Tag Archives: North Carolina State University

Making diamonds at room temperature with a new carbon material

Scientists at North Carolina State University (NCSU) claim to have found a new phase for solid carbon which allows them to create diamond materials at room temperature. From a Nov. 30, 2015 news item on Nanowerk,

Researchers from North Carolina State University have discovered a new phase of solid carbon, called Q-carbon, which is distinct from the known phases of graphite and diamond. They have also developed a technique for using Q-carbon to make diamond-related structures at room temperature and at ambient atmospheric pressure in air.

Phases are distinct forms of the same material. Graphite is one of the solid phases of carbon; diamond is another.

“We’ve now created a third solid phase of carbon,” says Jay Narayan, the John C. Fan Distinguished Chair Professor of Materials Science and Engineering at NC State and lead author of three [?] papers describing the work. “The only place it may be found in the natural world would be possibly in the core of some planets.”

A Nov. 30, 2015 NCSU news release (also on EurekAlert), which originated the news item, describes some of the new material’s properties,

Q-carbon has some unusual characteristics. For one thing, it is ferromagnetic – which other solid forms of carbon are not. [definition from its Wikipedia entry: Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets.]

“We didn’t even think that was possible,” Narayan says.

In addition, Q-carbon is harder than diamond, and glows when exposed to even low levels of energy.

“Q-carbon’s strength and low work-function – its willingness to release electrons – make it very promising for developing new electronic display technologies,” Narayan says.

But Q-carbon can also be used to create a variety of single-crystal diamond objects. …

The news release describes the process for creating Q-carbon,

Researchers start with a substrate, such as such as sapphire, glass or a plastic polymer. The substrate is then coated with amorphous carbon – elemental carbon that, unlike graphite or diamond, does not have a regular, well-defined crystalline structure. The carbon is then hit with a single laser pulse lasting approximately 200 nanoseconds. During this pulse, the temperature of the carbon is raised to 4,000 Kelvin (or around 3,727 degrees Celsius) and then rapidly cooled. This operation takes place at one atmosphere – the same pressure as the surrounding air.

The end result is a film of Q-carbon, and researchers can control the process to make films between 20 nanometers and 500 nanometers thick.

By using different substrates and changing the duration of the laser pulse, the researchers can also control how quickly the carbon cools. By changing the rate of cooling, they are able to create diamond structures within the Q-carbon.

“We can create diamond nanoneedles or microneedles, nanodots, or large-area diamond films, with applications for drug delivery, industrial processes and for creating high-temperature switches and power electronics,” Narayan says. “These diamond objects have a single-crystalline structure, making them stronger than polycrystalline materials. And it is all done at room temperature and at ambient atmosphere – we’re basically using a laser like the ones used for laser eye surgery. So, not only does this allow us to develop new applications, but the process itself is relatively inexpensive.”

And, if researchers want to convert more of the Q-carbon to diamond, they can simply repeat the laser-pulse/cooling process.

If Q-carbon is harder than diamond, why would someone want to make diamond nanodots instead of Q-carbon ones? Because we still have a lot to learn about this new material.

“We can make Q-carbon films, and we’re learning its properties, but we are still in the early stages of understanding how to manipulate it,” Narayan says. “We know a lot about diamond, so we can make diamond nanodots. We don’t yet know how to make Q-carbon nanodots or microneedles. That’s something we’re working on.”

NC State has filed two provisional patents on the Q-carbon and diamond creation techniques.

While the news release mentions Narayan is the lead author of three papers about this work, only two papers are cited at the end of the news release.

Here are the links and citations,

Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air by Jagdish Narayan and Anagh Bhaumik. APL Mater. 3, 100702 (2015); http://dx.doi.org/10.1063/1.4932622 [Published Oct. 7, 2015]

Novel Phase of Carbon, Ferromagnetism and Conversion into Diamond by Jagdish Narayan and Anagh Bhaumik. Published online Nov. 30 [, 2015] in the Journal of Applied Physics  DOI: 10.1063/1.4936595

Both articles are open access.

A 244-atom submarine powered by light

James Tour lab researchers at Rice University announce in a Nov. 16, 2015 news item on Nanowerk,

Though they’re not quite ready for boarding a lá “Fantastic Voyage,” nanoscale submarines created at Rice University are proving themselves seaworthy.

Each of the single-molecule, 244-atom submersibles built in the Rice lab of chemist James Tour has a motor powered by ultraviolet light. With each full revolution, the motor’s tail-like propeller moves the sub forward 18 nanometers.
And with the motors running at more than a million RPM, that translates into speed. Though the sub’s top speed amounts to less than 1 inch per second, Tour said that’s a breakneck pace on the molecular scale.

“These are the fastest-moving molecules ever seen in solution,” he said.

Expressed in a different way, the researchers reported this month in the American Chemical Society journal Nano Letters that their light-driven nanosubmersibles show an “enhancement in diffusion” of 26 percent. That means the subs diffuse, or spread out, much faster than they already do due to Brownian motion, the random way particles spread in a solution.

While they can’t be steered yet, the study proves molecular motors are powerful enough to drive the sub-10-nanometer subs through solutions of moving molecules of about the same size.

“This is akin to a person walking across a basketball court with 1,000 people throwing basketballs at him,” Tour said.

A Nov. 16, 2015 Rice University news release (also on EurekAlert), which originated the news item, provides context and details about the research,

Tour’s group has extensive experience with molecular machines. A decade ago, his lab introduced the world to nanocars, single-molecule cars with four wheels, axles and independent suspensions that could be “driven” across a surface.

Tour said many scientists have created microscopic machines with motors over the years, but most have either used or generated toxic chemicals. He said a motor that was conceived in the last decade by a group in the Netherlands proved suitable for Rice’s submersibles, which were produced in a 20-step chemical synthesis.

“These motors are well-known and used for different things,” said lead author and Rice graduate student Victor García-López. “But we were the first ones to propose they can be used to propel nanocars and now submersibles.”

The motors, which operate more like a bacteria’s flagellum than a propeller, complete each revolution in four steps. When excited by light, the double bond that holds the rotor to the body becomes a single bond, allowing it to rotate a quarter step. As the motor seeks to return to a lower energy state, it jumps adjacent atoms for another quarter turn. The process repeats as long as the light is on.

For comparison tests, the lab also made submersibles with no motors, slow motors and motors that paddle back and forth. All versions of the submersibles have pontoons that fluoresce red when excited by a laser, according to the researchers. (Yellow, sadly, was not an option.)

“One of the challenges was arming the motors with the appropriate fluorophores for tracking without altering the fast rotation,” García-López said.

Once built, the team turned to Gufeng Wang at North Carolina State University to measure how well the nanosubs moved.

“We had used scanning tunneling microscopy and fluorescence microscopy to watch our cars drive, but that wouldn’t work for the submersibles,” Tour said. “They would drift out of focus pretty quickly.”

The North Carolina team sandwiched a drop of diluted acetonitrile liquid containing a few nanosubs between two slides and used a custom confocal fluorescence microscope to hit it from opposite sides with both ultraviolet light (for the motor) and a red laser (for the pontoons).

The microscope’s laser defined a column of light in the solution within which tracking occurred, García-López said. “That way, the NC State team could guarantee it was analyzing only one molecule at a time,” he said.

Rice’s researchers hope future nanosubs will be able to carry cargoes for medical and other purposes. “There’s a path forward,” García-López said. “This is the first step, and we’ve proven the concept. Now we need to explore opportunities and potential applications.”

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

Unimolecular Submersible Nanomachines. Synthesis, Actuation, and Monitoring by Víctor García-López, Pinn-Tsong Chiang, Fang Chen, Gedeng Ruan, Angel A. Martí, Anatoly B. Kolomeisky, Gufeng Wang, and James M. Tour. Nano Lett., Article ASAP DOI: 10.1021/acs.nanolett.5b03764 Publication Date (Web): November 5, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

There is an illustration of the 244-atom submersible,

Rice University scientists have created light-driven, single-molecule submersibles that contain just 244 atoms. Illustration by Loïc Samuel

Rice University scientists have created light-driven, single-molecule submersibles that contain just 244 atoms. Illustration by Loïc Samuel

$81M for US National Nanotechnology Coordinated Infrastructure (NNCI)

Academics, small business, and industry researchers are the big winners in a US National Science Foundation bonanza according to a Sept. 16, 2015 news item on Nanowerk,

To advance research in nanoscale science, engineering and technology, the National Science Foundation (NSF) will provide a total of $81 million over five years to support 16 sites and a coordinating office as part of a new National Nanotechnology Coordinated Infrastructure (NNCI).

The NNCI sites will provide researchers from academia, government, and companies large and small with access to university user facilities with leading-edge fabrication and characterization tools, instrumentation, and expertise within all disciplines of nanoscale science, engineering and technology.

A Sept. 16, 2015 NSF news release provides a brief history of US nanotechnology infrastructures and describes this latest effort in slightly more detail (Note: Links have been removed),

The NNCI framework builds on the National Nanotechnology Infrastructure Network (NNIN), which enabled major discoveries, innovations, and contributions to education and commerce for more than 10 years.

“NSF’s long-standing investments in nanotechnology infrastructure have helped the research community to make great progress by making research facilities available,” said Pramod Khargonekar, assistant director for engineering. “NNCI will serve as a nationwide backbone for nanoscale research, which will lead to continuing innovations and economic and societal benefits.”

The awards are up to five years and range from $500,000 to $1.6 million each per year. Nine of the sites have at least one regional partner institution. These 16 sites are located in 15 states and involve 27 universities across the nation.

Through a fiscal year 2016 competition, one of the newly awarded sites will be chosen to coordinate the facilities. This coordinating office will enhance the sites’ impact as a national nanotechnology infrastructure and establish a web portal to link the individual facilities’ websites to provide a unified entry point to the user community of overall capabilities, tools and instrumentation. The office will also help to coordinate and disseminate best practices for national-level education and outreach programs across sites.

New NNCI awards:

Mid-Atlantic Nanotechnology Hub for Research, Education and Innovation, University of Pennsylvania with partner Community College of Philadelphia, principal investigator (PI): Mark Allen
Texas Nanofabrication Facility, University of Texas at Austin, PI: Sanjay Banerjee

Northwest Nanotechnology Infrastructure, University of Washington with partner Oregon State University, PI: Karl Bohringer

Southeastern Nanotechnology Infrastructure Corridor, Georgia Institute of Technology with partners North Carolina A&T State University and University of North Carolina-Greensboro, PI: Oliver Brand

Midwest Nano Infrastructure Corridor, University of  Minnesota Twin Cities with partner North Dakota State University, PI: Stephen Campbell

Montana Nanotechnology Facility, Montana State University with partner Carlton College, PI: David Dickensheets
Soft and Hybrid Nanotechnology Experimental Resource,

Northwestern University with partner University of Chicago, PI: Vinayak Dravid

The Virginia Tech National Center for Earth and Environmental Nanotechnology Infrastructure, Virginia Polytechnic Institute and State University, PI: Michael Hochella

North Carolina Research Triangle Nanotechnology Network, North Carolina State University with partners Duke University and University of North Carolina-Chapel Hill, PI: Jacob Jones

San Diego Nanotechnology Infrastructure, University of California, San Diego, PI: Yu-Hwa Lo

Stanford Site, Stanford University, PI: Kathryn Moler

Cornell Nanoscale Science and Technology Facility, Cornell University, PI: Daniel Ralph

Nebraska Nanoscale Facility, University of Nebraska-Lincoln, PI: David Sellmyer

Nanotechnology Collaborative Infrastructure Southwest, Arizona State University with partners Maricopa County Community College District and Science Foundation Arizona, PI: Trevor Thornton

The Kentucky Multi-scale Manufacturing and Nano Integration Node, University of Louisville with partner University of Kentucky, PI: Kevin Walsh

The Center for Nanoscale Systems at Harvard University, Harvard University, PI: Robert Westervelt

The universities are trumpeting this latest nanotechnology funding,

NSF-funded network set to help businesses, educators pursue nanotechnology innovation (North Carolina State University, Duke University, and University of North Carolina at Chapel Hill)

Nanotech expertise earns Virginia Tech a spot in National Science Foundation network

ASU [Arizona State University] chosen to lead national nanotechnology site

UChicago, Northwestern awarded $5 million nanotechnology infrastructure grant

That is a lot of excitement.

Audience perceptions of emerging technologies and media stories that emphasize conflict over nuance

A few names popped into my head, as soon as I saw a news release focused on audience perceptions and emerging technologies. I was right about one of the authors (Dominique Brossard of the University of Wisconsin-Madison [UWM] often writes on the topic) however, the lead author is Andrew Binder of North Carolina State University (NCSU). An August 31, 2015 NCSU news release describes a joint NCSU-UWM research project  (Note: Links have been removed),

Researchers from NC State University and the University of Wisconsin-Madison have found more evidence that how media report on emerging technologies – such as nanotechnology or genetically modified crops – influences public opinion on those subjects.

Specifically, when news stories highlight conflict in the scientific community on an emerging technology, people who accept the authority of scientists on scientific subjects are more likely to view the emerging technology as risky.

“Scientists – even scientists who disagree – often incorporate caveats and nuance into their comments on emerging technologies,” says Andrew R. Binder, lead author of a paper on the work and an associate professor of communication at NC State. “For example, a scientist may voice an opinion but note a lack of data on the subject. But that nuance is often lost in news stories.

“We wanted to know stories that present scientists as being in clear conflict, leaving out the nuance, affected the public’s perception of uncertainty on an issue – particularly compared to stories that incorporate the nuances of each scientist’s position,” Binder says.

For their experiment, the researchers had 250 college students answer a questionnaire on their deference to scientific authority and their perceptions of nanotechnology. Participants were split into four groups. Before asking about nanotechnology, one group was asked to read a news story about nanotech that quoted scientists and presented them as being in conflict; one group read a news story with quotes that showed disagreement between scientists but included nuance on each scientist’s position; one group read a story without quotes; and one group – the control group – was given no reading.

In most instances, the reading assignments did not have a significant impact on study participants’ perception of risks associated with nanotechnology. However, those participants who were both “highly deferent” to scientific authority and given the “conflict” news item perceived nanotechnology as being significantly more risky as compared to those highly deferent study participants who read the “nuance” article.

“One thing that’s interesting here is that participants who were highly deferential to scientific authority but were in the control group or read the news item without quotes – they landed about halfway between the ‘conflict’ group and the ‘nuance’ group,” Binder says. “So it would seem that the way reporters frame scientific opinion can sway an audience one way or the other.”

The researchers also found that, while an appearance of conflict can increase one’s perception of risk, it did not increase participants’ sense of certainty in their position.

As a practical matter, the findings raise questions for journalists – since scientists have limited control over how they’re portrayed in the news. Previous surveys have found that many people are deferent to scientific authority – they trust scientists – so a reporter’s decision to cut nuance or highlight conflict could make a very real impact on how the public perceives emerging technologies.

“Reporters can’t include every single detail, and scientists want to include everything,” Binder says. “So I don’t think there’s a definitive solution out there that will make everyone happy. But hopefully this will encourage both parties to meet in the middle.”

I have one comment, this research was conducted on college students whose age range is likely more restricted than what you’d find in the general populace. I don’t know if the research team has plans or more funding but it would seem the next step would be to tested a wider range to see if the results with the college students can be generalized.

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

Conflict or Caveats? Effects of Media Portrayals of Scientific Uncertainty on Audience Perceptions of New Technologies by Andrew R. Binder, Elliott D. Hillback, and Dominique Brossard. Risk Analysis DOI: 10.1111/risa.12462 Article first published online: 13 AUG 2015

© 2015 Society for Risk Analysis

This paper is behind a paywall.

Building nanocastles in the sand

Scientists have taken inspiration from sandcastles to build robots made of nanoparticles. From an Aug. 5, 2015 news item on ScienceDaily,

If you want to form very flexible chains of nanoparticles in liquid in order to build tiny robots with flexible joints or make magnetically self-healing gels, you need to revert to childhood and think about sandcastles.

In a paper published this week in Nature Materials, researchers from North Carolina State University and the University of North Carolina-Chapel Hill show that magnetic nanoparticles encased in oily liquid shells can bind together in water, much like sand particles mixed with the right amount of water can form sandcastles.

An Aug. 5, 2015 North Carolina State University (NCSU) news release (also on EurekAlert) by Mick Kulikowski, which originated the news item, expands on the theme,

“Because oil and water don’t mix, the oil wets the particles and creates capillary bridges between them so that the particles stick together on contact,” said Orlin Velev, INVISTA Professor of Chemical and Biomolecular Engineering at NC State and the corresponding author of the paper.

“We then add a magnetic field to arrange the nanoparticle chains and provide directionality,” said Bhuvnesh Bharti, research assistant professor of chemical and biomolecular engineering at NC State and first author of the paper.

Chilling the oil is like drying the sandcastle. Reducing the temperature from 45 degrees Celsius to 15 degrees Celsius freezes the oil and makes the bridges fragile, leading to breaking and fragmentation of the nanoparticle chains. Yet the broken nanoparticles chains will re-form if the temperature is raised, the oil liquefies and an external magnetic field is applied to the particles.

“In other words, this material is temperature responsive, and these soft and flexible structures can be pulled apart and rearranged,” Velev said. “And there are no other chemicals necessary.”

The paper is also co-authored by Anne-Laure Fameau, a visiting researcher from INRA [French National Institute for Agricultural Research or Institut National de la Recherche Agronomique], France. …

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

Nanocapillarity-mediated magnetic assembly of nanoparticles into ultraflexible filaments and reconfigurable networks by Bhuvnesh Bharti, Anne-Laure Fameau, Michael Rubinstein, & Orlin D. Velev. Nature Materials (2015) doi:10.1038/nmat4364 Published online 03 August 2015

This paper is behind a paywall.

Greening silver nanoparticles with lignin

A July 13, 2015 news item on phys.org highlights a new approach to making silver nanoparticles safer in the environment,

North Carolina State University researchers have developed an effective and environmentally benign method to combat bacteria by engineering nanoscale particles that add the antimicrobial potency of silver to a core of lignin, a ubiquitous substance found in all plant cells. The findings introduce ideas for better, greener and safer nanotechnology and could lead to enhanced efficiency of antimicrobial products used in agriculture and personal care.

A July 13, 2015 North Carolina State University (NCSU) news release (also on EurekAlert), which originated the news item, adds a bit more information,

As the nanoparticles wipe out the targeted bacteria, they become depleted of silver. The remaining particles degrade easily after disposal because of their biocompatible lignin core, limiting the risk to the environment.

“People have been interested in using silver nanoparticles for antimicrobial purposes, but there are lingering concerns about their environmental impact due to the long-term effects of the used metal nanoparticles released in the environment,” said Velev, INVISTA Professor of Chemical and Biomolecular Engineering at NC State and the paper’s corresponding author. “We show here an inexpensive and environmentally responsible method to make effective antimicrobials with biomaterial cores.”

The researchers used the nanoparticles to attack E. coli, a bacterium that causes food poisoning; Pseudomonas aeruginosa, a common disease-causing bacterium; Ralstonia, a genus of bacteria containing numerous soil-borne pathogen species; and Staphylococcus epidermis, a bacterium that can cause harmful biofilms on plastics – like catheters – in the human body. The nanoparticles were effective against all the bacteria.

The method allows researchers the flexibility to change the nanoparticle recipe in order to target specific microbes. Alexander Richter, the paper’s first author and an NC State Ph.D. candidate who won a 2015 Lemelson-MIT prize, says that the particles could be the basis for reduced risk pesticide products with reduced cost and minimized environmental impact.

“We expect this method to have a broad impact,” Richter said. “We may include less of the antimicrobial ingredient without losing effectiveness while at the same time using an inexpensive technique that has a lower environmental burden. We are now working to scale up the process to synthesize the particles under continuous flow conditions.”

I don’t quite understand how the silver nanoparticles/ions are rendered greener. I gather the lignin is harmless but where do the silver nanoparticles/ions go after they’ve been stripped of their lignin cover and have killed the bacteria? I did try reading the paper’s abstract (not much use for someone with my science level),

Silver nanoparticles have antibacterial properties, but their use has been a cause for concern because they persist in the environment. Here, we show that lignin nanoparticles infused with silver ions and coated with a cationic polyelectrolyte layer form a biodegradable and green alternative to silver nanoparticles. The polyelectrolyte layer promotes the adhesion of the particles to bacterial cell membranes and, together with silver ions, can kill a broad spectrum of bacteria, including Escherichia coli, Pseudomonas aeruginosa and quaternary-amine-resistant Ralstonia sp. Ion depletion studies have shown that the bioactivity of these nanoparticles is time-limited because of the desorption of silver ions. High-throughput bioactivity screening did not reveal increased toxicity of the particles when compared to an equivalent mass of metallic silver nanoparticles or silver nitrate solution. Our results demonstrate that the application of green chemistry principles may allow the synthesis of nanoparticles with biodegradable cores that have higher antimicrobial activity and smaller environmental impact than metallic silver nanoparticles.

If you can explain what happens to the silver nanoparticles, please let me know.

Meanwhile, here’s a link to and a citation for the paper,

An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core by Alexander P. Richter, Joseph S. Brown, Bhuvnesh Bharti, Amy Wang, Sumit Gangwal, Keith Houck, Elaine A. Cohen Hubal, Vesselin N. Paunov, Simeon D. Stoyanov, & Orlin D. Velev. Nature Nanotechnology (2015) doi:10.1038/nnano.2015.141 Published online 13 July 2015

This paper is behind a paywall.

The science of the Avengers: Age of Ultron

The American Chemical Society (ACS) has produced a video (almost 4 mins.) in their Reactions Science Video Series of podcasts focusing on the Avengers, super heroes, as portrayed in Avengers: Age of Ultron and science. From an April 29, 2015 ACS news release on EurekAlert,

Science fans, assemble! On May 1, the world’s top superhero team is back to save the day in “Avengers: Age of Ultron.” This week, Reactions looks at the chemistry behind these iconic heroes’ gear and superpowers, including Tony Stark’s suit, Captain America’s shield and more.

Here’s the video,

While the chemists are interested in the metal alloys, there is more ‘super hero science’ writing out there. Given my interests, I found the ‘Captain America’s shield as supercapacitor theory’ as described in Matt Shipman’s April 15, 2014 post on The Abstract (North Carolina State University’s official newsroom blog quite interesting. I featured Shipman’s ‘super hero and science’ series of posts in my April 28, 2014 posting.

Who would buy foods that were nanotechnology-enabled or genetically modified?

A research survey conducted by scientists at North Carolina State University (NCSU) and the University of Minnesota suggests that under certain conditions, consumers in the US would be likely to purchase nanotechnology-enabled or genetically modified food. From a Dec. 2, 2014 news item on Nanowerk,

New research from North Carolina State University and the University of Minnesota shows that the majority of consumers will accept the presence of nanotechnology or genetic modification (GM) technology in foods – but only if the technology enhances the nutrition or improves the safety of the food.

A Dec. 2, 2014 NCSU news release (also on EurekAlert), which originated the news item, notes that while many people will pay more to avoid nanotechnology-enabled or genetically modified food there is an exception of sorts,

“In general, people are willing to pay more to avoid GM or nanotech in foods, and people were more averse to GM tech than to nanotech,” says Dr. Jennifer Kuzma, senior author of a paper on the research and co-director of the Genetic Engineering in Society Center at NC State. “However, it’s not really that simple. There were some qualifiers, indicating that many people would be willing to buy GM or nanotech in foods if there were health or safety benefits.”

The researchers conducted a nationally representative survey of 1,117 U.S. consumers. Participants were asked to answer an array of questions that explored their willingness to purchase foods that contained GM tech and foods that contained nanotech. The questions also explored the price of the various foods and whether participants would buy foods that contained nanotech or GM tech if the foods had enhanced nutrition, improved taste, improved food safety, or if the production of the food had environmental benefits.

The researchers found that survey participants could be broken into four groups.

Eighteen percent of participants belonged to a group labeled the “new technology rejecters,” which would not by GM or nanotech foods under any circumstances. Nineteen percent of participants belonged to a group labeled the “technology averse,” which would buy GM or nanotech foods only if those products conveyed food safety benefits. Twenty-three percent of participants were “price oriented,” basing their shopping decisions primarily on the cost of the food – regardless of the presence of GM or nanotech. And 40 percent of participants were “benefit oriented,” meaning they would buy GM or nanotech foods if the foods had enhanced nutrition or food safety.

“This tells us that GM or nanotech food products have greater potential to be viable in the marketplace if companies focus on developing products that have safety and nutrition benefits – because a majority of consumers would be willing to buy those products,” Kuzma says.

“From a policy standpoint, it also argues that GM and nanotech foods should be labeled, so that the technology rejecters can avoid them,” Kuzma adds.

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

Heterogeneous Consumer Preferences for Nanotechnology and Genetic-modification Technology in Food Products by Chengyan Yue, Shuoli Zhao, and Jennifer Kuzma. Journal of Agricultural Economics DOI: 10.1111/1477-9552.12090 Article first published online: 12 NOV 2014

© 2014 The Agricultural Economics Society

This paper is behind a paywall.

I have mentioned Jennifer Kuzma’s work previously in an Oct. 29, 2013 posting titled, Nano info on food labels wanted by public in the US?

Toughening up your electronics: kevlar with a tungsten fibre coating

An upcoming presentation at the 61st annual AVS Conference (Nov. 9 – 14, 2014) features a fibre made of tungsten that when added to kevlar offers the possibility of ‘tough’ electronics. From an Oct. 31, 2014 news item on Nanowerk (Note: A link has been removed),

A group of North Carolina State University researchers is exploring novel ways to apply semiconductor industry processes to unique substrates, such as textiles and fabrics, to “weave together” multifunctional materials with distinct capabilities.

During the AVS 61st International Symposium & Exhibition, being held November 9-14, 2014, in Baltimore, Maryland, the researchers will describe how they were able to “weave” high-strength, highly conductive yarns made of tungsten metal on Kevlar — aka body armor material — by using atomic layer deposition (ALD), a process commonly used for producing memory and logic devices.

An Oct. 28, 2014 AVS: Science & Technology of Materials, Interfaces, and Processing news release on Newswire, which originated the news item provides more details about this multifunctional material and a good description of atomic layer deposition (ALD),

“As a substrate, Kevlar was intriguing to us because it’s capable of withstanding the relatively high temperature (220°C) required by the ALD deposition process,” explains Sarah Atanasov, a Ph.D. candidate in the Biomolecular Engineering Department at North Carolina State University. “Kevlar doesn’t begin to degrade until it reaches nearly 400°C.”

The group selected ALD as a process because it allows them to deposit highly conformal films on nonplanar surfaces with nanometer-thickness precision. “This ensures that the entire surface of the yarn — made of nearly 600 fibers, each 12 microns in diameter — is evenly coated,” said Atanasov.

How does the ALD process work? It’s actually a cyclical process, which begins by exposing the substrate’s surface to one gas-phase chemical, in this case tungsten hexafluoride (WF6), followed by removal of any unreacted material. This is chased with surface exposure to a second gas-phase chemical, silane (SiH4), after which any unreacted material is once again removed.

By the end of the ALD cycle, the two chemicals have reacted to produce tungsten. “This is a self-limited process, meaning that a single atomic layer is deposited during each cycle — in this case ~5.5 Angstroms per cycle,” Atanasov said. “The process can be cycled through a number of times to achieve any specifically desired thickness. As a bonus, ALD occurs in the gas phase, so it doesn’t require any solution processing and is considered to be a more sustainable deposition technique.”

While weaving together multiple fabrics to combine multiple capabilities certainly isn’t new, characteristics such as high strength, high conductivity, and flexibility are frequently regarded as being mutually exclusive — so concessions are often made to get the most important one.

The work by Atanasov and colleagues shows, however, that ALD of tungsten on Kevlar yields yarns that are highly flexible and highly conductive, around 2,000 S/cm (“Siemens per centimeter,” a common unit used for conductivity). The yards are also within 90 percent of their original prior-to-coating tensile strength.

“Introducing well-established processes from one area into a completely new field can lead to some very interesting and useful results,” Atanasov noted.

The group’s tungsten-on-Kevlar yarns are expected to find applications in multifunctional protective electronics materials for electromagnetic shielding and communications, as well as erosion-resistant antistatic fabrics for space and automated technologies.

Presentation #MS+PS+TF-ThA4, “Multifunctional Fabrics via Tungsten ALD on Kevlar,” authored by Sarah Atanasov, B. Kalanyan and G.N. Parsons, will be at 3:20 p.m. ET on Thursday, Nov. 13, 2014.

Atanasov recently published a paper about another kevlar project where she worked to enhance its ‘stab resistance’ with a titanium dioxide/aluminum mixture as Anisha Ratan notes in her Sept. 12, 2014 article (Oxide armour offers Kevlar better stab resistance)  (excerpt from Ratan’s article for the Royal Society; Note: Links have been removed),

Scientists in the US have synthesised an ultrathin inorganic bilayer coating for Kevlar that could improve its stab resistance by 30% and prove invaluable for military and first-responders requiring multi-threat protection clothes.

Developed in 1965 by Stephanie Kwolek at DuPont, poly(p-phenylene terephthalamide) (PPTA), or Kevlar, is a para-aramid synthetic fiber deriving its strength from interchain hydrogen bonding. It finds use in flexible energy and electronic systems, but is most commonly associated with bullet-proof body armour.

However, despite its anti-ballistic properties, it offers limited cut and stab protection. In a bid to overcome this drawback, Sarah Atanasov, from Gregory Parsons’ group at North Carolina State University, and colleagues, have developed a TiO2/Al2O3 bilayer that significantly enhances the cut resistance of Kevlar fibers. The coating is added to Kevlar by atomic layer deposition, a low temperature technique with nanoscale precision.

Unfortunately the team’s research paper is no longer open access but you can find a link to it from Ratan’s article.

Lung injury, carbon nanotubes, and aluminum oxide

It’s pretty much undisputed that long, multi-walled carbon nanotubes (MWCNTs) are likely to present a serious health hazard given their resemblance to asbestos fibres. It’s a matter of some concern that has resulted in a US National Institute of Occupational Safety and Health (NIOSH) recommendation for workplace exposure to all carbon nanotubes that is stringent. (My April 26, 2013 posting features the recommendation.)

Some recent research from North Carolina State University (NCSU) suggests that there may be a way to make long, multi-walled carbon nanotubes safer. From an Oct. 3, 2014 news item on Nanowerk,

A new study from North Carolina State University and the National Institute of Environmental Health Sciences (NIEHS) finds that coating multiwalled carbon nanotubes (CNTs) with aluminum oxide reduces the risk of lung scarring, or pulmonary fibrosis, in mice.

“This could be an important finding in the larger field of work that aims to predict and prevent future diseases associated with engineered nanomaterials,” says James Bonner, a professor of environmental and molecular toxicology at NC State …

An Oct. 3, 2014 NCSU news release, which originated the news item, describes the research in a little more detail,

Multiwalled CNTs have a wide array of applications, ranging from sporting goods to electronic devices. And while these materials have not been associated with adverse health effects in humans, research has found that multi-walled CNTs can cause pulmonary fibrosis and lung inflammation in animal models.

“Because multiwalled CNTs are increasingly used in a wide variety of products, it seems likely that humans will be exposed to them at some point,” Bonner says. “That means it’s important for us to understand these materials and the potential risk they pose to human health. The more we know, the better we’ll be able to engineer safer materials.”

For this study, the researchers used atomic layer deposition to coat multiwalled CNTs with a thin film of aluminum oxide and exposed mice to a single dose of the CNTs, via inhalation.

The researchers found that CNTs coated with aluminum oxide were significantly less likely to cause pulmonary fibrosis in mice. However, the coating of aluminum oxide did not prevent lung inflammation.

“The aluminum oxide coating doesn’t eliminate health risks related to multi-walled CNTs,” Bonner says, “but it does lower them.”

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

Atomic Layer Deposition Coating of Carbon Nanotubes with Aluminum Oxide Alters Pro-Fibrogenic Cytokine Expression by Human Mononuclear Phagocytes In Vitro and Reduces Lung Fibrosis in Mice In Vivo by Alexia J. Taylor, Christina D. McClure, Kelly A. Shipkowski, Elizabeth A. Thompson, Salik Hussain, Stavros Garantziotis, Gregory N. Parsons, and James C. Bonner. Published: September 12, 2014 DOI: 10.1371/journal.pone.0106870

This is an open access article.

The researchers offered this conclusion (part of the paper’s abstract),

These findings indicate that ALD [atomic layer deposition] thin film coating of MWCNTs with Al2O3 reduces fibrosis in mice and that in vitro phagocyte expression of IL-6, TNF-α, and OPN, but not IL-1β, predict MWCNT-induced fibrosis in the lungs of mice in vivo.

However, what I found most striking was this from the paper’s Discussion (section),

While the Al2O3 coating on MWCNTs appears to be the major factor that alters cytokine production in THP-1 and PBMCs in vitro, nanotube length is still likely an important determinant of the inflammatory and fibroproliferative effects of MWCNTs in the lung in vivo. In general, long asbestos fibers or rigid MWCNTs (i.e., >20 µm) remain in the lung and are much more persistent than shorter fibers or nanotubes [20]. Therefore, the nanotube fragments resulting from breakage of A-MWCNTs coated with 50 or 100 ALD cycles of Al2O3 would likely be cleared from the lungs more rapidly than uncoated long MWCNTs or those coated with only 10 ALD cycles of Al2O3. We observed that the fracturing of A-MWCNTs occurred only after sonication prior to administration to cells in vitro or mice in vivo. However, unsonicated A-MWCNTs could be more likely to fracture over time in tissues as compared to U-MWCNTs [uncoated]. We did not address the issue of A-MWCNT clearance before or after fracturing in the present study, but future work should focus the relative clearance rates from the lungs of mice exposed to A-MWCNTs in comparison to U-MWCNTs. Another potentially important consideration is whether or not ALD coating with Al2O3 alters the formation of a protein corona around MWCNTs. It is possible that differences in cytokine levels in the supernatants from cells treated with U- or A-MWCNTs could be due to differences in protein corona formation around functionalized MWCNTs that could modify the adsorptive capacity of the nanomaterial. Characterization of the protein corona and the adsorptive capacity for cytokines after ALD modification of MWCNTs should be another important focus for future work. [emphases mine]

In other words, researchers think coating long, MWCNTs with a certain type of aluminum might be safer due to its effect on various proteins and because coated MWCNTs are likely to fracture into smaller pieces and we know that short MWCNTs don’t seem to present a problem when inhaled.

Of course, there’s the research from Duke University (my Oct. 3, 2014 post) which suggests CNTs could present a different set of problems over time as they accumulate in the environment.