Tag Archives: North Carolina State University

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.

Targeted nanoparticles stimulate growth of healthy heart cells in damaged hearts

Don’t get too excited, the research is at the rat stage sometimes called ‘animal models’ as in ‘these nanoparticles are being tested on animal models’. Still it’s exciting news from North Carolina State University (NCSU; my second item from that university today, Sept. 12, 2014).

From a Sept. 12, 2014 news item on Azonano,

A targeted nanoparticle created by researchers at North Carolina State University and the Cedars-Sinai Heart Institute may help heart attack patients regenerate healthy heart tissue without using donated or processed stem cells. This new nanomedicine could also alleviate some of the difficulties involved with stem cell therapy, including treatment delays and invasive procedures.

A Sept. ?, 2014 NCSU news release, which originated the news item, provides a little more detail about the work,

The particle, a “magnetic bi-functional cell engager” called MagBICE, consists of an iron platform with two different antibodies attached. These antibodies have different functions – one locates a patient’s own stem cells after a heart attack, and the other grabs injured tissue, allowing MagBICE to act as a matchmaker between injury and repair crew. The iron platform makes MagBICE magnetically active, allowing physicians to direct the particles to the heart with an external magnetic field. The iron platform also enables magnetic resonance imaging (MRI).

Ke Cheng, associate professor of regenerative medicine at NC State, and his colleagues at Cedars-Sinai Heart Institute tested MagBICE in rats and found that the particle was effective in redirecting stem cells in the blood to the injured heart. [emphasis] Additionally, MagBICE was easier and faster to administer than current stem cell therapy products.

“MagBICE optimizes and amplifies the body’s own repair process, which means we don’t have to worry about patient rejection of donated stem cells, or delay treatment while a patient’s stem cells are being processed, purified and prepared,” Cheng says. “The drug can be offered to patients immediately after blood vessels to the damaged areas are reopened and can be given intravenously, which isn’t possible with stem cell therapy.”

Courtesy of NCSU, there’s an artist’s illustration of the MagBICE and the heart,

MagBICE engaging therapeutic stem cells with injured cardiomyocytes. Credit: Alice Harvey, NC State

MagBICE engaging therapeutic stem cells with injured cardiomyocytes. Credit: Alice Harvey, NC State

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

Magnetic antibody-linked nanomatchmakers for therapeutic cell targeting by Ke Cheng, Deliang Shen, M. Taylor Hensley, Ryan Middleton, Baiming Sun, Weixin Liu, Geoffrey De Couto, & Eduardo Marbán. Nature Communications 5, Article number: 4880 doi:10.1038/ncomms5880 Published 10 September 2014

This is an open access paper.

World’s largest DNA origami: 200nm x 300nm

If the 200nm x 300nm size is the world’s largest DNA origami, what is the standard size?  Before you get the answer to that question, here’s more about the world’s largest from a Sept. 11, 2014 news item on Nanowerk,

Researchers from North Carolina State University, Duke University and the University of Copenhagen have created the world’s largest DNA origami, which are nanoscale constructions with applications ranging from biomedical research to nanoelectronics.

“These origami can be customized for use in everything from studying cell behavior to creating templates for the nanofabrication of electronic components,” says Dr. Thom LaBean, an associate professor of materials science and engineering at NC State and senior author of a paper describing the work …

A Sept. ?, 2014 North Carolina State University (NCSU) news release, which originated the news item, describes DNA origami and the process for creating it,

DNA origami are self-assembling biochemical structures that are made up of two types of DNA. To make DNA origami, researchers begin with a biologically derived strand of DNA called the scaffold strand. The researchers then design customized synthetic strands of DNA, called staple strands. Each staple strand is made up of a specific sequence of bases (adenine, cytosine, thaline and guanine – the building blocks of DNA), which is designed to pair with specific subsequences on the scaffold strand.

The staple strands are introduced into a solution containing the scaffold strand, and the solution is then heated and cooled. During this process, each staple strand attaches to specific sections of the scaffold strand, pulling those sections together and folding the scaffold strand into a specific shape.

Here’s the answer to the question I asked earlier about the standard size for DNA origami and a description for how the researchers approached the problem of making a bigger piece (from the news release,

The standard for DNA origami has long been limited to a scaffold strand that is made up of 7,249 bases, creating structures that measure roughly 70 nanometers (nm) by 90 nm, though the shapes may vary.

However, the research team led by LaBean has now created DNA origami consisting of 51,466 bases, measuring approximately 200 nm by 300 nm.

“We had to do two things to make this viable,” says Dr. Alexandria Marchi, lead author of the paper and a postdoctoral researcher at Duke. “First we had to develop a custom scaffold strand that contained 51 kilobases. We did that with the help of molecular biologist Stanley Brown at the University of Copenhagen.

“Second, in order to make this economically feasible, we had to find a cost-effective way of synthesizing staple strands – because we went from needing 220 staple strands to needing more than 1,600,” Marchi says.

The researchers did this by using what is essentially a converted inkjet printer to synthesize DNA directly onto a plastic chip.

“The technique we used not only creates large DNA origami, but has a fairly uniform output,” LaBean says. “More than 90 percent of the origami are self-assembling properly.”

For the curious, a link to and a citation for the paper,

Toward Larger DNA Origami by Alexandria N. Marchi, Ishtiaq Saaem, Briana N. Vogen, Stanley Brown, and Thomas H. LaBean. Nano Lett., Article ASAP DOI: 10.1021/nl502626s Publication Date (Web): September 1, 2014
Copyright © 2014 American Chemical Society

This paper is behind a paywall.

Cookies, ants, and a citizen science project plus a call for proposals for a 2015 Citizen Science Conference

My first citizen science item concerns summertime when the ants are out and about, oftentimes as uninvited participants to a picnic. Scientists at North Carolina State University (NCSU) and the University of Florida (UF) have decided to take advantage of this summer phenomenon as per a July 7, 2014 news item on ScienceDaily,

Scientists from North Carolina State University and the University of Florida have combined cookies, citizen science and robust research methods to track the diversity of ant species across the United States, and are now collaborating with international partners to get a global perspective on how ants are moving and surviving in the modern world.

“We think our School of Ants project serves as a good model for how citizen science can be used to collect more data, more quickly, from more places than a research team could do otherwise,” says Dr. Andrea Lucky, a researcher at the University of Florida who started work on the School of Ants while a postdoctoral researcher at NC State and now heads the project. Lucky is co-lead author of a paper describing the work and its early findings. “And our protocols help ensure that the data we are collecting are high quality.”

A July 7, 2014 NCSU news release (also on EurekAlert), which originated the news item, describes the various objectives for the project,

The School of Ants project was developed at NC State to help researchers get a handle on the diversity of ant species across the United States, with a particular focus on Chicago, Raleigh and New York City. In short, to discover which ant species are living where.

“But we also wanted to launch a citizen science project that both increased the public’s ecological literacy and addressed criticisms that public involvement made citizen science data unreliable,” says Dr. Amy Savage , a postdoctoral biological sciences researcher at NC State and the other co-lead author of the paper.

The research protocol, process, and outcomes are then described (from the news release),

The researchers developed a simple protocol involving Pecan Sandies cookies and sealable plastic bags, detailing precisely how the public should collect and label ant samples before shipping them to NC State or UF. [emphasis mine] This process was designed to engage the public in the aspect of the research that was easiest for non-scientists to enjoy and participate in, while also limiting the chances that the public could make mistakes that would skew the findings.

Once the samples arrive at NC State or UF, they are sorted, identified by a team of national experts and entered into a database. That information is then made publicly available in a user-friendly format on the project’s schoolofants.org site, allowing study participants to track the survey.

“This information is helping us tackle a variety of ecological and evolutionary questions, such as how ants may be evolving in urban environments, and how invasive species are spreading in the U.S.,” Savage says.

More than 1,000 participants, with samples from all 50 states, have taken part in the project since its 2011 launch – and there have already been some surprising findings.

For example, the researchers learned that a venomous invasive species, the Asian needle ant (Pachycondyla chinensis), had spread thousands of miles farther than anyone expected. Researchers knew the species had established itself in the Southeast, but study participants sent in Asian needle ant samples from as far afield as Wisconsin and Washington state.

To build on the School of Ants model, the researchers have launched collaborations with counterparts in Italy and Australia.

“We’re optimistic that this project will give us a broader view of ant diversity and how these species intersect with us, where we live and work around the world,” Lucky says.

The researchers are also working with teachers to incorporate the project into K-12 instruction modules that incorporate key elements of common core education standards. One early teacher collaboration has led to a research paper co-written by 4th and 5th graders.

“We also collaborated with a science writer to produce a free series of iBooks featuring natural history stories about the most common ants that our citizen science partners are collecting in their backyards and sidewalks,” Savage says.

“One of our big goals now is to move from collecting data and finding patterns to identifying ways that we can work with the public to figure out what is driving those patterns,” says Dr. Rob Dunn, an associate professor of biological sciences at NC State and co-author of the paper.

Not being familiar with Pecan Sandies cookies I went searching on the internet and found many recipes including this one from Martha Stewart’s website,

 Pecan Sandies

prep: 15 mins
total time: 30 mins
yield: Makes 18

Ingredients

1/2 cup (1 stick) unsalted butter, room temperature
1/2 cup packed light-brown sugar
1 1/2 teaspoons pure vanilla extract
1/4 teaspoon salt
1 cup all-purpose flour (spooned and leveled)
1 cup pecans, coarsely chopped

Cook’s Note
For best results, line cookie sheets with parchment prior to baking.
Directions

Step 1

Preheat oven to 350 degrees, with racks in upper and lower thirds. In a large bowl, using an electric mixer, beat butter and sugar until light and fluffy; beat in vanilla and salt. With mixer on low, gradually add flour, beating just until combined. Fold in pecans.

Step 2

Roll dough into 1 1/2-inch balls, and place on two baking sheets, 2 inches apart. With the dampened bottom of a glass, lightly flatten each ball.

Step 3

Bake until cookies are golden brown, 15 to 17 minutes, rotating sheets halfway through. Transfer to wire racks, and let cool.

This is what they look like (also from the Martha Stewart website),

[downloaded from http://www.marthastewart.com/342386/pecan-sandies]

[downloaded from http://www.marthastewart.com/342386/pecan-sandies]

I also checked out the School of Ants project website and found this,

The School of Ants project is a citizen-scientist driven study of the ants that live in urban areas, particularly around homes and schools. Participation is open to anyone interested!
Learn More!

Anyone can participate! Learn how to create your own sampling kit, sample your backyard or schoolyard, and get our collection back to us so that we can ID the ants and add your species list to the big School of Ants map. Together we’ll map ant diversity and species ranges across North America! Click here to get started!

There is at least one question you might want to ask before running off to collect ants, the researchers specify Keebler Pecan Sandies cookies are to be used as bait. I’m not sure how available those specific cookies and brand are in Canada, Mexico, Italy, or Australia. You may want to check with the organizers as to what alternatives might be acceptable. From the Participate webpage on the School of Ants website,

SAMPLING ANTS for the School of Ants involves placing cookie baits outdoors in green spaces (lawns, gardens, woods) and paved places (asphalt, concrete, cobblestone) for one hour on a warm day. We want to know what ants discover the baits in your neighborhood!(ALLERGY WARNING!: this activity uses Keebler Pecan Sandies cookies, which contain pecans, wheat, egg and whey).

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

Ecologists, educators, and writers collaborate with the public to assess backyard diversity in The School of Ants Project [PDF] by Andrea Lucky, Amy M. Savage, Lauren M. Nichols, Leonora Shell, Robert R. Dunn, Cristina Castracani, Donato A. Grasso, and Alessandra Mori. Ecosphere 5(7):78. http://dx.doi.org/10.1890/ES13-00364.1 Published: online July 7, 2014,

Ecosphere is an open access journal. The PDF is 23 pp.

For my second citizen science item, I have a call for proposals for the Citizen Science 2015 Conference (CS2015), February 11 & 12, 2015 in San Jose, California (prior to the 2015 AAAS [American Association for the Advancement of Science] annual meeting February 12 -16, 2015 also in San Jose). Here’s more about the Citizen Science conference from the Overview page,

Anyone involved in citizen science is invited to attend this conference. Attendees will include citizen science participants, researchers, project leaders, educators, technology specialists, evaluators, and others – representing many disciplines including astronomy, molecular biology, human and environmental health, psychology, linguistics, environmental justice, biodiversity, conservation biology, public health, genetics, engineering, cyber technology, gaming, and more – at any level of expertise. There will be opportunities throughout the conference to make connections, share insights, and help move this field forward.

We have identified six main themes for this year’s conference:

  1. Tackling Grand Challenges and Everyday Problems with Citizen Science
  2. Broadening Engagement to Foster Diversity and Inclusion
  3. Making Education and Lifelong Learning Connections (K-12, university, informal)
  4. Digital Opportunities and Challenges in Citizen Science
  5. Research on and Evaluation of the Citizen Science Experience
  6. Best Practices for Designing, Implementing, and Managing Citizen Science Projects and Programs

Here are important dates for the conference (from a June 30, 2014 email announcement),

September 15, 2014          CS2015 Deadline to submit proposals* (talks, posters, etc)
October 6, 2014                 CS2015 Proposal selection notices sent out
November 10, 2014           CS2015 Early-bird registration discount ends
February 11 & 12, 2015     CS2015 Conference

Here’s more detail, from the Presentation Styles webpage,

… Several formats are available to choose from: three styles of oral presentations; symposia/panel discussions; and posters.

Audio-visual equipment will be provided as needed for all session types except posters.

Oral Presentations
Talks allow speakers to present their work in 12 minutes, with 3 additional minutes for audience questions. Talks with similar themes will be grouped together into sessions.

Speed Talks, as the name suggests, challenge each presenter to cover his or her topic in 5 minutes or less. Following a series of speed presentations, there will be time for audience members to gather with presenters for discussion.

Story Presentations (15 minutes) emphasize sharing valuable lessons through storytelling. We especially encourage telling stories of “what didn’t work and why” and strategies for addressing challenges and unintended consequences.

Symposium Sessions or Panel Discussions (1 to 2 hours)
Every symposium or panel has one convener (most likely the person submitting this proposal); that person is responsible for organizing the session and will act as the session’s contact person with conference organizers. Additionally, that person will moderate/guide the session. Symposia/Panels may be 1-to-2 hours in length, depending on the number of proposed talks, and must include at least 15 minutes for questions and discussion with the audience.

The proposal must (1) describe the symposium or panel’s objective, (2) how it will contribute to the overall theme of the conference, and (3) include a list of proposed speakers (and, in the case of a symposium, each speaker’s topic).

Posters
Posters are designed to visually display information and engage fellow attendees in an informal way. There will be two Poster Sessions—one each day—inviting attendees to discuss posters with authors. Posters will also be on display outside of formal poster-session times. All accepted posters will be given a display space measuring 4 x 4 feet (1.2 X 1.2 meters) in the Poster Hall (no additional audio-visual aids are permitted).

You can access a link to submit your proposal here.

CS2015 is being called a pre-conference to the AAAS meeting as per the Prepare for the Conference page,

Registration
Registration details, including the conference registration fee, are not yet finalized. We are seeking funding to help support the conference and keep it affordable to all. Check back for updates, or join the CSA to receive periodic updates.

Attend Two Great Conferences
CS2015 is a pre-conference of the Annual Meeting of the American Association for the Advancement of Science (AAAS), which immediately follows our meeting at the San Jose Convention Center. The AAAS theme for 2015 is “Innovations, Information, and Imaging.” Once you have completed your CS2015 registration, you will receive instructions on how to register for the AAAS Annual Meeting (February 12-16, 2015) at the discounted rate of $235. AAAS registration will open in August 2014.

Good luck with your proposal and with your ant-captures!

Captain America, Wolverine, Iron Man, and Thor on The Abstract, North Carolina State University’s news blog

Captain America’s shield as a supercapacitor? Intriguing, oui? Thank you to Matt Shipman and his April 15, 2014 post on The Abstract (North Carolina State University’s official newsroom blog, [h/t phys.org]) for presenting a very intriguing exploration of the science to be found in comic books and, now, the movies,

Image from Captain America By Ed Brubaker Vol. 2 Premiere HC (2011 – Present). Release Date: February 21, 2012. Image credit: Marvel.com

Image from Captain America By Ed Brubaker Vol. 2 Premiere HC (2011 – Present).
Release Date: February 21, 2012. Image credit: Marvel.com
Courtesy: NCSU

I have a new appreciation for Captain America (never one of my favourite super heroes). From Shipman’s April 15, 2014 posting on The Abstract (Note: Links have been removed),

It’s tough to explain how the shield works, in part because it behaves differently under different circumstances. Sometimes the shield is thrown and becomes embedded in a wall; but sometimes it bounces off of walls, ricocheting wildly. Sometimes the shield seems to easily absorb tremendous force; but sometimes it is damaged by the attacks of Cap’s most powerful foes.

“However, from a scientific perspective, it’s important to remember that we’re talking about the first law of thermodynamics,” says Suveen Mathaudhu, a program manager in the materials science division of the U.S. Army Research Office, adjunct materials science professor at NC State University and hardcore comics fan. “Energy is conserved. It doesn’t disappear, it just changes form.

“When enormous energy, such as a blow from Thor’s hammer, strikes Cap’s shield, that energy needs to go somewhere.”

Normally, that energy would need to be either stored or converted into heat or sound. But comic-book readers and moviegoers know that Cap’s shield usually doesn’t give off waves of heat or roaring shrieks (that shockwave from Thor’s hammer in The Avengers film notwithstanding).

“That absence of heat and sound means that the energy has to be absorbed somehow; the atomic bonds in the shield – which is made of vibranium – must be able to store that energy in some form,” Mathaudhu says.

Mathaudhu, later in the posting, describes the shield’s qualities as a supercapacitor. (For more information about supercapacitors, you can look at my April 9, 2014 posting.)

Shipman’s piece appears to be part of a series featuring Wolverine, Iron Man, and Thor, which you can access by scrolling past the end of the Captain America posting (April 15, 2014 post), where you will also find at least one comment, which is worth checking out.

Ditch toxic ammonia and grow your vertically aligned carbon nanofibers with ambient air say scientists and their high school colleagues

Ditching the ammonia used in the processing of vertically aligned carbon nanofibers is both healthier, occupationally and environmentally, and more profitable as it paves the way to easier manufacturing. Scientists at North Carolina State University (NCSU) working alongside high school students have demonstrated their new technique, according to a March 24, 2014 news item on Nanowerk,

Researchers from North Carolina State University have demonstrated that vertically aligned carbon nanofibers (VACNFs) can be manufactured using ambient air, making the manufacturing process safer and less expensive. VACNFs hold promise for use in gene-delivery tools, sensors, batteries and other technologies.

The March 24, 2014 NCSU news release (also on EurekAlert), which originated the news item, features an image illustrating VACNFs and more details about the research,

Researchers have shown they can grow vertically-aligned carbon nanofibers using ambient air, rather than ammonia gas. Click to enlarge image. (Image free for use. Credit: Anatoli Melechko.)

Researchers have shown they can grow vertically-aligned carbon nanofibers using ambient air, rather than ammonia gas. Click to enlarge image. (Image free for use. Credit: Anatoli Melechko.)

Conventional techniques for creating VACNFs rely on the use of ammonia gas, which is toxic. And while ammonia gas is not expensive, it’s not free.

“This discovery makes VACNF manufacture safer and cheaper, because you don’t need to account for the risks and costs associated with ammonia gas,” says Dr. Anatoli Melechko, an adjunct associate professor of materials science and engineering at NC State and senior author of a paper on the work. “This also raises the possibility of growing VACNFs on a much larger scale.”

In the most common method for VACNF manufacture, a substrate coated with nickel nanoparticles is placed in a vacuum chamber and heated to 700 degrees Celsius. The chamber is then filled with ammonia gas and either acetylene or acetone gas, which contain carbon. When a voltage is applied to the substrate and a corresponding anode in the chamber, the gas is ionized. This creates plasma that directs the nanofiber growth. The nickel nanoparticles free carbon atoms, which begin forming VACNFs beneath the nickel catalyst nanoparticles. However, if too much carbon forms on the nanoparticles it can pile up and clog the passage of carbon atoms to the growing nanofibers.

Ammonia’s role in this process is to keep carbon from forming a crust on the nanoparticles, which would prevent the formation of VACNFs.

“We didn’t think we could grow VACNFs without ammonia or a hydrogen gas,” Melechko says. But he tried anyway.

The researchers had some unlikely collaborators who inspired them to try a new approach (from the news release),

Melechko’s team tried the conventional vacuum technique, using acetone gas. However, they replaced the ammonia gas with ambient air – and it worked. The size, shape and alignment of the VACNFs were consistent with the VACNFs produced using conventional techniques.

“We did this using the vacuum technique without ammonia,” Melechko says. “But it creates the theoretical possibility of growing VACNFs without a vacuum chamber. If that can be done, you would be able to create VACNFs on a much larger scale.”

Melechko also highlights the role of two high school students involved in the work: A. Kodumagulla and V. Varanasi, who are lead authors of the paper. [emphases mine] “This discovery would not have happened if not for their approach to the problem, which was free from any preconceptions,” Melechko says. “I think they’re future materials engineers.”

Kudos to the students! Dr. Melechko should also be lauded for his flexible attitude towards collaboration and research and for his acknowledgment of the students both in this news release and in the published paper where they have lead author status.

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

Aerosynthesis: Growth of Vertically-aligned Carbon Nanofibres with Air DC Plasma by A. Kodumagulla, V. Varanasi, R. C. Pearce, W. C. Wu, D. K. Hensley, J. B. Tracy, T. E. McKnight and A. V. Melechko. Nanomaterials and Nanotechnology DOI: 10.5772/58449

This is an open access paper in an open access journal.

Nano info on food labels wanted by public in the US?

There’s some social science research about nanotechnology and food labeling in the US making its rounds on the internet. From an Oct. 28, 2013 news item on Nanowerk (Note: A link has been removed),

New research from North Carolina State University and the University of Minnesota finds that people in the United States want labels on food products that use nanotechnology – whether the nanotechnology is in the food or is used in food packaging. The research (“Hungry for Information: Public Attitudes Toward Food Nanotechnology and Labeling”) also shows that many people are willing to pay more for the labeling.

Study participants were particularly supportive of labeling for products in which nanotechnology had been added to the food itself, though they were also in favor of labeling products in which nanotechnology had only been incorporated into the food packaging.

The Oct. 28, 2013 North Carolina State University (NCSU) news release (also on EurekAlert), which originated the news item, has a title that can be viewed as misleading  especially in light of how other news media have interpreted it,

Public wants labels for food nanotech — and they’re willing to pay for it

Yes but it’s not exactly ‘the public’ (from the news release),

“We wanted to know whether people want nanotechnology in food to be labeled, and the vast majority of the participants in our study do,” says Dr. Jennifer Kuzma, senior author of a paper on the research and Goodnight-Glaxo Wellcome Distinguished Professor of Public Administration at NC State. “Our study is the first research in the U.S. to take an in-depth, focus group approach to understanding the public perception of nanotechnology in foods.” [emphasis mine]

The researchers convened six focus groups – three in Minnesota and three in North Carolina – and gave study participants some basic information about nanotechnology and its use in food products. Participants were then asked a series of questions addressing whether food nanotechnology should be labeled. Participants were also sent a follow-up survey within a week of their focus group meeting. [emphasis mine]

Since ‘focus group’ isn’t likely to grab attention in a headline whoever wrote the news release decided on a more dramatic approach citing the ‘public’ which resulted in this still more dramatic headline for an Oct. 29, 2013 news item on Red Orbit (Note: Links have been removed),

Most Americans Want To See Labels On Their Nanofoods

Americans overwhelmingly want to know when they are eating food products that use nanotechnology, and are happy to pay the additional labeling costs, according to a new study published this month in the journal Review of Policy Research.

“Our study is the first research in the United States to take an in-depth, focus group approach to understanding the public perception of nanotechnology in foods,” said Dr. Jennifer Kuzma of North Carolina State University, the study’ s senior author. [emphasis mine] “We wanted to know whether people want nanotechnology in food to be labeled, and the vast majority of the participants in our study do.”

Curious, I read the paper (which is open access),

Hungry for Information: Public Attitudes Toward Food Nanotechnology and Labeling by Jonathan Brown, University of Minnesota; Jennifer Kuzma, North Carolina State University. Published: Online Oct. 7 [2013] in Review of Policy Research DOI: 10.1111/ropr.12035

First off, this study is, by my standards, a well written piece of research. The writers have grounded their work in the literature,  explained their approach and methodology, and provided many appendices including one with the script used by the focus group moderators. Surprisingly, I’ve read more than one piece of ‘social science research’ which did not provide one or more of the previously mentioned aspects essential to a basic, solid research paper. In other words, there are a lot of sloppy social science research papers out there. Thankfully, this is not one of them. That said, I do have a comment about the paper’s title and a nit to pick regarding the methodology.

The paper’s title has a ‘look at me’ quality which has found its way into the news release and ultimately some of the headlines in various online publications (including this post). The paper’s title in the context of a publication called Review of Policy Research is less problematic due to its audience, i.e., policy wonks who are likely to discount the title as simply an attempt to get attention. The point is that the audience for Review of Policy Research is not likely to take that title at face value, i.e., uncritically. However, as this ‘look at me’ title is rewritten and makes its way through various media outlets, the audience changes to one that is much more likely to take it at face value.

Researchers are in a bind. They want attention for their work but can risk media coverage which distorts their findings. As for the level of distortion to be found, here’s information about the methodology and sample (participants), from the research paper,

Seven focus groups, 90 minutes in length and ranging in size from seven to ten participants, were conducted between September 2010 and January 2011 in the Minnesota cities of Minneapolis, Richfield, and Bloomington, and the North Carolina cities of Raleigh, Garner, and Cary. [emphasis mine’ Cities were selected based on the main city location, the largest suburb, and finally a randomly selected city between 30,000 and 60,000 residents, all within the counties of Hennepin, Minnesota, and Wake, North Carolina.

Participants were recruited using a stratified random sample, with the goal of having equal female and male numbers in each group, while matching a demographic county profile. Those who had a prior background in or extensive knowledge of nanotechnology were excluded from participation. The profiles were based on age, sex, race, education, family household income, and ideology (liberal, moderate, and conservative) criteria and generated by means of census data in conjunction with information supplied from select city community centers. Telephone and cell phone samples for each city were acquired and used to recruit 12 participants for each focus group, with the expectation of 75 percent attendance per group. Participants were given light dinner refreshments and $100 cash for their participation.

A total of 56 participants partook in one of the seven focus groups (n1 = 8, n2 = 10, n3 = 8, n4 = 7, n5 = 8, n6 = 7, and n7  = 8). The overall demographic distribution contained more males (64 percent, n = 36) versus females (36 percent, n = 20); whites/Caucasians (84 percent, n = 47) versus blacks/African Americans (11 percent, n = 6) and Asians/Pacific Islanders (4 percent, n = 2); and those with a postgraduate or professional degree (27 percent, n = 15) versus college graduate (23 percent, n = 13), some college (16 percent, n = 9), high school graduate (14 percent, n = 8), technical college graduate (7 percent, n = 4), some high school (5 percent, n = 3), some technical college (2 percent, n = 1), and “Other” education (2 percent, n = 1). Race/ethnicity and education had n = 1 and n = 2 “No Answer” responses, respectively. The most common age bracket was 50–60 (36 percent, n = 20) compared with “Over 60” (23 percent, n = 13), 41–49 (23 percent, n = 13), 31–39 (7 percent, n = 4), and “Under 30” (7 percent, n = 4). Additionally, two provided “No Answer” for their ages.

So, 56 people, at the most. from two different states are representing Americans. Under Study Limitations subhead, the researchers outline some of their own concerns regarding this research (from the paper),

Several limitations of our focus group study are worth noting. The small sample size (n = 56 for focus groups and worksheet responses; n = 34 for postsurvey) reduces inferential power for the quantitative worksheet and postsurvey results.  Additionally, a small sample size coupled with underrepresentation for multiple demographics (e.g., non-Caucasians, females, those under age 40, and so on) restricts generalizability of results, whether quantitative or qualitative. For focus groups, however, this is to be expected as the goal is in-depth and quality discussions that explore issues heretofore under-investigated. [all emphases mine]

The nature of focus group execution presents further challenges. For example, introverted individuals may not participate as readily, and this potential imbalance skews the discussion toward the extraverted participants’ ideas. A technique to mitigate this bias, which was employed by our moderators, is to directly ask quieter participants questions once a topic is generated. Although directed calling is effective at ensuring all views on a specific topic are eventually heard, more talkative participants nonetheless exert essential control as their initial contributions determine the topics to be covered. Extraverts will thus be overrepresented in the conversation flow.

Another challenge with employing focus groups relates to moderator-controlled variations. While one discussion guide (i.e., set of specific guiding questions) was used for all focus groups (see Appendix A), the moderator frequently had to ask various follow-up questions to maintain substantive dialog. Consequently, several impromptu questions stimulating important exchanges were not raised uniformly in all groups. Fortunately, such variability was not widely problematic, as all focus groups consisted of the same six phases with the same preliminary prompts. Below we present the results from our study that relate to food and nanotechnology products and their labeling.

The results from the research are suggestive but this work does not offer proof that Americans want nano information on their food labels and are will to pay more. However this research lays the groundwork for future queries as the researchers themselves note in their Discussion at the end of the paper,

This study is the first, to our knowledge, to concentrate on public attitudes toward nanofood labeling in the United States. As such, we took an exploratory and grounded theory approach to reveal insights that could be important for developing policies and programs. Focus group discussions, in-group response worksheets, and postsurvey results from this study begin to form a picture of what people view as important for nanofood governance and labeling more specifically. Future studies will be needed to further explore these results, as there were several limitations to this study including the small sample sizes for the postsurvey (n = 34) and focus groups (n = 56) in the context of applying inferential statistics, sample underrepresentation for some demographic variables, potential overrepresentation of extroverted opinions in focus group conversations, and intergroup moderator consistency (see also the “Study Limitations” section above). These limitations are often associated with focus group research.

The researchers also describe the various themes that emerged from the focus group discussions,

Labeling discussions activated numerous topics directly and indirectly related to nanofood product labeling. Skepticism and the influence of historical experiences were two themes that emerged in this study that have not been extensively covered in previous literature on public perception of nanotechnology. Participants were skeptical concerning actions, intentions, and promised outcomes, often without reference to particular organizations or their trust of them. In part, skepticism stemmed from historical experiences with other product domains like pesticides, nutritional and allergenicity labels, and prior food safety claims. Participants relied heavily on previous experiences related to nanofood labeling in order to form opinions on this new domain.

I encourage you to read the research yourself. As these things go, this study is quite readable. However, I do have one final nit to pick, household income. While the researchers used the data to develop their stratified, random sample, they don’t seem to have taken income into account when analyzing the results or considering problems in the methodology. It seems to me that household income might be a factor in how people feel about paying more for food labels that include nano information.

This is the second nanofood-themed post I’ve published recently, see my Oct. 23, 2013 posting for a report of a food and nano panel held at the Guardian’s (newspaper) offices in London, UK>

Squishy wonderfulness: new possibilities for hydrogels

i have two items for this posting about hydrogels and biomimicry (aka biomimetics). One concerns the use of light to transform hydrogels and the other concerns the potential for using hydrogels in ‘soft’ robotics. First, researchers at the University of Pittsburgh have found a way to make hydrogels change their shapes, from an Aug. 1, 2013 news item on Nanowerk,

Some animals—like the octopus and cuttlefish—transform their shape based on environment, fending off attackers or threats in the wild. For decades, researchers have worked toward mimicking similar biological responses in non-living organisms, as it would have significant implications in the medical arena.

Now, researchers at the University of Pittsburgh have demonstrated such a biomimetic response using hydrogels—a material that constitutes most contact lenses and microfluidic or fluid-controlled technologies.

The Aug. 1, 2013 University of Pittsburgh news release, which originated the news item, offers this description from the paper’s lead authorl,

“Imagine an apartment with a particular arrangement of rooms all in one location,” said lead author Anna Balazs, Pitt Distinguished Professor of Chemical and Petroleum Engineering in the Swanson School of Engineering. “Now, consider the possibility of being able to shine a particular configuration of lights on this structure and thereby completely changing not only the entire layout, but also the location of the apartment. This is what we’ve demonstrated with hydrogels.”

The news release goes on to provide more specific details about the work,

Together with Olga Kuksenok, research associate professor in the Swanson School, Balazs experimented with a newer type of hydrogel containing spirobenzopyran molecules. Such materials had been previously shown to form distinct 2-D patterns on initially flat surfaces when introduced to varying displays of light and are hydrophilic (“liking” water) in the dark but become hydrophobic (“disliking” water) under blue light illumination. Therefore, Balazs and Kuksenok anticipated that light could be a useful stimulus for tailoring the gel’s shape.

Using computer modeling, the Pitt team demonstrated that the gels “ran away” when exposed to the light, exhibiting direct, sustained motion. The team also factored in heat—combining the light and local variations in temperature to further control the samples’ motions. Controlling a material with light and temperature could be applicable, Balazs said, in terms of regulating the movement of a microscopic “conveyor belt” or “elevator” in a microfluidic device.

“This theoretical modeling points toward a new way of configuring the gels into any shape, while simultaneously driving the gels to move due to the presence of light,” said Kuksenok.

“Consider, for example, that you could take one sheet of hydrogel and, with the appropriate use of light, fashion it into a lens-shaped object, which could be used in optical applications”, added Balazs.

The team also demonstrated that the gels could undergo dynamic reconfiguration, meaning that, with a different combination of lights, the gel could be used for another purpose. Reconfigurable systems are particularly useful because they are reusable, leading to a significant reduction in cost.

“You don’t need to construct a new device for every new application,” said Balazs. “By swiping light over the system in different directions, you can further control the movements of a system, further regulating the flow of materials.”

Balazs said this type of dynamic reconfiguration in response to external cues is particularly advantageous in the realm of functional materials. Such processes, she said, would have a dramatic effect on manufacturing and sustainability, since the same sample could be used and reused for multiple applications.

The team will now study the effect of embedding microscopic fibers into the gel to further control the shape and response of the material to other stimuli.

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

Modeling the Photoinduced Reconfiguration and Directed Motion of Polymer Gels by Olga Kuksenok and Anna C. Balazs. Article first published online: 31 JUL 2013, Adv. Funct. Mater.. doi: 10.1002/adfm.201203876

© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall. However, there is a video of Anna Balazs’s June 27, 2013 talk (Reconfigurable assemblies of active, auto-chemotactic gels) on these gels at the Isaac Newton Institute for Mathematical Sciences.

Meanwhile, researchers at North Carolina State University are pursuing a different line of query involving hydrogels. From an Aug. 2, 2013 North Carolina State University news release (also on EurekAlert),

Researchers from North Carolina State University have developed a new technique for creating devices out of a water-based hydrogel material that can be patterned, folded and used to manipulate objects. The technique holds promise for use in “soft robotics” and biomedical applications.

“This work brings us one step closer to developing new soft robotics technologies that mimic biological systems and can work in aqueous environments,” says Dr. Michael Dickey, an assistant professor of chemical and biomolecular engineering at NC State and co-author of a paper describing the work.

“In the nearer term, the technique may have applications for drug delivery or tissue scaffolding and directing cell growth in three dimensions, for example,” says Dr. Orlin Velev, INVISTA Professor of Chemical and Biomolecular Engineering at NC State, the second senior author of the paper.

The technique they’ve developed uses hydrogels, which are water-based gels composed of water and a small fraction of polymer molecules. Hydrogels are elastic, translucent and – in theory – biocompatible. The researchers found a way to modify and pattern sections of hydrogel electrically by using a copper electrode to inject positively charged copper ions into the material. Those ions bond with negatively charged sites on the polymer network in the hydrogel, essentially linking the polymer molecules to each other and making the material stiffer and more resilient. The researchers can target specific areas with the electrodes to create a framework of stiffened material within the hydrogel. The resulting patterns of ions are stable for months in water.

“The bonds between the biopolymer molecules and the copper ions also pull the molecular strands closer together, causing the hydrogel to bend or flex,” Velev says. “And the more copper ions we inject into the hydrogel by flowing current through the electrodes, the further it bends.”

The researchers were able to take advantage of the increased stiffness and bending behavior in patterned sections to make the hydrogel manipulate objects. For example, the researchers created a V-shaped segment of hydrogel. When copper ions were injected into the bottom of the V, the hydrogel flexed – closing on an object as if the hydrogel were a pair of soft tweezers. By injecting ions into the back side of the hydrogel, the tweezers opened – releasing the object.

The researchers also created a chemically actuated “grabber” out of an X-shaped segment of hydrogel with a patterned framework on the back of the X. When the hydrogel was immersed in ethanol, the non-patterned hydrogel shrank. But because the patterned framework was stiffer than the surrounding hydrogel, the X closed like the petals of a flower, grasping an object. When the X-shaped structure was placed in water, the hydrogel expanded, allowing the “petals” to unfold and release the object. Video of the hydrogels in action is available here.

“We are currently planning to use this technique to develop motile, biologically compatible microdevices,” Velev says.

“It’s also worth noting that this technique works with ions other than copper, such as calcium, which are biologically relevant,” Dickey says.

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

Reversible patterning and actuation of hydrogels by electrically assisted ionoprinting by Etienne Palleau, Daniel Morales, Michael D. Dickey & Orlin D. Velev. Nature Communications 4, Article number: 2257 doi:10.1038/ncomms3257 Published 02 August 2013

This article is behind a paywall.

Liquid metal taking shape

A North Carolina State University July 9, 2013 news release (also on EurekAlert) avoids a Terminator 2: Judgment Day movie reference (which I am making) in its description of building 3D structures out of liquid metal,

“It’s difficult to create structures out of liquids, because liquids want to bead up. But we’ve found that a liquid metal alloy of gallium and indium reacts to the oxygen in the air at room temperature to form a ‘skin’ that allows the liquid metal structures to retain their shapes,” says Dr. Michael Dickey, an assistant professor of chemical and biomolecular engineering at NC State and co-author of a paper describing the work.

The researchers developed multiple techniques for creating these structures, which can be used to connect electronic components in three dimensions. White it is relatively straightforward to pattern the metal “in plane” – meaning all on the same level – these liquid metal structures can also form shapes that reach up or down.

One technique involves stacking droplets of liquid metal on top of each other, much like a stack of oranges at the supermarket. The droplets adhere to one another, but retain their shape – they do not merge into a single, larger droplet. Video of the process is available here.

Another technique injects liquid metal into a polymer template, so that the metal takes on a specific shape. The template is then dissolved, leaving the bare, liquid metal in the desired shape. The researchers also developed techniques for creating liquid metal wires, which retain their shape even when held perpendicular to the substrate.

Dickey’s team is currently exploring how to further develop these techniques, as well as how to use them in various electronics applications and in conjunction with established 3-D printing technologies.

The lead researcher, Michael Dickey has produced an image of liquid metal drops in a 3D structure,

Researchers have developed three-dimensional structures out of liquid metal. Image: Michael Dickey.

Researchers have developed three-dimensional structures out of liquid metal. Image: Michael Dickey.

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

3D Printing of Free Standing Liquid Metal Microstructures by Collin Ladd,  Ju-Hee So, John Muth, Michael D. Dickey. Article first published online: 4 JUL 2013 DOI: 10.1002/adma.201301400

Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

For anyone who isn’t familiar with Terminator 2 and doesn’t understand why it was mentioned  in the context of this posting, here’s an excerpt from the Wikipedia essay (Note: Links and footnotes have been removed),

The T-1000 is a fictional robotic assassin and the main antagonist in Terminator 2: Judgment Day. Created by the series main antagonist Skynet, the T-1000 is a shapeshifter whose body is composed of a mimetic poly-alloy (liquid metal) body that allows it to assume the form of other objects or people of equal mass. [emphasis mine]