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.

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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.

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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.

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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.

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Progress Toward a Blood Test for Depression

Researchers at Northwestern University are trying to devise a simple blood test that not only can diagnose depression, but can also tell clinicians which treatments the patient is most likely to respond to. It may seem like a far-fetched, futuristic idea, but they’re making strong headway. Two years ago, the team reported the finding of 11 biomarkers that could accurately differentiate between untreated teens with depression from those without. In a new study, the team reports nine biomarkers that can do the same in adults.

Borrowing heavily from that post two years ago, depression is a difficult condition to fight. For one thing, there’s no physical manifestation like a lesion or rash that gives a chemical imbalance in the brain away to a physician. The only way to diagnose it is through a patient voluntarily describing all of his or her conditions in an accurate manner, hopefully to a trained specialist who is able to recognize the problem.

First of all, a lot of people don’t really like opening up and talking about their feelings, especially to a stranger. Plus, social stigmas may make them apprehensive about telling the whole truth about what’s going on in their noggin. And when a lot of people see their depression and think, geeze, I just have to be happier – let’s just say a lot of depression goes undiagnosed.

Eva Redei, a professor of psychiatry and behavioral sciences is trying to create a blood test to recognize depression, and she may have just taken the first step. Depression isn’t all just about being sad or having whacky emotions. There can be real, physical changes that occur in the body that trigger the symptoms. Naturally, Redei thought, “Why not try to figure out a way to spot these changes?”

Redei took a line of rats that have been bred to show classical signs of depression. For example, they give up really quickly and easily when swimming for their lives in a tub of water with no way out. She took blood samples and compared the genetic activity between them and rats that fought like hell in the pool to find 26 biomarkers that could be useful in differentiating blood from a depressed person and one feeling just fine and dandy.

Next, Redei took blood samples from 14 adolescents with major depression who had not been clinically treated as well as samples from 14 normal teenagers. After running the samples through the genetic tests for the biomarkers, she discovered that she could indeed spot the depressed individuals using 11 of the biomarkers together.

In the new study, Redei took blood samples from 32 clinically depressed patients as well as 32 controls. The participants covered a wide range of gender, ethnicity and age. After some fancy pants statistics, the researchers showed that nine RNA biomarkers could accurately differentiate between depressed and non-depressed patients. What’s more, after an 18-week therapeutic intervention, the researchers also found a set of genes with a particular “fingerprint” in those who responded to the treatment but not those who remained depressed. This means these genes might be useful in predicting who would respond well to cognitive behavioral therapy.

Finally, a separate set of three genes remained significantly different from the control group whether or not the depressed patients recovered or not. The researchers believe these might be the hallmarks of spotting people vulnerable to depression even before it hits.

Of course, this study only looked at 32 depressed patients, and only 22 completed the entire study with treatment and additional blood draws and all. They’re going to need to do a giant study of thousands of different people in a large cross-section of the population to find out if these RNA biomarkers are actually useful for predicting and spotting depression.

The study, “Blood transcriptomic biomarkers in adult primary care patients with major depressive disorder undergoing cognitive behavioral therapy,” was published in Translational Psychiatry by Redei, Brian M. Andrus, Mary J. Kwasny, Junhee Seok, Xuan Cai, and Joyce Ho.

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Saving the World $1 Trillion on Climate Change (or Not)

According to the study, the red areas would yield the most calories while preserving the most carbon; the green areas have the highest carbon storage potential and lowest yield potential.

According to the study, the red areas would yield the most calories while preserving the most carbon; the green areas have the highest carbon storage potential and lowest yield potential.

Don’t feel like eating crops that have been genetically altered in a laboratory to produce more food? Think we have a moral obligation to stop others from eating such “unnatural” products around the world? Well, then you’d better get ready to expand the current amount of landmass used to grow food, because we’re going to need a hell of a lot of it. And a recent study from the University of Minnesota points to where we out to look.

There are a lot of factors to consider when choosing what land to turn to food production, and unfortunately, almost nobody cares to look at any of it. Governments and corporations everywhere are just haphazardly turning wilderness into farmland—a practice that spells trouble for global warming.

Plants store a lot of carbon. When you kill them off, that carbon gets released into the environment. Plus, they’re no longer alive to breath in carbon dioxide and further sequester existing carbon in the atmosphere. To mitigate this effect as much as possible, global agencies out to be looking to expand food production in areas that will release the least amount of carbon while producing the most about of consumable calories.

The new study led by Justin Andrew Johnson, an economist with the Natural Capital Project at the University of Minnesota’s Institute on the Environment, did just that. Johnson analyzed high-resolution geospatial data from approximately 10 million locations around the world for 175 different crops in search of prospective croplands that produce the most calories relative to the amount of carbon stored, called the crop advantage.

The researchers valued the carbon storage potential of each area using the social cost of carbon, an estimate used in economics that monetizes the damages carbon contributes to the economy. The higher the crop advantage, the higher the calorie potential and the better the trade-off for lost carbon storage due to cultivation. If done right, the researchers estimate the world could save $1 trillion in climate change mitigation costs over “business as usual” growth.

So where should we grow food for India and China’s future population?

Areas with the highest crop advantage include the U.S. Corn Belt, parts of Western Europe, the Nile Valley, the Ganges River Plain and eastern China. Although these regions are already heavily farmed, the researchers found that expanding farmlands at the edges could produce more calories while limiting carbon loss relative to expansion in other parts of the world.

Parts of Eastern Europe, the Ukraine, Russia and several pockets in Southeast Asia also showed potential for agricultural expansion; tropical regions such as the Philippines, Indonesia, Southern India, parts of sub-Saharan Africa and Central America were found to have a low crop advantage. “There are high costs with developing agriculture in the tropics, and we need to consider them,” Johnson said.

Johnson did not, however, have any insight into how to get global governments to agree on something as mild as a preferred brand of toothpaste, much less who gets to dominate the future global agricultural economy.

So I’m guessing not a whole lot is going to come out of this one.

The study, “Global agriculture and carbon trade-offs,” was published in the Proceedings of the National Academy of Sciences by Johnson and colleagues Carlisle Ford Runge, Benjamin Senauer, Jonathan Foley, and Stephen Polasky.

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Wandering Peepers Give Away the Creepers

downloadI’m pretty sure every single woman in the world has experienced talking to a (straight) man and having his gaze slip down from her face about a foot. Intuition would probably tell a woman in such an instance that the guy she was talking to might be interested in more of a short term engagement rather than something more permanent than a night – or a few hours, for that matter.

Well, now there’s science to back that intuition.

Researchers at the University of Chicago have shown that a person’s feelings can be deduced by the motion of their eyes. More specifically, if a person’s – that is, a man’s or woman’s – first thought is love, their eyes tend to focus on the face. If they have more physical thoughts on the mind, however, their first gaze goes toward the body.

Stephanie Cacioppo, director of the UChicago High-Performance Electrical NeuroImaging Laboratory, who co-authored the paper, had a group of males and females look at a series of images. In the first run, the images all showed a couple interacting with one another. In the second, the images were of people from the opposite sex looking straight at the camera.

Some photos were a bit more provocative than others.

Some photos were a bit more provocative than others.

In both cases, the scientists asked participants to report as quickly and accurately as possible whether the image stirred feelings of love or pure unadulterated sexual desire. While people responded with love just as quickly as lust, making it impossible to predict their answer based on response time, their first eye movements within a half-second gave their thoughts away.

I personally don’t find this very surprising. When presented with a photo of attractive yet fully covered women, my own eyes don’t go straight for the body quite as fast as they do in more provocative photographs.

I mean, look at the difference in the photos used in the experiments. I’ll give the method credit for the types of photos shown above, but in the picture below, how does anyone’s eyes go to the bodies of the couple to the left or to the faces of the couple on the right? They might have picked some more ambiguous photos with both the faces and bodies of the folks readily visible.

And some photos were much more provocative than others.

And some photos were much more provocative than others.

Would even the most star-crossed, giddy, vomit-inducing person in love immediately look at the faces on the right first? That’s not where the attention is drawn.

In any event, one situation where these findings might come in handy is in actual encounters where people are trying to lie about their intentions. It might be too difficult to spot the initial glance below the border in real-time, but I think the future potential for Google Glass applications is boundless.

The study, “Love Is in the Gaze: An Eye-Tracking Study of Love and Sexual Desire,” was published by Cacioppo along with colleagues from UChicago’s Departments of Psychiatry and Psychology, and the University of Geneva. – See more at:

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