Tag Archives: Plate

Ultra-thin gold sheet.

Scientists create the thinnest gold plates ever, just two atoms thick

Researchers at the University of Leeds have created the thinnest unsupported gold plate ever — just two atoms thick.

Ultra-thin gold sheet.

The nanoscale gold sheet. Image has been artificially colored.
Image credits University of Leeds.

The team reports that the thickness of their gold plate is just 0.47 nanometres, making it one million times thinner than a human fingernail. For comparison, the thickness of a human strand of hair ranges between 17 to 181 nanometres. The researchers call the plate ‘2-D’ gold because it’s just two-atoms thick.

Nanometals

“This work amounts to a landmark achievement,” says lead author Dr. Sunjie Ye, from Leeds’ Molecular and Nanoscale Physics Group and the Leeds Institute of Medical Research.

“Not only does it open up the possibility that gold can be used more efficiently in existing technologies, it is providing a route which would allow material scientists to develop other 2-D metals. This method could innovate nanomaterial manufacturing.”

As the plate is built from only two layers of atoms, all of them are surface atoms, i.e. none of them are completely covered by others. This is especially important for catalysts, whose efficiency varies with the amount of surface area they can present to the environment.

Gold zoom.

Electron microscope image showing the arrangement of gold atoms on the nanosheet.
Image credits University of Leeds.

Laboratory tests show that the 2-D gold plate is 10 times more efficient as a catalytic substrate than the currently used gold nanoparticles. These gold nanoparticles are 3-D materials and the majority of their atoms reside in their bulk rather than on the surface, so they are inactive.

In addition to pointing the way towards new, better catalysts for a range of industrial processes, the material could also have applications in the medical device and electronics industries. The team writes that it can also form the basis of artificial enzymes that could be applied in rapid, point-of-care medical diagnostic tests and in water purification systems.

The team’s synthesis process takes place in a watered-down solution of chloroauric acid, an inorganic substance that contains gold. This substance is then reduced to produce metallic gold using a ‘confinement agent,’ a chemical that encourages the gold to form as a very thin sheet.

Because at this point the gold particles are still in the nanoscale, it appears green in the water. Also due to the resulting shapes, the team describes it as ‘gold nanoseaweed’.

Gold sheets.

Image credits University of Leeds.

Professor Stephen Evans, head of the Leeds’ Molecular and Nanoscale Research Group and lead researcher on the project, says that the findings could help several industries cut down on production costs due to the high surface-to-volume ratios of the 2-D gold sheets.

“Gold is a highly effective catalyst. Because the nanosheets are so thin, just about every gold atom plays a part in the catalysis. It means the process is highly efficient,” says Professor Evans.

“Our data suggests that industry could get the same effect from using a smaller amount of gold, and this has economic advantages when you are talking about a precious metal.”

Furthermore, the sheets are also flexible despite their extreme thinness. This makes them ideal for a variety of applications in electronics, especially in the building of components, bendable screens, electronic inks, or transparent conducting displays.

Professor Evans says there are many similarities between the 2-D gold and graphene, the first 2-d material ever created in the lab. However, he also cautions that the transition from new materials to working products takes a long time, and that “you can’t force it to do everything you might like to”.

“With graphene, people have thought that it could be good for electronics or for transparent coatings — or as carbon nanotubes that could make an elevator to take us into space because of its super strength,” he explains. “I think with 2-D gold we have got some very definite ideas about where it could be used, particularly in catalytic reactions and enzymatic reactions.”

“We know it will be more effective than existing technologies, so we have something that we believe people will be interested in developing with us.”

The paper “Sub‐Nanometer Thick Gold Nanosheets as Highly Efficient Catalysts” has been published in the journal Advanced Science.

A tectonic plate off the coast of Portugal might be peeling off

Geologists believe we may be witnessing the birth of a new subduction zone.

Image via Wikipedia.

Researchers have long puzzled over a plain, featureless area off the coast of Portugal. The seemingly-boring area stood out in 1969 when it triggered a massive earthquake that generated a tsunami. This was highly unusual — earthquakes don’t just happen in random areas. Most often, they take place in tectonically active areas, at the edges of tectonic plates. The correlation is so good that if you’d look at a global map of large earthquakes (see below), it looks like a map of tectonic plates.

So why then did a 7.9 earthquake shake the coast of Portugal? João Duarte, a marine geologist from the Instituto Dom Luiz at the University of Lisbon, believes he has the answer. According to a recent study published by Duarte, the tectonic plate off Portugal’s coast might be peeling away from its top.

Actively tectonic

The Earth might seem static from our point of view, but from a geological perspective, it’s very active. Our planet’s crust is split into rigid plates which are always in motion to each other, at a rate of a few centimeters per year — which, in millions of years, can dramatically change the surface of the Earth.

Earthquakes happen most commonly on the edge of tectonic plates. Image via Wikipedia

Naturally, when the plates are moving, they will sometimes be pushing against each other. If one plate is heavier than the other, it will slide beneath it — a process called subduction. We’re quite familiar with subduction as we’ve observed it and its effects in several parts of the world, but we’ve never actually seen it start. Until now.

Suspicions of a potential subduction-related peeling event started after the 1969 earthquake, but it wasn’t until 2012 that researchers got a good view of the area, using seismic wave analysis (which works somewhat similar to an ultrasound). In 2018, Chiara Civiero, a postdoctoral researcher at University of Lisbon’s Instituto Dom Luiz, and her colleagues published a high-resolution peek into Earth in this region, and confirmed the discovery of the unusual blob.

Now, Duarte found new evidence to support this theory in a seemingly innocuous geological layer, one which allows water to percolate (infiltrate) through. This water transforms the minerals inside the plate, transforming them into softer minerals, producing just enough weakness to allow the bottom of the plate to peel away.

“Now we are 100-percent sure it’s there,” Duarte told Nationl Geographic. Other researchers found that above this deep body, which stretches 155 miles below the surface, tiny quakes seemed to tremble.

Of course, work is still needed to confirm the find, but Duarte is confident.

“It’s a big statement,” Duarte says of the conclusions, acknowledging that he and his team still have work to do. “Maybe this is not the solution to all the problems. But I think we have something new here.”

The study was presented at the European Geosciences Union meeting.
Breakfast.

Sharing a plate helps with both love and work

Need a boost to persuasion power at your next big meeting? Try changing the setting to someplace less plate-y.

Breakfast.

Image via Pixabay.

Business negotiations go more smoothly and take less time when participants share a plate, not just a meal, new research reveals. Shared plates are customary in Chinese and Indian cultures (among others), and people sharing a plate are able to collaborate better and reach deals faster, the study explains.

Breaking Bread

Ayelet Fishbach and Kaitlin Wooley, a Professor at the University of Chicago and PhD student Cornell University, respectively, say a family-style meal with a prospective business partner can help the deal go through smoothly.

The duo asked a group of participants (all strangers to one another) to pair off in a lab experiment regarding negotiation patterns. Before the experiments began, participants were invited to have a snack of chips and salsa with their partners. Half of the pairs received one bowl of chips and one bowl of salsa to share, while the others each had their own bowls.

After this light snack, the pairs were asked to simulate a negotiation between a member of management and a union representative. Their goal was to settle on an acceptable wage for workers of both parties in the span of 22 rounds of negotiations. To put a little bit of pressure on the hypothetical scenario, a “costly union strike” was scheduled to start on round three. Each party would incur costs from this strike which, the team hoped, would help coax the participants into reaching a deal as quickly as possible.

On average, participants that shared a bowl of snacks reached an agreement in nine strike days (i.e. in twelve turns). Their separate-bowl counterparts needed, on average, took four days longer to agree on their terms. In the team’s hypothetical scenario, these four extra days translated to an extra $1.5 million in combined losses.

What’s particularly interesting is that it didn’t much matter if the two parties liked one another — what mattered was whether or not they had coordinated their eating. This finding came from a repeat experiment carried out by Woolley and Fishbach, in which they had both friends and strangers participate. Both groups received pairs of both friends and strangers, and sharing plates had a significant effect in both cases.

The degree to which a person felt they were collaborating with their partner while eating — sharing food rather than competing for that last bite — predicted their feelings of collaboration during the negotiation phase, the team adds. Fischbach says that the results showcase the powerful effect a meal can have on interpersonal connections. Despite how convenient remote meetings can be, they simply don’t stack up to sharing a meal — and, he adds, this holds true for professional as well as personal relationships.

“Basically, every meal that you’re eating alone is a missed opportunity to connect to someone,” says Fishbach. “And every meal that involves food sharing fully utilizes the opportunity to create that social bond.”

The paper ” Shared Plates, Shared Minds: Consuming from a Shared Plate Promotes Cooperation” has been published in the journal Psychological Science.

Tibetan Plateau.

A shattered tectonic plate underpins the Tibetan Plateau — explaining the area’s weird earthquakes

A new geophysical model shines some light on the Tibetan Plateau’s unique geology.

Tibetan Plateau.

Natural-color image of the Tibetan Plateau.
Image credits NASA Earth Observatory.

Some 50 million years ago, India was a huge hit in Asia — quite literally, as the peninsula smashed into the continent after breaking up with Gondwana, creating the Himalayas of today. We don’t know very much about the specifics of this collision, as the Tibetan Plateau — an area at the epicenter of this collision — is quite inhospitable and hard to reach, for earth scientists and laymen alike.

New research, led by scientists from the University of Illinois at Urbana-Champaign, comes to shed more light on the event. Not only do the findings help patch our understanding of the area’s geology. The results also help explain the highly-peculiar — and very violent — seismic activity in this area.

Shaking things up

“The continental collision between the Indian and Asian tectonic plates shaped the landscape of East Asia, producing some of the deadliest earthquakes in the world,” said Xiaodong Song, a geology professor at the University of Illinois and co-author of the new study.

“However, the vast, high plateau is largely inaccessible to geological and geophysical studies.”

Song and his team drew on high-resolution seismic (earthquake) data to generate the clearest model of the Tibetan Plateau’s geology to date. They pooled together geophysical data from various studies and other sources, and collated them to generate seismic tomography images of Tibet — think of them as ultrasound imaging for geology — that peer down to about 160 kilometers under the surface.

Their work reveals that the upper mantle layer of the Indian tectonic plate is broken into four distinct pieces that push under the Eurasian plate. Each of these four fragments lies at a different distance from the origin of the tear and moves at a different angle relative to the surface than its peers. The new data match well with recorded earthquake activity, geological, and geochemical observations in the area, the team writes, which helps improve confidence in the results.

Model Tibet Plateau.

Seismic wave velocity images of the Tibetan Plateau in image a (map view) and image b (cross-section view). In image b, T1, T2 and T3 mark mantle tears, the circles indicate earthquakes deeper than 40 kilometers and the white contours show earthquake density.
Image credits Jiangtao Lia, Xiaodong Songa, (2018), PNAS.

“The presence of these tears helps give a unified explanation as to why mantle-deep earthquakes occur in some parts of southern and central Tibet and not others,” Song said.

While the Indian plate was definitely shredded after the impact, the bodies of intact crust between the tears (the four fingers themselves) are still strong enough to accumulate strain — and such strain, when released, is what causes earthquakes. At the same time, heat upwelling from the deeper mantle can pass through the torn areas more readily. Areas of crust directly above the tears become more ductile and less susceptible to earthquakes as they warm.

This last tidbit of information helps explain the “unusual locations” of some of the earthquakes in the plateaus’ southern reaches, according to co-author Jiangtao Li, who adds that “there is a striking correlation with the location of the earthquakes and the orientation of the fragmented Indian upper mantle”.

The model also helps us get a better idea of the local geology as a whole, explaining some of the area’s more peculiar surface deformation patterns, such as a series of unusual north-south rifts along the plateau, for example. Such deformation patterns, together with the location of most earthquakes in the area, further suggest that the crust and upper mantle are strongly coupled in southern Tibet — i.e. surface rocks are very well ‘glued’ to deeper formations.

Simplified model.

Idealized cartoon illustration of the tearing of the Indian plate and coupling between the crust (orange) and the mantle lithosphere (blue) in south-central Tibet. The thickness of the crust and mantle lithosphere is not to scale. The white dashed line marks the possible boundary between the underthrusting Indian crust and the overriding Himalayan orogenic prism and Tibetan crust.
Image credits Jiangtao Lia, Xiaodong Songa, (2018), PNAS.

Overall, the findings offer a clearer picture of the state of the crust and upper mantle in the Tibetan Plateau. The findings will also help us better assess areas that are at risk from earthquakes, the team adds, with the potential to safeguard lives and property from their devastating effects.

The paper “Tearing of Indian mantle lithosphere from high-resolution seismic images and its implications for lithosphere coupling in southern Tibet” has been published in the journal Proceedings of the National Academy of Sciences.

Composite metal foam better at stopping bullets than solid plates

After developing metal aerogels, foams and glass (here and here) researchers have found yet another novel way to structure these substances. Composite metal foam (CMF) is a type of material created by incorporating hollow beads of one metal into a substrate cast from another. Considering their low density, you could be fooled into assuming that they’re very flimsy. But they boast impressive physical characteristics — they can even stop armor piercing bullets.

Check out this video North Carolina State University recently uploaded to their YouTube channel.

The video shows a 7.62 x 63 mm standard-issue M2 armor piercing bullet, fired at the plate according to the testing procedures established by the National Institute of Justice (NIJ). The plate, less than one inch thick, was tough enough to turn the bullet to dust. While solid metal plates of similar thickness would also be able to stop the projectile, the test CMF plate actually performed better at the task. Not bad for what is essentially metal Swiss cheese.

Afsaneh Rabiei, professor of mechanical and aerospace engineering at NC State, explains:

“We could stop the bullet at a total thickness of less than an inch, while the indentation on the back was less than 8 millimeters,” he says.

“To put that in context, the NIJ standard allows up to 44 millimeters indentation in the back of an armor.”

As a bonus, they’re also lighter than metal plating. So there’s obviously a lot of interest in creating new types of body and vehicle armor based on them.

But what if even incredibly light and strong just doesn’t cut it? What if you need to haul nuclear waste around or need a material that can withstand the enormous temperatures of atmospheric re-entry? CMFs can help with that too.

Last year, aided by the Department of Energy’s Office of Nuclear Energy, Rabiei showed that these materials are very effective at shielding X-rays, gamma rays and neutron radiation. Rabiei independently published his work demonstrating that these metal foams handle fire and heat twice as well as the plain metals they are made of earlier this year.

A full paper of the ballistic properties of CMFs, with the title “Ballistic performance of composite metal foams” has been published online in the journal Composite Structures and can be read here.