Tag Archives: University of Missouri

Equality doesn’t necessarily lead to greater women’s STEM (science, technology, engineering, and mathematics) participation?

It seems counter-intuitive but societies where women have achieved greater equality see less participation by women in STEM (science, technology, engineering and mathematics) than countries where women are treated differently. This rather stunning research was released on February 14, 2018 (yes, Valentine’s Day).

Women, equality, STEM

Both universities involved in this research have made news/press releases available. First, there’s the February 14, 2018 Leeds Beckett University (UK) press release,

Countries with greater gender equality see a smaller proportion of women taking degrees in science, technology, engineering and mathematics (STEM), a new study by Leeds Beckett has found.

Dubbed the ‘gender equality paradox’, the research found that countries such as Albania and Algeria have a greater percentage of women amongst their STEM graduates than countries lauded for their high levels of gender equality, such as Finland, Norway or Sweden.

The researchers, from Leeds Beckett’s School of Social Sciences and the University of Missouri, believe this might be because countries with less gender equality often have little welfare support, making the choice of a relatively highly-paid STEM career more attractive.

The study, published in Psychological Science, also looked at what might motivate girls and boys to choose to study STEM subjects, including overall ability, interest or enjoyment in the subject and whether science subjects were a personal academic strength.

Using data on 475,000 adolescents across 67 countries or regions, the researchers found that while boys’ and girls’ achievement in STEM subjects was broadly similar, science was more likely to be boys’ best subject.

Girls, even when their ability in science equalled or excelled that of boys, were often likely to be better overall in reading comprehension, which relates to higher ability in non-STEM subjects.

Girls also tended to register a lower interest in science subjects. These differences were near-universal across all the countries and regions studied.

This could explain some of the gender disparity in STEM participation, according to Leeds Beckett Professor in Psychology Gijsbert Stoet.

“The further you get in secondary and then higher education, the more subjects you need to drop until you end with just one.

“We are inclined to choose what we are best at and also enjoy. This makes sense and matches common school advice.

“So, even though girls can match boys in terms of how well they do at science and mathematics in school, if those aren’t their best subjects and they are less interested in them, then they’re likely to choose to study something else.”

The researchers also looked at how many girls might be expected to choose further study in STEM based on these criteria.

They took the number of girls in each country who had the necessary ability in STEM and for whom it was also their best subject and compared this to the number of women graduating in STEM.

They found there was a disparity in all countries, but with the gap once again larger in more gender equal countries.

In the UK, 29 per cent of STEM graduates are female, whereas 48 per cent of UK girls might be expected to take those subjects based on science ability alone. This drops to 39 per cent when both science ability and interest in the subject are taken into account.

Countries with higher gender equality tend also to be welfare states, providing a high level of social security for their citizens.

Professor Stoet said: “STEM careers are generally secure and well-paid but the risks of not following such a path can vary.

“In more affluent countries where any choice of career feels relatively safe, women may feel able to make choices based on non-economic factors.

“Conversely, in countries with fewer economic opportunities, or where employment might be precarious, a well-paid and relatively secure STEM career can be more attractive to women.”

Despite extensive efforts to increase participation of women in STEM, levels have remained broadly stable for decades, but these findings could help target interventions to make them more effective, say the researchers.

“It’s important to take into account that girls are choosing not to study STEM for what they feel are valid reasons, so campaigns that target all girls may be a waste of energy and resources,” said Professor Stoet.

“If governments want to increase women’s participation in STEM, a more effective strategy might be to target the girls who are clearly being ‘lost’ from the STEM pathway: those for whom science and maths are their best subjects and who enjoy it but still don’t choose it.

“If we can understand their motivations, then interventions can be designed to help them change their minds.”

Then, there’s the February 14, 2018 University of Missouri news release, some of which will be repetitive,

The underrepresentation of girls and women in science, technology, engineering and mathematics (STEM) fields occurs globally. Although women currently are well represented in life sciences, they continue to be underrepresented in inorganic sciences, such as computer science and physics. Now, researchers from the University of Missouri and Leeds Beckett University in the United Kingdom have found that as societies become wealthier and more gender equal, women are less likely to obtain degrees in STEM. The researchers call this a “gender-equality paradox.” Researchers also discovered a near-universal sex difference in academic strengths and weaknesses that contributes to the STEM gap. Findings from the study could help refine education efforts and policies geared toward encouraging girls and women with strengths in science or math to participate in STEM fields.

The researchers found that, throughout the world, boys’ academic strengths tend to be in science or mathematics, while girls’ strengths are in reading. Students who have personal strengths in science or math are more likely to enter STEM fields, whereas students with reading as a personal strength are more likely to enter non-STEM fields, according to David Geary, Curators Professor of Psychological Sciences in the MU College of Arts and Science. These sex differences in academic strengths, as well as interest in science, may explain why the sex differences in STEM fields has been stable for decades, and why current approaches to address them have failed.

“We analyzed data on 475,000 adolescents across 67 countries or regions and found that while boys’ and girls’ achievements in STEM subjects were broadly similar in all countries, science was more likely to be boys’ best subject,” Geary said. “Girls, even when their abilities in science equaled or excelled that of boys, often were likely to be better overall in reading comprehension, which relates to higher ability in non-STEM subjects. As a result, these girls tended to seek out other professions unrelated to STEM fields.”

Surprisingly, this trend was larger for girls and women living in countries with greater gender equality. The authors call this a “gender-equality paradox,” because countries lauded for their high levels of gender equality, such as Finland, Norway or Sweden, have relatively few women among their STEM graduates. In contrast, more socially conservative countries such as Turkey or Algeria have a much larger percentage of women among their STEM graduates.

“In countries with greater gender equality, women are actively encouraged to participate in STEM; yet, they lose more girls because of personal academic strengths,” Geary said. “In more liberal and wealthy countries, personal preferences are more strongly expressed. One consequence is that sex differences in academic strengths and interests become larger and have a stronger influence college and career choices than in more conservative and less wealthy countries, creating the gender-equality paradox.”

The combination of personal academic strengths in reading, lower interest in science, and broader financial security explains why so few women choose a STEM career in highly developed nations.

“STEM careers are generally secure and well-paid but the risks of not following such a path can vary,” said Gijsbert Stoet, Professor in Psychology at Leeds Beckett University. “In more affluent countries where any choice of career feels relatively safe, women may feel able to make choices based on non-economic factors. Conversely, in countries with fewer economic opportunities, or where employment might be precarious, a well-paid and relatively secure STEM career can be more attractive to women.”

Findings from this study could help target interventions to make them more effective, say the researchers. Policymakers should reconsider failing national policies focusing on decreasing the gender imbalance in STEM, the researchers add.

The University of Missouri also produced a brief video featuring Professor David Geary discussing the work,

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

The Gender-Equality Paradox in Science, Technology, Engineering, and Mathematics Education by Gijsbert Stoet, David C. Geary. Psychological Studies https://doi.org/10.1177/0956797617741719 First Published February 14, 2018 Research Article

This paper is behind a paywall.

Gender equality and STEM: a deeper dive

Olga Khazan in a February 18, 2018 article for The Atlantic provides additional insight (Note: Links have been removed),

Though their numbers are growing, only 27 percent of all students taking the AP Computer Science exam in the United States are female. The gender gap only grows worse from there: Just 18 percent of American computer-science college degrees go to women. This is in the United States, where many college men proudly describe themselves as “male feminists” and girls are taught they can be anything they want to be.

Meanwhile, in Algeria, 41 percent of college graduates in the fields of science, technology, engineering, and math—or “STEM,” as its known—are female. There, employment discrimination against women is rife and women are often pressured to make amends with their abusive husbands.

According to a report I covered a few years ago, Jordan, Qatar, and the United Arab Emirates were the only three countries in which boys are significantly less likely to feel comfortable working on math problems than girls are. In all of the other nations surveyed, girls were more likely to say they feel “helpless while performing a math problem.”

… this line of research, if it’s replicated, might hold useful takeaways for people who do want to see more Western women entering STEM fields. In this study, the percentage of girls who did excel in science or math was still larger than the number of women who were graduating with STEM degrees. That means there’s something in even the most liberal societies that’s nudging women away from math and science, even when those are their best subjects. The women-in-STEM advocates could, for starters, focus their efforts on those would-be STEM stars.

Final thoughts

This work upends notions (mine anyway) about equality and STEM with regard to women’s participation in countries usually described as ‘developed’ as opposed to ‘developing’. I am thankful to have my ideas shaken up and being forced to review my assumptions about STEM participation and equality of opportunity.

John Timmer in a February 19, 2018 posting on the Ars Technica blog offers a critique of the research and its conclusions,

… The countries where the science-degree gender gap is smaller tend to be less socially secure. The researchers suggest that the economic security provided by fields like engineering may have a stronger draw in these countries, pulling more women into the field.

They attempt to use a statistical pathway analysis to see if the data is consistent with this being the case, but the results are inconclusive. It may be right, but there would be at least one other strong factor that they have not identified involved.

Timmer’s piece is well worth reading.

For some reason the discussion about a lack of social safety nets and precarious conditions leading women to greater STEM participation reminds me of a truism about the arts. Constraints can force you into greater creativity. Although balance is necessary as you don’t want to destroy what you’re trying to encourage. In this case, it seems that comfortable lifestyles can lead women to pursue that which comes more easily whereas women trying to make a better life in difficult circumstance will pursue a more challenging path.

Not enough silver nanoparticles in water supply to be harmful?

While the news of a low concentration of silver nanoparticles in the water supply seems good in the short term, one can’t help wondering what will happen as more of them end up in the our water. As for the news itself, here’s the announcement concerning a review of some 300 papers, from an Oct. 13, 2016 news item on Nanowerk,

Silver nanoparticles have a wide array of uses, one of which is to treat drinking water for harmful bacteria and viruses. But do silver nanoparticles also kill off potentially beneficial bacteria or cause other harmful effects to water-based ecosystems? A new paper from a team of University of Missouri College of Engineering researchers says that’s not the case.

An Oct. 12, 2016 University of Missouri news release (also on EurekAlert), which originated the news item, expands on the theme (Note: Links have been removed),

In their paper, “Governing factors affecting the impacts of silver nanoparticles on wastewater treatment,” recently published in Science of the Total Environment, Civil and Environmental Engineering Department doctoral students Chiqian Zhang and Shashikanth Gajaraj and Department Chair and Professor Zhiqiang Hu worked with Ping Li of the South China University of Technology to analyze the results of approximately 300 published works on the subject of silver nanoparticles and wastewater. What they found was while silver nanoparticles can have moderately or even significantly adverse effects in large concentrations, the amount of silver nanoparticles found in our wastewater at present isn’t harmful to humans or the ecosystem as a whole.

“If the concentration remains low, it’s not a serious problem,” Zhang said.

Silver nanoparticles are used in wastewater treatment and found increasingly in everyday products in order to combat bacteria. In terms of wastewater treatment, silver nanoparticles frequently react with sulfides in biosolids, vastly limiting their toxicity.

Zhang said many of the studies looked at high concentrations and added that if, over time, the concentration rose to much higher levels of several milligrams per liter or higher), toxicity could become a problem. But he explained that it would take decades or even longer potentially to get to that point.

“People evaluate the toxicity in a small-scale system,” he said. “But with water collection systems, much of the silver nanoparticles become silver sulfide and not be harmful.”

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

Governing factors affecting the impacts of silver nanoparticles on wastewater treatment by Chiqian Zhang, Zhiqiang Hu, Ping Li, Shashikanth Gajaraj. Science of The Total Environment http://dx.doi.org/10.1016/j.scitotenv.2016.07.145 Available online 16 August 2016

This study is behind a paywall.

For the curious, I have a Feb. 28, 2013 posting where I contrasted two silver nanoparticle studies one of which found little risk and the other which raised serious concerns. Scroll down about about 60% of the way for the ‘cautionary’ study.

Personally, I’m inclined to agree silver nanoparticles are not an immediate concern but since no one knows what the tipping point might be, now would be a good time to get serious about research, policies, and regulation.

Making ordinary microscopes image objects at the nanoscale

The researchers believe this technique for making ordinary microscopes capable of nanoscale imaging will make research into diseases easier, especially in developing countries. A July 20, 2016 news item on phys.org announces the new technique,

Research completed through a collaboration with University of Missouri [MU] engineers, biologists, and chemists could transform how scientists study molecules and cells at sub-microscopic (nanoscale) levels. Shubra Gangopadhyay, an electrical and computer engineer and her team at MU recently published studies outlining a new, relatively inexpensive imaging platform that enables single molecule imaging. This patented method highlights Gangopadhyay’s more than 30 years of nanoscale research that has proven invaluable in biological research and battling diseases.

This diagram shows the difference between regular and plasmonic gratings in terms of fluorescent intensity. Credit: Shubhra Gangopadhyay/Nanoscale.

This diagram shows the difference between regular and plasmonic gratings in terms of fluorescent intensity. Credit: Shubhra Gangopadhyay/Nanoscale.

A July 19, 2016 University of Missouri news release (also received via email), which originated the news item, explains further,

“Usually, scientists have to use very expensive microscopes to image at the sub-microscopic level,” said Gangopadhyay, the C.W. LaPierre Endowed Chair of electrical and computer engineering in the MU College of Engineering. “The techniques we’ve established help to produce enhanced imaging results with ordinary microscopes. The relatively low production cost for the platform also means it could be used to detect a wide variety of diseases, particularly in developing countries.”

The team’s custom platform uses an interaction between light and the surface of the metal grating to generate surface plasmon resonance (SPR), a rapidly developing imaging technique that enables super-resolution imaging down to 65 nanometers—a resolution normally reserved for electron microscopes. Using HD-DVD and Blu-Ray discs as starting templates, a repeating grating pattern is transferred onto the microscope slides where the specimen will be placed. Since the patterns originate from a widely used technology, the manufacturing process remains relatively inexpensive.

“In previous studies, we’ve used plasmonic gratings to detect cortisol and even tuberculosis,” Gangopadhyay said. “Additionally, the relatively low production cost for the platform also means it could be used to further detect a wide variety of diseases, particularly in developing countries. Eventually, we might even be able to use smartphones to detect disease in the field.”

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

Plasmonic gratings with nano-protrusions made by glancing angle deposition for single-molecule super-resolution imaging by B. Chen, A. Wood, A. Pathak, J. Mathai, S. Bok, H. Zheng, S. Hamm, S. Basuray, S. Grant, K. Gangopadhyay, P. V. Cornish, and S. Gangopadhyay. Nanoscale, 2016,8, 12189-12201 DOI: 10.1039/C5NR09165A First published online 24 May 2016

This paper is behind a paywall.

ETA July 22, 2016: Dexter Johnson’s July 21, 2016 posting provides both a neat summary and added detail from an engineer’s perspective.

Studying corrosion from the other side

Corrosion can be beautiful as well as destructive,

Typically, the process of corrosion has been studied from the metal side of the equation - See more at: http://www.anl.gov/articles/core-corrosion#sthash.ZPqFF13I.dpuf. Courtesy of the Argonne National Laboratory

Typically, the process of corrosion has been studied from the metal side of the equation – See more at: http://www.anl.gov/articles/core-corrosion#sthash.ZPqFF13I.dpuf. Courtesy of the Argonne National Laboratory

A Feb. 18, 2014 news item on Nanowerk expands on the theme of corrosion as destruction (Note: Links have been removed),

Anyone who has ever owned a car in a snowy town – or a boat in a salty sea – can tell you just how expensive corrosion can be.

One of the world’s most common and costly chemical reactions, corrosion happens frequently at the boundaries between water and metal surfaces. In the past, the process of corrosion has mostly been studied from the metal side of the equation.

However, in a new study (“Chloride ions induce order-disorder transition at water-oxide interfaces”), scientists at the Center for Nanoscale Materials at the U.S. Department of Energy’s Argonne National Laboratory investigated the problem from the other side, looking at the dynamics of water containing dissolved ions located in the regions near a metal surface.

The Feb. 14, 2014 Argonne National Laboratory news release by Jared Sagoff, which originated the news item, describes how the scientists conducted their research,

A team of researchers led by Argonne materials scientist Subramanian Sankaranarayanan simulated the physical and chemical dynamics of dissolved ions in water at the atomic level as it corrodes metal oxide surfaces. “Water-based solutions behave quite differently near a metal or oxide surface than they do by themselves,” Sankaranarayanan said. “But just how the chemical ions in the water interact with a surface has been an area of intense debate.”

Under low-chlorine conditions, water tends to form two-dimensional ordered layers near solid interfaces because of the influence of its strong hydrogen bonds. However, the researchers found that increasing the proportion of chlorine ions above a certain threshold causes a change in which the solution loses its ordered nature near the surface and begins to act similar to water away from the surface. This transition, in turn, can increase the rate at which materials corrode as well as the freezing temperature of the solution.

This switch between an ordered and a disordered structure near the metal surface happens incredibly quickly, in just fractions of a nanosecond. The speed of the chemical reaction necessitates the use of high-performance computers like Argonne’s Blue/Gene Q supercomputer, Mira.

To further explore these electrochemical oxide interfaces with high-performance computers, Sankaranarayanan and his colleagues from Argonne, Harvard University and the University of Missouri have also been awarded 40 million processor-hours of time on Mira.

“Having the ability to look at these reactions in a more powerful simulation will give us the opportunity to make a more educated guess of the rates of corrosion for different scenarios,” Sankaranarayanan said. Such studies will open up for the first time fundamental studies of corrosion behavior and will allow scientists to tailor materials surfaces to improve the stability and lifetime of materials.

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

Chloride ions induce order-disorder transition at water-oxide interfaces by Sanket Deshmukh, Ganesh Kamath, Shriram Ramanathan, and Subramanian K. R. S. Sankaranarayanan. Phys. Rev. E 88 (6), 062119 (2013) [5 pages]

This article is behind a paywall on both the primary site and the beta site (the American Physical Society is testing a new website for its publications).

Reliable method for detecting silver nanoparticle in fresh food and produce

The tone of an Aug. 22, 2013 news item on ScienceDaily about detecting silver naooparticles seems a bit alarmist,

Over the last few years, the use of nanomaterials for water treatment, food packaging, pesticides, cosmetics and other industries has increased. For example, farmers have used silver nanoparticles as a pesticide because of their capability to suppress the growth of harmful organisms. However, a growing concern is that these particles could pose a potential health risk to humans and the environment. In a new study, researchers at the University of Missouri have developed a reliable method for detecting silver nanoparticles in fresh produce and other food products. [emphasis mine]

“More than 1,000 products on the market are nanotechnology-based products,” said Mengshi Lin, associate professor of food science in the MU College of Agriculture, Food and Natural Resources. “This is a concern because we do not know the toxicity of the nanoparticles. [emphasis mine] Our goal is to detect, identify and quantify these nanoparticles in food and food products and study their toxicity as soon as possible.” [emphasis mine]

We leap from “could pose a potential health risk” to “we do not know the toxicity” to “study their toxicity as soon as possible” within the space of a few sentences. It’s a bit dizzying for those of us who prefer a more measured approach. The Aug. 22, 2013 University of Missouri news release on EurekAlert, which originated the news item, continues in this vein,

Lin and his colleagues, including MU scientists Azlin Mustapha and Bongkosh Vardhanabhuti, studied the residue and penetration of silver nanoparticles on pear skin. First, the scientists immersed the pears in a silver nanoparticle solution similar to pesticide application. The pears were then washed and rinsed repeatedly. Results showed that four days after the treatment and rinsing, silver nanoparticles were still attached to the skin, and the smaller particles were able to penetrate the skin and reach the pear pulp.

“The penetration of silver nanoparticles is dangerous to consumers because they have the ability to relocate in the human body after digestion,” Lin said. “Therefore, smaller nanoparticles may be more harmful to consumers than larger counterparts.”

When ingested, nanoparticles pass into the blood and lymph system, circulate through the body and reach potentially sensitive sites such as the spleen, brain, liver and heart.

The growing trend to use other types of nanoparticles has revolutionized the food industry by enhancing flavors, improving supplement delivery, keeping food fresh longer and brightening the colors of food. However, researchers worry that the use of silver nanoparticles could harm the human body.

Before I point out one of the other problems I have with this news release, here’s an image that seemingly shows how the silver nanoparticles were applied to the pears,

Caption: Graduate student Zhong Zhang applies silver nanoparticles to a piece of fruit. In a recent study, University of Missouri researchers found that these particles could pose a potential health risk to humans and the environment. Credit: University of Missouri

Caption: Graduate student Zhong Zhang applies silver nanoparticles to a piece of fruit. In a recent study, University of Missouri researchers found that these particles could pose a potential health risk to humans and the environment.
Credit: University of Missouri

Using a syringe to apply silver nanoparticles to a portion of a pear is not the same thing as applying a pesticide in an orchard.  I think it’s problematic to draw conclusions from a testing procedure that does not begin to emulate real life conditions where wind, rain, soil conditions and biological processes come into play.

I have written elsewhere about the difficulties of deciding if silver nanoparticles are good or bad notably in my April 16, 2013 posting, Silver nanoparticles: we love you/we hate you, which features links to various research pieces arguing both pro and con. The Duke University mesocosm project is mentioned in the April 16 posting and is featured in the Feb. 28, 2013 posting, Silver nanoparticles, water, the environment, and toxicity, because it that testing emulated real life conditions.

Reservations about the tone of the news release aside, here’s a link to and a citation for the published paper from the University of Missouri researchers,

Detection of Engineered Silver Nanoparticle Contamination in Pears by Zhong Zhang, Fanbin Kong, Bongkosh Vardhanabhuti, Azlin Mustapha, and Mengshi Lin. J. Agric. Food Chem., 2012, 60 (43), pp 10762–10767 DOI: 10.1021/jf303423q Publication Date (Web): October 19, 2012
Copyright © 2012 American Chemical Society

This article is behind a paywall.

Nanoparticles detect food safety and bioterrorist threats

About a week ago, a team of researchers at the University of Missouri (MU) announced a technique they’d developed that could make food safer (from the Apr. 18, 2013 news item on Nanowerk),

Sales of chicken products in China plummeted recently during an outbreak of a deadly new strain of bird flu. From bird flu to mad cow disease, numerous food scares have made global headlines in recent years. A technique developed by University of Missouri Professor of Engineering Shubhra Gangopadhyay’s group may make food contamination testing more rapid and accurate. The detection test also could accelerate warnings after bioterrorism attacks.

The University of Missouri Apr. 18, 2013 news release, which originated the news item, doesn’t offer much more in the way of detail about the technique although there is some discussion about business opportunities,

“Quickly stopping the spread of toxins saves lives, whether those toxins are from natural processes or enemy attacks,” said lead author Sangho Bok, postdoctoral fellow working under the supervision of Shubhra Gangopadhyay in MU’s College of Engineering. “Our technique uses nanoparticles to make detection one hundred times more sensitive than the standard method now used, known as ELISA. We have also reduced the time needed to detect a threat to only one hour, compared to four to six hours for ELISA.”

Currently, Bok’s testing method detects a toxin that causes food poisoning, a chemical known as Clostriudium botulinum neurotoxin A. Engineers and biologists at MU now seek to adapt the test to detect many other dangerous chemicals.

Beyond helping protect people from deadly toxins, Bok’s technique may bring jobs and foreign investment to America. Study co-author and MU research professor, Keshab Gangopadhyay, hopes to open a factory in Missouri that will manufacture the nanoparticles used in the detection technique. To achieve this goal, Gangopadhyay founded Nanos Technologies LLC.

“Science, employment and economic development are all tied together,” said Gangopadhyay. “Food safety testing presents a large market that is growing quickly in developing nations like China and India. MU engineering research helps Missouri tap into that market while creating local jobs and attracting the attention of investors.”

I did find the Nanos Technologies website and, given that they currently sell gold slides, I’m assuming the company is not newly founded although this latest technology may make the dream of opening up a factory in Missouri more attainable.

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

Femtogram-level detection of Clostridium botulinum neurotoxin type A by sandwich immunoassay using nanoporous substrate and ultra-bright fluorescent suprananoparticles by Sangho Bok, Venumadhav Korampally, Charles M. Darr, William R. Folk, Luis Polo-Parada, Keshab Gangopadhyay, Shubhra Gangopadhyay. Biosensors and Bioelectronics Volume 41, 15 March 2013, Pages 409–416  http://dx.doi.org/10.1016/j.bios.2012.08.063

This paper is behind a paywall.

University of Missouri and the US Geological survey study carbon nanotubes in aquatic environments

The University of Missouri’s Aug. 22, 2012 news release (by Timothy Wall) announces the result of a carbon nanotube study in aquatic environments,

A joint study by the University of Missouri and United States Geological Survey found that they [carbon nanotubes or CNTs] can be toxic to aquatic animals. The researchers urge that care be taken to prevent the release of CNTs into the environment as the materials enter mass production.

“The great promise of carbon nanotubes must be balanced with caution and preparation,” said Baolin Deng, professor and chair of chemical engineering at the University of Missouri. “We don’t know enough about their effects on the environment and human health. The EPA and other regulatory groups need more studies like ours to provide information on the safety of CNTs.”

CNTs are microscopically thin cylinders of carbon atoms that can be hundreds of millions of times longer than they are wide, but they are not pure carbon. Nickel, chromium and other metals used in the manufacturing process can remain as impurities. Deng and his colleagues found that these metals and the CNTs themselves can reduce the growth rates or even kill some species of aquatic organisms. The four species used in the experiment were mussels (Villosa iris), small flies’ larvae (Chironomus dilutus), worms (Lumbriculus variegatus) and crustaceans (Hyalella azteca).

“One of the greatest possibilities of contamination of the environment by CNTs comes during the manufacture of composite materials,” said Hao Li, associate professor of mechanical and aerospace engineering at MU. “Good waste management and handling procedures can minimize this risk. Also, to control long-term risks, we need to understand what happens when these composite materials break down.”

I found the abstract for the team’s paper gave a good overview of how the research was conducted,

Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.00 g/L (dry wt) of commercial sources of CNTs significantly reduced the survival or growth of the invertebrates. Toxicity was influenced by the type and source of the CNTs, by whether the materials were precleaned by acid, by whether sonication was used to disperse the materials, and by species of the test organisms. Light and electron microscope imaging of the surviving test organisms showed the presence of CNTs in the gut as well as on the outer surface of the test organisms, although no evidence was observed to show penetration of CNTs through cell membranes. The present study demonstrated that both the metals solubilized from CNTs such as nickel and the “metal-free” CNTs contributed to the toxicity.

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

Toxicity of carbon nanotubes to freshwater aquatic invertebrates by Joseph N. Mwangi, Ning Wang, Christopher G. Ingersoll, Doug K. Hardesty, Eric L. Brunson, Hao Li, and Baolin Deng in Environmental Toxicology and Chemistry, Volume 31, Issue 8, pages 1823–1830, August 2012

For anyone who’s curious about what carbon nanotubes look like, here’s an image provided by the University of MIssouri,

Carbon Nanotubes Credit: Shaddack, Wikimedia Commons
Multi-walled carbon nanotubes. 3-15 walls, mean inner diameter 4nm, mean outer diameter 13-16 nm, length 1-10+ micrometers. Black clumpy powder, grains shown, partially smeared on paper. Scale in centimeters.

I could have included a larger version of the image but, given that we’re talking about the nanoscale, the smaller image seems more appropriate.

Babies—natural physicists?

I don’t often get a chance to do cute but here we go,

Are these babies capable of physics?

I came across a Jan. 24, 2012 news item on Medical Xpress about research showing that babies intuitively understand physics (it makes sense when you see the reasoning),

In a review of related scientific literature from the past 30 years, vanMarle [Kristi vanMarle, an assistant professor in the Department of Psychological Sciences at the University of Missouri] and Susan Hespos of Northwestern University found that the evidence for intuitive physics occurs in infants as young as two months – the earliest age at which testing can occur. At that age, infants show an understanding that unsupported objects will fall and that hidden objects do not cease to exist. Scientific testing also has shown that by five months, infants have an expectation that non-cohesive substances like sand or water are not solid. In a previous publication, vanMarle found that children as young as 10 months consistently choose larger amounts when presented with two different amounts of food substance.

For any parents planning to discuss physics with their babies or start them on a physics enhancement programme, vanMarle has a few words of advice,

“Despite the intuitive physics knowledge, a parent probably cannot do much to ‘get their child ahead’ at the infant stage, including exposing him or her to videos marketed to improve math or language skills,” vanMarle said. “Natural interaction with the child, such as talking to him/her, playing peek-a-boo, and allowing him/her to handle safe objects, is the best method for child development. Natural interaction with the parent and objects in the world gives the child all the input that evolution has prepared the child to seek, accept and use to develop intuitive physics.”

For those who want examine the research first hand,

“Physics for infants: characterizing the origins of knowledge about objects, substances and number,” is published in the January issue of WIREs Cognitive Science.

I suppose you could say we are natural physicists.