Tag Archives: Duke University

Burning coal produces harmful titanium dioxide nanoparticles

It turns out that Canada has the fifth largest reserve of coal in the world, according to the Coal in Canada Wikipedia entry (Note: Links have been removed),

Coal reserves in Canada rank fifth largest in the world (following the former Soviet Union, the United States, the People’s Republic of China and Australia) at approximately 10 billion tons, 10% of the world total.[1] This represents more energy than all of the oil and gas in the country combined. The coal industry generates CDN$5 billion annually.[2] Most of Canada’s coal mining occurs in the West of the country.[3] British Columbia operates 10 coal mines, Alberta 9, Saskatchewan 3 and New Brunswick one. Nova Scotia operates several small-scale mines, Westray having closed following the 1992 disaster there.[4]

So, this news from Virginia holds more than the usual interest for me (I’m in British Columbia). From an Aug. 8, 2017 Virginia Tech news release (also on EurekAlert),

Environmental scientists led by the Virginia Tech College of Science have discovered that the burning of coal produces incredibly small particles of a highly unusual form of titanium oxide.

When inhaled, these nanoparticles can enter the lungs and potentially the bloodstream.

The particulates — known as titanium suboxide nanoparticles — are unintentionally produced as coal is burned, creating these tiniest of particles, as small as 100 millionths of a meter [emphasis mine], said the Virginia Tech-led team. When the particles are introduced into the air — unless captured by high-tech particle traps — they can float away from power plant stacks and travel on air currents locally, regionally, and even globally.

As an example of this, these nanoparticles were found on city streets, sidewalks, and in standing water in Shanghai, China.

The findings are published in the latest issue of Nature Communications under team leader Michael F. Hochella Jr., University Distinguished Professor of Geosciences with the College of Science, and Yi Yang, a professor at East China Normal University in Shanghai. Other study participants include Duke University, the University of Kentucky, and Laurentian University in Canada.

“The problem with these nanoparticles is that there is no easy or practical way to prevent their formation during coal burning,” Hochella said, adding that in nations with strong environmental regulations, such as the United States, most of the nanoparticles would be caught by particle traps. Not so in Africa [a continent not a nation], China, or India, where regulations are lax or nonexistent, with coal ash and smoke entering the open air.

“Due to advanced technology used at U.S.-based coal burning power plants, mandated by the Clean Air Act and the Environmental Protection Agency, most of these nanoparticles and other tiny particles are removed before the final emission of the plant’s exhaust gases,” Hochella said. “But in countries where the particles from the coal burning are not nearly so efficiently removed, or removed at all, these titanium suboxide nanoparticles and many other particle types are emitted into the atmosphere, in part resulting in hazy skies that plague many countries, especially in China and India.”

Hochella and his team found these previously unknown nanoparticles not only in coal ash from around the world and in the gaseous waste emissions of coal plants, but on city streets, in soils and storm water ponds, and at wastewater treatment plants.

“I could not believe what I have found at the beginning, because they had been reported so extremely rarely in the natural environment,” said Yang, who once worked as a visiting professor in Virginia Tech’s Department of Geosciences with Hochella. “It took me several months to confirm their occurrence in coal ash samples.”

The newly found titanium suboxide — called Magnéli phases — was once thought rare, found only sparingly on Earth in some meteorites, from a small area of rock formations in western Greenland, and occasionally in moon rocks. The findings by Hochella and his team indicate that these nanoparticles are in fact widespread globally. They are only now being studied for the first time in natural environments using powerful electron microscopes.

Why did the discovery occur now? According to the report, nearly all coal contains traces of the minerals rutile and/or anatase, both “normal,” naturally occurring, and relatively inert titanium oxides, especially in the absence of light. When those minerals are burned in the presence of coal, research found they easily and quickly converted to these unusual titanium suboxide nanoparticles. The nanoparticles then become entrained in the gases that leave the power plant.

When inhaled, the nanoparticles enter deep into the lungs, potentially all the way into the air sacs that move oxygen into our bloodstream during the normal breathing process. While human lung toxicity of these particles is not yet known, a preliminary biotoxicity test by Hochella and Richard Di Giulio, professor of environmental toxicology, and Jessica Brandt, a doctoral candidate, both at Duke University, indicates that the particles do indeed have toxicity potential.

According to the team, further study is clearly needed, especially biotoxicity testing directly relevant to the human lung. Partnering with coal-power plants either in the United States or China would be ideal, said Yang.

More troubling, the study shows that titanium suboxide nanoparticles are biologically active in the dark, making the particles highly suspect. Exact human health effects are yet unknown.

“Future studies will need to very carefully investigate and access the toxicity of titanium suboxide nanoparticles in the human lung, and this could take years, a sobering thought considering its potential danger,” Hochella said.

As the titanium suboxide nanoparticle itself is produced incidentally, Hochella and his team came across the nanoparticle by accident while studying a 2014 coal ash spill in the Dan River, North Carolina. During the study of the downstream movement of toxic metals in the ash in the Dan River, the team discovered and recognized the presence of small amounts of the highly unusual titanium suboxide.

The group later produced the titanium suboxide nanoparticles when burning coal in a lab simulation.

This new potential air pollution health hazard builds on already established findings from the World Health Organization. It estimates that 3.3 million premature deaths occur worldwide per year due to polluted air, Hochella said. In China, 1.6 million premature deaths are estimated annually due to cardiovascular and respiratory injury from air pollution. Most Chinese megacities top 100 severely hazy days each year with particle concentrations two to four times higher than WHO guidelines, Yang said.

Direct health effects on humans is only one factor. Findings of thousands of scientists have determined that the biggest driver of warming of the planet and the resulting climate change is industrial-scale coal burning. The impact of titanium suboxide nanoparticles found in the atmosphere, in addition to greenhouse gases, on animals, water, and plants is not yet known.

They’ve used an unusual unit of measurement, “100 millionths of a meter,” nanoparticles are usually described in nanometers.

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

Discovery and ramifications of incidental Magnéli phase generation and release from industrial coal-burning by Yi Yang, Bo Chen, James Hower, Michael Schindler, Christopher Winkler, Jessica Brandt, Richard Di Giulio, Jianping Ge, Min Liu, Yuhao Fu, Lijun Zhang, Yuru Chen, Shashank Priya, & Michael F. Hochella Jr. Nature Communications 8, Article number: 194 (2017) doi:10.1038/s41467-017-00276-2 Published online: 08 August 2017

This paper is behind a paywall.

This put me in mind of the famous London smog, which one doesn’t hear about much anymore. For anyone not familiar with that phenomenon, here’s more from the Great Smog of London Wikipedia entry (Note: Links have been removed),

The Great Smog of London, or Great Smog of 1952 sometimes called the Big Smoke,[1] was a severe air-pollution event [emphasis mine] that affected the British capital of London in December 1952. A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants – mostly arising from the use of coal [emphasis mine]– to form a thick layer of smog over the city. It lasted from Friday, 5 December to Tuesday, 9 December 1952 and then dispersed quickly when the weather changed.

It caused major disruption by reducing visibility and even penetrating indoor areas, far more severe than previous smog events experienced in the past, called “pea-soupers”. Government medical reports in the following weeks, however, estimated that up until 8 December, 4,000 people had died as a direct result of the smog and 100,000 more were made ill by the smog’s effects on the human respiratory tract. More recent research suggests that the total number of fatalities was considerably greater, about 12,000.[2]

London had suffered since the 1200s from poor air quality,[3] which worsened in the 1600s,[4][5] but the Great Smog is known to be the worst air-pollution event in the history of the United Kingdom,[6] and the most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health.[2][4] It led to several changes in practices and regulations, including the Clean Air Act 1956. …

Investigating nanoparticles and their environmental impact for industry?

It seems the Center for the Environmental Implications of Nanotechnology (CEINT) at Duke University (North Carolina, US) is making an adjustment to its focus and opening the door to industry, as well as, government research. It has for some years (my first post about the CEINT at Duke University is an Aug. 15, 2011 post about its mesocosms) been focused on examining the impact of nanoparticles (also called nanomaterials) on plant life and aquatic systems. This Jan. 9, 2017 US National Science Foundation (NSF) news release (h/t Jan. 9, 2017 Nanotechnology Now news item) provides a general description of the work,

We can’t see them, but nanomaterials, both natural and manmade, are literally everywhere, from our personal care products to our building materials–we’re even eating and drinking them.

At the NSF-funded Center for Environmental Implications of Nanotechnology (CEINT), headquartered at Duke University, scientists and engineers are researching how some of these nanoscale materials affect living things. One of CEINT’s main goals is to develop tools that can help assess possible risks to human health and the environment. A key aspect of this research happens in mesocosms, which are outdoor experiments that simulate the natural environment – in this case, wetlands. These simulated wetlands in Duke Forest serve as a testbed for exploring how nanomaterials move through an ecosystem and impact living things.

CEINT is a collaborative effort bringing together researchers from Duke, Carnegie Mellon University, Howard University, Virginia Tech, University of Kentucky, Stanford University, and Baylor University. CEINT academic collaborations include on-going activities coordinated with faculty at Clemson, North Carolina State and North Carolina Central universities, with researchers at the National Institute of Standards and Technology and the Environmental Protection Agency labs, and with key international partners.

The research in this episode was supported by NSF award #1266252, Center for the Environmental Implications of NanoTechnology.

The mention of industry is in this video by O’Brien and Kellan, which describes CEINT’s latest work ,

Somewhat similar in approach although without a direction reference to industry, Canada’s Experimental Lakes Area (ELA) is being used as a test site for silver nanoparticles. Here’s more from the Distilling Science at the Experimental Lakes Area: Nanosilver project page,

Water researchers are interested in nanotechnology, and one of its most commonplace applications: nanosilver. Today these tiny particles with anti-microbial properties are being used in a wide range of consumer products. The problem with nanoparticles is that we don’t fully understand what happens when they are released into the environment.

The research at the IISD-ELA [International Institute for Sustainable Development Experimental Lakes Area] will look at the impacts of nanosilver on ecosystems. What happens when it gets into the food chain? And how does it affect plants and animals?

Here’s a video describing the Nanosilver project at the ELA,

You may have noticed a certain tone to the video and it is due to some political shenanigans, which are described in this Aug. 8, 2016 article by Bartley Kives for the Canadian Broadcasting Corporation’s (CBC) online news.

‘Brewing up’ conductive inks for printable electronics

Scientists from Duke University aren’t exactly ‘brewing’ or ‘cooking up’ the inks but they do come close according to a Jan. 3, 2017 news item on ScienceDaily,

By suspending tiny metal nanoparticles in liquids, Duke University scientists are brewing up conductive ink-jet printer “inks” to print inexpensive, customizable circuit patterns on just about any surface.

A Jan. 3, 2017 Duke University news release (also on EurekAlert), which originated the news item, explains why this technique could lead to more accessible printed electronics,

Printed electronics, which are already being used on a wide scale in devices such as the anti-theft radio frequency identification (RFID) tags you might find on the back of new DVDs, currently have one major drawback: for the circuits to work, they first have to be heated to melt all the nanoparticles together into a single conductive wire, making it impossible to print circuits on inexpensive plastics or paper.

A new study by Duke researchers shows that tweaking the shape of the nanoparticles in the ink might just eliminate the need for heat.

By comparing the conductivity of films made from different shapes of silver nanostructures, the researchers found that electrons zip through films made of silver nanowires much easier than films made from other shapes, like nanospheres or microflakes. In fact, electrons flowed so easily through the nanowire films that they could function in printed circuits without the need to melt them all together.

“The nanowires had a 4,000 times higher conductivity than the more commonly used silver nanoparticles that you would find in printed antennas for RFID tags,” said Benjamin Wiley, assistant professor of chemistry at Duke. “So if you use nanowires, then you don’t have to heat the printed circuits up to such high temperature and you can use cheaper plastics or paper.”

“There is really nothing else I can think of besides these silver nanowires that you can just print and it’s simply conductive, without any post-processing,” Wiley added.

These types of printed electronics could have applications far beyond smart packaging; researchers envision using the technology to make solar cells, printed displays, LEDS, touchscreens, amplifiers, batteries and even some implantable bio-electronic devices. The results appeared online Dec. 16 [2016] in ACS Applied Materials and Interfaces.

Silver has become a go-to material for making printed electronics, Wiley said, and a number of studies have recently appeared measuring the conductivity of films with different shapes of silver nanostructures. However, experimental variations make direct comparisons between the shapes difficult, and few reports have linked the conductivity of the films to the total mass of silver used, an important factor when working with a costly material.

“We wanted to eliminate any extra materials from the inks and simply hone in on the amount of silver in the films and the contacts between the nanostructures as the only source of variability,” said Ian Stewart, a recent graduate student in Wiley’s lab and first author on the ACS paper.

Stewart used known recipes to cook up silver nanostructures with different shapes, including nanoparticles, microflakes, and short and long nanowires, and mixed these nanostructures with distilled water to make simple “inks.” He then invented a quick and easy way to make thin films using equipment available in just about any lab — glass slides and double-sided tape.

“We used a hole punch to cut out wells from double-sided tape and stuck these to glass slides,” Stewart said. By adding a precise volume of ink into each tape “well” and then heating the wells — either to relatively low temperature to simply evaporate the water or to higher temperatures to begin melting the structures together — he created a variety of films to test.

The team say they weren’t surprised that the long nanowire films had the highest conductivity. Electrons usually flow easily through individual nanostructures but get stuck when they have to jump from one structure to the next, Wiley explained, and long nanowires greatly reduce the number of times the electrons have to make this “jump”.

But they were surprised at just how drastic the change was. “The resistivity of the long silver nanowire films is several orders of magnitude lower than silver nanoparticles and only 10 times greater than pure silver,” Stewart said.

The team is now experimenting with using aerosol jets to print silver nanowire inks in usable circuits. Wiley says they also want to explore whether silver-coated copper nanowires, which are significantly cheaper to produce than pure silver nanowires, will give the same effect.

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

Effect of Morphology on the Electrical Resistivity of Silver Nanostructure Films by Ian E. Stewart, Myung Jun Kim, and Benjamin J. Wiley. ACS Appl. Mater. Interfaces, Article ASAP
DOI: 10.1021/acsami.6b12289 Publication Date (Web): December 16, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall but there is an image of the silver nanowires, which is not exactly compensation but is interesting,

Caption: Duke University chemists have found that silver nanowire films like these conduct electricity well enough to form functioning circuits without applying high temperatures, enabling printable electronics on heat-sensitive materials like paper or plastic.
Credit: Ian Stewart and Benjamin Wiley

Bringing multispectral imaging into daily use

Caption: Researchers tested a new technique for printing and imaging in both color and infrared with this image of a parrot. The inlay shows how a simple RGB color scheme was created by building rectangles of varying lengths for each of the colors, as well as individual nanocubes on top of a gold film that create the plasmonic element. Credit: imageBROKER / Alamy Stock Photo

That caption makes a lot more sense after reading the news item and the news release announcing the work. First, there’s the Dec. 15, 2016 news item on ScienceDaily,

Duke University researchers believe they have overcome a longstanding hurdle to producing cheaper, more robust ways to print and image across a range of colors extending into the infrared.

As any mantis shrimp will tell you, there are a wide range of “colors” along the electromagnetic spectrum that humans cannot see but which provide a wealth of information. Sensors that extend into the infrared can, for example, identify thousands of plants and minerals, diagnose cancerous melanomas and predict weather patterns, simply by the spectrum of light they reflect.

Current imaging technologies that can detect infrared wavelengths are expensive and bulky, requiring numerous filters or complex assemblies in front of an infrared photodetector. The need for mechanical movement in such devices reduces their expected lifetime and can be a liability in harsh conditions, such as those experienced by satellites.

A closeup of the colorful parrot picture printed on a thin gold wafer using the new nanocube-based technology. The colors appear off because of the underlying gold, as well as the difficulties that typical cameras have of imaging the new technology. Credit: Maiken Mikkelsen, Duke University

A Dec. 14, 2016 Duke University news release, which originated the news item, provides more detail (Note: A link has been removed),

In a new paper, a team of Duke engineers reveals a manufacturing technique that promises to bring a simplified form of multispectral imaging into daily use. Because the process uses existing materials and fabrication techniques that are inexpensive and easily scalable, it could revolutionize any industry where multispectral imaging or printing is used.

The results appear online December 14 [2016] in the journal Advanced Materials.

“It’s challenging to create sensors that can detect both the visible spectrum and the infrared,” said Maiken Mikkelsen, the Nortel Networks Assistant Professor of Electrical and Computer Engineering and Physics at Duke.

“Traditionally you need different materials that absorb different wavelengths, and that gets very expensive,” Mikkelsen said. “But with our technology, the detectors’ responses are based on structural properties that we design rather than a material’s natural properties. What’s really exciting is that we can pair this with a photodetector scheme to combine imaging in both the visible spectrum and the infrared on a single chip.”

The new technology relies on plasmonics — the use of nanoscale physical phenomena to trap certain frequencies of light.

Engineers fashion silver cubes just 100 nanometers wide and place them only a few nanometers above a thin gold foil. When incoming light strikes the surface of a nanocube, it excites the silver’s electrons, trapping the light’s energy — but only at a certain frequency.

The size of the silver nanocubes and their distance from the base layer of gold determines that frequency, while controlling the spacing between the nanoparticles allows tuning the strength of the absorption. By precisely tailoring these spacings, researchers can make the system respond to any specific color they want, all the way from visible wavelengths out to the infrared.

The challenge facing the engineers is how to build a useful device that could be scalable and inexpensive enough to use in the real world. For that, Mikkelsen turned to her research team, including graduate student Jon Stewart.

“Similar types of materials have been demonstrated before, but they’ve all used expensive techniques that have kept the technology from transitioning to the market,” said Stewart. “We’ve come up with a fabrication scheme that is scalable, doesn’t need a clean room and avoids using million-dollar machines, all while achieving higher frequency sensitivities. It has allowed us to do things in the field that haven’t been done before.”

To build a detector, Mikkelsen and Stewart used a process of light etching and adhesives to pattern the nanocubes into pixels containing different sizes of silver nanocubes, and thus each sensitive to a specific wavelength of light. When incoming light strikes the array, each area responds differently depending on the wavelength of light it is sensitive to. By teasing out how each part of the array responds, a computer can reconstruct what color the original light was.

The technique can be used for printing as well, the team showed. Instead of creating pixels with six sections tuned to respond to specific colors, they created pixels with three bars that reflect three colors: blue, green and red. By controlling the relative lengths of each bar, they can dictate what combination of colors the pixel reflects. It’s a novel take on the classic RGB scheme first used in photography in 1861.

But unlike most other applications, the plasmonic color scheme promises to never fade over time and can be reliably reproduced with tight accuracy time and again. It also allows its adopters to create color schemes in the infrared.

“Again, the exciting part is being able to print in both visible and infrared on the same substrate,” said Mikkelsen. “You could imagine printing an image with a hidden portion in the infrared, or even covering an entire object to tailor its spectral response.”

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

Toward Multispectral Imaging with Colloidal Metasurface Pixels by Jon W. Stewart, Gleb M. Akselrod, David R. Smith, and Maiken H. Mikkelsen. DOI: 10.1002/adma.201602971 Version of Record online: 14 DEC 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall. (There is a free preview but it is page 1 only of the paper.)


Are living bacteria providing camouflage for crustaceans?

When you have no place to hide, you can develop some unique methods to avoid detection according to an Oct. 27, 2016 news item on ScienceDaily,

Crustaceans that thrive in the vastness of the open ocean have no place to hide from their predators. Consequently, many creatures that live at depths where sunlight fades to darkness have developed transparent bodies to be less visible when spotted against the twilight by upward-looking predators. But they also face predators with bioluminescent searchlights that should cause the clear animals to flash brightly, just like shining a flashlight across a window pane.

Well, it turns out the midwater crustaceans have camouflage for that too.

An Oct. 27, 2016 Duke University news release on EurekAlert, which originated the news item, expands on the theme,

A new study from Duke University and the Smithsonian Institution has found that these midwater hyperiid amphipods are covered with anti-reflective coatings on their legs and bodies that can dampen the reflection of light by 250-fold in some cases and prevent it from bouncing back to a hungry lantern fish’s eye.

Weirder still, these coatings appear to be made of living bacteria.

When viewed under an electron microscope, the optical coating appears as a sheet of fairly uniform beads, smaller than the wavelength of light. “This coating of little spheres reduces reflections the same way putting a shag carpet on the walls of a recording studio would soften echoes,” said study leader Laura Bagge, a Ph.D. candidate at Duke working with biologist Sönke Johnsen.

The spheres range from 50 to 300 nanometers in diameter on different species of amphipod, but a sphere of 110 nm would be optimal, resulting in up to a 250-fold reduction in reflectance, Bagge calculated. “But every size of these bumps helps.”

Adding to the impression that the spheres might be bacteria, they are sometimes connected with a net of filaments like a biofilm. Each of the seven amphipod species Bagge looked at appears to have its own species of symbiotic optical bacteria. But that’s not a sure thing yet.

“They have all the features of bacteria, but to be 100 percent sure, we’re going to have to perform an in-depth sequencing project,” Bagge said. That project is already underway.

If the spheres are bacteria, they’re very small ones. But it’s not hard to imagine the natural selection — having your host spotted and eaten — that would drive the microbes to an optimal size, said research zoologist Karen Osborn of the Smithsonian National Museum of Natural History, who provided some of the species for this study.

If the optical coating is alive, the researchers will have to figure out how this symbiotic relationship got started in the first place.

Crustaceans molt to grow, shedding the old shell and perhaps its attendant anti-reflective bacteria. But Osborn thinks it would be pretty easy to re-seed the animal’s new shell. “In that whole process, they’re touching the old carapace.” There’s also a species of hyperiid, Phronima, that raises its young in a little floating nest hollowed out of the body of a salp. In that case, the kids could adopt mom’s anti-reflective bacteria pretty easily, Osborn said.

Another amphipod species, Cystisoma, also extrudes brush-like structures on the exoskeleton of its legs which are just the right size and shape to serve the same purpose as the antireflective spheres. At up to six inches in length, Cystisoma has a serious need for stealth.

“They’re remarkably transparent,” Osborn said. “Mostly you see them because you don’t see them. When you pull up a trawl bucket packed full of plankton, you see an empty spot – why is nothing there? You reach in and pull out a Cystisoma. It’s a firm cellophane bag, essentially.”

“We care about this for the basic biology,” Bagge said. But the discovery of living anti-reflective coatings may have technological applications as well. Reflection-reducing “nipple arrays” are being used in the design of glass windows and have also been found in the eyes of moths, apparently to help them see better at night.

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

Nanostructures and Monolayers of Spheres Reduce Surface Reflections in Hyperiid Amphipods by Laura E. Bagge, Karen J. Osborn, Sönke Johnsen. Current Biology DOI: http://dx.doi.org/10.1016/j.cub.2016.09.033 Publication stage: In Press Corrected Proof

This paper is behind a paywall.

Doing math in a test tube using analog DNA

Basically, scientists at Duke University (US) have created an analog computer at the nanoscale, which can perform basic arithmetic. From an Aug. 23, 2016 news item on ScienceDaily,

Often described as the blueprint of life, DNA contains the instructions for making every living thing from a human to a house fly.

But in recent decades, some researchers have been putting the letters of the genetic code to a different use: making tiny nanoscale computers.

In a new study, a Duke University team led by professor John Reif created strands of synthetic DNA that, when mixed together in a test tube in the right concentrations, form an analog circuit that can add, subtract and multiply as they form and break bonds.

Rather than voltage, DNA circuits use the concentrations of specific DNA strands as signals.

An Aug. 23, 2016 Duke University news release (also on EurekAlert), which originated the news item, describes how most DNA-based circuits operate and what makes the one from Duke different,

Other teams have designed DNA-based circuits that can solve problems ranging from calculating square roots to playing tic-tac-toe. But most DNA circuits are digital, where information is encoded as a sequence of zeroes and ones.

Instead, the new Duke device performs calculations in an analog fashion by measuring the varying concentrations of specific DNA molecules directly, without requiring special circuitry to convert them to zeroes and ones first.

Unlike the silicon-based circuits used in most modern day electronics, commercial applications of DNA circuits are still a long way off, Reif said.

For one, the test tube calculations are slow. It can take hours to get an answer.

“We can do some limited computing, but we can’t even begin to think of competing with modern-day PCs or other conventional computing devices,” Reif said.

But DNA circuits can be far tinier than those made of silicon. And unlike electronic circuits, DNA circuits work in wet environments, which might make them useful for computing inside the bloodstream or the soupy, cramped quarters of the cell.

The technology takes advantage of DNA’s natural ability to zip and unzip to perform computations. Just like Velcro and magnets have complementary hooks or poles, the nucleotide bases of DNA pair up and bind in a predictable way.

The researchers first create short pieces of synthetic DNA, some single-stranded and some double-stranded with single-stranded ends, and mix them in a test tube.

When a single strand encounters a perfect match at the end of one of the partially double-stranded ones, it latches on and binds, displacing the previously bound strand and causing it to detach, like someone cutting in on a dancing couple.

The newly released strand can in turn pair up with other complementary DNA molecules downstream in the circuit, creating a domino effect.

The researchers solve math problems by measuring the concentrations of specific outgoing strands as the reaction reaches equilibrium.

To see how their circuit would perform over time as the reactions proceeded, Reif and Duke graduate student Tianqi Song used computer software to simulate the reactions over a range of input concentrations. They have also been testing the circuit experimentally in the lab.

Besides addition, subtraction and multiplication, the researchers are also designing more sophisticated analog DNA circuits that can do a wider range of calculations, such as logarithms and exponentials.

Conventional computers went digital decades ago. But for DNA computing, the analog approach has its advantages, the researchers say. For one, analog DNA circuits require fewer strands of DNA than digital ones, Song said.

Analog circuits are also better suited for sensing signals that don’t lend themselves to simple on-off, all-or-none values, such as vital signs and other physiological measurements involved in diagnosing and treating disease.

The hope is that, in the distant future, such devices could be programmed to sense whether particular blood chemicals lie inside or outside the range of values considered normal, and release a specific DNA or RNA — DNA’s chemical cousin — that has a drug-like effect.

Reif’s lab is also beginning to work on DNA-based devices that could detect molecular signatures of particular types of cancer cells, and release substances that spur the immune system to fight back.

“Even very simple DNA computing could still have huge impacts in medicine or science,” Reif said.

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

Analog Computation by DNA Strand Displacement Circuits by Tianqi Song, Sudhanshu Garg, Reem Mokhtar, Hieu Bui, and John Reif. ACS Synth. Biol., 2016, 5 (8), pp 898–912 DOI: 10.1021/acssynbio.6b00144 Publication Date (Web): July 01, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Being solid and liquid over a range of 1000 degrees Fahrenheit means it’s perpetual ice

Duke University researchers along with their international collaborators have made an extraordinary observation. From an Aug. 3, 2016 news item on ScienceDaily,

Imagine pouring a glass of ice water and having the ice cubes remain unchanged hours later, even under a broiler’s heat or in the very back corner of the freezer.

That’s fundamentally the surprising discovery recently made by an international group of researchers led by an electrical engineering professor at Duke University in a paper published online in Nature Matter on July 25, 2016. But instead of a refreshing mixture of H2O in a pint glass, the researchers were working with the chemical element gallium on a nanoscopic scale.

This image shows a single gallium nanoparticle sitting on top of a sapphire base. The black sphere in the center reveals the presence of solid gallium within the liquid drop exterior. The sapphire base is important, as it is rigid with a relatively high surface energy. As the nanoparticle and sapphire try to minimize their total energy, this combination of properties drives the formation and coexistence of the two phases. Courtesy: Duke University

This image shows a single gallium nanoparticle sitting on top of a sapphire base. The black sphere in the center reveals the presence of solid gallium within the liquid drop exterior. The sapphire base is important, as it is rigid with a relatively high surface energy. As the nanoparticle and sapphire try to minimize their total energy, this combination of properties drives the formation and coexistence of the two phases. Courtesy: Duke University

An Aug. 3, 2016 Duke University news release (also on EurekAlert), which originated the news item, explains more about gallium and about this new state,

Gallium is a soft, silvery bluish metal at room temperature. Raise the heat to 86 degrees Fahrenheit, however, and it melts. Drop the temperature to subzero levels, and it becomes hard and brittle. But when gallium nanoparticles sit on top of a sapphire surface, they form a solid core surrounded by a liquid outer layer. The discovery marks the first time that this stable phase coexistence phenomenon at the nanoscale has ever been directly observed.

“This odd combination of a liquid and solid state existing together has been predicted theoretically and observed indirectly in other materials in narrow bands of specific temperatures,” said April Brown, the John Cocke Professor of Electrical and Computer Engineering at Duke. “But this finding was very unexpected, especially because of its stability over such a large temperature range.”

The temperature range Brown is referring to covers more than 1,000 degrees Fahrenheit, all the way from -135 to 980 degrees.

“At a fundamental level, this finding reveals the need to reconsider all our presumptions about solid–liquid equilibrium,” wrote Andrés Aguado, professor of theoretical, atomic and optical physics at the University of Valladolid in Spain, in a News and Views piece appearing in the same edition of Nature Matter. “At a more applied level, the results hold much promise for future nanotechnology applications.”

Gallium is an important element in electronics and is used in microwave circuits, high-speed switching circuits and infrared circuits. The discovery of this novel part-solid, part-liquid nanoparticle phase could be useful in ultraviolet sensors, molecular sensing devices and enhanced photodetectors.

Brown hopes this work is just the tip of the iceberg, as she is planning on creating a facility at Duke to investigate what other nanoparticles might have similar unexpected phase qualities.

The research was conducted in conjunction with researchers at the Institute of Nanotechnology-CNR-Italy, the University of Western Australia, the University of Melbourne and Johannes Kepler University Linz.

This is an atomic view of liquid and solid gallium coexisting in a single nanoparticle taken by a transmission electron microscope. The circular shape on the left-hand side shows gallium atoms in an organized, crystalline, solid structure, while the atoms on the right are in liquid form, showing no organized structure at all. Courtesy: Duke University

This is an atomic view of liquid and solid gallium coexisting in a single nanoparticle taken by a transmission electron microscope. The circular shape on the left-hand side shows gallium atoms in an organized, crystalline, solid structure, while the atoms on the right are in liquid form, showing no organized structure at all. Courtesy: Duke University

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

Thermally stable coexistence of liquid and solid phases in gallium nanoparticles by Maria Losurdo, Alexandra Suvorova, Sergey Rubanov, Kurt Hingerl, & April S. Brown.  Nature Materials (2016) doi:10.1038/nmat4705 Published online 25 July 2016

This paper is behind a paywall.

Korea Advanced Institute of Science and Technology (KAIST) at summer 2016 World Economic Forum in China

From the Ideas Lab at the 2016 World Economic Forum at Davos to offering expertise at the 2016 World Economic Forum in Tanjin, China that is taking place from June 26 – 28, 2016.

Here’s more from a June 24, 2016 KAIST news release on EurekAlert,

Scientific and technological breakthroughs are more important than ever as a key agent to drive social, economic, and political changes and advancements in today’s world. The World Economic Forum (WEF), an international organization that provides one of the broadest engagement platforms to address issues of major concern to the global community, will discuss the effects of these breakthroughs at its 10th Annual Meeting of the New Champions, a.k.a., the Summer Davos Forum, in Tianjin, China, June 26-28, 2016.

Three professors from the Korea Advanced Institute of Science and Technology (KAIST) will join the Annual Meeting and offer their expertise in the fields of biotechnology, artificial intelligence, and robotics to explore the conference theme, “The Fourth Industrial Revolution and Its Transformational Impact.” The Fourth Industrial Revolution, a term coined by WEF founder, Klaus Schwab, is characterized by a range of new technologies that fuse the physical, digital, and biological worlds, such as the Internet of Things, cloud computing, and automation.

Distinguished Professor Sang Yup Lee of the Chemical and Biomolecular Engineering Department will speak at the Experts Reception to be held on June 25, 2016 on the topic of “The Summer Davos Forum and Science and Technology in Asia.” On June 27, 2016, he will participate in two separate discussion sessions.

In the first session entitled “What If Drugs Are Printed from the Internet?” Professor Lee will discuss the future of medicine being impacted by advancements in biotechnology and 3D printing technology with Nita A. Farahany, a Duke University professor, under the moderation of Clare Matterson, the Director of Strategy at Wellcome Trust in the United Kingdom. The discussants will note recent developments made in the way patients receive their medicine, for example, downloading drugs directly from the internet and the production of yeast strains to make opioids for pain treatment through systems metabolic engineering, and predicting how these emerging technologies will transform the landscape of the pharmaceutical industry in the years to come.

In the second session, “Lessons for Life,” Professor Lee will talk about how to nurture life-long learning and creativity to support personal and professional growth necessary in an era of the new industrial revolution.

During the Annual Meeting, Professors Jong-Hwan Kim of the Electrical Engineering School and David Hyunchul Shim of the Aerospace Department will host, together with researchers from Carnegie Mellon University and AnthroTronix, an engineering research and development company, a technological exhibition on robotics. Professor Kim, the founder of the internally renowned Robot World Cup, will showcase his humanoid micro-robots that play soccer, displaying their various cutting-edge technologies such as imaging processing, artificial intelligence, walking, and balancing. Professor Shim will present a human-like robotic piloting system, PIBOT, which autonomously operates a simulated flight program, grabbing control sticks and guiding an airplane from take offs to landings.

In addition, the two professors will join Professor Lee, who is also a moderator, to host a KAIST-led session on June 26, 2016, entitled “Science in Depth: From Deep Learning to Autonomous Machines.” Professors Kim and Shim will explore new opportunities and challenges in their fields from machine learning to autonomous robotics including unmanned vehicles and drones.

Since 2011, KAIST has been participating in the World Economic Forum’s two flagship conferences, the January and June Davos Forums, to introduce outstanding talents, share their latest research achievements, and interact with global leaders.

KAIST President Steve Kang said, “It is important for KAIST to be involved in global talks that identify issues critical to humanity and seek answers to solve them, where our skills and knowledge in science and technology could play a meaningful role. The Annual Meeting in China will become another venue to accomplish this.”

I mentioned KAIST and the Ideas Lab at the 2016 Davos meeting in this Nov. 20, 2015 posting and was able to clear up my (and possible other people’s) confusion as to what the Fourth Industrial revolution might be in my Dec. 3, 2015 posting.

Frankenstein and Switzerland in 2016

The Frankenstein Bicentennial celebration is in process as various events and projects are now being launched. In a Nov. 12, 2015 posting I made mention of the Frankenstein Bicentennial Project 1818-2018 at Arizona State University (ASU; scroll down about 15% of the way),

… the Transmedia Museum (Frankenstein Bicentennial Project 1818-2018).  This project is being hosted by Arizona State University. From the project homepage,

No work of literature has done more to shape the way people imagine science and its moral consequences than Frankenstein; or The Modern Prometheus, Mary Shelley’s enduring tale of creation and responsibility. The novel’s themes and tropes—such as the complex dynamic between creator and creation—continue to resonate with contemporary audiences. Frankenstein continues to influence the way we confront emerging technologies, conceptualize the process of scientific research, imagine the motivations and ethical struggles of scientists, and weigh the benefits of innovation with its unforeseen pitfalls.

The Frankenstein Bicentennial Project will infuse science and engineering endeavors with considerations of ethics. It will use the power of storytelling and art to shape processes of innovation and empower public appraisal of techno-scientific research and creation. It will offer humanists and artists a new set of concerns around research, public policy, and the ramifications of exploration and invention. And it will inspire new scientific and technological advances inspired by Shelley’s exploration of our inspiring and terrifying ability to bring new life into the world. Frankenstein represents a landmark fusion of science, ethics, and literary expression.

The bicentennial provides an opportunity for vivid reflection on how science is culturally framed and understood by the public, as well as our ethical limitations and responsibility for nurturing the products of our creativity. It is also a moment to unveil new scientific and technological marvels, especially in the areas of synthetic biology and artificial intelligence. Engaging with Frankenstein allows scholars and educators, artists and writers, and the public at large to consider the history of scientific invention, reflect on contemporary research, and question the future of our technological society. Acting as a network hub for the bicentennial celebration, ASU will encourage and coordinate collaboration across institutions and among diverse groups worldwide.

2016 Frankenstein events

Now, there’s an exhibition in Switzerland where Frankenstein was ‘born’ according to a May 12, 2016 news item on phys.org,

Frankenstein, the story of a scientist who brings to life a cadaver and causes his own downfall, has for two centuries given voice to anxiety surrounding the unrelenting advance of science.

To mark the 200 years since England’s Mary Shelley first imagined the ultimate horror story during a visit to a frigid, rain-drenched Switzerland, an exhibit opens in Geneva Friday called “Frankenstein, Creation of Darkness”.

In the dimly-lit, expansive basement at the Martin Bodmer Foundation, a long row of glass cases holds 15 hand-written, yellowed pages from a notebook where Shelley in 1816 wrote the first version of what is considered a masterpiece of romantic literature.

The idea for her “miserable monster” came when at just 18 she and her future husband, English poet Percy Bysshe Shelley, went to a summer home—the Villa Diodati—rented by literary great Lord Byron on the outskirts of Geneva.

The current private owners of the picturesque manor overlooking Lake Geneva will also open their lush gardens to guided tours during the nearby exhibit which runs to October 9 [May 13 – Oct. 9, 2016].

While the spot today is lovely, with pink and purple lilacs spilling from the terraces and gravel walkways winding through rose-covered arches, in the summer of 1816 the atmosphere was more somber.

A massive eruption from the Tambora volcano in Indonesia wreaked havoc with the global climate that year, and a weather report for Geneva in June on display at the exhibit mentions “not a single leaf” had yet appeared on the oak trees.

To pass the time, poet Lord Byron challenged the band of literary bohemians gathered at the villa to each invent a ghost story, resulting in several famous pieces of writing.

English doctor and author John Polidori came up with the idea for “The Vampyre”, which was published three years later and is considered to have pioneered the romantic vampyre genre, including works like Bram Stoker’s “Dracula”.

That book figures among a multitude of first editions at the Geneva exhibit, including three of Mary Shelley’s “Frankenstein, or the Modern Prometheus”—the most famous story to emerge from the competition.

Here’s a description of the exhibit, from the Martin Bodmer Foundation’s Frankenstein webpage,

To celebrate the 200th anniversary of the writing of this historically influential work of literature, the Martin Bodmer Foundation presents a major exhibition on the origins of Frankenstein, the perspectives it opens and the questions it raises.

A best seller since its first publication in 1818, Mary Shelley’s novel continues to demand attention. The questions it raises remain at the heart of literary and philosophical concerns: the ethics of science, climate change, the technologisation of the human body, the unconscious, human otherness, the plight of the homeless and the dispossessed.

The exposition Frankenstein: Creation of Darkness recreates the beginnings of the novel in its first manuscript and printed forms, along with paintings and engravings that evoke the world of 1816. A variety of literary and scientific works are presented as sources of the novel’s ideas. While exploring the novel’s origins, the exhibition also evokes the social and scientific themes of the novel that remain important in our own day.

For what it’s worth, I have come across analyses which suggest science and technology may not have been the primary concern at the time. There are interpretations which suggest issues around childbirth (very dangerous until modern times) and fear of disfigurement and disfigured individuals. What makes Frankenstein and the book so fascinating is how flexible interpretations can be. (For more about Frankenstein and flexibility, read Susan Tyler Hitchcock’s 2009 book, Frankenstein: a cultural history.)

There’s one more upcoming Frankenstein event, from The Frankenstein Bicentennial announcement webpage,

On June 14 and 15, 2016, the Brocher Foundation, Arizona State University, Duke University, and the University of Lausanne will host “Frankenstein’s Shadow,” a symposium in Geneva, Switzerland to commemorate the origin of Frankenstein and assess its influence in different times and cultures, particularly its resonance in debates about public policy governing biotechnology and medicine. These dates place the symposium almost exactly 200 years after Mary Shelley initially conceived the idea for Frankenstein on June 16, 1816, and in almost exactly the same geographical location on the shores of Lake Geneva.

If you’re interested in details such as the programme schedule, there’s this PDF,



Molecular ‘lightbulb’ could mean new form of magnetic resonance imaging (MRI)

A new technique promises to show body chemistry in action according to a March 25, 2016 news item on phys.org,

Duke University researchers have taken a major step towards realizing a new form of MRI that could record biochemical reactions in the body as they happen.

In the March 25 issue of Science Advances, they report the discovery of a new class of molecular tags that enhance MRI signals by 10,000-fold and generate detectable signals that last over an hour. The tags are biocompatible and inexpensive to produce, paving the way for widespread use of magnetic resonance imaging (MRI) to monitor metabolic processes of conditions like cancer and heart disease in real time.

“This represents a completely new class of molecules that doesn’t look anything at all like what people thought could be made into MRI tags,” said Warren S. Warren, James B. Duke Professor and Chair of Physics at Duke, and senior author on the study. “We envision it could provide a whole new way to use MRI to learn about the biochemistry of disease.”

A March 25, 2016 Duke University news release (also on EurekAlert), which originated the news item, offers more information about the new technique,

MRI takes advantage of a property called spin, which makes the nuclei in hydrogen atoms act like tiny magnets. Applying a strong magnetic field, followed by a series of radio waves, induces these hydrogen magnets to broadcast their locations. Since most of the hydrogen atoms in the body are bound up in water, the technique is used in clinical settings to create detailed images of soft tissues like organs, blood vessels and tumors inside the body.

But the technique also has the potential to show body chemistry in action, said Thomas Theis, assistant research professor of chemistry at Duke and co-lead author on the paper. “With magnetic resonance in general, you have this unique sensitivity to chemical transformations. You can see them and track them in real time,” Theis said.

MRI’s ability to track chemical transformations in the body has been limited by the low sensitivity of the technique, which makes small numbers of molecules impossible to detect without using unattainably massive magnetic fields.

For the past decade, researchers have been developing methods to “hyperpolarize” biologically important molecules, converting them into what Warren calls magnetic resonance “lightbulbs.”

With this boosted signal, these “lightbulbs” can be detected even in low numbers. “Hyperpolarization gives them 10,000 times more signal than they would normally have if they had just been magnetized in an ordinary magnetic field,” Warren said.

While promising, Warren says these hyperpolarization techniques face two fundamental problems: incredibly expensive equipment — around 3 million dollars for one machine — and most of these molecular lightbulbs burn out in a matter of seconds.

“It’s hard to take an image with an agent that is only visible for seconds, and there are a lot of biological processes you could never hope to see,” said Warren. “We wanted to try to figure out what molecules could give extremely long-lived signals so that you could look at slower processes.”

Jerry Ortiz Jr., a graduate student at Duke and co-lead author on the paper, synthesized a series of molecules containing diazarines, a chemical structure which is composed of two nitrogen atoms bound together in a ring. Diazirines were a promising target for screening because their geometry traps hyperpolarization in a “hidden state” where it cannot relax quickly.

Using a simple and inexpensive approach to hyperpolarization called SABRE-SHEATH, in which the molecular tags are mixed with a spin-polarized form of hydrogen and a catalyst, the researchers were able to rapidly hyperpolarize one of the diazirine-containing molecules, greatly enhancing its magnetic resonance signals for over an hour.

Qiu Wang, assistant professor of chemistry at Duke and co-author on the paper, said this structure is a particularly exciting target for hyperpolarization because it has already been demonstrated as a tag for other types of biomedical imaging.

“It can be tagged on small molecules, macro molecules, amino acids, without changing the intrinsic properties of the original compound,” said Wang. “We are really interested to see if it would be possible to use it as a general imaging tag.”

The scientists believe their SABRE-SHEATH catalyst could be used to hyperpolarize a wide variety of chemical structures at a fraction of the cost of other methods.

“You could envision, in five or ten years, you’ve got the container with the catalyst, you’ve got the bulb with the hydrogen gas. In a minute, you’ve made the hyperpolarized agent, and on the fly you could actually take an image,” Warren said. “That is something that is simply inconceivable by any other method.”

The researchers have provided an artistic representation of the molecular ‘lightbulbs’,

Caption: Duke scientists have discovered a new class of inexpensive and long-lived molecular tags that enhance MRI signals by 10,000-fold. To activate the tags, the researchers mix them with a newly developed catalyst (center) and a special form of hydrogen (gray), converting them into long-lived magnetic resonance 'lightbulbs' that might be used to track disease metabolism in real time. Credit: Thomas Theis, Duke University

Caption: Duke scientists have discovered a new class of inexpensive and long-lived molecular tags that enhance MRI signals by 10,000-fold. To activate the tags, the researchers mix them with a newly developed catalyst (center) and a special form of hydrogen (gray), converting them into long-lived magnetic resonance ‘lightbulbs’ that might be used to track disease metabolism in real time. Credit: Thomas Theis, Duke University

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

Direct and cost-efficient hyperpolarization of long-lived nuclear spin states on universal 15N2-diazirine molecular tags by Thomas Theis, Gerardo X. Ortiz Jr, Angus W. J. Logan, Kevin E. Claytor, Yesu Feng, William P. Huhn, Volker Blum, Steven J. Malcolmson, Eduard Y. Chekmenev, Qiu Wang, and Warren S. Warren. Science Advances  25 Mar 2016: Vol. 2, no. 3, e1501438 DOI: 10.1126/sciadv.1501438

This paper appears to be open access.