Monthly Archives: February 2013

Sensitive plasmon resonance and the Lycurgus Cup

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It’s been a while since I’ve written about the Lycurgus Cup (my Sept. 21, 2010 posting). Dated from the 4th Century AD or CE, the cup is often cited as ancient nanotechnology due to certain optical properties made possible by the inclusion of nanoparticles so it glows green or red depending on the direction of the light.

A Feb. 14, 2013 news item on ScienceDaily features some work in the area of nanoplasmonics that was inspired by the cup,

Utilizing optical characteristics first demonstrated by the ancient Romans, researchers at the University of Illinois at Urbana-Champaign have created a novel, ultra-sensitive tool for chemical, DNA, and protein analysis.

“With this device, the nanoplasmonic spectroscopy sensing, for the first time, becomes colorimetric sensing, requiring only naked eyes or ordinary visible color photography,” explained Logan Liu, an assistant professor of electrical and computer engineering and of bioengineering at Illinois. “It can be used for chemical imaging, biomolecular imaging, and integration to portable microfluidics devices for lab-on-chip-applications. His research team’s results were featured in the cover article of the inaugural edition of Advanced Optical Materials (AOM, optical section of Advanced Materials).

The Lycurgus cup was created by the Romans in 400 A.D. Made of a dichroic glass, the famous cup exhibits different colors depending on whether or not light is passing through it; red when lit from behind and green when lit from in front. It is also the origin of inspiration for all contemporary nanoplasmonics research — the study of optical phenomena in the nanoscale vicinity of metal surfaces.

The University of Illinois College of Engineering Feb. 14, 2013 news release, which originated the news item,

“This dichroic effect was achieved by including tiny proportions of minutely ground gold and silver dust in the glass,” Liu added. “In our research, we have created a large-area high density array of a nanoscale Lycurgus cup using a transparent plastic substrate to achieve colorimetric sensing. The sensor consists of about one billion nano cups in an array with sub-wavelength opening and decorated with metal nanoparticles on side walls, having similar shape and properties as the Lycurgus cups displayed in a British museum. Liu and his team were particularly excited by the extraordinary characteristics of the material, yielding  100 times better sensitivity than any other reported nanoplasmonic device.

This image shows a model of nano cup arrays. (Credit: University of Illinois at Urbana-Champaign)

This image shows a model of nano cup arrays. (Credit: University of Illinois at Urbana-Champaign)

Here’s a little more about colorimetrics and what the researchers are trying to accomplish (from the news release; Note: A link has been removed),

Colorimetric techniques are mainly attractive because of their low cost, use of inexpensive equipment, requirement of fewer signal transduction hardware, and above all, providing simple-to-understand results. … The current design will also enable new technology development in the field of DNA/protein microarray.

“Our label-free colorimetric sensor eliminates the need of problematic fluorescence tagging of DNA/ protein molecules, and the hybridization of probe and target molecule is detected from the color change of the sensor,” stated Manas Gartia, first author of the article, “Colorimetrics: Colorimetric Plasmon Resonance Imaging Using Nano Lycurgus Cup Arrays.” “Our current sensor requires just a light source and a camera to complete the DNA sensing process. This opens the possibility for developing affordable, simple and sensitive mobile phone-based DNA microarray detector in near future. Due to its low cost, simplicity in design, and high sensitivity, we envisage the extensive use of the device for DNA microarrays, therapeutic antibody screening for drug discovery, and pathogen detection in resource poor setting.”

…

In addition to Gartia and Liu, the paper’s co-authors included Austin Hsiao, Anusha Pokhriyal, Sujin Seo, Gulsim Kulsharova, and Brian T. Cunningham at Illinois, and  Tiziana C. Bond, at the Meso, Micro and Nano Technologies Center at Lawrence Livermore National Laboratory, California.

The team’s article is behind a paywall and you can find a complete citation by clicking on the link to ScienceDaily news item.

Nanodiamonds as imaging devices

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Two different teams have recently published studies in Science magazine (Feb. 1, 2013 issue) about their work with nanodiamonds, flaws, and imaging in what seems to be a case of synchronicity as there are no obvious connections between the teams.

Sabrina Richards writes in her Jan. 31, 2013 article for The Scientist about the possibility of taking snapshots of molecules at some time in the future (Note: Links have been removed),

A miniscule diamond flaw—just two atoms different—could someday enable researchers to image single molecules without resorting to time-consuming and technically exacting X-ray crystallography. The new approach, published today (January 31 [sic]) in Science, relies on a single electron to detect perturbation in molecular magnetic fields, which can provide clues about the structures of proteins and other molecules.

…

The work was inspired by magnetic resonance imaging (MRI), which uses electromagnetic coils to detect the magnetic fields emitted by hydrogen atom protons.  But traditional MRI requires many trillions of protons to get a clear image—of a brain, for example—preventing scientists from visualizing anything much smaller than millimeters-wide structures. To detect just a few protons, such as those of a single molecule, scientists would need an atomic-scale sensor.

To construct such a sensor, physicists Daniel Rugar at IBM Research and David Awschalom at the University of California, Santa Barbara, turned to diamonds. A perfect diamond, made entirely of carbon atoms covalently bonded to each other, has no free electrons and therefore no magnetic properties, explained Hammel. But a special kind of defect, known as a nitrogen-vacancy (NV) center, confers unique magnetic properties.

Jyllian Kemsley’s Jan. 31, 2013 article for C&EN (Chemical and Engineering News) discusses the work from both teams and describes the technique they used,

To downscale NMR [aka MRI], both groups used a detector made of diamond with a site defect called a single nitrogen-vacancy (NV) center, in which a nitrogen atom and a lattice hole replace two adjacent carbon atoms. Prior work had determined that NV centers are sensitive to the internal magnetic fields of the diamond. The new research demonstrates that the fluorescence of such centers can be used to detect magnetic fields emanating from just outside the diamond. Both groups were able to use NV centers to detect nuclear polarization of hydrogens in poly(methyl methacrylate) with a sample volume lower limit of about (5 nm)3. Further development is necessary to extract structural information.

Still, nothing much has happened with this technique as Richards notes in her article,

So far, the study is “just a proof of principle,” noted Awschalom. The researchers haven’t actually imaged any molecules yet, but simply detected their presence. Still, Awschalom said, “we’ve shown it’s not a completely ridiculous idea to detect external nuclear magnetic fields with one electron.” …

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

Nanoscale Nuclear Magnetic Resonance with a Nitrogen-Vacancy Spin Sensor by H. J. Mamin, M. Kim, M. H. Sherwood, C. T. Rettner, K. Ohno, D. D. Awschalom, D. Rugar. Science 1 February 2013: Vol. 339 no. 6119 pp. 557-560 DOI: 10.1126/science.1231540

The other research is described in a Feb. 14, 2013 news item on Azonano,

Magnetic resonance imaging (MRI) reveals details of living tissues, diseased organs and tumors inside the body without x-rays or surgery. What if the same technology could peer down to the level of atoms? Doctors could make visual diagnoses of a person’s molecules – examining damage on a strand of DNA, watching molecules misfold, or identifying a cancer cell by the proteins on its surface.

It is remarkably  similar work as Kemsley notes not helped by the fact that the one line description for both articles in Science magazine’s Table of Contents is identical.  (One line description: The optical response of the spin of a near-surface atomic defect in diamond can be used to sense proton magnetic fields.) The City College of New York City Feb. 13, 2013 news release, which originated the Azonano news item about the other team, offers more details,

 … Dr. Carlos Meriles, associate professor of physics at The City College of New York, and an international team of researchers at the University of Stuttgart and elsewhere have opened the door for nanoscale MRI. They used tiny defects in diamonds to sense the magnetic resonance of molecules. They reported their results in the February 1 [2013] issue of Science.

“It is bringing MRI to a level comparable to an atomic force microscope,” said Professor Meriles, referring to the device that traces the contours of atoms or tugs on a molecule to measure its strength. A nanoscale MRI could display how a molecule moves without touching it.

“Standard MRI typically gets to a resolution of 100 microns,” about the width of a human hair, said Professor Meriles. “With extraordinary effort,” he said, “it can get down to about 10 microns” – the width of a couple of blood cells. Nanoscale MRI would have a resolution 1,000 to 10,000 times better.

To try to pick up magnetic resonance on such a small scale, the team took advantage of the spin of protons in an atom, a property usually used to investigate quantum computing. In particular, they used minute imperfections in diamonds.

Diamonds are crystals made up almost entirely of carbon atoms. When a nitrogen atom lodges next to a spot where a carbon atom is missing, however, it creates a defect known as a nitrogen-vacancy (NV) center.

“These imperfections turn out to have a spin – like a little compass – and have some remarkable properties,” noted Professor Meriles. In the last few years, researchers realized that these NV centers could serve as very sensitive sensors. They can pick up the magnetic resonance of nearby atoms in a cell, for example. But unlike the atoms in a cell, the NVs shine when a light is directed at them, signaling what their spin is. If you illuminate it with green light it flashes red back.

“It is a form of what is called optically detected magnetic resonance,” he said. Like a hiker flashing Morse code on a hillside, the sensor “sends back flashes to say it is alive and well.”

“The NV can also be thought of as an atomic magnet. You can manipulate the spin of that atomic magnet just like you do with MRI by applying a radio frequency or radio pulses,” Professor Meriles explained. The NV responds. Shine a green light at it when the spin is pointing up and it will respond with brighter red light. A down spin gives a dimmer red light.

…

In the lab, graduate student Tobias Staudacher — the first author in this work — used NVs that had been created just below the diamond’s surface by bombarding it with nitrogen atoms. The team detected magnetic resonance within a film of organic material applied to the surface, just as one might examine a thin film of cells or tissue.

“Ultimately,” said Professor Meriles, “One will use a nitrogen-vacancy mounted on the tip of an atomic force microscope – or an array of NVs distributed on the diamond surface – to allow a scanning view of a cell, for example, to probe nuclear spins with a resolution down to a nanometer or perhaps better.”

Here’s a citation and a link to this team’s study,

Nuclear Magnetic Resonance Spectroscopy on a (5-Nanometer)3 Sample Volume by T. Staudacher, F. Shi, S. Pezzagna, J. Meijer, J. Du, C. A. Meriles, F. Reinhard1, J. Wrachtrup. Science 1 February 2013: Vol. 339 no. 6119 pp. 561-563 DOI: 10.1126/science.1231675

Both articles are behind paywalls.

It takes more than research to change energy sources and use

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Much of the talk about reducing or eliminating dependency on fossil fuels is focused on research to accomplish these goals or policies to support and promote new patterns of energy use as opposed to the details needed to implement a change in the infrastructures. For example, one frequently sees news about various energy research efforts such as this one at the University of Texas at Dallas featured in a Feb. 14, 2013 news item on Azonano,

University of Texas at Dallas researchers and their colleagues at other institutions are investigating ways to harvest energy from such diverse sources as mechanical vibrations, wasted heat, radio waves, light and even movements of the human body.

The goal is to develop ways to convert this unused energy into a form that can self-power the next generation of electronics, eliminating or reducing the need for bulky, limited-life batteries.

Beyond the more familiar wind and solar power, energy harvesting has a wide range of potential applications. These include: powering wireless sensor networks placed in “intelligent” buildings, or in hard-to-reach or dangerous areas; monitoring the structural health of aircraft; and biomedical implants that might transmit health data to your doctor or treat a chronic condition.

The Feb. 14, 2013 University of Texas at Dallas news release, which originated the news item, describes a recent energy research event and highlights some of the work being performed by the Center for Energy Harvesting Materials and Systems (CEHMS) consortium (Note: A link has been removed),

At a recent scientific conference held at UT Dallas, experts from academia, industry and government labs gathered to share their latest research on energy harvesting. Energy Summit 2013 focused on research initiatives at UT Dallas, Virginia Tech and Leibniz University in Germany, which form a consortium called the Center for Energy Harvesting Materials and Systems (CEHMS).

Founded in 2010, CEHMS is an Industry/University Cooperative Research Center funded in part by the National Science Foundation. It includes not only academic institutions, but also corporate members who collaborate on research projects and also provide funding for the center.  Roger Nessen, manager of sales and marketing at Exelis Inc. is chairman of the CEHMS advisory board.

Here are some examples of the research,

For example, Dr. Mario Rotea, the Erik Jonsson Chair and head of the Department of Mechanical Engineering at UT Dallas, discussed some of his work aimed at advancing the development of wind energy systems. He represents UT Dallas in a proposed new consortium of universities and companies called WindSTAR that would collaborate with CEHMS on wind energy science and technology issues.

On the chemistry front, Smith’s [Dennis Smith, co-director of CEHMS and the Robert A. Welch Distinguished Chair in Chemistry at UT Dallas] synthetic chemistry lab is working with advanced materials that use piezoelectrics. If a piezoelectric material is deformed by a mechanical stress – such as stepping on it or subjecting it to vibrations – it produces an electric current. Smith’s lab is investigating whether the addition of nanoparticles to certain piezoelectric materials can boost this so-called piezoelectric effect.

CEHMS co-director Dr. Shashank Priya, professor of mechanical engineering and the James and Elizabeth Turner Fellow of Engineering at Virginia Tech, collaborates with Smith on piezoelectric research. Among many projects, researchers at Virginia Tech are incorporating piezoelectrics into “smart” tiles that produce electricity when stepped upon, as well as into materials that might be applied like wallpaper to gather light and vibrational energy from walls.

Other university and industry projects include:

  • Investigating how to redesign systems to require less power.
  • An intelligent tire system that harvests energy from the vibrations in a rotating tire, powering embedded sensors that gather and report data on tire pressure, tire conditions and road conditions.
  • A new class of magnetoelectric materials that can simultaneously convert magnetic fields and vibrations into energy.
  • A textile-type material that converts wasted thermal energy into electricity, which could be wrapped around hot pipes or auto exhaust pipes to generate power.
  • Flexible solar cells that could be integrated into textiles, and worn by hikers or soldiers to power portable electronic devices far away from an electric socket.

It’s exciting to talk about research, startups, and policies but at some point one needs to develop an infrastructure to support these efforts as Kyle Vanhemert points out (in an elliptical fashion) in his Feb.14, 2013 article, A Deeply Thought-Out Plan for EV [electric vehicle] Charging Stations, on the Fast Company website,

Currently, the best estimates suggest that upwards of 80% of electric vehicle charging happens at home. … If we want to see wider adoption of EVs, however, one thing is obvious: We need to make it possible for drivers to charge in places other than their garage. It’s a more complex problem than it might seem, but a series of reports by the New York-based architecture and design studio WXY will at least give urban planners and prospective charging station entrepreneurs a place to start.

The studies, sponsored by the U.S. Department of Energy and the New York State Energy Research and Development Authority, address a major obstacle standing in the way of more ubiquitous charging–namely, that no one knows exactly what ubiquitous charging looks like. And in fairness, that’s because it doesn’t look like any one thing.  …

The WXY design studio has developed guidelines for these hypothetical EV charging stations,

The study identifies 22 design elements in all, divided into three categories: installation, access, and operation. The first looks at the infrastructural nuts and bolts of the site, including factors like physical dimensions of the station and its proximity to the power grid. Access deals with the factors that shape the basic user experience, things like proximity to traffic and building entrances, lighting, and signage. …

Vanhemert’s article includes some design diagrams, more details about these charging stations, and links to the design studio’s report and other reports that have been commissioned for the US Northeast Electric Vehicle Network.

Thank you to Kyle Vanhemert for a thought-provoking article, which raises questions about what kinds of changes will need to be made to infrastructure and everyday gadgets as we transition to new energy sources.

Biosensing cocaine

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Amusingly, the Feb. 13, 2013 news item on Nanowerk highlights the biosensing aspect of the work in its title,

New biosensing nanotechnology adopts natural mechanisms to detect molecules

(Nanowerk News) Since the beginning of time, living organisms have developed ingenious mechanisms to monitor their environment.

The Feb. 13, 2013 news release from the University of Montreal (Université de Montréal) takes a somewhat different tack by focusing on cocaine,

Detecting cocaine “naturally”

Since the beginning of time, living organisms have developed ingenious mechanisms to monitor their environment. As part of an international study, a team of researchers has adapted some of these natural mechanisms to detect specific molecules such as cocaine more accurately and quickly. Their work may greatly facilitate the rapid screening—less than five minutes—of many drugs, infectious diseases, and cancers.

Professor Alexis Vallée-Bélisle of the University of Montreal Department of Chemistry has worked with Professor Francesco Ricci of the University of Rome Tor Vergata and Professor Kevin W. Plaxco of the University of California at Santa Barbara to improve a new biosensing nanotechnology. The results of the study were recently published in the Journal of American Chemical Society (JACS).

The scientists have provided an interesting image to illustrate their work,

Artist's rendering: the research team used an existing cocaine biosensor (in green) and revised its design to react to a series of inhibitor molecules (in blue). They were able to adapt the biosensor to respond optimally even within a large concentration window. Courtesy: University of Montreal

Artist’s rendering: the research team used an existing cocaine biosensor (in green) and revised its design to react to a series of inhibitor molecules (in blue). They were able to adapt the biosensor to respond optimally even within a large concentration window. Courtesy: University of Montreal

The news release provides some insight into the current state of biosensing and what the research team was attempting to accomplish,

“Nature is a continuing source of inspiration for developing new technologies,” says Professor Francesco Ricci, senior author of the study. “Many scientists are currently working to develop biosensor technology to detect—directly in the bloodstream and in seconds—drug, disease, and cancer molecules.”

“The most recent rapid and easy-to-use biosensors developed by scientists to determine the levels of various molecules such as drugs and disease markers in the blood only do so when the molecule is present in a certain concentration, called the concentration window,” adds Professor Vallée-Bélisle. “Below or above this window, current biosensors lose much of their accuracy.”

To overcome this limitation, the international team looked at nature: “In cells, living organisms often use inhibitor or activator molecules to automatically program the sensitivity of their receptors (sensors), which are able to identify the precise amount of thousand of molecules in seconds,” explains Professor Vallée-Bélisle. “We therefore decided to adapt these inhibition, activation, and sequestration mechanisms to improve the efficiency of artificial biosensors.”

The researchers put their idea to the test by using an existing cocaine biosensor and revising its design so that it would respond to a series of inhibitor molecules. They were able to adapt the biosensor to respond optimally even with a large concentration window. “What is fascinating,” says Alessandro Porchetta, a doctoral student at the University of Rome, “is that we were successful in controlling the interactions of this system by mimicking mechanisms that occur naturally.”

“Besides the obvious applications in biosensor design, I think this work will pave the way for important applications related to the administration of cancer-targeting drugs, an area of increasing importance,” says Professor Kevin Plaxco. “The ability to accurately regulate biosensor or nanomachine’s activities will greatly increase their efficiency.”

The funders for this project are (from the news release),

… the Italian Ministry of Universities and Research (MIUR), the Bill & Melinda Gates Foundation Grand Challenges Explorations program, the European Commission Marie Curie Actions program, the U.S. National Institutes of Health, and the Fonds de recherche du Québec Nature et Technologies.

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

Using Distal-Site Mutations and Allosteric Inhibition To Tune, Extend, and Narrow the Useful Dynamic Range of Aptamer-Based Sensors by Alessandro Porchetta, Alexis Vallée-Bélisle, Kevin W. Plaxco, and Francesco Ricci. J. Am. Chem. Soc., 2012, 134 (51), pp 20601–20604 DOI: 10.1021/ja310585e Publication Date (Web): December 6, 2012

Copyright © 2012 American Chemical Society

This article is behind a paywall.

One final note, Alexis Vallée-Bélisle has been mentioned here before in the context of a ‘Grand Challenges Canada programme’ (not the Bill and Melinda Gates ‘Grand Challenges’) announcement of several fundees  in my Nov. 22, 2012 posting. That funding appears to be for a difference project.

Love Day’s nano carbon tube cupid from Brigham Young University (Utah, US)

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Valentine’s Day which is sometimes also known as ‘Love Day’, is being celebrated at Brigham Young University with an image of cupid made from carbon nanotubes according to the university’s Feb. 12, 2013 news release,

Got a “little crush” on someone this Valentine’s Day? Maybe you’ve been hit by a little arrow belonging to this cupid made from carbon nanotubes by Brigham Young University physics students.

You don’t have to be a science lover to be amazed at how they build on such a small scale. First, they put a pattern of microscopic iron “seeds” onto a plate. A blast of heated gas causes a miniature forest of carbon nanotubes to spring up. Each nanotube measures about 20 atoms across and is 99 percent air.

And while love is in the air, both love and the nano-cupid are fragile.

“It’s a really fragile structure at this point – blowing on it or touching it would destroy it,” said BYU physics professor Robert Davis.

To strengthen both the cupid and other micro-machines, Davis and his colleague Richard Vanfleet coat the nanostructures with metals and other materials. That opens the door to all kinds of uses.

I’m not sure how the carbon nanotube (CNT) cupid can be described as a machine, micro or otherwise, since the CNTs seem merely to be arranged in a pattern that is cupid-shaped,

This cupid's arm is the width of a human hair. It's made from nanotubes that are 10,000 times smaller. Courtesy Brigham Young University

This cupid’s arm is the width of a human hair. It’s made from nanotubes that are 10,000 times smaller. Courtesy Brigham Young University

In any event, it seems this news release is more concerned with other research being performed,

For example, the researchers can design and produce filters with higher precision than other methods. Their process makes equally-sized holes that are about one-tenth the circumference of a human hair. And unlike other micro-filters, the holes are evenly spaced throughout the filter.

“One application is in the area of compressed gases like oxygen in the areas of health care, mining operations or scuba diving,” Davis said. “Compressed gas systems can generate particles that need to be filtered out.”

Lawrence Barrett, a junior studying physics, recently took the concept to a business plan competition and was crowned Utah’s “Innovation Idol.” His winning presentation almost didn’t get off the ground. Barrett first learned about the competition just 48 hours before the entry deadline.

“I worked on the proposal through the night and Dr. Davis edited it for me on a Saturday,” Barrett said.

There’s a lot of information and ideas packed into this news release to the point where it’s overcrowded. Still, it does seem that exciting things are happening in Utah.

Spider skin image winner of FEI/National Geographic contest

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In a July 4, 2012 posting, I described an FEI/National Geographic image contest “Explore the Unseen” which was then open for entries. FEI, a microscopy company, runs the contest annually and in 2012 partnered with National Geographic to offer a grand prize that featured two coach class tickets to a US destination of the winner’s choosing and inclusion of their image in a special gallery promoting National Geographic’s film, “Invisible Worlds.”

The grand prize winner has been announced in a Feb. 13, 2013 news item on Azonano,

FEI is proud to announce that María Carbajo of the Electron Microscopy Unit in the Research Support Services of the University of Extremadura has been awarded the grand prize in the 2012 FEI Owner Image Contest for her entry “Spider Skin”.

FEI asked vistors to their website to vote for their favorite image among the monthly winners. A total of nearly 1000 votes were received and María Carbajo’s image, Spider Skin, narrowly beat out other worthy images.

María’s entry shows the texture of the skin of a spider, with a hair root and brochosomes from a leafhopper preyed upon by the spider.

The following “Spider Skin” image and its technical details were downloaded from FEI’s 2012 contest winners (undated) news release,

Image Details: Instrument used:QUANTA 3D FEG Magnification: 12000x Horizontal Field Width: 24.9 Vacuum: 2.7e-3 Pa Voltage: 10kV Spot: 5 Working Distance: 10 Detector: ETD Credit: María Carbajo of the Electron Microscopy Unit in the Research Support Services of the University of Extremadura

Image Details:
Instrument used:QUANTA 3D FEG
Magnification: 12000x
Horizontal Field Width: 24.9
Vacuum: 2.7e-3 Pa
Voltage: 10kV
Spot: 5
Working Distance: 10
Detector: ETD
Credit: María Carbajo of the Electron Microscopy Unit in the Research Support Services of the University of Extremadura

You can find more images that were submitted to the contest here.

 

Skills training: get ready for the robots

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If the boffins at the Massachusetts Institute of Technology (MIT) are right, soon we may be learning alongside robots and using the same techniques.  Helen Knight’s Feb. 11, 2013 news release for MIT highlights a recent study showing that robots, like humans, learn better if they cross-train. From the news release,

Robots are increasingly being used in the manufacturing industry to perform tasks that bring them into closer contact with humans. But while a great deal of work is being done to ensure robots and humans can operate safely side-by-side, more effort is needed to make robots smart enough to work effectively with people, says Julie Shah, an assistant professor of aeronautics and astronautics at MIT and head of the Interactive Robotics Group in the Computer Science and Artificial Intelligence Laboratory (CSAIL).

“People aren’t robots, they don’t do things the same way every single time,” Shah says. “And so there is a mismatch between the way we program robots to perform tasks in exactly the same way each time and what we need them to do if they are going to work in concert with people.”

Most existing research into making robots better team players is based on the concept of interactive reward, in which a human trainer gives a positive or negative response each time a robot performs a task.

However, human studies carried out by the military have shown that simply telling people they have done well or badly at a task is a very inefficient method of encouraging them to work well as a team.

Here’s the experiment Shah and her student performed,

So Shah and PhD student Stefanos Nikolaidis began to investigate whether techniques that have been shown to work well in training people could also be applied to mixed teams of humans and robots. One such technique, known as cross-training, sees team members swap roles with each other on given days. “This allows people to form a better idea of how their role affects their partner and how their partner’s role affects them,” Shah says.

In a paper to be presented at the International Conference on Human-Robot Interaction in Tokyo in March [2013], Shah and Nikolaidis will present the results of experiments they carried out with a mixed group of humans and robots, demonstrating that cross-training is an extremely effective team-building tool.

More specifically,

To allow robots to take part in the cross-training experiments, the pair first had to design a new algorithm to allow the devices to learn from their role-swapping experiences. So they modified existing reinforcement-learning algorithms to allow the robots to take in not only information from positive and negative rewards, but also information gained through demonstration. In this way, by watching their human counterparts switch roles to carry out their work, the robots were able to learn how the humans wanted them to perform the same task.

Each human-robot team then carried out a simulated task in a virtual environment, with half of the teams using the conventional interactive reward approach, and half using the cross-training technique of switching roles halfway through the session. Once the teams had completed this virtual training session, they were asked to carry out the task in the real world, but this time sticking to their own designated roles.

Shah and Nikolaidis found that the period in which human and robot were working at the same time — known as concurrent motion — increased by 71 percent in teams that had taken part in cross-training, compared to the interactive reward teams. They also found that the amount of time the humans spent doing nothing — while waiting for the robot to complete a stage of the task, for example — decreased by 41 percent.

What’s more, when the pair studied the robots themselves, they found that the learning algorithms recorded a much lower level of uncertainty about what their human teammate was likely to do next — a measure known as the entropy level — if they had been through cross-training.

Finally, when responding to a questionnaire after the experiment, human participants in cross-training were far more likely to say the robot had carried out the task according to their preferences than those in the reward-only group, and reported greater levels of trust in their robotic teammate. “This is the first evidence that human-robot teamwork is improved when a human and robot train together by switching roles, in a manner similar to effective human team training practices,” Nikolaidis says.

Shah believes this improvement in team performance could be due to the greater involvement of both parties in the cross-training process. “When the person trains the robot through reward it is one-way: The person says ‘good robot’ or the person says ‘bad robot,’ and it’s a very one-way passage of information,” Shah says. “But when you switch roles the person is better able to adapt to the robot’s capabilities and learn what it is likely to do, and so we think that it is adaptation on the person’s side that results in a better team performance.”

The work shows that strategies that are successful in improving interaction among humans can often do the same for humans and robots, says Kerstin Dautenhahn, a professor of artificial intelligence at the University of Hertfordshire in the U.K. “People easily attribute human characteristics to a robot and treat it socially, so it is not entirely surprising that this transfer from the human-human domain to the human-robot domain not only made the teamwork more efficient, but also enhanced the experience for the participants, in terms of trusting the robot,” Dautenhahn says.

The paper (Human-Robot Cross-Training: Computational Formulation, Modeling and Evaluation of a Human Team Training Strategy) written by Nikolaidis and Shah can be found here and the website for the conference (International Conference on Human-Robot Interaction [HRI]; 8th ACM [Association of Computing Machinery]/IEEE [Institute of Electrical and Electronics Engineers] Conference on Human-Robot Interaction) where it will be presented is here.

Soybeans and nanoparticles redux

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If you read the Feb. 6, 2013 news release on EurekAlert too quickly you might not realize that only one of the two types of the tested nanoparticles adversely affects soybean plants,

Two of the most widely used nanoparticles (NPs) accumulate in soybeans — second only to corn as a key food crop in the United States — in ways previously shown to have the potential to adversely affect the crop yields and nutritional quality, a new study has found. It appears in the journal ACS Nano. [emphasis mine]

Jorge L. Gardea-Torresdey and colleagues cite rapid increases in commercial and industrial uses of NPs, the building blocks of a nanotechnology industry projected to put $1 trillion worth of products on the market by 2015. Zinc oxide and cerium dioxide are among today’s most widely used NPs. Both are used in cosmetics, lotions, sunscreens and other products. They eventually go down the drain, through municipal sewage treatment plants, and wind up in the sewage sludge that some farmers apply to crops as fertilizer. Gardea-Torresdey’s team previously showed that soybean plants grown in hydroponic solutions accumulated zinc and cerium dioxide in ways that alter plant growth and could have health implications.

The question remained, however, as to whether such accumulation would occur in the real-world conditions in which farmers grow soybeans in soil, rather than nutrient solution. Other important questions included the relationship of soybean plants and NPs, the determination of their entrance into the food chain, their biotransformation and toxicity and the possible persistence of these products into the next plant generation. Their new study, performed at two world-class synchrotron facilities — the SLAC National Accelerator Laboratory in California and the European Synchrotron Radiation Facility in Grenoble, France, addressed those questions. “To our knowledge, this is the first report on the presence of cerium dioxide and zinc compounds in the reproductive/edible portions of the soybean plant grown in farm soil with cerium dioxide and zinc oxide nanoparticles. In addition, our results have shown that cerium dioxide NPs in soil can be taken up by food crops and are not biotransformed in soybeans. [emphasis mine] This suggests that cerium dioxide NPs can reach the food chain and the next soybean plant generation, with potential health implications,” the study notes.

The University of Texas El Paso Feb. 6, 2013 news release provides more detail and more clarity about the results of the research ,

Experiments led by Jorge Gardea-Torresdey, Ph.D., of The University of Texas at El Paso (UTEP) have shown that certain man-made nanoparticles that land in soil can be transferred from the roots of plants to the grains, thus entering the food supply via crops grown for human consumption.

…

Cerium dioxide, which is commonly used in sunscreens and oil refining, remained intact when it was absorbed by the plant, and was transferred all the way into the edible soybean grains. [emphasis mine]

On the other hand, zinc oxide – commonly used in sunscreens and cosmetics – was transferred to the grain, but had broken down to a nontoxic form. [emphasis mine]

To track the nanoparticles’ route within the plants, the researchers used the intense beams of X-rays from the SLAC National Accelerator Laboratory’s Stanford Synchrotron Radiation Lightsource (SSRL) and the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The X-rays also helped reveal whether or not the nanoparticles were chemically transformed in the process.

While studies are under way, Gardea-Torresdey says there is currently little information on the potential health implications of nanoparticles.

UTEP has produced a video titled, UTEP Study Shows Engineered Nanoparticles Can Enter Food Supply. This piece, which features Gardea-Torresdey and a student,  seems to be less about the study and more about the benefits of studying at UTEP and the impact of the Latino community in the US,


Here’s a citation and a link to the article (Note: This work bears a remarkable resemblance to the work mentioned in my Aug. 20, 2012 posting about soybeans and nanoparticles, not least because the studies share three or more authors),

In Situ Synchrotron X-ray Fluorescence Mapping and Speciation of CeO2 and ZnO Nanoparticles in Soil Cultivated Soybean (Glycine max) by Jose A. Hernandez-Viezcas, Hiram Castillo-Michel, Joy Cooke Andrews , Marine Cotte , Cyren Rico, Jose R. Peralta-Videa, Yuan Ge, John H. Priester, Patricia Ann Holden, and Jorge L. Gardea-Torresdey. ACS Nano, DOI: 10.1021/nn305196q Publication Date (Web): January 15, 2013

Copyright © 2013 American Chemical Society

The article is behind a paywall.

American Society for Testing and Materials (ASTM) approves standards for tracking and measuring nanoparticles

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The American Society for Testing and Materials (ASTM) has announced new standards for tracking and measuring nanoparticles as per a Feb. 11, 2013 news item on Nanowerk (Note: A link has been removed),

Two new standards developed by ASTM International Committee E56 on Nanotechnology will assist a variety of users in aspects of nanomaterial measurement. ASTM E2834, Guide for Measurement of Particle Size Distribution of Nanomaterials in Suspension by Nanoparticle Tracking Analysis (NTA), and ASTM E2859, Guide for Size Measurement of Nanoparticles Using Atomic Force Microscopy, are both under the jurisdiction of Subcommittee E56.02 on Physical and Chemical Characterization.

The ASTM Feb. 4, 2013 news release, which originated the news item, describes the new standards,

Nanoparticle Tracking Analysis
ASTM E2834 describes nanoparticle tracking analysis, a new measurement technique for direct and real-time visualization and analysis of nanoparticles in liquids. In NTA, particles in suspension are illuminated with a focused laser beam and light scattered from each particle is visible through magnifying optics fitted to a digital camera.

ASTM E2834 discusses the scientific basis for nanoparticle tracking analysis, as well as size limits, concentration ranges, sampling and sample preparation considerations, condition and analysis selection, data interpretation and comparison to other techniques.

Duncan Griffiths, an E56 member, says that, as a new technique, NTA has been deliberately kept simple and general to cover possible variants of the basic theory. “Many of the details of the hardware and software involved are evolving rapidly, so there may be some extension or revision of the standard in the future,” says Griffiths, who is the business development manager with NanoSight USA. “In the near term, test methods for specific sample types are expected to follow from this base document.”

Griffiths notes that NTA is applicable to many nanomaterials, as well as a range of biotech and pharmaceutical samples, including drug delivery and virus and protein aggregates. The standard will be used primarily by industries regulated by the Food and Drug Administration and the Environmental Protection Agency as a means of referencing the basis of NTA.

Nanoparticle Size Measurement
According to Vince Hackley, research chemist and project leader in the Materials Measurement Science Division of the National Institute of Standards and Technology, ASTM E2859 provides guidelines for sample preparation, measurement and analysis of results related to the use of atomic force microscopy, or AFM. AFM is a technique used to image, measure and manipulate matter at the nanoscale. The standard guide describes the use of height measurements in order to determine the size of nanoparticles deposited on a flat substrate. AFM measurement has been adopted extensively within the nanotechnology community as an important tool for visualizing and quantifying structures on the nanoscale.

ASTM E2859 provides practical and metrological guidance for applying AFM to measure the size of substrate-supported nanoparticles, including:
• Procedures for dispersing nanoparticles on various surfaces in order for the particles to be  suitable for imaging and height measurement via intermittent contact mode AFM;
• General AFM calibration and operation guidelines; and
• Procedures for data analysis and reporting.

“We believe this to be the first AFM-based international standard for particle size measurement on the nanoscale,” says Hackley, an ASTM E56 member. “While the standard is a guide, it could potentially be converted into a test method in the future. E56.02 is interested in developing standards for nanoparticle characterization that have practical and immediate impact for the nanotechnology community.”

The news release includes an invitation,

E56 invites all interested parties from industry, regulatory agencies and others with an interest in the safe commercialization of nanotechnology to participate in the development of its standards.

To purchase ASTM standards, visit www.astm.org and search by the standard designation, or contact ASTM Customer Relations (phone: 877-909-ASTM; sales@astm.org). ASTM International welcomes participation in the development of its standards. For more information on becoming an ASTM member, visit www.astm.org/JOIN.

For more news in this sector, visit www.astm.org/sn-quality or follow us on Twitter @ASTMQuality.

ASTM Committee E56 Next Meeting: May 20-21, 2013, May Committee Week, Indianapolis, Ind.
Technical Contact: (E2834) Duncan Griffiths, NanoSight USA, Costa Mesa, Calif., Phone: 714-747-9955; duncan.griffiths@nanosight.com; (E2859) Vincent A. Hackley, Ph.D., National Institute of Science and Technology, Gaithersburg, Md., Phone: 301-975-5790; vince.hackley@nist.gov
ASTM Staff Contact: Kathleen McClung, Phone: 610-832-9717; kmcclung@astm.org
ASTM PR Contact: Barbara Schindler, Phone: 610-832-9603; bschindl@astm.org

ASTM Committee E56 on Nanotechnology was formed in 2005 and has a membership of 180 according to its webpage,

E56 meets twice each year, in May and November, with about 25 members attending three days of technical meetings (every 3rd to 4th meeting of E56 is held outside of the United States). This Committee addresses issues related to standards and guidance materials for nanotechnology & nanomaterials, as well as the coordination of existing ASTM standardization related to nanotechnology needs. This coordination includes the apportioning of specific requests for nanotechnology standards through ASTM’s existing committee base, as well as the maintenance of appropriate global liaison relationships with activities (internal and external) related to this subject area.

Of course this announcement raises some questions about previous research that made claims about nanoparticle sizes and tracking. What standards, if any, were being used?

Picasso, paint, and the hard x-ray nanoprobe

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There’s the paint you put on your walls and there’s the paint you put on your body and there’s the paint artists use for their works of art. Well, it turns out that a very well known artist used common house paint to create some of his masterpieces,

Among the Picasso paintings in the Art Institute of Chicago collection, The Red Armchair is the most emblematic of his Ripolin usage and is the painting that was examined with APS X-rays at Argonne National Laboratory. To view a larger version of the image, click on it. Courtesy Art Institute of Chicago, Gift of Mr. and Mrs. Daniel Saidenberg (AIC 1957.72) © Estate of Pablo Picasso / Artists Rights Society (ARS), New York [downloaded from http://www.anl.gov/articles/high-energy-x-rays-shine-light-mystery-picasso-s-paints]

Among the Picasso paintings in the Art Institute of Chicago collection, The Red Armchair is the most emblematic of his Ripolin usage and is the painting that was examined with APS X-rays at Argonne National Laboratory. To view a larger version of the image, click on it. Courtesy Art Institute of Chicago, Gift of Mr. and Mrs. Daniel Saidenberg (AIC 1957.72) © Estate of Pablo Picasso / Artists Rights Society (ARS), New York [downloaded from http://www.anl.gov/articles/high-energy-x-rays-shine-light-mystery-picasso-s-paints]

The Art Institute of Chicago teamed with the US Argonne National Laboratory to solve a decades-long mystery as to what kind of paint Picasso used. From the Feb. 8, 2013 news item on Azonano,

The Art Institute of Chicago teamed up with Argonne National Laboratory to unravel a decades-long debate among art scholars about what kind of paint Picasso used to create his masterpieces.

The results published last month in the journal Applied Physics A: Materials Science & Processing adds significant weight to the widely held theory that Picasso was one of the first master painters to use common house paint rather than traditional artists’ paint. That switch in painting material gave birth to a new style of art marked by canvasses covered in glossy images with marbling, muted edges, and occasional errant paint drips but devoid of brush marks. Fast-drying enamel house paint enabled this dramatic departure from the slow-drying heavily blended oil paintings that dominated the art world up until Picasso’s time.

The key to decoding this long-standing mystery was the development of a unique high-energy X-ray instrument, called the hard X-ray nanoprobe, at the U.S. Department of Energy’s Advanced Photon Source (APS) X-ray facility and the Center for Nanoscale Materials, both housed at Argonne. The nanoprobe is designed to advance the development of high-performance materials and sustainable energies by giving scientists a close up view of the type and arraignment of chemical elements in material.

At that submicroscopic level is where science and art crossed paths.

The Argonne National Laboratory Feb. 6, 2013 news release by Tona Kunz, which originated the news item,  provides more  technical detail,

Volker Rose, a physicist at Argonne, uses the nanoprobe at the APS [Advanced Photon Source]/CNM [Center for Nanoscale Materials] to study zinc oxide, a key chemical used in wide-band-gap semiconductors. White paint contains the same chemical in varying amounts, depending on the type and brand of paint, which makes it a valuable clue for learning about Picasso’s work.

By comparing decades-old paint samples collected through e-Bay purchases with samples from Picasso paintings, scientists were able to learn that the chemical makeup of paint used by Picasso matched the chemical makeup of the first commercial house paint, Ripolin. Scientists also learned about the correlation of the spacing of impurities at the nanoscale in zinc oxide, offering important clues to how zinc oxide could be modified to improve performance in a variety of products, including sensors for radiation detection, LEDs and energy-saving windows as well as liquid-crystal displays for computers, TVs and instrument panels.

“Everything that we learn about how materials are structured and how chemicals react at the nanolevel can help us in our quest to design a better and more sustainable future,” Rose said.

Physicists weren’t the first to investigate the question,

Many art conservators and historians have tried over the years to use traditional optical and electron microscopes to determine whether Picasso or one of his contemporaries was the first to break with the cultural tradition of professional painters using expensive paints designed specifically for their craft. Those art world detectives all failed, because traditional tools wouldn’t let them see deeply enough into the layers of paint or with enough resolution to distinguish between store-bought enamel paint and techniques designed to mimic its appearance.

“Appearances can deceive, so this is where art can benefit from scientific research,” said Francesca Casadio, senior conservator scientist at the Art Institute of Chicago, and co-lead author on the result publication. “We needed to reverse-engineer the paint so that we could figure out if there was a fingerprint that we could then go look for in the pictures around the world that are suspected to be painted with Ripolin, the first commercial brand of house paint.”

Just as criminals leave a signature at a crime scene, each batch of paint has a chemical signature determined by its ingredients and impurities from the area and time period it was made. These signatures can’t be imitated and lie in the nanoscale range.

Yet until now, it was difficult to differentiate the chemical components of the paint pigments from the chemical components in the binders, fillers, other additives and contaminates that were mixed in with the pigments or layered on top of them. Only the nanoprobe at the APS /CNM can distinguish that level of detail: elemental composition and nanoscale distribution of elements within individualized submicrometeric pigment particles.

“The nanoprobe at the APS and CNM allowed unprecedented visualization of information about chemical composition within a singe grain of paint pigment, significantly reducing doubt that Picasso used common house paint in some of his most famous works,” said Rose, co-lead author on the result publication titled “High-Resolution Fluorescence Mapping of Impurities in the Historical Zinc Oxide Pigments: Hard X-ray Nanoprobe Applications to the Paints of Pablo Picasso.”

The nanoprobe’s high spatial resolution and micro-focusing abilities gave it the unique ability to identify individual chemical elements and distinguish between the size of paint particles crushed by hand in artists’ studios and those crushed even smaller by manufacturing equipment. The nanoprobe peered deeper than previous similar paint studies limited to a one-micrometer viewing resolution. The nanoprobe gave scientists an unprecedented look at 30-nanometer-wide particles of paint and impurities from the paint manufacturing process. For comparison, a typical sheet of copier paper is 100,000 nanometers thick.

Using the nanoprobe, scientists were able to determine that Picasso used enamel paint to create in 1931 The Red Armchair, on display at the Art Institute of Chicago. They were also able to determine the paint brand and from what manufacturing region the paint originated.

X-ray analysis of white paints produced under the Ripolin brand and used in artists’ traditional tube paints revealed that both contained nearly contaminate-free zinc oxide pigment. However, artists’ tube paints contained more fillers of other white-colored pigments than did the Ripolin, which was mostly pure zinc oxide.

Casaido [sic] views this type of chemical characterization of paints as a having a much wider application than just the study of Picasso’s paintings. By studying the chemical composition of art materials, she said, historians can learn about trade movements in ancient times, better determine the time period a piece was created, and even learn about the artist themselves through their choice of materials.

Perhaps not so coincidentally, the Art Institute of Chicago is celebrating the 100 year relationship between Picasso and Chicago, excerpted from their Jan. 14, 2013 news release,

THE ART INSTITUTE HONORS 100-YEAR RELATIONSHIP BETWEEN PICASSO AND CHICAGO WITH LANDMARK MUSEUM–WIDE CELEBRATION

First Large-Scale Picasso Exhibition Presented by the Art Institute in 30 Years Commemorates Centennial Anniversary of the Armory Show

Picasso and Chicago on View Exclusively at the Art Institute February 20–May 12, 2013

…

This winter, the Art Institute of Chicago celebrates the unique relationship between Chicago and one of the preeminent artists of the 20th century—Pablo Picasso—with special presentations, singular paintings on loan from the Philadelphia Museum of Art, and programs throughout the museum befitting the artist’s unparalleled range and influence. The centerpiece of this celebration is the major exhibition Picasso and Chicago, on view from February 20 through May 12, 2013 in the Art Institute’s Regenstein Hall, which features more than 250 works selected from the museum’s own exceptional holdings and from private collections throughout Chicago. Representing Picasso’s innovations in nearly every media—paintings, sculpture, prints, drawings, and ceramics—the works not only tell the story of Picasso’s artistic development but also the city’s great interest in and support for the artist since the Armory Show of 1913, a signal event in the history of modern art.

The Art Institute of Chicago, Francesca Casadio, and art conservation (specifically in regard to Winslow Homer) were mentioned here in an April 11, 2011 posting.