Want to keep bacteria at bay? You could pop down to the pharmacy to buy some antiseptic soap, for example, but it might be easier to reach into your desk drawer. A roll of transparent adhesive tape can be turned into a nifty antibacterial film.

Depositing metal nanoparticles on a film surface can give it remarkable properties: silver turns it antibacterial, copper anti-fungal, and gold makes the film conduct electricity. What is tricky is getting the film to accept nanoparticles in the first place: in most cases you need a harsh chemical bath to break the bonds on its surface.

But adhesive tape comes primed to do chemistry. Just unpeeling it breaks chemical bonds in the adhesive, priming it to react with metals like silver or copper, Bartosz Grzybowski of Northwestern University in Evanston, Illinois, and colleagues have found.

Peel, then soak

This means that if you want to coat the tape with nanoparticles, you can simply peel off a length and soak it in a solution of metal salts. For large sheets of tape that aren’t on a roll, physically pressing on the tape primes it to react with the solution.

Tweaking the ingredients of the solution yields tape with various properties. Antibacterial bandages and electrically conducting tape are feasible, for example. You can also produce antifungal films that could be stuck on walls in mouldy places like humid basements.

“It’s clever,” say chemist Katherine Holt of University College London. The potential to tailor and control the nanoparticle growth is worth exploring further, she says.

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Precisely how an acid molecule falls apart when surrounded by a handful of water molecules is a long-standing mystery, even though it’s a common and important interaction. “This is fundamental,” says chemist of the University of Minnesota in Minneapolis. “Proton transfer is ubiquitous; it’s the simplest chemical reaction.”

Previous work was largely theoretical and probed water-acid mixes only at exceedingly low temperatures. So physicist of the University of Southern California in Los Angeles and colleagues decided to study the less unearthly temperature of 200 kelvin (-73.15 °C).

The team blasted hot water vapour through a pinhole a mere 75 micrometres wide and added hydrochloric acid to the spray. The spray of water-acid clusters was then passed through an electric field, which deflected the clusters certain distances. Previous work suggested that the distribution of positive and electric charges in the clusters changes when the acid splits apart, and this knowledge, combined with the measured deflections, allowed the team to deduce how many water molecules it took to spur the acid into ditching its proton.

Communal proton

The simplest scenario is that just one water molecule in the cluster is the lucky recipient. But the team also did some modelling that hints at quantum effects kicking in once there are half a dozen or so water molecules. In this scenario, the proton is shared, bouncing freely around the cluster. “Protons are very small and mobile, they can bounce all over the place,” says Kresin, “and each water molecule can spin and very easily change shape.”

There’s a third possibility: perhaps the experiment wasn’t seeing the acid splitting at all. In this scenario, the water molecules in the clusters redistribute their charges, leading to the deflections the team saw. If that’s the case, then more water is needed to make the acid break apart, and some other experiment will have to be devised to see it happening.

Whatever the case, a better understanding of proton transfer will shed light on biochemical reactions, and on atmospheric processes in which acids and water form aerosols that affect the climate and human health.

Journal reference:

Exo-forecast: it’s foggy out there. For the first time, water vapour has been detected in the atmosphere of a Neptune-sized planet outside the solar system.

Previously, astronomers had found water in the atmospheres of so-called hot Jupiters, which are as massive or larger than Jupiter and orbit scorchingly close to their stars. But similar efforts for smaller planets had been stymied by hard-to-interpret data.

Now, of the University of Maryland, College Park, and colleagues have used the Hubble and Spitzer space telescopes to study , a planet 123 light-years away in the constellation Cygnus. With a radius four times that of Earth, it’s the smallest yet to have its atmosphere probed.

In addition to water vapour, they found a lot of hydrogen, and some oxygen and heavier elements.

“It does look like a Neptune clone, only hotter,” says planetary scientist of the Space Science Institute in Seabrook, Texas. This molecular profile suggests that the planet formed far from its star, then moved closer.

The observation is a “rung on the ladder” down to being able to study the atmospheres of Earth-like exoplanets, says of Grinnell College in Iowa.

It isn’t clear why other exo-Neptunes’ atmospheres have been so hard to probe. High clouds or a very compressed atmosphere of heavier molecules such as carbon dioxide might be to blame for the lack of signal. “It has been an annoyance,” says Kempton. “We kept observing these planets that should be interesting and we’ve see nothing.”

Journal reference: Nature, DOI: 10.1038/nature13785

Video: Hard to crush

Put the squeeze on a ceramic mug and you’ll crush it to powder. But ultra-tiny ceramic scaffolds can now be made that bounce back under pressure. Such materials can be made so light that they approach density of air, and might serve as shock absorbers in cellphones and other fragile devices.

“This, for ceramics, is unheard of,” says at the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany, who was not involved in the work. “They are usually brittle and will fracture.”

Such brittle materials typically contain tiny defects – little cracks or holes – that lead to cracking under pressure. To tackle this problem, researchers led by at the California Institute of Technology in Pasadena built tiny lattices out of superthin ceramic tubes with walls just 5 to 60 nanometres thick. This thinness leaves little room for defects that might otherwise send cracks throughout the lattice.

Stress tests revealed that some of the lattices with tube walls 10 nanometre thick bounced back to more than 95 per cent of their original height after being compressed by more than 50 per cent.

Take the strain

“The strain is the most striking,” says materials scientist of the National Centre for Scientific Research in Cavaillon, France. Ceramics usually break after being compressed by 1 per cent, he notes, “so 50 per cent strain is really huge”.

The tube walls wrinkle and warp under compression, then the tubes bend under the stress. Any cracks that appear in the lattice seem unable to propagate past these stressed bends in the tubes, so they are stopped in their tracks. When the research team made lattices with tubes with walls 60 nanometres thick, the lattices behaved like a normal brittle material and were crushed to dust.

“Elastic ceramics is a holy grail in materials science,” says Fratzl. “With the thinness, they’ve achieved a very unusual effect.” But he cautions that the technique may be difficult and expensive to scale up.

Journal reference: Science, DOI: 10.1126/science.1255908

RATHER than searching for aliens phoning home, scientists are looking for signs of the homes themselves. A new project proposing that galaxy-spanning alien civilisations should generate detectable heat has turned up a few dozen galaxies that hold promise as harbours for life.

The best-known technique used to search for tech-savvy aliens is eavesdropping on their communications with each other. But this approach assumes ET is chatty in channels we can hear.

The new approach, dubbed G-HAT for Glimpsing Heat from Alien Technologies, makes no assumptions about what alien civilisations may be like.

“This approach is very different,” says Franck Marchis at the SETI Institute in California, who was not involved in the project. “I like it because it doesn’t put any constraints on the origin of the civilisation or their willingness to communicate.”

Instead, it utilises the laws of thermodynamics. All machines and living things give off heat, and that heat is visible as infrared radiation. The G-HAT team combed through the catalogue of images generated by the Wide-field Infrared Survey Explorer, or WISE, which released an infrared map of the entire sky in 2012. A galaxy should emit about 10 per cent of its light in the mid-infrared range, says team leader Jason Wright at Pennsylvania State University. If it gives off much more, it could be being warmed by vast networks of alien technology – though it could also be a sign of more prosaic processes, such as rapid star formation or an actively feeding black hole at the galaxy’s centre.

The team’s preliminary survey suggests that such galaxies are rare, but they are out there. “We have found several dozen galaxies giving out a superlative amount of mid-infrared light,” says Wright. About 50 of these are emitting more than half of their starlight in the mid-infrared, the team reports ().

Could that mean we have already found alien civilisations that have spread across galaxies?

“If by ‘found them’ you mean that WISE detected the waste heat from them, then yes, that’s right – if these sorts of energy-hungry civilisations exist, WISE should have detected them,” Wright says. But identifying them is another story. “Distinguishing that waste heat from ordinary astrophysical dust will be very difficult in many cases, and proving it’s of alien origin will be even harder,” he says.

The next step is to look at the stars and galaxies that raised the infrared flag in the WISE survey and figure out if there are more ordinary processes at work.

“This effort is important because it tries to resolve the question of extraterrestrial life scientifically, using the laws of chemistry and physics that govern the universe,” says astronomer Geoff Marcy of the University of California, Berkeley.

Even if the effort doesn’t discover intelligent aliens, it is still doing solid science, says Marchis. “This work is useful no matter what because it’s cataloguing the mid-infrared of our stars and galaxies,” he says. “Like our exoplanet search and using rovers to look for microbes on Mars, this search for extraterrestrial life is driving useful science.”

This article appeared in print under the headline “Spot ET’s waste heat for chance to find alien life”

Captured dust grains that flew into our solar system from interstellar space are providing our first on-the-ground glimpse of the stuff between the stars. Having the particles in hand will hopefully shed light on the chemistry of the cosmos.

“Dust grains are the place where things happen in space – they provide a place for molecules to meet,” says Anthony Remijan at the National Radio Astronomy Observatory in Charlottesville, Virginia, who was not involved with the research. “It’s very exciting, we’ve actually grabbed a piece of the universe that we can examine in the lab.”

The grains were captured by NASA’s , which launched in 1999 and collected particles from the tail of comet Wild 2. On the way to the comet, the spacecraft also exposed its dust collectors – made of aerogel and aluminium foil – to a dust stream thought to come from interstellar space. It delivered its precious cargo to Earth in 2006.

Since then, the Stardust team has combed through millions of close-up images of the spacecraft’s dust collectors, an effort aided online by more than 30,000 citizen scientists, dubbed “Dusters”, who participated in the .

Now, the team has published results on the physical analyses of seven samples of debris that hit the collectors that they are confident came from interstellar space.

Liquid smoke

Although they have not yet found a smoking gun for interstellar origin, the team has ruled out a number of other origins for the grains. They showed that the grains contain a magnesium-iron-silicate mineral called olivine, meaning it could not have come from the spacecraft itself or its collectors.

The impact tracks that the grains made in the collectors’ aerogel – often called liquid smoke because its density approaches that of air – were also consistent with coming from high-speed interstellar particles. Because of the way the sun moves through the galaxy, material from interstellar space enters the solar system from a particular direction, creating a wind. To maximise the chance of catching interstellar grains, Stardust opened the collectors when the spacecraft was heading in the same direction as these interstellar winds.

The team expected any grains they caught to be amorphous blobs, because earlier calculations suggested that the harsh radiation environment of the interstellar medium should smear out crystalline structure, and that the grains would be moving at velocities of at least 25 kilometres per second. Such velocities would mean that when they struck the collectors, they would probably have been crushed somewhat.

Orion and Hylabrook

But surprisingly, the grains they caught were intact. Two of the grains, dubbed Orion and Hylabrook by their Duster discoverers, are unexpectedly large – about two micrometres in diameter – and have an intricate structure, like fluffy snowflakes.

“Our models say they shouldn’t be so big and they are more crystalline than expected,” says at Princeton University, an authority on interstellar dust. “But that doesn’t mean they aren’t interstellar grains.”

The particles could have survived thanks to radiation pressure exerted by the sun slowing them down to a velocity in the region of 5 kilometres per second, says Stardust scientist Andrew Westphal at the University of California, Berkeley. Similarly slow collisions created in lab experiments yield similar aerogel tracks as those left by the examined particles.

Building blocks

It’s too early to say how the dust grains might affect existing theories on the formation of the solar system or other galactic matters, says Westphal, who compares the effort to analysing a few bits of ancient bones in Africa and trying to say something meaningful about human evolution.

But there’s much more to discover. The team has only examined 71 tracks in the aerogel and 25 craters in the aluminium foil, and more than 150 tracks have yet to be investigated.

“The interstellar medium is interesting because fundamentally, it’s what we’re made of,” says Westphal. “Like the Apollo mission, these samples are undoubtedly going to be studied for years to come.”

Journal reference: Science, DOI: 10.1126/science.1252496

The approach, which mimics the Japanese paper-cutting technique , should have a host of uses, such as flexible sensors for the body or foldable TV screens.

Graphene is a chicken wire-like layer of carbon just a single atom thick, yet it is more than 100 times stronger than steel. “It’s very counter-intuitive,” says of Boston University. “Graphene is the thinnest possible material, but it’s the strongest material.”

Experiments have shown that cutting graphene into patterned sheets, akin to cutting paper into intricate snowflakes or flowers, makes the material stretchable.

Park’s colleague Zenan Qi made various simulated cuts, and found a pattern involving numerous overlapping rectangles had the most effect on the stretchiness of the sheets. While ordinary graphene tears haphazardly when stretched less than 30 per cent, the kirigami graphene elongated roughly 65 per cent before tears began to form at the interior of the cuts.

Figuring out where, how and when graphene rips is important for using the material, says of Cornell University in New York, who is using graphene kirigami to make . “These are questions you can’t answer by playing with a sheet of paper.”

Journal reference: www.arxiv.org/abs/1407.8113

Video: Making waves creates patterns of beads

These are waves worth catching. Generating tiny swells in a dish of saline solution prompts beads, copper powder and even cells to assemble into a panoply of intricate patterns. It could offer a simple way to build elaborate structures that may be useful for microelectronics and making human tissue.

Many attempts at small-scale construction build structures piece by piece, which can be time-consuming for complex products. Other methods can only use specific building blocks, such as magnetic materials. Now a team led by at Stanford University in California has found a way to quickly build micro-sized structures from almost anything, using a “liquid template”.

The team started by making acrylic containers, each roughly 1 centimetre by 1 centimetre, but sculpted in various shapes. They filled the containers with saline solution and connected them to a vibration generator and amplifier to create acoustic pressure.

Sound method

After adding a handful of starter pieces, such as silicon chips or small plastic beads, the researchers tuned the generator to various frequencies to create waves in the solution. Depending on their surface chemistry, the added particles spontaneously collected in either the crests or the valleys. Retuning the generator let the team switch between multiple patterns.

The team also cajoled cells into forming delicate structures. To get networks of cells, scientists typically have to grow them on special scaffolding or within a gel that provides support. “We wondered if we could create tissues by using sound,” says Demirci. “Acoustic forces are gentle and wouldn’t harm cells.”

He and his colleagues cultured mouse cells and put them in the liquid template. The cells collected into little spheres that became the building blocks of larger geometric patterns. Adding blood clotting proteins to the saline solution locked the cells in place, an approach that the team is now investigating for growing liver tissue.

DIY micro-patterns

The method can also create networks of cells that are a specific distance apart. Seeding tiny beads with rat nerve cells resulted in delicate shapes that could be fixed in place with a protein, allowing the researchers to study which geometries of cell networks best promote growth.

The diverse array of patterns generated by the technique and the ability to switch from one pattern to another in real time is impressive, says at Johns Hopkins University in Baltimore, Maryland, an expert in self-assembling materials. And there’s nothing fancy about the required equipment, so researchers could easily take advantage of the approach for all kinds of uses.

“It’s relatively easy – I could put together the set-up with stuff I have in the lab already,” says Gracias.

Journal reference: Advanced Materials,

Video: Stellar bubble creates ‘pillars of creation’

Building a towering cosmic icon may be as easy as blowing bubbles. Simulations of the billowing wind from a massive star may reveal how the famous “pillars of creation” were created.

The finger-like columns of interstellar gas and dust known as the pillars of creation are part of the Eagle Nebula, a star-forming region about 7000 light years away from Earth. A spectacular image snapped by the Hubble Space Telescope in 1995 catapulted the pillars to stardom.

The dense columns of gas are being sculpted and eroded by ultraviolet radiation from the incredibly massive stars that live in the nebula. Detailed images from also show dense clumps inside the pillars that suggest new stars are being born.

at Cardiff University, UK, wanted to understand how such massive stars are affecting their birthplaces. He made a computer simulation of the birth of a very massive star, which emerges when a dense cloud of hydrogen gas collapses under its own weight. He then mimicked stellar life over a 1.6-million-year period. As with real stars, the model star had powerful winds of radiation that created a giant bubble, which collected and compressed the leftover dust and gas as it grew.

Bubbling birth

The model tested different intensities of the star’s UV radiation. In runs with the lowest UV output, the bubble expanded and then collapsed back in on itself. When the star pumped out the most UV light, the bubble just kept expanding, and the simulation yielded bright rimmed clouds and pillars. But these structures weren’t dense enough to lead to the creation of new stars, a hallmark of the real pillars.

Stellar nurseries appeared only when the UV output was “just right” – the bubble expanded, contracted a little and then stopped, disintegrating at the edges. As the bubble fell apart, it left a halo of scraggly trunk-like columns of gas that were dense enough to give birth to new stars inside.

The work neatly reproduces cloud structures like the iconic pillars, suggesting that they could have been created by a stellar bubble, says Balfour, who presented the work this week at the in Portsmouth, UK. He says the model also shows that the role of massive stars in sparking the births of new stars is more complex than imagined.

The role that massive stars play in triggering new star formation has been in debate for a while, says at NASA’s Jet Propulsion Laboratory in Pasadena, California. Balfour’s simulation adds a level of sophistication to how and when such star formation might happen, he says.