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The Days of Lithium Are Numbered

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Forget the toxic material lithium as researchers from the Massachusetts Institute of Technology (MIT) have come up with an alternative system for generating electricity which harnesses heat and uses no metals or toxic materials for powering smartphones or cars, even deep space missions.

The new approach is based on a discovery announced in 2010 by Michael Strano, the Carbon P. Dubbs professor in chemical engineering at the MIT, and his co-workers.

A wire made from tiny cylinders of carbon known as carbon nanotubes can produce an electrical current when it is progressively heated from one end to the other, for example, by coating it with a combustible material and then lighting one end to let it burn like a fuse.

Now, Strano and his team have increased the efficiency of the process more than a thousandfold and have produced devices that can put out power that can be produced by today’s best batteries.

The researchers, however, caution that it could take some years to develop the concept into a commercialisable product.

“It’s actually remarkable that this [phenomenon] hasn’t been studied before. The latest experiments show good agreement between theory and experimental results, providing strong confirmation of the underlying mechanism,” said Strano in a paper published in the journal Energy & Environmental Science.

Already, the device is powerful enough to show that it can power simple electronic devices such as an LED light.

Unlike batteries that can gradually lose power if they are stored for long periods, the new system should have a virtually indefinite shelf life.

That could make it suitable for uses such as a deep-space probe that remains dormant for many years as it travels to a distant planet and then needs a quick burst of power to send back data when it reaches its destination.

Basically, the effect arises as a pulse of heat pushes electrons through the bundle of carbon nanotubes, carrying the electrons with it like a bunch of surfers riding a wave.

The improvements in efficiency, Strano says, “brings [the technology] from a laboratory curiosity to being within striking distance of other portable energy technologies,” such as lithium-ion batteries or fuel cells.

In their latest version, the device is more than one percent efficient in converting heat energy to electrical energy, the team reports, which is “orders of magnitude more efficient than what’s been reported before.”

In fact, the energy efficiency is about 10,000 times greater than that reported in the original discovery paper.

“It took lithium-ion technology 25 years to get where they are” in terms of efficiency, Strano pointed out, whereas this technology has had only about a fifth of that development time.

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Ever Wonder How Two Pendulum Clocks Always Oscillate In Sync?

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Two pendulum clocks, hung from the same wooden structure, will always oscillate in synchronicity. Called “Huygens synchronisation” after the renowned Dutch physicist Christiaan Huygens, the secret behind this 350-year-old phenomenon has now been solved.

Researchers from Eindhoven University of Technology along with Mexican colleagues have presented the most accurate and detailed description of “Huygens synchronisation’ to date.

The insights help us understand synchronisation in all kinds of oscillating systems such as the biological rhythms of the human body, they noted.

Lacking the requisite mathematics at the time, Huygens contended that the effect was being caused by tiny vibrations in the wooden structure on which the clocks were hanging.

Henk Nijmeijer, professor of dynamics and control at Eindhoven University, found that Huygens explanation was right.

In the journal Scientific Reports, the team described the most comprehensive study undertaken to date on the effect.

“An odd sympathy” was the way Huygens termed the unexpected discovery he made at home in The Hague in 1665.

The team performed a modern variant of Huygens’ experiment whereby two pendulum clocks specially made for the purpose by the Mexican clock manufacturer Relojes Centenario were placed on a wooden undersurface.

In addition to taking extensive measurements, they analysed and simulated the effect using the most detailed mathematical model developed for this experiment.

This enabled them to dissect the mechanism behind the synchronisation correctly and in detail and consign to the bin the theory proposed two years ago that the synchronisation was attributable to acoustic pulses.

The team also discovered what variables determine whether the clocks swing in parallel with or counter to each other, something that Huygens did not observe.

“Another new discovery is that pendulum clocks are not only synchronous but also move more slowly over time and thus are not very reliable timekeepers,” they noted.
The scientists believe many similar occurrences of synchronisation are present in engineering and in nature like imbalanced rotor motion or the human heartbeat.

There are also indications that certain epileptic attacks are caused by the synchronisation of neurons that takes place in the brain.

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Coming Soon, A Polymer Nanobrush That Repels Dirt And Dust

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Scientists have developed a new way to make “polymer nanobrush” — bristly materials which prevent dust from accumulating on various surfaces.

Polymer brushes have been used to coat everything from eyeglass lenses, boats and medical devices — where they keep away smudges, damaging chemicals and germs — to artificial joints and mechanical components in vehicles where they act as a lubricant.

Developed by a team of engineers led by Christopher Li, professor at Drexel University’s college of engineering in Philadelphia, it gives scientists a higher degree of control over the shape of the brush and bristles and is much more efficient.

“The past few decades witnessed exciting progresses in studies on polymer brushes, and they show great promises in various fields, including coating, biomedical, sensing, catalysis to name just a few,” Li said.

His approach involves growing a functional two-dimensional sheet of polymer crystals — similar to a nanoscale piece of double-sided tape. When the sheet is stuck to an existing substrate, and the crystals are dissolved, the remaining polymer chains spring up, forming the bristles of the brush.

“We believe that our discovery of a new way to make polymer brushes is a significant advance in the field and will enable use of the brushes in exciting new ways,” added Li in the study published in the journal Nature Communications.

The new brush is the most densely packed polymer brushes to date, with bristles less than a nanometre apart.

Polymer brush materials are especially useful in situations where pieces need to fit tightly together but need to be able to move without friction throwing a wrench in the works.

These are also effective for keeping important surfaces free of particles, chemicals, proteins and other fouling agents.

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Now Don’t Wash Clothes, Just Expose Them To Light

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The day when you can look tidy even without washing your clothes does not seem too distant as researchers, including one of Indian origin, have developed a technology to make textiles clean themselves within less than six minutes when put them under a light bulb or out in the sun.

The researchers at RMIT University in Melbourne, Australia, have developed a cheap and efficient new way to grow special nanostructures — which can degrade organic matter when exposed to light — directly onto textiles.

“There’s more work to do to before we can start throwing out our washing machines, but this advance lays a strong foundation for the future development of fully self-cleaning textiles,” said researcher Rajesh Ramanathan.

The research paper was published in the journal Advanced Materials Interfaces.

The work paves the way towards nano-enhanced textiles that can spontaneously clean themselves of stains and grime simply by being put under light.

The process developed by the team had a variety of applications for catalysis-based industries such as agrochemicals, pharmaceuticals and natural products, and could be easily scaled up to industrial levels, Ramanathan said.

“The advantage of textiles is they already have a 3D structure so they are great at absorbing light, which in turn speeds up the process of degrading organic matter,” he explained.

The researchers worked with copper and silver-based nanostructures, which are known for their ability to absorb visible light.

When the nanostructures are exposed to light, they receive an energy boost that creates “hot electrons”.

These “hot electrons” release a burst of energy that enables the nanostructures to degrade organic matter.

The challenge for researchers has been to bring the concept out of the lab by working out how to build these nanostructures on an industrial scale and permanently attach them to textiles.

The RMIT team’s novel approach was to grow the nanostructures directly onto the textiles by dipping them into a few solutions, resulting in the development of stable nanostructures within 30 minutes.

When exposed to light, it took less than six minutes for some of the nano-enhanced textiles to spontaneously clean themselves.

“Our next step will be to test our nano-enhanced textiles with organic compounds that could be more relevant to consumers, to see how quickly they can handle common stains like tomato sauce or wine,” Ramanathan said.

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