Tag: University of California

This Skin Patch Can Power A Radio For 2 Days Using Your Own Sweat

Researchers have created a new skin patch that has powered a radio for two days using only human sweat. The Biofuel Skin Patch uses the sweat to provide its power – meaning it could be used to charge up devices like phones in the near future.




“If you were out for a run, you would be able to power a mobile device,” said Joseph Wang from the University of California, San Diego.

His research team at the university have been working on the technology. The biofuel patch is a few centimeters wide and sticks directly on the skin.

skin patch

It works by using enzymes that act like the metals inside regular batteries, which are then powered up by feeding off the lactic acid found in sweat.

Please like, share and tweet this article.

Pass it on: New Scientist

Mussel-Inspired Plastic May Lead To Self-Repairing Body Armour

Scientists have developed a new mussels inspired plastic that can stretch without snapping and repair its own molecular bonds, paving the way for self- repairing body armour.

The material could also find an application in the joints of robotic arms that need to bear heavy weights but still move around, researchers said.

Mussels and some other molluscs hang onto solid surfaces using an adhesive protein and tough, plastic like fibers, which are extremely strong and can repair themselves when a few molecular bonds within them are broken, they said.

The study, published in the journal Science, found that for a mussel, these stretchy yet strong fibres come in handy when a wave hits.




Researchers from University of California, Santa Barbara in the US created a plastic with these same properties by mimicking the chemistry the mussels use.

Molecular bonds between iron and an organic compound called catechol make the material difficult to break or tear, while still allowing it to remain stretchy, they said.

The iron-catechol bonds dissipate energy from something hitting or stretching the material. These “sacrificial bonds” break, but the overall structure stays intact.

It is like a bike helmet: if you are in a bike accident, the foam inside the helmet crushes and dissipates some of the energy.

“All that energy that would have gone into a skull fracture, instead goes into the helmet,” Megan Valentine from University of California said.

In our case, instead of foam we have this sacrificial bonding that protects the underlying polymer system,” Valentine said.

By sacrificing the iron-catechol bonds, the material can stretch by 50 per cent. Then, once the stress is taken away, the bonds reform, making it reusable, researchers said.

Adding these bonds results in the plastic being 770 times stretchier and 58 times stronger than it is without them, they said.

Please like, share and tweet this article.

Pass it on: New Scientist

The Big Bang: What Really Happened At Our Universe’s Birth?

It took quite a bit more than seven days to create the universe as we know it today.

Our universe was born about 13.7 billion years ago in a massive expansion that blew space up like a gigantic balloon.

That, in a nutshell, is the Big Bang theory, which virtually all cosmologists and theoretical physicists endorse. The evidence supporting the idea is extensive and convincing.

We know, for example, that the universe is still expanding even now, at an ever-accelerating rate.

Scientists have also discovered a predicted thermal imprint of the Big Bang, the universe-pervading cosmic microwave background radiation.




And we don’t see any objects obviously older than 13.7 billion years, suggesting that our universe came into being around that time.

All of these things put the Big Bang on an extremely solid foundation,” said astrophysicist Alex Filippenko of the University of California, Berkeley. “The Big Bang is an enormously successful theory.

So what does this theory teach us? What really happened at the birth of our universe, and how did it take the shape we observe today?

The beginning

Traditional Big Bang theory posits that our universe began with a singularity — a point of infinite density and temperature whose nature is difficult for our minds to grasp.

However, this may not accurately reflect reality, researchers say, because the singularity idea is based on Einstein’s theory of general relativity.

The problem is, there’s no reason whatsoever to believe general relativity in that regime,” said Sean Carroll, a theoretical physicist at Caltech.

It’s going to be wrong, because it doesn’t take into account quantum mechanics. And quantum mechanics is certainly going to be important once you get to that place in the history of the universe.

So the very beginning of the universe remains pretty murky. Scientists think they can pick the story up at about 10 to the minus 36 seconds one trillionth of a trillionth of a trillionth of a second after the Big Bang.

Inflation was the ‘bang’ of the Big Bang,” Filippenko said. “Before inflation, there was just a little bit of stuff, quite possibly, expanding just a little bit. We needed something like inflation to make the universe big.

During inflation, dark energy made the universe smooth out and accelerate. But it didn’t stick around for long.

Scientists don’t know what might have spurred inflation. That remains one of the key questions in Big Bang cosmology, Filippenko said.

Cosmologists and physicists are working hard to refine their theories and bring the universe’s earliest moments into sharper and sharper focus.

But will they ever truly know what happened at the Big Bang?

Please like, share and tweet this article.

Pass it on: New Scientist

The Toughest Ceramic Is Made From Mother-Of-Pearl Mimic

scientist

Biomimicry, technological innovation inspired by nature is one of the hottest ideas in science but has yet to yield many practical advances.

Scientists with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have mimicked the structure of mother of pearl to create what may well be the toughest ceramic ever produced.

Through the controlled freezing of suspensions in water of an aluminum oxide and the addition of a well known polymer, polymethylmethacrylate (PMMA), a team of researchers has produced ceramics that are 300 times tougher than their constituent components.




The team was led by Robert Ritchie, who holds joint appointments with Berkeley Lab’s Materials Sciences Division and the Materials Science and Engineering Department at the University of California, Berkeley.

Mother of pearl, or nacre, the inner lining of the shells of abalone, mussels and certain other mollusks, is renowned for both its iridescent beauty and its amazing toughness.

Nacre is 95-percent aragonite, a hard but brittle calcium carbonate mineral, with the rest of it made up of soft organic molecules. Yet nacre can be 3,000 times (in energy terms) more resistant to fracture than aragonite.

ceramic

No human-synthesized composite outperforms its constituent materials by such a wide margin. The problem has been that nacre’s remarkable strength is derived from a structural architecture that varies over lengths of scale ranging from nanometers to micrometers.

Two years ago, however, Berkeley Lab researchers Tomsia and Saiz found a way to improve the strength of bone substitutes through a processing technique that involved the freezing of seawater.

This process yielded a ceramic that was four times stronger than artificial bone. When seawater freezes, ice crystals form a scaffolding of thin layers.

ceramic

These layers are pure ice because during their formation impurities, such as salt and microorganisms, are expelled and entrapped in the space between the layers. The resulting architecture roughly resembles that of nacre.

In this latest research, Ritchie, working with Tomsia and Saiz, refined the freeze-casting technique and applied it to alumina/PMMA hybrid materials to create large porous ceramic scaffolds that much more closely mirrored the complex hierarchical microstructure of nacre.

To do this, they first employed directional freezing to promote the formation of thin layers (lamellae) of ice that served as templates for the creation of the layered alumina scaffolds.

ceramic

After the ice was removed, spaces between the alumina lamellae were filled with polymer.

For ceramic materials that are even tougher in the future, Ritchie says he and his colleagues need to improve the proportion of ceramic to polymer in their composites.

The alumina/PMMA hybrid was only 85-percent alumina. They want to boost ceramic content and thin the layers even further. They also want to replace the PMMA with a better polymer and eventually replace the polymer content altogether with metal.

ceramic

Such future composite materials would be lightweight and strong as well as tough, he says, and could find important applications in energy and transportation.

This research was supported by DOE’s Office of Science, through the Division of Materials Sciences and Engineering in the Basic Energy Sciences office.

Please like, share and tweet this article.

Pass it on: New Scientist