A Made-to-Order Materials Menu

aflowlib_screenshotIf you think ordering a drink from Starbucks can be a tall order, try picking out the right material for a new product or experiment. An iced, half-caff, four-pump, sugar-free, venti cinnamon dolce soy skinny latte may be a mouthful, but there are hundreds of thousands of known—and unknown—compounds to choose from, each with their own set of characteristics.

For example, take the family of materials Bi2Sr2Can-1CunO2n+4+x, or bismuth strontium calcium copper oxide for short, if you can call it that. These compounds have the potential to change the world because of their ability to become superconducting at relatively high temperatures. But each sibling, cousin or distant relative has its own physical variations…so how to choose which to pursue?

Thanks to Stefano Curtarolo and his research group, now there’s an app for that.
Curtarolo leads a collection of research groups from seven universities specializing in something they call materials genomics. The group—called the AFLOW consortium—uses supercomputers to comb databases for similar structures and builds theoretical models atom-by-atom to predict how they might behave.

With help from several members of the consortium, Pratt School of Engineering postdocs Cormac Toher, Jose Javier Plata Ramos and Frisco Rose, along with Duke student Harvey Shi, have spent the past few months building a system that combs through four materials databases. Users can choose the elements and characteristics they want a material to have—or not to have—and the website will play matchmaker.

Want a two-element compound containing either silicon or germanium—but not gallium—that is stable enough to withstand high temperatures? Not a problem. How about an electric insulator made from transition metals with a certain crystal structure? AFLOW has you covered.

One of the four databases searched by the program draws from an international collection of compounds with structures known from experimentation. The other three contain single- double- or triple-element compounds, and are not limited to previously explored materials. Through their molecule-building algorithms, the AFLOW consortium is constantly adding prospective materials to these four libraries.

The search engine currently can sort through more than 622,000 known and unknown compounds, and more than 1,000 new ones are added each week. Curtarolo, a professor of materials science and physics, hopes that the open-source program will continue to grow in materials and searchable characteristics to help scientists connect to their ideal material. To see how it works for yourself, take it for a test drive here.

As for an equivalent database of coffee drinks, that has yet to be built. So if you’re looking through AFLOW for a hot, lactose-free drink featuring 150 to 200 mg of caffeine and less than 200 calories made with beans from South America, you’re out of luck.

Posted in Duke | Leave a comment

Chimps Need No Help for Violence

chimpanzee-glockWhoever wrote the script for Dawn of the Planet of the Apes should have done some more homework. The primary antagonist of the film is Koba, a scarred bonobo who holds a grudge against humans for his mistreatment.

The only problem is that bonobos don’t seem to hold a grudge. Nor do they seem to have any violent tendencies whatsoever, for that matter.

The two closest species to humans are chimpanzees and bonobos, and one could argue that violence is one of the largest differences between the three . While humans kill each other for smudging their Pumas and chimpanzees have hundreds of documented instances of in-species killings , bonobos just don’t. Of four different bonobos communities constantly observed, there has been only one killing, and it can only be described as a suspected killing, at best.

This leads to some interesting questions. Did the last common ancestor of all three species have violent tendencies, and bonobos have evolved out of them? Was the last primate common to humans and chimps peaceful, and the two species since evolved same-species violence independently? Or was it some combination of the two?

There is a fourth option that many conservationists have taken to recently—that it is humans that are causing chimps to be aggressive, not their own nature. Perhaps by constricting their habitats, injecting ourselves into their lives, feeding some groups while not others, and otherwise interfering with their natural lives, we are the cause of their killings.

Michael Wilson says, “nope.”

Wilson, lead author of a recent paper published in Nature and a researcher at the University of Minnesota, looked at the question by gathering data from 15 chimp and 4 bonobo communities. Over the past five decades, there have been 152 instances of observed, inferred and suspected killings in 15 chimp communities.

After crunching the numbers, he determined that humans are not the cause of the observed aggression. Besides the best statistical models pointing to natural variables such as population size and density, there is plenty of anecdotal evidence.

The highest killing rate occurred at a relatively undisturbed and never-provisioned site, the least disturbed site had at least two suspected killings, and the site that was rated as the most disturbed by humans had zero.

What’s more, one would think that if humans were the cause, the communities would be getting more violent over time. Despite some claims that this is indeed happening, Wilson found no statistical increase in reports of killings during the past five decades. Sure there are more reported instances, but that’s because there are more communities being watched.

“The most important predictors of violence were thus variables related to adaptive strategies: species; age–sex class of attackers and victims; community membership; numerical asymmetries; and demography,” wrote Wilson in the paper. “We conclude that patterns of lethal aggression in [chimps] show little correlation with human impacts, but are instead better explained by the adaptive hypothesis that killing is a means to eliminate rivals when the costs of killing are low.”

The paper, “Lethal aggression in Pan is better explained by adaptive strategies than human impacts,” was published in Nature by Wilson, along with 29 co-authors at sites across Africa.

Posted in Minnesota | Leave a comment

Sunday Runday Funday Scientifically Proven

beermilefeetA new study from Northwestern University that is making use of all of those new-fangled fitness applications and wearables has revealed an athletic truism that I would have bet money on based on anecdotal evidence—people drink more on days that they exercise.

I know I, for one, do this on a regular basis.

There’s two reasons for this. First, after an hour-long, tough workout, I usually feel I can spare the calories and indulge in an extra Founders Breakfast Stout. Rather than seeing the workout as an accomplishment toward my health, I take the typical American route and use it as an excuse to completely erase the good I just did.

The second reason is simply a matter of convenience. People tend to work out more toward the end of the week and on the weekends. Why is that, you might ask? In my experience, it’s because they have more time on their hands, particularly on Saturday and Sunday. More free time equals more exercise time.

But it also means more time to drink.

In the study, researchers asked 150 study participants ranging in age from 18 to some bad-ass 89-year-olds to record their physical activity and alcohol consumption daily on their smartphones for 21 days. They did this at three different times during the year. Not only did this allow participants to take a break and hopefully take better care of their recordings during their three-week intervals, it also helped account for seasonal variations in exercise and alcohol consumption.

Let’s face it, if the study were done entirely during football season, the results would probably be pretty skewed.

“In this study, people only have to remember one day of activity or consumption at time, so they are less vulnerable to memory problems (outside of blackouts*) or other biases that come in to play when asked to report the past 30 days of behavior,” said David Conroy, lead author and a professor of preventive medicine and deputy director of the Center for Behavior and Health at Northwestern University. “We think this is a really good method for getting around some of those self-report measurement problems.

“We zoomed in the microscope and got a very up-close and personal look at these behaviors on a day-to-day basis and see it’s not people who exercise more drink more — it’s that on days when people are more active they tend to drink more than on days they are less active,” Conroy continued. “This finding was uniform across study participants of all levels of physical activity and ages.”

It’s a vicious cycle. Button down the hatches Monday – Thursday, eat well, drink less, and try to undo all the drinking damage that Friday – Sunday brought. It sounds like I’m not alone.

The study, “Daily Physical Activity and Alcohol Use Across the Adult Lifespan,” was published in Health Psychology by Conroy and Northwestern colleagues Nilam Ram, Aaron L. Pincus, Donna L. Coffman, Amy E. Lorek, Amanda L. Rebar and Michael J. Roche of The Pennsylvania State University.

*comment added by me, not originally quoted from Northwestern

Posted in Northwestern | Leave a comment

Nanoparticles Accumulate Quickly in Wetland Sediment

Nanotechnology researcher Lee Ferguson stands amid a collection of simulated wetlands called mescosms at Duke University. Each wetland-in-a-box is used to run the experiment under varying conditions. Credit Duke University.

Nanotechnology researcher Lee Ferguson stands amid a collection of simulated wetlands called mescosms at Duke University. Each wetland-in-a-box is used to run the experiment under varying conditions. Credit Duke University.

A Duke University team has found that nanoparticles called single-walled carbon nanotubes accumulate quickly in the bottom sediments of an experimental wetland setting, an action they say could indirectly damage the aquatic food chain.

The results indicate little risk to humans ingesting the particles through drinking water, say scientists at Duke’s Center for the Environmental Implications of Nanotechnology (CEINT). But the researchers warn that, based on their previous research, the tendency for the nanotubes to accumulate in sediment could indirectly damage the aquatic food chain in the long term if the nanoparticles provide “Trojan horse” piggyback rides to other harmful molecules.

The results appear online in the journal Environmental Science: Nano.

Carbon nanotubes are rapidly becoming more common because of their usefulness in nanoelectric devices, composite materials and biomedicine.

The Duke study was done using small-scale replications of a wetland environment, called “mesocosms,” that include soil, sediments, microbes, insects, plants and fish. These ecosystems-in-a-box are “semi-closed,” meaning they get fresh air and rainwater but don’t drain to their surroundings. While not perfect representations of a natural environment, mesocosms provide a reasonable compromise between the laboratory and the real world.

“The wetland mesocosms we used are a much closer approximation of the natural processes constantly churning in the environment,” said Lee Ferguson, associate professor of civil and environmental engineering at Duke. “Although it’s impossible to know if our results are fully accurate to natural ecosystems, it is clear that the processes we’ve seen should be considered by regulators and manufacturers.”

Ferguson and his colleagues dosed the mesocosms with single-walled carbon nanotubes and measured their concentrations in the water, soil and living organisms during the course of a year. They found that the vast majority of the nanoparticles quickly accumulated in the sediment on the “pond” floor. However, they found no sign of nanoparticle buildup in any plants, insects or fish living in the mesocosms.

While this is good news for humans or other animals drinking water after a potential spill or other contamination event, the accumulation in sediment does pose concerns for both sediment-dwelling organisms and the animals that eat them. Previous research has shown that carbon nanotubes take a long time to degrade through natural processes — if they do at all — and any chemical that binds to them cannot easily be degraded either.

“These nanoparticles are really good at latching onto other molecules, including many known organic contaminants,” said Ferguson. “Coupled with their quick accumulation in sediment, this may allow problematic chemicals to linger instead of degrading. The nanoparticle-pollutant package could then be eaten by sediment-dwelling organisms in a sort of ‘Trojan horse’ effect, allowing the adsorbed contaminants to accumulate up the food chain.

“The big question is whether or not these pollutants can be stripped away from the carbon nanotubes by these animals’ digestive systems after being ingested,” continued Ferguson. “That’s a question we’re working to answer now.”

This research was supported by the National Science Foundation, the Environmental Protection Agency under the National Science Foundation cooperative agreement EF-0830093, the Center for the Environmental Implications of Nanotechnology and the Environmental Protection Agency’s Science to Achieve Results (STAR) program (RD833859).


Fate of single walled carbon nanotubes in wetland ecosystems.” Schierz, A., Espinasse, B., Wiesner, M.R., Bisesi, J.H., Sabo-Attwood, T., Ferguson, P.L. Environmental Science: Nano, Sept. 2014. DOI: 10.1039/c4en00063c.

Posted in Duke | Leave a comment

Get Mo’ Graphene

A model of the intercalation of Brønsted acid molecules between single-atomic layers of graphene.  Credit: Mallouk Lab, Penn State University.

A model of the intercalation of Brønsted acid molecules between single-atomic layers of graphene. Credit: Mallouk Lab, Penn State University.

Want your own sample of science’s next wundermaterial? Have a pencil and some scotch tape at your side?

Graphene is a one-atom thick layer of carbon atoms that science has long denoted as the next super material. Besides its super strength, it has the ability to conduct heat and electricity better than any other known material. The applications are useless, with current endeavors underway to use graphene for flexible electronic displays, high-speed computing, stronger wind-turbine blades, and more-efficient solar cells.

And note that that’s not just theoretical uses. Those are actual products currently underway in the private industrial sector.

And they expect results.

Interestingly enough, all it really takes to make yourself some graphene is a lead pencil and some tape. Just roll the sharpened point of the pencil over the sticky side of the tape, and there you have it. The material left behind is basically graphene.

Of course, there are a huge number of molecular flaws and incongruences that make it completely unusable in the high tech world. It’s also no way to produce industrial amounts of the stuff for use in actual devices.

That’s where the scientists come in.

In a new paper from Penn State, Thomas Mallouk, the Evan Pugh Professor of Chemistry, Physics, and Biochemistry and Molecular Biology at Penn State, describes a potentially better way for graphene production. The trick is to take ions of another chemical and insert them between the carbon layers of graphite to bull the sheets apart.

The first time this was achieved was all the way back in 1841. Naturally, however, the method left much to be desired. Requiring a harsh oxidizing agent, the resulting graphene was about as usable as that layer on your scotch tape.

So Mallouk and Nina Kovtyukhova, a research associate in Mallouk’s lab, started playing around with a newer method developed in 1999. After trying the technique in several variations by leaving out single chemicals—much like that high school experiment where you leave single ingredients out of chocolate chip cookies—they discovered that the harsh oxidizing agent wasn’t necessary for the reaction to take place in materials similar to graphite.

Mallouk asked her to try a similar experiment without the oxidizing agent on graphite, but aware of the extensive literature saying that the oxidizing agent was required, Kovtyukhova balked.

“I kept asking her to try it and she kept saying no,” Mallouk said. “Finally, we made a bet, and to make it interesting I gave her odds. If the reaction didn’t work I would owe her $100, and if it did she would owe me $10. I have the ten dollar bill on my wall with a nice Post-it note from Nina complimenting my chemical intuition.”

Whether the discovery will actually be useful to industry or not remains to be seen. The process is still clumsy and slow. But it’s promising. The next step for Mallouk and colleagues will be to figure out how to speed the reaction up in order to scale up production.

Their results appear in the Nature Chemistry article titled “Non-oxidative intercalation and exfoliation of graphite by Brønsted acids,” by Nina I. Kovtyukhova, Yuanxi Wang, Ayse Berkdemir, Mauricio Terrones, Vincent H. Crespi, and Thomas E. Mallouk — all of Penn State — and Rodolfo Cruz-Silva of the Research Center for Exotic Nanocarbons, Shinshu University, Nagano, Japan.

Posted in Penn State | Leave a comment

Zombie Fungus Ants Die Precisely on Their Doorsteps

After killing its host, the so-called zombie ant fungus grows from the cadaver and produces spores, which rain down on the forest floor to infect new hosts. Image: Penn State

After killing its host, the so-called zombie ant fungus grows from the cadaver and produces spores, which rain down on the forest floor to infect new hosts. Image: Penn State

Just in case you’ve never heard about this phenomenon–it’s been covered plenty of times before in the media–I just wanted to let you know that zombies are real. They exist in many places in the animal kingdom, most notably in ants.

In many zombie movies, the culprit of the plague turning humans into flesh-eating, walking cadavers is some sort of virus. In the wild, the most notable culprit is actually a fungus.

Mario never knew what Toad was really up to.

This fungus, called Ophiocordyceps camponoti-rufipedis, requires the bodies of ants to reproduce. In a stunning display of gruesomeness, the fungus grows a stalk, called the stroma, which protrudes from the ant cadaver. A large round structure, known as the ascoma, forms on the stroma. Infectious spores then develop in the ascoma and are discharged onto the forest floor below, where they can infect foraging ants from the colony.

And to make sure those spores infect the next round of hosts, the fungus controls the body of the dying ant to make sure it dies in exactly the right spot. Before it can’t move anymore, an infected ant will approach its colony, climb up some foliage, clamp down on the underside of a leaf, and perish, leaving only the body behind for the fungus to grow out of.

In a recent study, David Hughes, assistant professor of entomology and biology at Penn State, showed that this behavior is deadly accurate and is used to evade social immunity. He and his colleagues put 28 freshly killed and infected ants inside two separate ant nests–one with a colony living inside and one with vacant halls.

None of the cadavers were able to grow fungus. In the live nest, the ants cleared away most of their deceased so that the fungus could not spread. In the empty, the conditions weren’t right for the fungus to grow.

They then took a close look at four ant colonies for a 20-month time span and mapped out all of the commonly used ant trails into and out of the colony. They discovered that diseased ants are remarkably good at finding just the right spot to die in.

“What the zombie fungi essentially do is create a sniper’s alley through which their future hosts must pass,” Hughes said. “The parasite doesn’t need to evolve mechanisms to overcome the effective social immunity that occurs inside the nest. At the same time, it ensures a constant supply of susceptible hosts.”

The paper, “Long-Term Disease Dynamics for a Specialized Parasite of Ant Societies: A Field Study,” was published by Hughes along with lead author Raquel Loreto, doctoral candidate in entomology, Penn State’s College of Agricultural Sciences.

Posted in Penn State | Leave a comment

Higher Education No Longer Killing God; DOA Instead

downloadIt’s a widely accepted fact that going to college has a negative effect on a person’s chances of remaining religiously inclined. And for sure, that used to be absolutely true. By looking at recent trends and statistics, however, researchers from the University of Nebraska say, “Not so fast.”

It appears that the trend is over. By and large, going to college no longer raises a person’s likelihood of disaffiliating from their religious views and practices. In fact, for those born after 1970, going to college actually increases the chance that he or she will remain with their church.

So what gives?

It’s a widely accepted fact that higher levels of education has a negative effect on a person’s chances of remaining religiously inclined. And that remains true.

The difference, it appears, is in the education of the masses. Back in the early 1900s, the public education system isn’t nearly what it is today. More children were dropping out early to help with agrarian chores. More people lived in rural areas without much of a chance of having a decent teacher, let alone a decent school.

Today, people have access to—comparatively speaking—awesome educational opportunities. Even if they live out in the middle of nowhere, they probably go to a decent public school and at least have access to the entire world’s worth of knowledge via the internet.

So, Philip Schwadel argues, the rising of the educational tide sinks all religious ships. Since people are already more likely to have a decent education and drop their religious views, going to college for even more education doesn’t have the same religious impact that it did 50 years ago.

Plus, Schwadel argues that there are many more opportunities to join religious groups in today’s colleges than there used to be.

“College education has grown so much that it’s also possible that who goes to college has changed and led to some of the changes we see in the study,” he said. “There are a lot more opportunities to maintain your religiosity while you’re in college. Unless something drastic happens to change this relationship again, I would expect in 50 years, the college-educated would be no more likely, and potentially less likely, to claim no affiliation than the non-college educated.”

And in case you’re wondering, no, most of the respondents did not go to Liberty or any actual institutions of higher education in the south. The data comes from the General Social Survey, which takes place biannually across the entire nation at random.

The study, “Birth Cohort Changes in the Association Between College Education and Religious Non-Affiliation,” was published in the journal Social Forces by Schwadel and Schwadel alone.

Posted in Nebraska | Leave a comment