Tag Archives: US Dept. of Energy

Windows and roofs ‘self-adapt’ to heating and cooling conditions

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I have two items about thermochromic coatings. It’s a little confusing since the American Association for the Advancement of Science (AAAS), which publishes the journal featuring both papers has issued a news release that seemingly refers to both papers as a single piece of research.

Onto, the press/new releases from the research institutions to be followed by the AAAS news release.

Nanyang Technological University (NTU) does windows

A December 16, 2021 news item on Nanowerk announced work on energy-saving glass,

An international research team led by scientists from Nanyang Technological University, Singapore (NTU Singapore) has developed a material that, when coated on a glass window panel, can effectively self-adapt to heat or cool rooms across different climate zones in the world, helping to cut energy usage.

Developed by NTU researchers and reported in the journal Science (“Scalable thermochromic smart windows with passive radiative cooling regulation”), the first-of-its-kind glass automatically responds to changing temperatures by switching between heating and cooling.

The self-adaptive glass is developed using layers of vanadium dioxide nanoparticles composite, Poly(methyl methacrylate) (PMMA), and low-emissivity coating to form a unique structure which could modulate heating and cooling simultaneously.

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A December 17, 2021 NTU press release (PDF), also on EurekAlert but published December 16, 2021, which originated the news item, delves further into the research (Note: A link has been removed),

The newly developed glass, which has no electrical components, works by exploiting the spectrums of light responsible for heating and cooling.

During summer, the glass suppresses solar heating (near infrared light), while boosting radiative cooling (long-wave infrared) – a natural phenomenon where heat emits through surfaces towards the cold universe – to cool the room. In the winter, it does the opposite to warm up the room.

In lab tests using an infrared camera to visualise results, the glass allowed a controlled amount of heat to emit in various conditions (room temperature – above 70°C), proving its ability to react dynamically to changing weather conditions.

New glass regulates both heating and cooling

Windows are one of the key components in a building’s design, but they are also the least energy-efficient and most complicated part. In the United States alone, window-associated energy consumption (heating and cooling) in buildings accounts for approximately four per cent of their total primary energy usage each year according to an estimation based on data available from the Department of Energy in US.[1]

While scientists elsewhere have developed sustainable innovations to ease this energy demand – such as using low emissivity coatings to prevent heat transfer and electrochromic glass that regulate solar transmission from entering the room by becoming tinted – none of the solutions have been able to modulate both heating and cooling at the same time, until now.

The principal investigator of the study, Dr Long Yi of the NTU School of Materials Science and Engineering (MSE) said, “Most energy-saving windows today tackle the part of solar heat gain caused by visible and near infrared sunlight. However, researchers often overlook the radiative cooling in the long wavelength infrared. While innovations focusing on radiative cooling have been used on walls and roofs, this function becomes undesirable during winter. Our team has demonstrated for the first time a glass that can respond favourably to both wavelengths, meaning that it can continuously self-tune to react to a changing temperature across all seasons.”

As a result of these features, the NTU research team believes their innovation offers a convenient way to conserve energy in buildings since it does not rely on any moving components, electrical mechanisms, or blocking views, to function.

To improve the performance of windows, the simultaneous modulation of both solar transmission and radiative cooling are crucial, said co-authors Professor Gang Tan from The University of Wyoming, USA, and Professor Ronggui Yang from the Huazhong University of Science and Technology, Wuhan, China, who led the building energy saving simulation.

“This innovation fills the missing gap between traditional smart windows and radiative cooling by paving a new research direction to minimise energy consumption,” said Prof Gang Tan.

The study is an example of groundbreaking research that supports the NTU 2025 strategic plan, which seeks to address humanity’s grand challenges on sustainability, and accelerate the translation of research discoveries into innovations that mitigate human impact on the environment.

Innovation useful for a wide range of climate types

As a proof of concept, the scientists tested the energy-saving performance of their invention using simulations of climate data covering all populated parts of the globe (seven climate zones).

The team found the glass they developed showed energy savings in both warm and cool seasons, with an overall energy saving performance of up to 9.5%, or ~330,000 kWh per year (estimated energy required to power 60 household in Singapore for a year) less than commercially available low emissivity glass in a simulated medium sized office building.

First author of the study Wang Shancheng, who is Research Fellow and former PhD student of Dr Long Yi, said, “The results prove the viability of applying our glass in all types of climates as it is able to help cut energy use regardless of hot and cold seasonal temperature fluctuations. This sets our invention apart from current energy-saving windows which tend to find limited use in regions with less seasonal variations.”

Moreover, the heating and cooling performance of their glass can be customised to suit the needs of the market and region for which it is intended.

“We can do so by simply adjusting the structure and composition of special nanocomposite coating layered onto the glass panel, allowing our innovation to be potentially used across a wide range of heat regulating applications, and not limited to windows,” Dr Long Yi said.

Providing an independent view, Professor Liangbing Hu, Herbert Rabin Distinguished Professor, Director of the Center for Materials Innovation at the University of Maryland, USA, said, “Long and co-workers made the original development of smart windows that can regulate the near-infrared sunlight and the long-wave infrared heat. The use of this smart window could be highly important for building energy-saving and decarbonization.”  

A Singapore patent has been filed for the innovation. As the next steps, the research team is aiming to achieve even higher energy-saving performance by working on the design of their nanocomposite coating.

The international research team also includes scientists from Nanjing Tech University, China. The study is supported by the Singapore-HUJ Alliance for Research and Enterprise (SHARE), under the Campus for Research Excellence and Technological Enterprise (CREATE) programme, Minster of Education Research Fund Tier 1, and the Sino-Singapore International Joint Research Institute.

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

Scalable thermochromic smart windows with passive radiative cooling regulation by Shancheng Wang, Tengyao Jiang, Yun Meng, Ronggui Yang, Gang Tan, and Yi Long. Science • 16 Dec 2021 • Vol 374, Issue 6574 • pp. 1501-1504 • DOI: 10.1126/science.abg0291

This paper is behind a paywall.

Lawrence Berkeley National Laboratory (Berkeley Lab; LBNL) does roofs

A December 16, 2021 Lawrence Berkeley National Laboratory news release (also on EurekAlert) announces an energy-saving coating for roofs (Note: Links have been removed),

Scientists have developed an all-season smart-roof coating that keeps homes warm during the winter and cool during the summer without consuming natural gas or electricity. Research findings reported in the journal Science point to a groundbreaking technology that outperforms commercial cool-roof systems in energy savings.

“Our all-season roof coating automatically switches from keeping you cool to warm, depending on outdoor air temperature. This is energy-free, emission-free air conditioning and heating, all in one device,” said Junqiao Wu, a faculty scientist in Berkeley Lab’s Materials Sciences Division and a UC Berkeley professor of materials science and engineering who led the study.

Today’s cool roof systems, such as reflective coatings, membranes, shingles, or tiles, have light-colored or darker “cool-colored” surfaces that cool homes by reflecting sunlight. These systems also emit some of the absorbed solar heat as thermal-infrared radiation; in this natural process known as radiative cooling, thermal-infrared light is radiated away from the surface.

The problem with many cool-roof systems currently on the market is that they continue to radiate heat in the winter, which drives up heating costs, Wu explained.

“Our new material – called a temperature-adaptive radiative coating or TARC – can enable energy savings by automatically turning off the radiative cooling in the winter, overcoming the problem of overcooling,” he said.

A roof for all seasons

Metals are typically good conductors of electricity and heat. In 2017, Wu and his research team discovered that electrons in vanadium dioxide behave like a metal to electricity but an insulator to heat – in other words, they conduct electricity well without conducting much heat. “This behavior contrasts with most other metals where electrons conduct heat and electricity proportionally,” Wu explained.

Vanadium dioxide below about 67 degrees Celsius (153 degrees Fahrenheit) is also transparent to (and hence not absorptive of) thermal-infrared light. But once vanadium dioxide reaches 67 degrees Celsius, it switches to a metal state, becoming absorptive of thermal-infrared light. This ability to switch from one phase to another – in this case, from an insulator to a metal – is characteristic of what’s known as a phase-change material.

To see how vanadium dioxide would perform in a roof system, Wu and his team engineered a 2-centimeter-by-2-centimeter TARC thin-film device.

TARC “looks like Scotch tape, and can be affixed to a solid surface like a rooftop,” Wu said.

In a key experiment, co-lead author Kechao Tang set up a rooftop experiment at Wu’s East Bay home last summer to demonstrate the technology’s viability in a real-world environment.

A wireless measurement device set up on Wu’s balcony continuously recorded responses to changes in direct sunlight and outdoor temperature from a TARC sample, a commercial dark roof sample, and a commercial white roof sample over multiple days.

How TARC outperforms in energy savings

The researchers then used data from the experiment to simulate how TARC would perform year-round in cities representing 15 different climate zones across the continental U.S.

Wu enlisted Ronnen Levinson, a co-author on the study who is a staff scientist and leader of the Heat Island Group in Berkeley Lab’s Energy Technologies Area, to help them refine their model of roof surface temperature. Levinson developed a method to estimate TARC energy savings from a set of more than 100,000 building energy simulations that the Heat Island Group previously performed to evaluate the benefits of cool roofs and cool walls across the United States.

Finnegan Reichertz, a 12th grade student at the East Bay Innovation Academy in Oakland who worked remotely as a summer intern for Wu last year, helped to simulate how TARC and the other roof materials would perform at specific times and on specific days throughout the year for each of the 15 cities or climate zones the researchers studied for the paper.

The researchers found that TARC outperforms existing roof coatings for energy saving in 12 of the 15 climate zones, particularly in regions with wide temperature variations between day and night, such as the San Francisco Bay Area, or between winter and summer, such as New York City.

“With TARC installed, the average household in the U.S. could save up to 10% electricity,” said Tang, who was a postdoctoral researcher in the Wu lab at the time of the study. He is now an assistant professor at Peking University in Beijing, China.

Standard cool roofs have high solar reflectance and high thermal emittance (the ability to release heat by emitting thermal-infrared radiation) even in cool weather.

According to the researchers’ measurements, TARC reflects around 75% of sunlight year-round, but its thermal emittance is high (about 90%) when the ambient temperature is warm (above 25 degrees Celsius or 77 degrees Fahrenheit), promoting heat loss to the sky. In cooler weather, TARC’s thermal emittance automatically switches to low, helping to retain heat from solar absorption and indoor heating, Levinson said.

Findings from infrared spectroscopy experiments using advanced tools at Berkeley Lab’s Molecular Foundry validated the simulations.

“Simple physics predicted TARC would work, but we were surprised it would work so well,” said Wu. “We originally thought the switch from warming to cooling wouldn’t be so dramatic. Our simulations, outdoor experiments, and lab experiments proved otherwise – it’s really exciting.”

The researchers plan to develop TARC prototypes on a larger scale to further test its performance as a practical roof coating. Wu said that TARC may also have potential as a thermally protective coating to prolong battery life in smartphones and laptops, and shield satellites and cars from extremely high or low temperatures. It could also be used to make temperature-regulating fabric for tents, greenhouse coverings, and even hats and jackets.

Co-lead authors on the study were Kaichen Dong and Jiachen Li.

The Molecular Foundry is a nanoscience user facility at Berkeley Lab.

This work was primarily supported by the DOE Office of Science and a Bakar Fellowship.

The technology is available for licensing and collaboration. If interested, please contact Berkeley Lab’s Intellectual Property Office, ipo@lbl.gov.

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

Temperature-adaptive radiative coating for all-season household thermal regulation by Kechao Tang, Kaichen Dong, Jiachen Li, Madeleine P. Gordon, Finnegan G. Reichertz, Hyungjin Kim, Yoonsoo Rho, Qingjun Wang, Chang-Yu Lin, Costas P. Grigoropoulos, Ali Javey, Jeffrey J. Urban, Jie Yao, Ronnen Levinson, Junqiao Wu. Science • 16 Dec 2021 • Vol 374, Issue 6574 • pp. 1504-1509 • DOI: 10.1126/science.abf7136

This paper is behind a paywall.

An interesting news release from the AAAS

While it’s a little confusing as it cites only the ‘window’ research from NTU, the body of this news release offers some additional information about the usefulness of thermochromic materials and seemingly refers to both papers, from a December 16, 2021 AAAS news release,

Temperature-adaptive passive radiative cooling for roofs and windows

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When it’s cold out, window glass and roof coatings that use passive radiative cooling to keep buildings cool can be designed to passively turn off radiative cooling to avoid heat loss, two new studies show.  Their proof-of-concept analyses demonstrate that passive radiative cooling can be expanded to warm and cold climate applications and regions, potentially providing all-season energy savings worldwide. Buildings consume roughly 40% of global energy, a large proportion of which is used to keep them cool in warmer climates. However, most temperature regulation systems commonly employed are not very energy efficient and require external power or resources. In contrast, passive radiative cooling technologies, which use outer space as a near-limitless natural heat sink, have been extensively examined as a means of energy-efficient cooling for buildings. This technology uses materials designed to selectively emit narrow-band radiation through the infrared atmospheric window to disperse heat energy into the coldness of space. However, while this approach has proven effective in cooling buildings to below ambient temperatures, it is only helpful during the warmer months or in regions that are perpetually hot. Furthermore, the inability to “turn off” passive cooling in cooler climes or in regions with large seasonal temperature variations means that continuous cooling during colder periods would exacerbate the energy costs of heating. In two different studies, by Shancheng Wang and colleagues and Kechao Tang and colleagues, researchers approach passive radiative cooling from an all-season perspective and present a new, scalable temperature-adaptive radiative technology that passively turns off radiative cooling at lower temperatures. Wang et al. and Tang et al. achieve this using a tungsten-doped vanadium dioxide and show how it can be applied to create both window glass and a flexible roof coating, respectively. Model simulations of the self-adapting materials suggest they could provide year-round energy savings across most climate zones, especially those with substantial seasonal temperature variations. 

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I wish them all good luck with getting these materials to market.

Preventing corrosion in oil pipelines at the nanoscale

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A June 7, 2019 news item on Azonano announces research into the process of oil pipeline corrosion at the nanoscale (Note: A link has been removed),

Steel pipes tend to rust and sooner or later fail. To anticipate disasters, oil companies and others have developed computer models to foretell when replacement is necessary. However, if the models themselves are incorrect, they can be amended only through experience, an expensive problem if detection happens too late.

Currently, scientists at Sandia National Laboratories, the Department of Energy’s Center for Integrated Nanotechnologies and the Aramco Research Center in Boston, have discovered that a specific form of nanoscale corrosion is responsible for suddenly diminishing the working life of steel pipes, according to a paper recently published in Nature’s Materials Degradation journal.

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A June 6, 2019 Sandia National Laboratories news release (also on EurekAlert), which originated the news item, provides more technical detail,

Using transmission electron microscopes, which shoot electrons through targets to take pictures, the researchers were able to pin the root of the problem on a triple junction formed by a grain of cementite — a compound of carbon and iron — and two grains of ferrite, a type of iron. This junction forms frequently during most methods of fashioning steel pipe.

Iron atoms slip-sliding away

The researchers found that disorder in the atomic structure of those triple junctions made it easier for the corrosive solution to remove iron atoms along that interface.
In the experiment, the corrosive process stopped when the triple junction had been consumed by corrosion, but the crevice left behind allowed the corrosive solution to attack the interior of the steel.

“We thought of a possible solution for forming new pipe, based on changing the microstructure of the steel surface during forging, but it still needs to be tested and have a patent filed if it works,” said Sandia’s principle investigator Katherine Jungjohann, a paper author and lead microscopist. “But now we think we know where the major problem is.”

Aramco senior research scientist Steven Hayden added, “This was the world’s first real-time observation of nanoscale corrosion in a real-world material — carbon steel — which is the most prevalent type of steel used in infrastructure worldwide. Through it, we identified the types of interfaces and mechanisms that play a role in the initiation and progression of localized steel corrosion. The work is already being translated into models used to prevent corrosion-related catastrophes like infrastructure collapse and pipeline breaks.”

To mimic the chemical exposure of pipe in the field, where the expensive, delicate microscopes could not be moved, very thin pipe samples were exposed at Sandia to a variety of chemicals known to pass through oil pipelines.

Sandia researcher and paper author Khalid Hattar put a dry sample in a vacuum and used a transmission electron microscope to create maps of the steel grain types and their orientation, much as a pilot in a plane might use a camera to create area maps of farmland and roads, except that Hattar’s maps had approximately 6 nanometers resolution. (A nanometer is one-billionth of a meter.)

“By comparing these maps before and after the liquid corrosion experiments, a direct identification of the first phase that fell out of the samples could be identified, essentially identifying the weakest link in the internal microstructure,” Hattar said.

Sandia researcher and paper author Paul Kotula said, “The sample we analyzed was considered a low-carbon steel, but it has relatively high-carbon inclusions of cementite which are the sites of localized corrosion attacks.

“Our transmission electron microscopes were a key piece of this work, allowing us to image the sample, observe the corrosion process, and do microanalysis before and after the corrosion occurred to identify the part played by the ferrite and cementite grains and the corrosion product.”

When Hayden first started working in corrosion research, he said, “I was daunted at how complex and poorly understood corrosion is. This is largely because realistic experiments would involve observing complex materials like steel in liquid environments and with nanoscale resolution, and the technology to accomplish such a feat had only recently been developed and yet to be applied to corrosion. Now we are optimistic that further work at Sandia and the Center for Integrated Nanotechnologies will allow us to rethink manufacturing processes to minimize the expression of the susceptible nanostructures that render the steel vulnerable to accelerated decay mechanisms.”

Invisible path of localized corrosion

Localized corrosion is different from uniform corrosion. The latter occurs in bulk form and is highly predictable. The former is invisible, creating a pathway observable only at its endpoint and increasing bulk corrosion rates by making it easier for corrosion to spread.

“A better understanding of the mechanisms by which corrosion initiates and progresses at these types of interfaces in steel will be key to mitigating corrosion-related losses,” according to the paper.

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

Localized corrosion of low-carbon steel at the nanoscale by Steven C. Hayden, Claire Chisholm, Rachael O. Grudt, Jeffery A. Aguiar, William M. Mook, Paul G. Kotula, Tatiana S. Pilyugina, Daniel C. Bufford, Khalid Hattar, Timothy J. Kucharski, Ihsan M. Taie, Michele L. Ostraat & Katherine L. Jungjohann. npj Materials Degradation volume 3, Article number: 17 (2019) DOI: https://doi.org/10.1038/s41529-019-0078-1 Published 12 April 2019

This paper is open access.

Carbon nanotube optics and the quantum

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A US-France-Germany collaboration has led to some intriguing work with carbon nanotubes. From a June 18, 2018 news item on ScienceDaily,

Researchers at Los Alamos and partners in France and Germany are exploring the enhanced potential of carbon nanotubes as single-photon emitters for quantum information processing. Their analysis of progress in the field is published in this week’s edition of the journal Nature Materials.

“We are particularly interested in advances in nanotube integration into photonic cavities for manipulating and optimizing light-emission properties,” said Stephen Doorn, one of the authors, and a scientist with the Los Alamos National Laboratory site of the Center for Integrated Nanotechnologies (CINT). “In addition, nanotubes integrated into electroluminescent devices can provide greater control over timing of light emission and they can be feasibly integrated into photonic structures. We are highlighting the development and photophysical probing of carbon nanotube defect states as routes to room-temperature single photon emitters at telecom wavelengths.”

A June 18, 2018 Los Alamos National Laboratory (LANL) news release (also on EurekAlert), which originated the news item, expands on the theme,

The team’s overview was produced in collaboration with colleagues in Paris (Christophe Voisin [Ecole Normale Supérieure de Paris (ENS)]) who are advancing the integration of nanotubes into photonic cavities for modifying their emission rates, and at Karlsruhe (Ralph Krupke [Karlsruhe Institute of Technology (KIT]) where they are integrating nanotube-based electroluminescent devices with photonic waveguide structures. The Los Alamos focus is the analysis of nanotube defects for pushing quantum emission to room temperature and telecom wavelengths, he said.

As the paper notes, “With the advent of high-speed information networks, light has become the main worldwide information carrier. . . . Single-photon sources are a key building block for a variety of technologies, in secure quantum communications metrology or quantum computing schemes.”

The use of single-walled carbon nanotubes in this area has been a focus for the Los Alamos CINT team, where they developed the ability to chemically modify the nanotube structure to create deliberate defects, localizing excitons and controlling their release. Next steps, Doorn notes, involve integration of the nanotubes into photonic resonators, to provide increased source brightness and to generate indistinguishable photons. “We need to create single photons that are indistinguishable from one another, and that relies on our ability to functionalize tubes that are well-suited for device integration and to minimize environmental interactions with the defect sites,” he said.

“In addition to defining the state of the art, we wanted to highlight where the challenges are for future progress and lay out some of what may be the most promising future directions for moving forward in this area. Ultimately, we hope to draw more researchers into this field,” Doorn said.

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

Carbon nanotubes as emerging quantum-light sources by X. He, H. Htoon, S. K. Doorn, W. H. P. Pernice, F. Pyatkov, R. Krupke, A. Jeantet, Y. Chassagneux & C. Voisin. Nature Materials (2018) DOI: https://doi.org/10.1038/s41563-018-0109-2 Published online June 18, 2018

This paper is behind a paywall.

Carbon nanotubes for water desalination

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In discussions about water desalination and carbon nanomaterials,  it’s graphene that’s usually mentioned these days. By contrast, scientists from the US Department of Energy’s Lawrence Livermore National Laboratory (LLNL) have turned to carbon nanotubes,

There are two news items about the work at LLNL on ScienceDaily, this first one originated by the American Association for the Advancement of Science (AAAS) offers a succinct summary of the work (from an August 24, 2017 news item on ScienceDaily,

At just the right size, carbon nanotubes can filter water with better efficiency than biological proteins, a new study reveals. The results could pave the way to new water filtration systems, at a time when demands for fresh water pose a global threat to sustainable development.

A class of biological proteins, called aquaporins, is able to effectively filter water, yet scientists have not been able to manufacture scalable systems that mimic this ability. Aquaporins usually exhibit channels for filtering water molecules at a narrow width of 0.3 nanometers, which forces the water molecules into a single-file chain.

Here, Ramya H. Tunuguntla and colleagues experimented with nanotubes of different widths to see which ones are best for filtering water. Intriguingly, they found that carbon nanotubes with a width of 0.8 nanometers outperformed aquaporins in filtering efficiency by a factor of six.

These narrow carbon nanotube porins (nCNTPs) were still slim enough to force the water molecules into a single-file chain. The researchers attribute the differences between aquaporins and nCNTPS to differences in hydrogen bonding — whereas pore-lining residues in aquaporins can donate or accept H bonds to incoming water molecules, the walls of CNTPs cannot form H bonds, permitting unimpeded water flow.

The nCNTPs in this study maintained permeability exceeding that of typical saltwater, only diminishing at very high salt concentrations. Lastly, the team found that by changing the charges at the mouth of the nanotube, they can alter the ion selectivity. This advancement is highlighted in a Perspective [in Science magazine] by Zuzanna Siwy and Francesco Fornasiero.

The second Aug. 24, 2017 news item on ScienceDaily offers a more technical  perspective,

Lawrence Livermore scientists, in collaboration with researchers at Northeastern University, have developed carbon nanotube pores that can exclude salt from seawater. The team also found that water permeability in carbon nanotubes (CNTs) with diameters smaller than a nanometer (0.8 nm) exceeds that of wider carbon nanotubes by an order of magnitude.

The nanotubes, hollow structures made of carbon atoms in a unique arrangement, are more than 50,000 times thinner than a human hair. The super smooth inner surface of the nanotube is responsible for their remarkably high water permeability, while the tiny pore size blocks larger salt ions.

There’s a rather lovely illustration for this work,

An artist’s depiction of the promise of carbon nanotube porins for desalination. The image depicts a stylized carbon nanotube pipe that delivers clean desalinated water from the ocean to a kitchen tap. Image by Ryan Chen/LLNL

An Aug. 24, 2017 LLNL news release (also on EurekAlert), which originated the second news item, proceeds

Increasing demands for fresh water pose a global threat to sustainable development, resulting in water scarcity for 4 billion people. Current water purification technologies can benefit from the development of membranes with specialized pores that mimic highly efficient and water selective biological proteins.

“We found that carbon nanotubes with diameters smaller than a nanometer bear a key structural feature that enables enhanced transport. The narrow hydrophobic channel forces water to translocate in a single-file arrangement, a phenomenon similar to that found in the most efficient biological water transporters,” said Ramya Tunuguntla, an LLNL postdoctoral researcher and co-author of the manuscript appearing in the Aug. 24 [2017]edition of Science.

Computer simulations and experimental studies of water transport through CNTs with diameters larger than 1 nm showed enhanced water flow, but did not match the transport efficiency of biological proteins and did not separate salt efficiently, especially at higher salinities. The key breakthrough achieved by the LLNL team was to use smaller-diameter nanotubes that delivered the required boost in performance.

“These studies revealed the details of the water transport mechanism and showed that rational manipulation of these parameters can enhance pore efficiency,” said Meni Wanunu, a physics professor at Northeastern University and co-author on the study.

“Carbon nanotubes are a unique platform for studying molecular transport and nanofluidics,” said Alex Noy, LLNL principal investigator on the CNT project and a senior author on the paper. “Their sub-nanometer size, atomically smooth surfaces and similarity to cellular water transport channels make them exceptionally suited for this purpose, and it is very exciting to make a synthetic water channel that performs better than nature’s own.”

This discovery by the LLNL scientists and their colleagues has clear implications for the next generation of water purification technologies and will spur a renewed interest in development of the next generation of high-flux membranes.

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

Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins by Ramya H. Tunuguntla, Robert Y. Henley, Yun-Chiao Yao, Tuan Anh Pham, Meni Wanunu, Aleksandr Noy. Science 25 Aug 2017: Vol. 357, Issue 6353, pp. 792-796 DOI: 10.1126/science.aan2438

This paper is behind a paywall.

And, Northeastern University issued an August 25, 2017 news release (also on EurekAlert) by Allie Nicodemo,

Earth is 70 percent water, but only a tiny portion—0.007 percent—is available to drink.

As potable water sources dwindle, global population increases every year. One potential solution to quenching the planet’s thirst is through desalinization—the process of removing salt from seawater. While tantalizing, this approach has always been too expensive and energy intensive for large-scale feasibility.

Now, researchers from Northeastern have made a discovery that could change that, making desalinization easier, faster and cheaper than ever before. In a paper published Thursday [August 24, 2017] in Science, the group describes how carbon nanotubes of a certain size act as the perfect filter for salt—the smallest and most abundant water contaminant.

Filtering water is tricky because water molecules want to stick together. The “H” in H2O is hydrogen, and hydrogen bonds are strong, requiring a lot of energy to separate. Water tends to bulk up and resist being filtered. But nanotubes do it rapidly, with ease.

A carbon nanotube is like an impossibly small rolled up sheet of paper, about a nanometer in diameter. For comparison, the diameter of a human hair is 50 to 70 micrometers—50,000 times wider. The tube’s miniscule size, exactly 0.8 nm, only allows one water molecule to pass through at a time. This single-file lineup disrupts the hydrogen bonds, so water can be pushed through the tubes at an accelerated pace, with no bulking.

“You can imagine if you’re a group of people trying to run through the hallway holding hands, it’s going to be a lot slower than running through the hallway single-file,” said co-author Meni Wanunu, associate professor of physics at Northeastern. Wanunu and post doctoral student Robert Henley collaborated with scientists at the Lawrence Livermore National Laboratory in California to conduct the research.

Scientists led by Aleksandr Noy at Lawrence Livermore discovered last year [2016] that carbon nanotubes were an ideal channel for proton transport. For this new study, Henley brought expertise and technology from Wanunu’s Nanoscale Biophysics Lab to Noy’s lab, and together they took the research one step further.

In addition to being precisely the right size for passing single water molecules, carbon nanotubes have a negative electric charge. This causes them to reject anything with the same charge, like the negative ions in salt, as well as other unwanted particles.

“While salt has a hard time passing through because of the charge, water is a neutral molecule and passes through easily,” Wanunu said. Scientists in Noy’s lab had theorized that carbon nanotubes could be designed for specific ion selectivity, but they didn’t have a reliable system of measurement. Luckily, “That’s the bread and butter of what we do in Meni’s lab,” Henley said. “It created a nice symbiotic relationship.”

“Robert brought the cutting-edge measurement and design capabilities of Wanunu’s group to my lab, and he was indispensable in developing a new platform that we used to measure the ion selectivity of the nanotubes,” Noy said.

The result is a novel system that could have major implications for the future of water security. The study showed that carbon nanotubes are better at desalinization than any other existing method— natural or man-made.

To keep their momentum going, the two labs have partnered with a leading water purification organization based in Israel. And the group was recently awarded a National Science Foundation/Binational Science Foundation grant to conduct further studies and develop water filtration platforms based on their new method. As they continue the research, the researchers hope to start programs where students can learn the latest on water filtration technology—with the goal of increasing that 0.007 percent.

As is usual in these cases there’s a fair degree of repetition but there’s always at least one nugget of new information, in this case, a link to Israel. As I noted many times, the Middle East is experiencing serious water issues. My most recent ‘water and the Middle East’ piece is an August 21, 2017 post about rainmaking at the Masdar Institute in United Arab Emirates. Approximately 50% of the way down the posting, I mention Israel and Palestine’s conflict over water.

Ferroelectric roadmap to neuromorphic computing

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Having written about memristors and neuromorphic engineering a number of times here, I’m  quite intrigued to see some research into another nanoscale device for mimicking the functions of a human brain.

The announcement about the latest research from the team at the US Department of Energy’s Argonne National Laboratory is in a Feb. 14, 2017 news item on Nanowerk (Note: A link has been removed),

Research published in Nature Scientific Reports (“Ferroelectric symmetry-protected multibit memory cell”) lays out a theoretical map to use ferroelectric material to process information using multivalued logic – a leap beyond the simple ones and zeroes that make up our current computing systems that could let us process information much more efficiently.

A Feb. 10, 2017 Argonne National Laboratory news release by Louise Lerner, which originated the news item, expands on the theme,

The language of computers is written in just two symbols – ones and zeroes, meaning yes or no. But a world of richer possibilities awaits us if we could expand to three or more values, so that the same physical switch could encode much more information.

“Most importantly, this novel logic unit will enable information processing using not only “yes” and “no”, but also “either yes or no” or “maybe” operations,” said Valerii Vinokur, a materials scientist and Distinguished Fellow at the U.S. Department of Energy’s Argonne National Laboratory and the corresponding author on the paper, along with Laurent Baudry with the Lille University of Science and Technology and Igor Lukyanchuk with the University of Picardie Jules Verne.

This is the way our brains operate, and they’re something on the order of a million times more efficient than the best computers we’ve ever managed to build – while consuming orders of magnitude less energy.

“Our brains process so much more information, but if our synapses were built like our current computers are, the brain would not just boil but evaporate from the energy they use,” Vinokur said.

While the advantages of this type of computing, called multivalued logic, have long been known, the problem is that we haven’t discovered a material system that could implement it. Right now, transistors can only operate as “on” or “off,” so this new system would have to find a new way to consistently maintain more states – as well as be easy to read and write and, ideally, to work at room temperature.

Hence Vinokur and the team’s interest in ferroelectrics, a class of materials whose polarization can be controlled with electric fields. As ferroelectrics physically change shape when the polarization changes, they’re very useful in sensors and other devices, such as medical ultrasound machines. Scientists are very interested in tapping these properties for computer memory and other applications; but the theory behind their behavior is very much still emerging.

The new paper lays out a recipe by which we could tap the properties of very thin films of a particular class of ferroelectric material called perovskites.

According to the calculations, perovskite films could hold two, three, or even four polarization positions that are energetically stable – “so they could ‘click’ into place, and thus provide a stable platform for encoding information,” Vinokur said.

The team calculated these stable configurations and how to manipulate the polarization to move it between stable positions using electric fields, Vinokur said.

“When we realize this in a device, it will enormously increase the efficiency of memory units and processors,” Vinokur said. “This offers a significant step towards realization of so-called neuromorphic computing, which strives to model the human brain.”

Vinokur said the team is working with experimentalists to apply the principles to create a working system

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

Ferroelectric symmetry-protected multibit memory cell by Laurent Baudry, Igor Lukyanchuk, & Valerii M. Vinokur. Scientific Reports 7, Article number: 42196 (2017) doi:10.1038/srep42196 Published online: 08 February 2017

This paper is open access.

Heat, evolution, and the shape of gold nanorods

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A Feb. 23, 2015 news item on Azonano features gold nanorods and their shapeshifting ways when releasing heat,

Researchers at the U.S. Department of Energy’s Argonne National Laboratory have revealed previously unobserved behaviors that show how details of the transfer of heat at the nanoscale cause nanoparticles to change shape in ensembles.

The new findings depict three distinct stages of evolution in groups of gold nanorods, from the initial rod shape to the intermediate shape to a sphere-shaped nanoparticle. The research suggests new rules for the behavior of nanorod ensembles, providing insights into how to increase heat transfer efficiency in a nanoscale system.

A Feb. 18, 2015 Argonne National Laboratory news release by Justin H. S. Breaux, which originated the news item, provides more details about the work,

At the nanoscale, individual gold nanorods have unique electronic, thermal and optical properties. Understanding these properties and managing how collections of these elongated nanoparticles absorb and release this energy as heat will drive new research towards next-generation technologies such as water purification systems, battery materials and cancer research.

A good deal is known about how single nanorods behave—but little is known about how nanorods behave in ensembles of millions. Understanding how the individual behavior of each nanorod, including how its orientation and rate of transition differ from those around it, impacts the collective kinetics of the ensemble and is critical to using nanorods in future technologies.

“We started with a lot of questions,” said Argonne physicist Yuelin Li, “like ‘How much power can the particles sustain before losing functionality? How do individual changes at the nanoscale affect the overall functionality? How much heat is released to the surrounding area?’ Each nanorod is continuously undergoing a change in shape when heated beyond melting temperature, which means a change in the surface area and thus a change in its thermal and hydrodynamic properties.”

The researchers used a laser to heat the nanoparticles and X-rays to analyze their changing shapes. Generally, nanorods transition into nanospheres more quickly when supplied with a higher intensity of laser power. In this case, completely different ensemble behaviors were observed when this intensity increased incrementally. The intensity of the heat applied changes not only the nanoparticles’ shape at various rates but also affects their ability to efficiently absorb and release heat.

“For us, the key was to understand just how efficient the nanorods were at transferring light into heat in many different scenarios,” said nanoscientist Subramanian Sankaranarayanan of Argonne’s Center for Nanoscale Materials. “Then we had to determine the physics behind how heat was transferred and all the different ways these nanorods could transition into nanospheres.”

To observe how the rod makes this transition, researchers first shine a laser pulse at the nanorod suspended in a water solution at Argonne’s Advanced Photon Source. The laser lasts for less than a hundred femtoseconds, nearly one trillion times faster than a blink of the eye. What follows is a series of focused and rapid X-ray bursts using a technique called small angle X-ray scattering. The resulting data is used to determine the average shape of the particle as it changes over time.

In this way, scientists can reconstruct the minute changes occurring in the shape of the nanorod. However, to understand the physics underlying this phenomenon, the researchers needed to look deeper at how individual atoms vibrate and move during the transition. For this, they turned to the field of molecular dynamics using the supercomputing power of the 10-petaflop Mira supercomputer at the Argonne Leadership Computing Facility.

Mira used mathematical equations to pinpoint the individual movements of nearly two million of the nanorods’ atoms in the water. Using factors such as the shape, temperature and rate of change, the researchers built simulations of the nanorod in many different scenarios to see how the structure changes over time.

“In the end,” said Sankaranarayanan, “we discovered the heat transfer rates for shorter but wider nanospheres are lower than for their rod-shaped predecessors. This decrease in heat transfer efficiency at the nanoscale plays a key role in accelerating the transition from rod to sphere when heated beyond the melting temperature.”

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

Femtosecond Laser Pulse Driven Melting in Gold Nanorod Aqueous Colloidal Suspension: Identification of a Transition from Stretched to Exponential Kinetics by Yuelin Li, Zhang Jiang, Xiao-Min Lin, Haidan Wen, Donald A. Walko, Sanket A. Deshmukh, Ram Subbaraman, Subramanian K. R. S. Sankaranarayanan, Stephen K. Gray, & Phay Ho. Scientific Reports 5, Article number: 8146 doi:10.1038/srep08146 Published 30 January 2015

This article is open access.

Dumbbells at the nanoscale according to researchers at the (US) Argonne National Laboratory

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Researchers at the US Dept. of Energy’s Argonne National Laboratory are providing new insight into how nanoparticles ‘grow’. From a Dec. 5, 2014 news item on Nanowerk,

Like snowflakes, nanoparticles come in a wide variety of shapes and sizes. The geometry of a nanoparticle is often as influential as its chemical makeup in determining how it behaves, from its catalytic properties to its potential as a semiconductor component.

Thanks to a new study from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, researchers are closer to understanding the process by which nanoparticles made of more than one material – called heterostructured nanoparticles – form. This process, known as heterogeneous nucleation, is the same mechanism by which beads of condensation form on a windowpane.

The scientists have provided an image which illustrates their findings,

This picture combines a transmission electron microscope image of a nanodumbbell with a gold domain oriented in direction. The seed and gold domains in the dumbbell in the image on the right are identified by geometric phase analysis. Image credit: Soon Gu Kwon.

This picture combines a transmission electron microscope image of a nanodumbbell with a gold domain oriented in direction. The seed and gold domains in the dumbbell in the image on the right are identified by geometric phase analysis. Image credit: Soon Gu Kwon.

A Dec. 4, 2014 Argonne National Laboratory news release by Jared Sagoff, which originated the news item, describes the structures being examined and the reason for doing so,

Heterostructured nanoparticles can be used as catalysts and in advanced energy conversion and storage systems. Typically, these nanoparticles are created from tiny “seeds” of one material, on top of which another material is grown.  In this study, the Argonne researchers noticed that the differences in the atomic arrangements of the two materials have a big impact on the shape of the resulting nanoparticle.

“Before we started this experiment, it wasn’t entirely clear what’s happening at the interface when one material grows on another,” said nanoscientist Elena Shevchenko of Argonne Center for Nanoscale Materials, a DOE Office of Science user facility.

In this study, the researchers observed the formation of a nanoparticle consisting of platinum and gold.  The researchers started with a platinum seed and grew gold around it. Initially, the gold covered the platinum seed’s surface uniformly, creating a type of nanoparticle known as “core-shell.” However, as more gold was deposited, it started to grow unevenly, creating a dumbbell-like structure.

Thanks to state-of-the-art X-ray analysis provided by Argonne’s Advanced Photon Source (APS), a DOE Office of Science user facility, the researchers identified the cause of the dumbbell formation as “lattice mismatch,” in which the spacing between the atoms in the two materials doesn’t align.

“Essentially, you can think of lattice mismatch as having a row of smaller boxes on the bottom layer and larger boxes on the top layer.  When you try to fit the larger boxes into the space for a smaller box, it creates an immense strain,” said Argonne physicist Byeongdu Lee.

While the lattice mismatch is only fractions of a nanometer, the effect accumulates as layer after layer of gold forms on the platinum. The mismatch can be handled by the first two layers of gold atoms – creating the core-shell effect – but afterwards it proves too much to overcome. “The arrangement of atoms is the same in the two materials, but the distance between atoms is different,” said Argonne postdoctoral researcher Soon Gu Kwon. “Eventually, this becomes unstable, and the growth of the gold becomes unevenly distributed.”

As the gold continues to accumulate on one side of the seed nanoparticle, small quantities “slide” down the side of the nanoparticle like grains of sand rolling down the side of a sand hill, creating the dumbbell shape.

The advantage of the Argonne study comes from the researchers’ ability to perform in situ observations of the material in realistic conditions using the APS. “This is the first time anyone has been able to study the kinetics of this heterogeneous nucleation process of nanoparticles in real-time under realistic conditions,” said Argonne physicist Byeongdu Lee. “The combination of two X-ray techniques gave us the ability to observe the material at both the atomic level and the nanoscale, which gave us a good view of how the nanoparticles form and transform.” All conclusions made based on the X-ray studies were further confirmed using atomic-resolution microscopy in the group of Professor Robert Klie of the University of Illinois at Chicago.

This analysis of nanoparticle formation will help to lay the groundwork for the formation of new materials with different and controllable properties, according to Shevchenko. “In order to design materials, you have to understand how these processes happen at a very basic level,” she said.

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

Heterogeneous nucleation and shape transformation of multicomponent metallic nanostructures by Soon Gu Kwon, Galyna Krylova, Patrick J. Phillips, Robert F. Klie, Soma Chattopadhyay, Tomohiro Shibata, Emilio E. Bunel, Yuzi Liu, Vitali B. Prakapenka, Byeongdu Lee, & Elena V. Shevchenko. Nature Materials (2014) doi:10.1038/nmat4115 Published online 02 November 2014

This paper is behind a paywall but there is a free preview via ReadCube Access.

Not ageing gracefully; the lithium-ion battery story

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There’s an alphabet soup’s worth of agencies involved in research on lithium-ion battery ageing which has resulted in two papers as noted in a May 30, 2014 news item Azonano,

Batteries do not age gracefully. The lithium ions that power portable electronics cause lingering structural damage with each cycle of charge and discharge, making devices from smartphones to tablets tick toward zero faster and faster over time. To stop or slow this steady degradation, scientists must track and tweak the imperfect chemistry of lithium-ion batteries with nanoscale precision.

In two recent Nature Communications papers, scientists from several U.S. Department of Energy national laboratories—Lawrence Berkeley, Brookhaven, SLAC, and the National Renewable Energy Laboratory—collaborated to map these crucial billionths-of-a-meter dynamics and lay the foundation for better batteries.

A May 29, 2014 Brookhaven National Laboratory news release by Justin Eure, which originated the news item, describes the research techniques in more detail,

“We discovered surprising and never-before-seen evolution and degradation patterns in two key battery materials,” said Huolin Xin, a materials scientist at Brookhaven Lab’s Center for Functional Nanomaterials (CFN) and coauthor on both studies. “Contrary to large-scale observation, the lithium-ion reactions actually erode the materials non-uniformly, seizing upon intrinsic vulnerabilities in atomic structure in the same way that rust creeps unevenly across stainless steel.”

Xin used world-leading electron microscopy techniques in both studies to directly visualize the nanoscale chemical transformations of battery components during each step of the charge-discharge process. In an elegant and ingenious setup, the collaborations separately explored a nickel-oxide anode and a lithium-nickel-manganese-cobalt-oxide cathode—both notable for high capacity and cyclability—by placing samples inside common coin-cell batteries running under different voltages.

“Armed with a precise map of the materials’ erosion, we can plan new ways to break the patterns and improve performance,” Xin said.

In these experiments, lithium ions traveled through an electrolyte solution, moving into an anode when charging and a cathode when discharging. The processes were regulated by electrons in the electrical circuit, but the ions’ journeys—and the battery structures—subtly changed each time.

The news release first describes the research involving the nickel-oxide anode, one of the two areas of interest,

For the nickel-oxide anode, researchers submerged the batteries in a liquid organic electrolyte and closely controlled the charging rates. They stopped at predetermined intervals to extract and analyze the anode. Xin and his collaborators rotated 20-nanometer-thick sheets of the post-reaction material inside a carefully calibrated transmission electron microscope (TEM) grid at CFN to catch the contours from every angle—a process called electron tomography.

To see the way the lithium-ions reacted with the nickel oxide, the scientists used a suite of custom-written software to digitally reconstruct the three-dimensional nanostructures with single-nanometer resolution. Surprisingly, the reactions sprang up at isolated spatial points rather than sweeping evenly across the surface.

“Consider the way snowflakes only form around tiny particles or bits of dirt in the air,” Xin said. “Without an irregularity to glom onto, the crystals cannot take shape. Our nickel oxide anode only transforms into metallic nickel through nanoscale inhomogeneities or defects in the surface structure, a bit like chinks in the anode’s armor.”

The electron microscopy provided a crucial piece of the larger puzzle assembled in concert with Berkeley Lab materials scientists and soft x-ray spectroscopy experiments conducted at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL). The combined data covered the reactions on the nano-, meso-, and microscales.

Next, there’s this about the second area of interest, a lithium-nickel-manganese-cobalt-oxide (NMC) cathode (from the news release),

In the other study, scientists sought the voltage sweet-spot for the high-performing lithium-nickel-manganese-cobalt-oxide (NMC) cathode: How much power can be stored, at what intensity, and across how many cycles?

The answers hinged on intrinsic material qualities and the structural degradation caused by cycles at 4.7 volts and 4.3 volts, as measured against a lithium metal standard.

As revealed through another series of coin-cell battery tests, 4.7 volts caused rapid decomposition of the electrolytes and poor cycling—the higher power comes at a price. A 4.3-volt battery, however, offered a much longer cycling lifetime at the cost of lower storage and more frequent recharges.

In both cases, the chemical evolution exhibited sprawling surface asymmetries, though not without profound patterns.

“As the lithium ions race through the reaction layers, they cause clumping crystallization—a kind of rock-salt matrix builds up over time and begins limiting performance,” Xin said. “We found that these structures tended to form along the lithium-ion reaction channels, which we directly visualized under the TEM. The effect was even more pronounced at higher voltages, explaining the more rapid deterioration.”

Identifying this crystal-laden reaction pathways hints at a way forward in battery design.

“It may be possible to use atomic deposition to coat the NMC cathodes with elements that resist crystallization, creating nanoscale boundaries within the micron-sized powders needed at the cutting-edge of industry,” Xin said. “In fact, Berkeley Lab battery experts Marca Doeff and Feng Lin are working on that now.”

Shirley Meng, a professor at UC San Diego’s Department of NanoEngineering, added, “This beautiful study combines several complementary tools that probe both the bulk and surface of the NMC layered oxide—one of the most promising cathode materials for high-voltage operation that enables higher energy density in lithium-ion batteries. The meaningful insights provided by this study will significantly impact the optimization strategies for this type of cathode material.”

The TEM measurements revealed the atomic structures while electron energy loss spectroscopy helped pinpoint the chemical evolution—both carried out at the CFN….

The scientists next want to observe these changes in real-time which will necessitate the custom design of some new equipment (“electrochemical contacts and liquid flow holders”).

Here are links to and citations for the papers,

Phase evolution for conversion reaction electrodes in lithium-ion batteries by Feng Lin, Dennis Nordlund, Tsu-Chien Weng, Ye Zhu, Chunmei Ban, Ryan M. Richards, & Huolin L. Xin. Nature Communications 5, Article number: 3358 doi:10.1038/ncomms4358 Published 24 February 2014

Surface reconstruction and chemical evolution of stoichiometric layered cathode materials for lithium-ion batteries by Feng Lin, Isaac M. Markus, Dennis Nordlund, Tsu-Chien Weng, Mark D. Asta, Huolin L. Xin & Marca M. Doeff. Nature Communications 5, Article number: 3529 doi:10.1038/ncomms4529 Published 27 March 2014

Both of these articles are behind a paywall and they both offer previews via ReadCube Access.

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

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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.

Cleaner greener diesel by way of bi-functional nanoparticles

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It’s always good to hear about cleaner greener diesel as per this May 13, 2014 news item on Azonano,

Ames Laboratory [US Dept. of Energy] scientists have developed a nanoparticle that is able to perform two processing functions at once for the production of green diesel, an alternative fuel created from the hydrogenation of oils from renewable feedstocks like algae.

The method is a departure from the established process of producing biodiesel, which is accomplished by reacting fats and oils with alcohols.

A May ??, 2014 Ames Laboratory news release,which originated the news item, describes the specifics of the problem the scientists are trying to solve,

“Conventionally, when you are producing biodiesel from a feedstock that is rich in free fatty acids like microalgae oil, you must first separate the fatty acids that can ruin the effectiveness of the catalyst, and then you can perform the catalytic reactions that produce the fuel,” said Ames Lab scientist Igor Slowing. “By designing multifunctional nanoparticles and focusing on green diesel rather than biodiesel, we can combine multiple processes into one that is faster and cleaner.” Contrary to biodiesel, green diesel is produced by hydrogenation of fats and oils, and its chemical composition is very similar to that of petroleum-based diesel. Green diesel has many advantages over biodiesel, like being more stable and having a higher energy density.

One of the research groups at Ames Laboratory stumbled across an exciting property while working with bi-functional nanoparticles (from the news release),

An Ames Lab research group, which included Slowing, Kapil Kandel, Conerd Frederickson, Erica A. Smith, and Young-Jin Lee, first saw success using bi-functionalized mesostructured nanoparticles. These ordered porous particles contain amine groups that capture free fatty acids and nickel nanoparticles that catalyze the conversion of the acids into green diesel. Nickel has been researched widely in the scientific community because it is approximately 2000 times less expensive as an alternative to noble metals traditionally used in fatty acid hydrogenation, like platinum or palladium.

Creating a bi-functional nanoparticle also improved the resulting green diesel. Using nickel for the fuel conversion alone, the process resulted in too strong of a reaction, with hydrocarbon chains that had broken down. The process, called “cracking,” created a product that held less potential as a fuel.

“A very interesting thing happened when we added the component responsible for the sequestration of the fatty acids,” said Slowing. “We no longer saw the cracking of molecules. So the result is a better catalyst that produces a hydrocarbon that looks much more like diesel. “

“It also leaves the other components of the oil behind, valuable molecules that have potential uses for the pharmaceutical and food industries,” said Slowing.

But Slowing, along with Kapil Kandel, James W. Anderegg, Nicholas C. Nelson, and Umesh Chaudhary, took the process further by using iron as the catalyst. Iron is 100 times cheaper than nickel. Using iron improved the end product even further, giving a faster conversion and also reducing the loss of CO2  in the process.

“As part of the mission of the DOE, [US Dept. of Energy] we are focused on researching the fundamental science necessary to create the process; but the resulting technology should in principle be scalable for industry,” he said.

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

Supported iron nanoparticles for the hydrodeoxygenation of microalgal oil to green diesel by Kapil Kandel, James W. Anderegg, Nicholas C. Nelson, Umesh Chaudhary, Igor I. Slowing. Journal of Catalysis Volume 314, May 2014, Pages 142–148 http://dx.doi.org/10.1016/j.jcat.2014.04.009

This paper is behind a paywall.

There is a patent pending on this technology (from the news release),

A patent application has been filed for this technology; it is available for licensing from the Iowa State University Research Foundation. Further information can be obtained at licensing@iastate.edu.

Patent or not, it would be nice to see at least one of these technologies successfully commercialized.