A digest of popular science news for the week that we haven't written about

Bacteria in the human mouth multiply thanks to a rare form of cell division, study finds

Elongation of cells at the tips of the filamentous bacteria Corynebacterium matruchotii

One of the most diverse ecosystems on the planet is closer than you think—right in your mouth. Your mouth is a thriving ecosystem of more than 500 different species of bacteria living in discrete, structured communities called biofilms. Almost all of these bacteria grow by dividing in two, with one mother cell giving rise to two daughter cells.

New study Marine Biological Laboratory (MBL) and ADA Forsyth have uncovered an unusual cell division mechanism in Corynebacterium matruchotii, one of the most common bacteria found in dental plaque. This filamentous bacterium doesn’t just divide, it splits into multiple cells at once, a rare process called multiple fission. The study is published in the journal Proceedings of the National Academy of Sciences.

Team observedas C. matruchotii cells divided simultaneously into 14 different cells, depending on the length of the original mother cell. In addition, these cells grow only at one pole of the mother filament, which is called “tip elongation.”

The filaments of C. matruchotii form the basis of dental plaque, which is a biofilm. Dental plaque is just one microbial community in a vast population of microorganisms that live and coexist in the healthy human body, an environment known as the “human microbiome.”

This discovery sheds light on how these bacteria reproduce, compete for resources with other bacteria, and maintain their structural integrity in the complex environment of dental plaque.

“Reefs have corals, forests have trees, and the plaque in our mouths has Corynebacterium. The Corynebacterium cells in plaque are like a big, bushy tree in a forest; they create a spatial structure that provides a habitat for many other species of bacteria around them,” says co-author Jessica Mark Welch, a senior scientist at ADA Forsyth and an adjunct scientist at MBL.

Chemists Create Gel to Prevent Leaks and Extend Life of Lithium-Ion Batteries

a) schematic representation of the preparation of the gel electrolyte and highlighted characteristic features, b) chemical structures of the gel components

A new type of gel developed by chemists at Martin Luther University Halle-Wittenberg (MLU) could help make lithium-ion batteries safer and more powerful. The gel is designed to prevent the leakage of the flammable electrolyte liquid.

Early lab studies have shown that it also improves performance and battery life. The researchers published their work in the journal Advanced Functional Materials.

Lithium-ion batteries are powerful batteries. “They charge faster than conventional batteries, so they can be used in almost all areas of life,” speaks Professor Wolfgang Binder, head of the Macromolecular Chemistry research group at MLU.

“However, the electrolytes that carry the ions that conduct current between the electrodes are highly flammable. This could cause the battery to catch fire or explode if damaged.”

Researchers at MLU are working to improve the safety of lithium-ion batteries. “We have developed a polymer that can be poured into a battery cell. The electrolyte binds to this substance, but the ions can circulate freely between the electrodes,” explains Dr. Anya Marinov, a chemist at MLU.

“The filler has a gel-like consistency and combines the high conductivity of liquids with the thermal stability and strength of polymers.”

Gel batteries with traditional electrolyte are nothing new in essence: they are used, for example, as starter batteries in motorcycles. However, in combination with lithium ions, they represent uncharted technological territory.

This is largely due to one specific problem. “In conventional lithium-ion batteries, liquid electrolytes create a stabilizing layer on the electrodes when they are first charged. This is critical to the performance and life of the battery,” explains Marinov.

“But for gel electrolytes, we needed a fundamentally new design.” The researchers solved this problem by embedding an ionic framework into the polymer’s molecular chains.

Cracked piece of metal heals on its own in experiment that stuns scientists

In an experiment, scientists observed metal healing itself. If this process can be fully understood and controlled, we could be at the beginning of a whole new era of engineering.

IN researchIn a paper published last year, a team from Sandia National Laboratory and Texas A&M University tested the metal's resilience by using a specialized transmission electron microscope technique to tug on the ends of the metal 200 times every second.

They then observed self-healing at ultra-small scales in a 40-nanometer-thick piece of platinum suspended in a vacuum.

Cracks caused by the type of deformation described above are known as fatigue damage: repeated stresses and movements cause microscopic tears, which eventually lead to failure of machines or structures.

Surprisingly, after about 40 minutes of observation, the crack in the platinum began to grow together and heal, and then went in the other direction again.

Tensile forces (red arrows) created a crack that healed (green) in the platinum metal.

“It was absolutely amazing to witness in person,” said materials scientist Brad Boyce of Sandia National Laboratory when the results were announced.

“We certainly weren't looking for that. We confirmed that metals have their own natural ability to self-heal, at least in the case of fatigue damage at the nanoscale.”

These are precise conditions, and we don’t yet know exactly how it happens or how we can use it. But when you consider the cost and effort required to repair everything from bridges to engines to phones, it becomes clear how big a difference self-healing metals can make.

While this observation is unprecedented, it’s not unexpected. In 2013, Texas A&M University materials scientist Michael Demkovich worked on a study that predicted that similar nanocrack healing could occur because tiny crystal grains inside metals essentially shift their boundaries in response to stress.

Demkovich also worked on this study, using updated computer models to show that his decades-old theories about metals self-healing at the nanoscale matched what was happening here.

That the automatic repair process occurred at room temperature is another promising aspect of the study. Metal typically requires a lot of heat to change shape, but the experiment was conducted in a vacuum; it remains to be seen whether the same process would occur with regular metals in a normal environment.

A possible explanation involves a process known as cold welding, which occurs at ambient temperatures when metal surfaces are brought close enough together that their atoms bond to each other.

'Unhackable' quantum communication closer to reality thanks to new, exceptionally bright photons

Scientists have created an “exceptionally bright” light source capable of generating quantum-entangled photons (particles of light) that could be used to securely transmit data in a future high-speed quantum communications network.

A future quantum internet could transmit information using pairs of entangled photons, meaning the particles exchange information across time and space regardless of distance. Based on the strange laws of quantum mechanics, the information encoded in these entangled photons could be transmitted at high speeds, and their “quantum coherence” — the state in which the particles are entangled — ensures that the data cannot be intercepted.

But one of the key challenges in creating a quantum internet is that the power of these photons can weaken as they travel; the light sources haven’t been bright enough. To build a successful quantum internet that can send data over vast distances, the photons need to be energetic enough to prevent “decoherence” — when entanglement is lost and the information they contain disappears.

IN researchIn a study published July 24 in the journal eLight, scientists from Europe, Asia and South America have created a new type of quantum signal source using existing technology and achieved extremely high brightness.

They achieved this by combining a photonic point emitter (a generator of single photons, or particles of light) with a quantum resonator (a device for amplifying a quantum signature) to create a new powerful quantum signal.

What is particularly interesting about the recent study is that the individual technologies have been independently tested in laboratories, but only tested individually. This study is the first time they have been used in combination.

Giant asteroid impact shifts axis of solar system's largest moon, study finds

About 4 billion years ago, an asteroid slammed into Jupiter's moon Ganymede. Now, a researcher at Kobe University has realized that the axis of the solar system's largest moon was shifted by the impact, confirming that the asteroid was about 20 times larger than the one that ended the age of dinosaurs on Earth and caused one of the largest, most clearly visible impacts in the solar system.

Ganymede is the largest moon in the solar system, larger even than the planet Mercury, and is interesting because it has oceans of liquid water beneath its icy surface. Like Earth's moon, it is tidally locked, meaning it always shows the same side to the planet it orbits. Large areas of its surface are covered in furrows that form concentric circles around one particular spot, leading researchers in the 1980s to conclude that they were the result of a major collision.

“Jupiter's moons – Io, Europa, Ganymede and Callisto – have interesting individual characteristics, but it was these grooves on Ganymede that caught my attention,” speaks Hirata Naoyuki, a planetary scientist at Kobe University, said: “We know that this feature was created by an asteroid impact about 4 billion years ago, but we didn't know how big the impact was or what impact it had on the moon.”

Data from a distant object is sparse, making research difficult, so Hirata was the first to realize that the suspected impact site was almost exactly on the meridian furthest from Jupiter. Based on similarities to the impact on Pluto, which caused the dwarf planet's rotation axis to shift, and what we've learned from the New Horizons spacecraft, this suggested that Ganymede had also undergone a similar reorientation. Hirata is an expert in modeling impacts with moons and asteroids, which allowed him to calculate what kind of impact might have caused such a reorientation.

Much of the surface of Jupiter's moon Ganymede has grooves (right) that form concentric circles around one specific spot (left, red cross), leading researchers in the 1980s to conclude that they were the result of a major impact. — Much of the surface of Jupiter's moon Ganymede has grooves (right) that form concentric circles around one specific location (left, red cross), leading researchers in the 1980s to conclude that they were the result of a major impact.

In the journal Scientific Reports, a researcher from Kobe University published evidence that the asteroid was likely about 300 kilometers (186 miles) in diameter, about 20 times larger than the one that struck Earth 65 million years ago, ending the age of dinosaurs, and created a transient crater between 1,400 and 1,600 kilometers (900 and 1000 miles) in diameter. (Transient craters, widely used in laboratory studies and computational modeling, are cavities formed immediately after a crater is excavated and before material has settled in and around the crater.)