Tag Archives: Australian National University (ANU)

The nanoscale precision of pearls

An October 21, 2021 news item on phys.org features a quote about nothingness and symmetry (Note: A link has been removed),

In research that could inform future high-performance nanomaterials, a University of Michigan-led team has uncovered for the first time how mollusks build ultradurable structures with a level of symmetry that outstrips everything else in the natural world, with the exception of individual atoms.

“We humans, with all our access to technology, can’t make something with a nanoscale architecture as intricate as a pearl,” said Robert Hovden, U-M assistant professor of materials science and engineering and an author on the paper. “So we can learn a lot by studying how pearls go from disordered nothingness to this remarkably symmetrical structure.” [emphasis mine]

The analysis was done in collaboration with researchers at the Australian National University, Lawrence Berkeley National Laboratory, Western Norway University [of Applied Sciences] and Cornell University.

a. A Keshi pearl that has been sliced into pieces for study. b. A magnified cross-section of the pearl shows its transition from its disorderly center to thousands of layers of finely matched nacre. c. A magnification of the nacre layers shows their self-correction—when one layer is thicker, the next is thinner to compensate, and vice-versa. d, e: Atomic scale images of the nacre layers. f, g, h, i: Microscopy images detail the transitions between the pearl’s layers. Credit: University of Michigan

An October 21, 2021 University of Michigan news release (also on EurekAlert), which originated the news item, reveals a surprise,

Published in the Proceedings of the National Academy of Sciences [PNAS], the study found that a pearl’s symmetry becomes more and more precise as it builds, answering centuries-old questions about how the disorder at its center becomes a sort of perfection. 

Layers of nacre, the iridescent and extremely durable organic-inorganic composite that also makes up the shells of oysters and other mollusks, build on a shard of aragonite that surrounds an organic center. The layers, which make up more than 90% of a pearl’s volume, become progressively thinner and more closely matched as they build outward from the center.

Perhaps the most surprising finding is that mollusks maintain the symmetry of their pearls by adjusting the thickness of each layer of nacre. If one layer is thicker, the next tends to be thinner, and vice versa. The pearl pictured in the study contains 2,615 finely matched layers of nacre, deposited over 548 days.

“These thin, smooth layers of nacre look a little like bed sheets, with organic matter in between,” Hovden said. “There’s interaction between each layer, and we hypothesize that that interaction is what enables the system to correct as it goes along.”

The team also uncovered details about how the interaction between layers works. A mathematical analysis of the pearl’s layers show that they follow a phenomenon known as “1/f noise,” where a series of events that seem to be random are connected, with each new event influenced by the one before it. 1/f noise has been shown to govern a wide variety of natural and human-made processes including seismic activity, economic markets, electricity, physics and even classical music.

“When you roll dice, for example, every roll is completely independent and disconnected from every other roll. But 1/f noise is different in that each event is linked,” Hovden said. “We can’t predict it, but we can see a structure in the chaos. And within that structure are complex mechanisms that enable a pearl’s thousands of layers of nacre to coalesce toward order and precision.”

The team found that pearls lack true long-range order—the kind of carefully planned symmetry that keeps the hundreds of layers in brick buildings consistent. Instead, pearls exhibit medium-range order, maintaining symmetry for around 20 layers at a time. This is enough to maintain consistency and durability over the thousands of layers that make up a pearl.

The team gathered their observations by studying Akoya “keshi” pearls, produced by the Pinctada imbricata fucata oyster near the Eastern shoreline of Australia. They selected these particular pearls, which measure around 50 millimeters in diameter, because they form naturally, as opposed to bead-cultured pearls, which have an artificial center. Each pearl was cut with a diamond wire saw into sections measuring three to five millimeters in diameter, then polished and examined under an electron microscope.

Hovden says the study’s findings could help inform next-generation materials with precisely layered nanoscale architecture.

“When we build something like a brick building, we can build in periodicity through careful planning and measuring and templating,” he said. “Mollusks can achieve similar results on the nanoscale by using a different strategy. So we have a lot to learn from them, and that knowledge could help us make stronger, lighter materials in the future.”

Here’s a link to and a citation for the paper,

The mesoscale order of nacreous pearls by Jiseok Gim, Alden Koch, Laura M. Otter, Benjamin H. Savitzky, Sveinung Erland, Lara A. Estroff, Dorrit E. Jacob, and Robert Hovden. PNAS vol. 118 no. 42 e2107477118 DOI: https://doi.org/10.1073/pnas.2107477118 Published in issue October 19, 2021 Published online October 18, 2021

This paper appears to be open access.

Bendable phones that are partially organic

It’s been about nine  or 10 years since I first heard about bendable phones (my September 29, 2010 posting). The concept keeps popping up from time to time (my April 25, 2017 posting) and this time, we have Australian scientists to thank for this latest work described in an October 5, 2018 news item on Nanowerk (Note: A link has been removed),

Engineers at ANU [Australian National University] have invented a semiconductor with organic and inorganic materials that can convert electricity into light very efficiently, and it is thin and flexible enough to help make devices such as mobile phones bendable (Advanced Materials, “Efficient and Layer-Dependent Exciton Pumping across Atomically Thin Organic–Inorganic Type-I Heterostructures”).

The invention also opens the door to a new generation of high-performance electronic devices made with organic materials that will be biodegradable or that can be easily recycled, promising to help substantially reduce e-waste.

An October 5, 2018 ANU press release (also on EurekAlert but published October 4, 2018) expands on the theme,

The huge volumes of e-waste generated by discarded electronic devices around the world is causing irreversible damage to the environment. Australia produces 200,000 tonnes of e-waste every year – only four per cent of this waste is recycled.

The organic component has the thickness of just one atom – made from just carbon and hydrogen – and forms part of the semiconductor that the ANU team developed. The inorganic component has the thickness of around two atoms. The hybrid structure can convert electricity into light efficiently for displays on mobile phones, televisions and other electronic devices.

Lead senior researcher Associate Professor Larry Lu said the invention was a major breakthrough in the field.

“For the first time, we have developed an ultra-thin electronics component with excellent semiconducting properties that is an organic-inorganic hybrid structure and thin and flexible enough for future technologies, such as bendable mobile phones and display screens,” said Associate Professor Lu from the ANU Research School of Engineering.

PhD researcher Ankur Sharma, who recently won the ANU 3-Minute Thesis competition, said experiments demonstrated the performance of their semiconductor would be much more efficient than conventional semiconductors made with inorganic materials such as silicon.

“We have the potential with this semiconductor to make mobile phones as powerful as today’s supercomputers,” said Mr Sharma from the ANU Research School of Engineering.

“The light emission from our semiconducting structure is very sharp, so it can be used for high-resolution displays and, since the materials are ultra-thin, they have the flexibility to be made into bendable screens and mobile phones in the near future.”

The team grew the organic semiconductor component molecule by molecule, in a similar way to 3D printing. The process is called chemical vapour deposition.

“We characterised the opto-electronic and electrical properties of our invention to confirm the tremendous potential of it to be used as a future semiconductor component,” Associate Professor Lu said.

“We are working on growing our semiconductor component on a large scale, so it can be commercialised in collaboration with prospective industry partners.”

Here’s a link to and a citation for the paper,

Efficient and Layer‐Dependent Exciton Pumping across Atomically Thin Organic–Inorganic Type‐I Heterostructures by Linglong Zhang, Ankur Sharma, Yi Zhu, Yuhan Zhang, Bowen Wang, Miheng Dong, Hieu T. Nguyen, Zhu Wang, Bo Wen, Yujie Cao, Boqing Liu, Xueqian Sun, Jiong Yang, Ziyuan Li. Advanced Materials Volume30, Issue 40 1803986 (October 4, 2018) DOI:https://doi.org/10.1002/adma.201803986 First published [onliine]: 30 August 2018

This paper is behind a paywall.

Materials that may protect astronauts from radiation in space

Sparing astronauts from harmful radiation  is one of the goals for this project according to a July 3, 2017 news item on Nanowerk (Note: A link has been removed),

Scientists at The Australian National University (ANU) have designed a new nano material that can reflect or transmit light on demand with temperature control, opening the door to technology that protects astronauts in space from harmful radiation (Advanced Functional Materials, “Reversible Thermal Tuning of All-Dielectric Metasurfaces”).

Lead researcher Dr Mohsen Rahmani from ANU said the material was so thin that hundreds of layers could fit on the tip of a needle and could be applied to any surface, including spacesuits.

The first speaker’s enthusiasm leaps off the screen,

For whose who prefer to read their news, a July 4, 2017 ANU press release, which originated the news item, provides more detail,

“Our invention has a lot of potential applications, such as protecting astronauts or satellites with an ultra-thin film that can be adjusted to reflect various dangerous ultraviolet or infrared radiation in different environments,” said Dr Rahmani, an Australian Research Council (ARC) Discovery Early Career Research Fellow at the Nonlinear Physics Centre within the ANU Research School of Physics and Engineering.

“Our technology significantly increases the resistance threshold against harmful radiation compared to today’s technologies, which rely on absorbing radiation with thick filters.”

Co-researcher Associate Professor Andrey Miroshnichenko said the invention could be tailored for other light spectrums including visible light, which opened up a whole array of innovations, including architectural and energy saving applications.

“For instance, you could have a window that can turn into a mirror in a bathroom on demand, or control the amount of light passing through your house windows in different seasons,” said Dr Miroshnichenko from the Nonlinear Physics Centre within the ANU Research School of Physics and Engineering.

“What I love about this invention is that the design involved different research disciplines including physics, materials science and engineering.”

Co-lead researcher Dr Lei Xu said achieving cost-efficient and confined temperature control such as local heating was feasible.

“Much like your car has a series of parallel resistive wires on the back windscreen to defog the rear view, a similar arrangement could be used with our invention to confine the temperature control to a precise location,” said Dr Xu from the Nonlinear Physics Centre within the ANU Research School of Physics and Engineering.

The innovation builds on more than 15 years of research supported by the ARC through CUDOS, a Centre of Excellence, and the Australian National Fabrication Facility.

Here’s a link to and a citation for the paper,

Reversible Thermal Tuning of All-Dielectric Metasurfaces by Mohsen Rahmani, Lei Xu, Andrey E. Miroshnichenko, Andrei Komar, Rocio Camacho-Morales, Haitao Chen, Yair Zárate, Sergey Kruk, Guoquan Zhang, Dragomir N. Neshev, and Yuri S. Kivshar. Advanced Functional Materials DOI: 10.1002/adfm.201700580 Version of Record online: 3 JUL 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Quantum device provides capabilities of Dr. Who’s sonic screwdriver and Star Trek’s tricorder

I think these Australian scientists are bigger fans of Dr. Who than Star Trek if I read this March 8, 2017 news item on Nanowerk rightly (Note: A link has been removed),

Physicists have designed a handheld device inspired by the sonic screwdriver in Doctor Who and the tricorder in Star Trek that will use the power of MRI and mass spectrometry to perform a chemical analysis of objects (Nano Letters, “Nanomechanical Sensing Using Spins in Diamond”).

The sonic screwdriver is a tool used in Doctor Who to scan and identify matter, among other functions, while the multi-purpose tricorder in Star Trek can provide a detailed analysis of living things.

This video confirms the scientists’ Dr. Who fanhood,

A March 8, 2017 Australian National University (ANU) news release, which originated the news item, provides more technical detail about the research,

Lead researcher Dr Marcus Doherty from ANU said the team had proven the concept of a diamond-based quantum device to perform similar functions to these science fiction tools and would now develop a prototype.

“Laboratories and hospitals will have the power to do full chemical analyses to solve complex problems with our device that they can afford and move around easily,” said Dr Doherty from the ANU Research School of Physics and Engineering (RSPE).

“This device is going to enable many people to use powerful instruments like molecular MRI machines and mass spectrometers much more readily.”

Dr Doherty said medical researchers could use the device to weigh and identify complex molecules such as proteins, which drive diseases, such as cancer, and cures for those diseases.

“Every great advance for microscopy has driven scientific revolution,” he said.

“Our invention will help to solve many complex problems in a wide range of areas, including medical, environmental and biosecurity research.”

Molecular MRI is a form of the common medical imaging technology that is capable of identifying the chemical composition of individual molecules, while mass spectrometers measure the masses within a sample.

Co-researcher Michael Barson said the device would use tiny defects in a diamond to measure the mass and chemical composition of molecules with advanced quantum techniques borrowed from atomic clocks and gravitational wave detectors.

“For the mass spectrometry, when a molecule attaches to the diamond device, its mass changes, which changes the frequency, and we measure the change in frequency using the defects in the diamond,” said Mr Barson, a PhD student from RSPE.

“For the MRI, we are looking at how the magnetic fields in the molecule will influence the defects as well.”

Here’s a link to and a citation for the paper,

Nanomechanical Sensing Using Spins in Diamond by Michael S. J. Barson, Phani Peddibhota, Preeti Ovartchaiyapong, Kumaravelu Ganesan, Richard L. Taylor, Matthew Gebert, Zoe Mielens, Berndt Koslowski, David A. Simpson, Liam P. McGuinness, Jeffrey McCallum, Steven Prawer, Shinobu Onoda, Takeshi Ohshima, Ania C. Bleszynski Jayich, Fedor Jelezko, Neil B. Manson, and Marcus W. Doherty. Nano Lett., 2017, 17 (3), pp 1496–1503 DOI: 10.1021/acs.nanolett.6b04544 Publication Date (Web): February 1, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.