Tag Archives: Oak Ridge National Laboratory

A new state for water molecules

ORNL researchers discovered that water in beryl displays some unique and unexpected characteristics. (Photo by Jeff Scovil)

ORNL researchers discovered that water in beryl displays some unique and unexpected characteristics. (Photo by Jeff Scovil)

That striking image from the Oak Ridge National Laboratory (ORNL; US) depicting a new state for water molecules looks like mixed media: photography and drawing/illustration. Thankfully, an April 22, 2016 news item on ScienceDaily provides a text description,

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy’s Oak Ridge National Laboratory [ORNL] describe a new tunneling state of water molecules confined in hexagonal ultra-small channels — 5 angstrom across — of the mineral beryl. An angstrom is 1/10-billionth of a meter, and individual atoms are typically about 1 angstrom in diameter.

The discovery, made possible with experiments at ORNL’s Spallation Neutron Source and the Rutherford Appleton Laboratory in the United Kingdom, demonstrates features of water under ultra confinement in rocks, soil and cell walls, which scientists predict will be of interest across many disciplines.

An April 22, 2016 ORNL news release (also on EurekAlert), which originated the news item, offers more detail,

“At low temperatures, this tunneling water exhibits quantum motion through the separating potential walls, which is forbidden in the classical world,” said lead author Alexander Kolesnikov of ORNL’s Chemical and Engineering Materials Division. “This means that the oxygen and hydrogen atoms of the water molecule are ‘delocalized’ and therefore simultaneously present in all six symmetrically equivalent positions in the channel at the same time. It’s one of those phenomena that only occur in quantum mechanics and has no parallel in our everyday experience.”

The existence of the tunneling state of water shown in ORNL’s study should help scientists better describe the thermodynamic properties and behavior of water in highly confined environments such as water diffusion and transport in the channels of cell membranes, in carbon nanotubes and along grain boundaries and at mineral interfaces in a host of geological environments.

ORNL co-author Lawrence Anovitz noted that the discovery is apt to spark discussions among materials, biological, geological and computational scientists as they attempt to explain the mechanism behind this phenomenon and understand how it applies to their materials.

“This discovery represents a new fundamental understanding of the behavior of water and the way water utilizes energy,” Anovitz said. “It’s also interesting to think that those water molecules in your aquamarine or emerald ring – blue and green varieties of beryl – are undergoing the same quantum tunneling we’ve seen in our experiments.”

While previous studies have observed tunneling of atomic hydrogen in other systems, the ORNL discovery that water exhibits such tunneling behavior is unprecedented. The neutron scattering and computational chemistry experiments showed that, in the tunneling state, the water molecules are delocalized around a ring so the water molecule assumes an unusual double top-like shape.

“The average kinetic energy of the water protons directly obtained from the neutron experiment is a measure of their motion at almost absolute zero temperature and is about 30 percent less than it is in bulk liquid or solid water,” Kolesnikov said. “This is in complete disagreement with accepted models based on the energies of its vibrational modes.”

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

Quantum Tunneling of Water in Beryl: A New State of the Water Molecule by Alexander I. Kolesnikov, George F. Reiter, Narayani Choudhury, Timothy R. Prisk, Eugene Mamontov, Andrey Podlesnyak, George Ehlers, Andrew G. Seel, David J. Wesolowski, and Lawrence M. Anovitz.
Phys. Rev. Lett. 116, 167802 – Published 22 April 2016

This paper is behind a paywall.

Large(!)-scale graphene composite fabrication at the US Oak Ridge National Laboratory (ORNL)

When you’re talking about large-scale production of nanomaterials, it would be more accurate term to say ‘relatively large when compared to the nanoscale’. A May 15, 2015 news item on ScienceDaily, trumpets the news,

One of the barriers to using graphene at a commercial scale could be overcome using a method demonstrated by researchers at the Department of Energy’s Oak Ridge National Laboratory [ORNL].

Graphene, a material stronger and stiffer than carbon fiber, has enormous commercial potential but has been impractical to employ on a large scale, with researchers limited to using small flakes of the material.

Now, using chemical vapor deposition, a team led by ORNL’s Ivan Vlassiouk has fabricated polymer composites containing 2-inch-by-2-inch sheets of the one-atom thick hexagonally arranged carbon atoms. [emphasis mine]

Once you understand where these scientists are coming from in terms of the material size, it becomes easier to appreciate the accomplishment and its potential. From a May 14, 2015 ORNL news release (also on EurekAlert), which originated the news item,

The findings, reported in the journal Applied Materials & Interfaces, could help usher in a new era in flexible electronics and change the way this reinforcing material is viewed and ultimately used.

“Before our work, superb mechanical properties of graphene were shown at a micro scale [one millionth of a metre],” said Vlassiouk, a member of ORNL’s Energy and Transportation Science Division. “We have extended this to a larger scale, which considerably extends the potential applications and market for graphene.”

While most approaches for polymer nanocomposition construction employ tiny flakes of graphene or other carbon nanomaterials that are difficult to disperse in the polymer, Vlassiouk’s team used larger sheets of graphene. This eliminates the flake dispersion and agglomeration problems and allows the material to better conduct electricity with less actual graphene in the polymer.

“In our case, we were able to use chemical vapor deposition to make a nanocomposite laminate that is electrically conductive with graphene loading that is 50 times less compared to current state-of-the-art samples,” Vlassiouk said. This is a key to making the material competitive on the market.

If Vlassiouk and his team can reduce the cost and demonstrate scalability, researchers envision graphene being used in aerospace (structural monitoring, flame-retardants, anti-icing, conductive), the automotive sector (catalysts, wear-resistant coatings), structural applications (self-cleaning coatings, temperature control materials), electronics (displays, printed electronics, thermal management), energy (photovoltaics, filtration, energy storage) and manufacturing (catalysts, barrier coatings, filtration).

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

Strong and Electrically Conductive Graphene-Based Composite Fibers and Laminates by Ivan Vlassiouk, Georgios Polizos, Ryan Cooper, Ilia Ivanov, Jong Kahk Keum, Felix Paulauskas, Panos Datskos, and Sergei Smirnov. ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/acsami.5b01367 Publication Date (Web): April 28, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Research into the properties of water at the nanoscale and water droplet networks

I have two pieces of research with the only common element being water. First, there’s a May 9, 2014 news release on EurekAlert issued by the Politecnico di Torino (Italy; rough translation: Turin Polytechnic),

Swimming in a honey pool. That’s the sensation a water molecule should “feel” while approaching a solid surface within a nanometer (i.e. less than a ten-thousandth of hair diameter). The reduction in water mobility in the very close proximity of surfaces at the nanoscale is the well-known phenomenon of “nanoconfinement”, and it is due to both electrostatic and van der Waals attractive forces ruling matter interactions at that scale.

In this context, scientists from Politecnico di Torino and Houston Methodist Research Institute have taken a further step forward, by formulating a quantitative model and a physical interpretation able of predicting the nanoconfinement effect in a rather general framework. In particular, geometric and chemical characteristics as well as physical conditions of diverse nanoconfining surfaces (e.g. proteins, carbon nanotubes, silica nanopores or iron oxide nanoparticles) have been quantitatively related to mobility reduction and “supercooling” conditions of water, namely the persistence of water in a liquid state at temperatures far below 0°C, when close to a solid surface.

This result has been achieved after two years of in silico (i.e. computer-based) and in vitro (i.e. experiment-driven) activities by Eliodoro Chiavazzo, Matteo Fasano, Pietro Asinari (Multi-Scale Modelling Lab, Department of Energy at Politecnico di Torino) and Paolo Decuzzi (Center for the Rational Design of Multifunctional Nanoconstructs at Houston Methodist Research Institute).

I love the image of swimming in a ‘honey pool’ and while developing a schema for predicting a nanoconfinement effect may not seem all that exciting to an outsider the applications are varied according to the news release,

This study may soon find applications in the optimization and rational design of a broad variety of novel technologies ranging from applied physics (e.g. “nanofluids”, suspensions made out of water and nanoparticles for enhancing heat transfer) to sustainable energy (e.g. thermal storage based on nanoconfined water within sorbent materials); from detection and removal of pollutant from water (e.g. molecular sieves) to nanomedicine.

In fact this work is finding an immediate application in the field of medicine as pertaining to magnetic resonance imaging (MRI), from the news release,

The latter is the field where the research has indeed found a first important application. Every year, almost sixty millions of Magnetic Resonance Imaging (MRI) scans are performed, with diagnostic purposes. In the past decade, MRI technology benefitted from various significant scientific advances, which allowed more precise and sharper images of pathological tissues. Among other, contrast agents (i.e. substances used for improving contrast of structures or fluids within the body) importantly contributed in enhancing MRI performances.

This research activity has been able to explain and predict the increase in MRI performances due to nanoconfined contrast agents, which are currently under development at the Houston Methodist Research Institute. Hence, the discovery paves the way to further increase in the quality of MRI images, in order to possibly improve chances of earlier and more accurate detection of diseases in millions of patients, every year.

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

Scaling behaviour for the water transport in nanoconfined geometries by Eliodoro Chiavazzo, Matteo Fasano, Pietro Asinari & Paolo Decuzzi. Nature Communications 5 Article number: 4565 doi:10.1038/ncomms4565 Published 03 April 2014

This is an open access paper and, unusually, I am excerpting the Abstract as I find it helps to further explain this work (although the more technical aspects are lost on me),

The transport of water in nanoconfined geometries is different from bulk phase and has tremendous implications in nanotechnology and biotechnology. Here molecular dynamics is used to compute the self-diffusion coefficient D of water within nanopores, around nanoparticles, carbon nanotubes and proteins. For almost 60 different cases, D is found to scale linearly with the sole parameter θ as D(θ)=DB[1+(DC/DB−1)θ], with DB and DC the bulk and totally confined diffusion of water, respectively. The parameter θ is primarily influenced by geometry and represents the ratio between the confined and total water volumes. The D(θ) relationship is interpreted within the thermodynamics of supercooled water. As an example, such relationship is shown to accurately predict the relaxometric response of contrast agents for magnetic resonance imaging. The D(θ) relationship can help in interpreting the transport of water molecules under nanoconfined conditions and tailoring nanostructures with precise modulation of water mobility.

The second piece of ‘water’ research was featured in a May 13, 2014 news item on Nanowerk,

A simple new technique to form interlocking beads of water in ambient conditions could prove valuable for applications in biological sensing, membrane research and harvesting water from fog.

Researchers at the Department of Energy’s Oak Ridge National Laboratory have developed a method to create air-stable water droplet networks known as droplet interface bilayers. These interconnected water droplets have many roles in biological research because their interfaces simulate cell membranes. Cumbersome fabrication methods, however, have limited their use.

A May 13, 2014 Oak Ridge National Laboratory (ORNL) news release, which originated the news item, provides more details,

“The way they’ve been made since their inception is that two water droplets are formed in an oil bath then brought together while they’re submerged in oil,” said ORNL’s Pat Collier, who led the team’s study published in the Proceedings of the National Academy of Sciences. “Otherwise they would just pop like soap bubbles.”

Instead of injecting water droplets into an oil bath, the ORNL research team experimented with placing the droplets on a superhydrophobic surface infused with a coating of oil. The droplets aligned side by side without merging.

To the researchers’ surprise, they were also able to form non-coalescing water droplet networks without including lipids in the water solution. Scientists typically incorporate phospholipids into the water mixture, which leads to the formation of an interlocking lipid bilayer between the water droplets.

“When you have those lipids at the interfaces of the water drops, it’s well known that they won’t coalesce because the interfaces join together and form a stable bilayer,” ORNL coauthor Jonathan Boreyko said. “So our surprise was that even without lipids in the system, the pure water droplets on an oil-infused surface in air still don’t coalesce together.”

The team’s research revealed how the unexpected effect is caused by a thin oil film that is squeezed between the pure water droplets as they come together, preventing the droplets from merging into one. Watch a video of the process on ORNL’s YouTube channel.

With or without the addition of lipids, the team’s technique offers new insight for a host of applications. Controlling the behavior of pure water droplets on oil-infused surfaces is key to developing dew- or fog-harvesting technology as well as more efficient condensers, for instance.

“Our finding of this non-coalescence phenomenon will shed light on these droplet-droplet interactions that can occur on oil-infused systems,” Boreyko said.

The ability to create membrane-like water droplet networks by adding lipids leads to a different set of functional applications, Collier noted.

“These bilayers can be used in anything from synthetic biology to creating circuits to bio-sensing applications,” he said. “For example, we could make a bio-battery or a signaling network by stringing some of these droplets together. Or, we could use it to sense the presence of airborne molecules.”

The team’s study also demonstrated ways to control the performance and lifetime of the water droplets by manipulating oil viscosity and temperature and humidity levels.

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

Air-stable droplet interface bilayers on oil-infused surfaces by Jonathan B. Boreyko, Georgios Polizos, Panos G. Datskos, Stephen A. Sarles, and C. Patrick Collier.  PNAS 2014 ; published ahead of print May 12, 2014, doi: 10.1073/pnas.1400381111

This paper is behind a paywall.

Chaos, brains, and ferroelectrics: “We started to see things that should have been completely impossible …”

Given my interest in neuromorphic (mimicking the human brain) engineering, this work at the US Oak Ridge National Laboratories was guaranteed to catch my attention. From the Nov. 18, 2013 news item on Nanowerk,

Unexpected behavior in ferroelectric materials explored by researchers at the Department of Energy’s Oak Ridge National Laboratory supports a new approach to information storage and processing.

Ferroelectric materials are known for their ability to spontaneously switch polarization when an electric field is applied. Using a scanning probe microscope, the ORNL-led team took advantage of this property to draw areas of switched polarization called domains on the surface of a ferroelectric material. To the researchers’ surprise, when written in dense arrays, the domains began forming complex and unpredictable patterns on the material’s surface.

“When we reduced the distance between domains, we started to see things that should have been completely impossible,” said ORNL’s Anton Ievlev, …

The Nov. 18, 2013 Oak Ridge National Laboratory news release, which originated the news item, provides more details,

“All of a sudden, when we tried to draw a domain, it wouldn’t form, or it would form in an alternating pattern like a checkerboard.  At first glance, it didn’t make any sense. We thought that when a domain forms, it forms. It shouldn’t be dependent on surrounding domains.”  [said Ievlev]

After studying patterns of domain formation under varying conditions, the researchers realized the complex behavior could be explained through chaos theory. One domain would suppress the creation of a second domain nearby but facilitate the formation of one farther away — a precondition of chaotic behavior, says ORNL’s Sergei Kalinin, who led the study.

“Chaotic behavior is generally realized in time, not in space,” he said. ”An example is a dripping faucet: sometimes the droplets fall in a regular pattern, sometimes not, but it is a time-dependent process. To see chaotic behavior realized in space, as in our experiment, is highly unusual.”

Collaborator Yuriy Pershin of the University of South Carolina explains that the team’s system possesses key characteristics needed for memcomputing, an emergent computing paradigm in which information storage and processing occur on the same physical platform.

Memcomputing is basically how the human brain operates: [emphasis mine] Neurons and their connections–synapses–can store and process information in the same location,” Pershin said. “This experiment with ferroelectric domains demonstrates the possibility of memcomputing.”

Encoding information in the domain radius could allow researchers to create logic operations on a surface of ferroelectric material, thereby combining the locations of information storage and processing.

The researchers note that although the system in principle has a universal computing ability, much more work is required to design a commercially attractive all-electronic computing device based on the domain interaction effect.

“These studies also make us rethink the role of surface and electrochemical phenomena in ferroelectric materials, since the domain interactions are directly traced to the behavior of surface screening charges liberated during electrochemical reaction coupled to the switching process,” Kalinin said.

For anyone who’s interested in exploring this particular approach to mimicking the human brain, here’s a citation for and a link to the researchers’ paper,

Intermittency, quasiperiodicity and chaos in probe-induced ferroelectric domain switching by A. V. Ievlev, S. Jesse, A. N. Morozovska, E. Strelcov, E. A. Eliseev, Y. V. Pershin, A. Kumar, V. Ya. Shur, & S. V. Kalinin. Nature Physics (2013) doi:10.1038/nphys2796 Published online 17 November 2013

This paper is behind a paywall although it is possible to preview it for free via ReadCube Access.