , soap bubbles , opals, or beetle shells don't come from any pigment molecules but from how they are structured—naturally occurring photonic crystals . In nature, scales of chitin (a polysaccharide common to insects), for example, are arranged like roof tiles. Essentially, they form a diffraction grating , except photonic crystals only produce specific colors, or wavelengths, of light, while a diffraction grating will produce the entire spectrum, much like a prism.

Also known as photonic band-gap materials, photonic crystals are "tunable," which means they are precisely ordered to block certain wavelengths of light while letting others through. Alter the structure by changing the size of the tiles, and the crystals become sensitive to a different wavelength. They are used in optical communications as waveguides and switches, as well as in filters, lasers, mirrors, and various anti-reflection stealth devices.

Enlarge / Levitation like this will apparently continue to require extremely cold temperatures for now. (credit: ClaudeLux )

The summer of room-temperature superconductivity was short-lived. It started with some manuscripts placed on the arXiv toward the end of July, which purportedly described how to synthesize a compound called LK-99, which would act as a superconductor at temperatures above the boiling point of water. High enough that, if its synthesis and material properties worked out, it could allow us to replace metals with superconductors in a huge range of applications.

Confusion quickly followed, as the nature of the chemical involved made it difficult to know when you were looking at the behavior of LK-99 and when you were looking at related chemicals or even impurities.

But the materials science community responded remarkably quickly. By the end of August, pure samples had been prepared, the role of impurities explored, and a strong consensus had developed: LK-99 was not a superconductor. Best yet, the work nicely provided explanations for why it had behaved a bit like one in a number of situations.

Enlarge (credit: Roman Studio/Getty Images)

Our atmosphere holds six times more water than you’ll find in all the rivers on Earth. The dew drops you see on grass and water droplets on a cold juice bottle are evidence of this natural reservoir of water. Despite its ubiquity, 2 billion people on Earth still don’t have access to clean drinking water .

A technique called atmospheric water harvesting (AWH) can allow us to extract some of this freshwater out of the air. But there are various challenges that have prevented us from implementing AWH on a large scale. In order to create an effective and continuous AWH system, scientists need to ensure two things. The first is that the water absorption from the air is fully reversible so that the water can be retrieved for use.

The second is efficient waste heat management . When an AWH system captures water from the air, the condensation of water releases heat. If this excess heat is not processed carefully, it can interfere with the entire process. However, it seems that we are now closer to a solution. Inspired by the structure of plant leaves, a team of researchers in China has created a core-shell structural cellulose nanofiber-based aerogel (called Core-Shell@CNF for short) that promises to overcome these challenges.

Enlarge / RoboMapper in action. (credit: Aram Amassian)

Earlier this year, two-layer solar cells broke records with 33 percent efficiency. The cells are made of a combination of silicon and a material called a perovskite. However, these tandem solar cells are still far from the theoretical limit of around 45 percent efficiency, and they degrade quickly under sun exposure, making their usefulness limited.

The process of improving tandem solar cells involves the search for the perfect materials to layer on top of each other, with each capturing some of the sunlight the other is missing. One potential material for this is perovskites, which are defined by their peculiar rhombus-in-a-cube crystal structure. This structure can be adopted by many chemicals in a variety of proportions. To make a good candidate for tandem solar cells, the combination of chemicals needs to have the right bandgap—the property responsible for absorbing the right part of the sun’s spectrum—be stable at normal temperatures, and, most challengingly, not degrade under illumination.

The number of possible perovskite materials is vast, and predicting the properties that a given chemical composition will have is very difficult. Trying all the possibilities out in the lab is prohibitively costly and time-consuming. To accelerate the search for the ideal perovskite, researchers at North Carolina State University decided to enlist the help of robots.

Enlarge (credit: IBM )

Large Language Models, the AI tech behind things like Chat GPT, are just what their name implies : big. They often have billions of individual computational nodes and huge numbers of connections among them. All of that means lots of trips back and forth to memory and a whole lot of power use to make that happen. And the problem is likely to get worse.

One way to potentially avoid this is to mix memory and processing. Both IBM and Intel have made chips that equip individual neurons with all the memory they need to perform their functions. An alternative is to perform operations in memory , an approach that has been demonstrated with phase-change memory.

Now, IBM has followed up on its earlier demonstration by building a phase-change chip that's much closer to a functional AI processor. In a paper released on Wednesday by Nature, the company shows that its hardware can perform speech recognition with reasonable accuracy and a much lower energy footprint.

Enlarge / H.G. Wells' The Invisible Man inspired a 1933 film. It's just one cultural example of the human fascination with invisibility. (credit: Universal Pictures)

There's a well-known story in Plato's Republic in which a humble shepherd named Gyges finds a magical gold ring that renders whoever wears it invisible. Gyges proceeds to use his newfound power to murder a king and take over the throne. Plato intended it as a cautionary tale about whether a man could act justly even if the fear of consequence was removed. (The fictional Gyges clearly failed that moral test.) The parable famously inspired J.R.R. Tolkien's Lord of the Rings trilogy, among other works. And it's one of the earliest examples of the longstanding human fascination with invisibility in both fiction and scientific pursuits.

"Invisibility represents the perfect merger of not being seen while being able to see others, which would be great if you were a primitive hunter-gatherer," Greg Gbur, a physicist at the University of North Carolina, Chapel Hill, told Ars. "But more purely, it represents power. You see that in the story of the Ring of Gyges, where the ability to make yourself unseen gives you a tremendous advantage over others. So it's fascinating as a symbol of pure power and how people might use and abuse it."

Gbur is the author of a new book from Yale University Press, Invisibility: The History and Science of How Not to Be Seen , covering the earliest discoveries in optical physics through to the present, along with how invisibility has been portrayed in science fiction (a longstanding passion for Gbur). He's also the author of 2019's fascinating Falling Felines and Fundamental Physics , which explored the surprisingly complicated physics of why cats always seem to land on their feet, ferreting out several obscure scientific papers spanning decades of research in the process. His interest in invisibility science dates back to his graduate school days when his advisor assigned him a project on the topic.