Posts Tagged ‘Duke University’

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Silver nanoparticles: we love you/we hate you

Tuesday, April 16th, 2013

We seem to have a love/hate affair with silver nanoparticles. Long recognized as biocides capable of killing bacteria, silver nanoparticles are used both in hospital settings and in sports wear. As the use of silver nanoparticles increases, there are concerns about unintended consequences to the environment and to human health. An Apr. 12, 2013 news item on Nanowerk highlights some research done in Europe in 2011 (Note: Links have been removed),

As part of an EU funded project called Prosuite, Walser [Tobias Walser, researcher at the Institute for environmental engineering at the Swiss Federal Institute of Technology Zürich {ETH}] and colleagues analysed the environmental impact of nanosilver T-shirts during their entire life cycle, from raw material extraction to end-of-life disposal (“Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts”). This, according to Walser, is the first of its kind for a nanomaterial. The scientists found that the T-shirt’s environmental impact during use would be reduced if they are washed less often than conventional ones, due to their antimicrobial properties. This would even compensate for a slightly higher climate footprint during production. Walser explains: “In comparison to all toxic releases during the life cycle of a T-shirt, the toxic releases from nanosilver from washing appear to be of minor relevance.” [emphasis mine]

The Apr. 11, 2013 article by Constanze Böttcher for Youris.com, which originated the news item, expands on the theme of toxicity, nanosilver, and wastewater (Note: A link has been removed),

Previous studies looked at single impacts of antibacterial textiles. For example, scientists found that nanosilver leaches into the wastewater during washing. According to other studies, this silver may not be that harmful to the environment because it is transformed into a nearly insoluble substance called silver sulphide in wastewater treatments. A study published by the Danish Environmental Protection Agency in 2012 did not find “specific risks” to health or environmental effects of nanosilver textiles available in Denmark.

This finding contrasts with more recent research at Duke University’s CEINT (Center for Environmental Implications of Nanotechnology) mesocosm project where a study did point to adverse responses (noted in my Feb. 28, 2013 posting where I highlighted two nanosilver environmental studies, a Finnish/Estonian research project and the CEINT project),

In experiments mimicking a natural environment, Duke University researchers have demonstrated that the silver nanoparticles used in many consumer products can have an adverse effect on plants and microorganisms.

…

The main route by which these particles enter the environment is as a by-product of water and sewage treatment plants. [emphasis] The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting “sludge,” which is then spread on the land surface as a fertilizer.

…

The researchers found that one of the plants studied, a common annual grass known as Microstegium vimeneum, had 32 percent less biomass in the mesocosms treated with the nanoparticles. Microbes were also affected by the nanoparticles, Colman [Benjamin Colman, a post-doctoral fellow in Duke's biology department and a member of the Center for the Environmental Implications of Nanotechnology (CEINT)] said. One enzyme associated with helping microbes deal with external stresses was 52 percent less active, while another enzyme that helps regulate processes within the cell was 27 percent less active. The overall biomass of the microbes was also 35 percent lower, he said.

As I’ve suggested before, analysing the impact that new products and materials may have on the environment and on our health is a complex process.  From Böttcher’s 2013 article (Note: Links have been removed),

Some experts are concerned about their environmental risks, however. The study “is very relevant” because it “gives a fingerprint” about the impact of such T-shirts, Anders Baun says. But the professor in risk assessment of nanomaterials at the department of environmental engineering at the Technical University of Denmark, based in Lyngby, considers it “a bad idea to distribute silver in the environment”. He points to a study that found evidence for nanosilver accumulating in the food web based on a study of plants and animals of an experimental wetland environment. Moreover, he says, it is unknown how the coating of nanosilver influences its environmental behaviour. Baun has previously criticised the European policies regarding nanosilver and is currently enrolled in a scientific committee on the topic as invited expert. The expert group will publish its opinion later this year, he says.

There’s also the possibility that bacteria will develop resistance with increased use of silver nanoparticles in medical environments and in sportswear and in other applications.

For those who want to conduct their own investigations, here’s a link to and a citation for Walser’s 2011 paper,

Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts by Tobias Walser, Evangelia Demou, Daniel J. Lang, and Stefanie Hellweg.  Environ. Sci. Technol [Environmental Science and Technology], 2011, 45 (10), pp 4570–4578 DOI: 10.1021/es2001248 Publication Date (Web): April 20, 2011
Copyright © 2011 American Chemical Society

This paper is open access.

A description of PROSUITE (PROspective SUstaInability assessment of TEchnologies project) can be found here and the PROSUITE project website can found here.

ETA Apr. 18, 2013: An Apr. 18, 2013 news item (Barely any nanosilver from consumer products in the water) on Nanowerk provides some insight into why at least one European country views the presence of silver nanoparticles in sewage sludge without any particular alarm,

The study did not examine what happens to nanosilver in the sewage sludge thereafter. In Switzerland, it is not permissible to use sewage sludge on farmland, and most of the sludge is therefore burned. [emphasis mine] The heavy metals separated in this process should not be released into the environment in large quantities.

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

Fate and transformation of silver nanoparticles in urban wastewater systems by Ralf Kaegia, Andreas Voegelina, Christoph Orta, Brian Sinneta, Basilius Thalmanna, Jasmin Krismerb, Harald Hagendorferc, Maline Elumelua, and Elisabeth Muellerd. Water Research, http://dx.doi.org/10.1016/j.watres.2012.11.060 Available online 26 March 2013

The article is behind a paywall.

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Posted in nanotechnology, risk | No Comments »

Prosthetics and the human brain

Friday, March 8th, 2013

On the heels of research which suggests that humans tend to view their prostheses, including wheel chairs, as part of their bodies, researchers in Europe  have announced the development of a working exoskeleton powered by the wearer’s thoughts.

First, there’s the ‘wheelchair’ research, from the Mar. 6, 2013 news item on ScienceDaily,

People with spinal cord injuries show strong association of wheelchairs as part of their body, not extension of immobile limbs.

The human brain can learn to treat relevant prosthetics as a substitute for a non-working body part, according to research published March 6 in the open access journal PLOS ONE by Mariella Pazzaglia and colleagues from Sapienza University and IRCCS Fondazione Santa Lucia of Rome in Italy, supported by the International Foundation for Research in Paraplegie.

The researchers found that wheelchair-bound study participants with spinal cord injuries perceived their body’s edges as being plastic and flexible to include the wheelchair, independent of time since their injury or experience with using a wheelchair. Patients with lower spinal cord injuries who retained upper body movement showed a stronger association of the wheelchair with their body than those who had spinal cord impairments in the entire body.

According to the authors, this suggests that rather than being thought of only as an extension of the immobile limbs, the wheelchairs had become tangible, functional substitutes for the affected body part. …

As I mentioned in a Jan. 30, 2013 posting,

There have been some recent legal challenges as to what constitutes one’s body (from The Economist article, You, robot? [you can find the article here: http://www.economist.com/node/21560986]),

If you are dependent on a robotic wheelchair for mobility, for example, does the wheelchair count as part of your body? Linda MacDonald Glenn, an American lawyer and bioethicist, thinks it does. Ms Glenn (who is not involved in the RoboLaw project) persuaded an initially sceptical insurance firm that a “mobility assistance device” damaged by airline staff was more than her client’s personal property, it was an extension of his physical body. The airline settled out of court.

According to the Mar. 6, 2013 news release on EurekAlert from the Public Library of Science (PLoS), the open access article by Pazzaglia and her colleagues can be found here (Note: I have added a link),

Pazzaglia M, Galli G, Scivoletto G, Molinari M (2013) A Functionally Relevant Tool for the Body following Spinal Cord Injury. PLOS ONE 8(3): e58312.doi:10.1371/journal.pone.0058312

At almost the same time as Pazzaglia’s work,  a “Mind-controlled Exoskeleton” is announced in a Mar. 7, 2013 news item on ScienceDaily,

Every year thousands of people in Europe are paralysed by a spinal cord injury. Many are young adults, facing the rest of their lives confined to a wheelchair. Although no medical cure currently exists, in the future they could be able to walk again thanks to a mind-controlled robotic exoskeleton being developed by EU-funded researchers.

The system, based on innovative ‘Brain-neural-computer interface’ (BNCI) technology — combined with a light-weight exoskeleton attached to users’ legs and a virtual reality environment for training — could also find applications in there habilitation of stroke victims and in assisting astronauts rebuild muscle mass after prolonged periods in space.

The Mar. 7, 2013 news release on CORDIS, which originated the news item, offers a description of the “Mindwalker” project,

‘Mindwalker was proposed as a very ambitious project intended to investigate promising approaches to exploit brain signals for the purpose of controlling advanced orthosis, and to design and implement a prototype system demonstrating the potential of related technologies,’ explains Michel Ilzkovitz, the project coordinator at Space Applications Services in Belgium.

The team’s approach relies on an advanced BNCI system that converts electroencephalography (EEG) signals from the brain, or electromyography (EMG) signals from shoulder muscles, into electronic commands to control the exoskeleton.

The Laboratory of Neurophysiology and Movement Biomechanics at the Université Libre de Bruxelles (ULB) focused on the exploitation of EEG and EMG signals treated by an artificial neural network, while the Foundation Santa Lucia in Italy developed techniques based on EMG signals modelled by the coupling of neural and biomechanical oscillators.

One approach for controlling the exoskeleton uses so-called ‘steady-state visually evoked potential’, a method that reads flickering visual stimuli produced at different frequencies to induce correlated EEG signals. Detection of these EEG signals is used to trigger commands such as ‘stand’, ‘walk’, ‘faster’ or ‘slower’.

A second approach is based on processing EMG signals generated by the user’s shoulders and exploits the natural arm-leg coordination in human walking: arm-swing patterns can be perceived in this way and converted into control signals commanding the exoskeleton’s legs.

A third approach, ‘ideation’, is also based on EEG-signal processing. It uses the identification and exploitation of EEG Theta cortical signals produced by the natural mental process associated with walking. The approach was investigated by the Mindwalker team but had to be dropped due to the difficulty, and time needed, in turning the results of early experiments into a fully exploitable system.

Regardless of which method is used, the BNCI signals have to be filtered and processed before they can be used to control the exoskeleton. To achieve this, the Mindwalker researchers fed the signals into a ‘Dynamic recurrent neural network’(DRNN), a processing technique capable of learning and exploiting the dynamic character of the BNCI signals.

‘This is appealing for kinematic control and allows a much more natural and fluid way of controlling an exoskeleton,’ Mr Ilzkovitz says.

The team adopted a similarly practical approach for collecting EEG signals from the user’s scalp. Most BNCI systems are either invasive, requiring electrodes to be placed directly into brain tissue, or require users to wear a ‘wet’ capon their head, necessitating lengthy fitting procedures and the use of special gels to reduce the electrical resistance at the interface between the skin and the electrodes. While such systems deliver signals of very good quality and signal-to-noise ratio, they are impractical for everyday use.

The Mindwalker team therefore turned to a ‘dry’ technology developed by Berlin-based eemagine Medical Imaging Solutions: a cap covered in electrodes that the user can fit themselves, and which uses innovative electronic components to amplify and optimise signals before sending them to the neural network.

‘The dry EEG cap can be placed by the subject on their head by themselves in less than a minute, just like a swimming cap,’ Mr Ilzkovitz says.

Before proceeding any further with details, here’s what the Mindwalker looks like,

© MINDWALKER (downladed from http://cordis.europa.eu/fetch?CALLER=OFFR_TM_EN&ACTION=D&RCN=10601)

© MINDWALKER (downloaded from http://cordis.europa.eu/fetch?CALLER=OFFR_TM_EN&ACTION=D&RCN=10601)

After finding a way to collect the EEG/EMG signals and interpret them, the researchers needed to create the exoskeleton (from the CORDIS news release),

The universities of Delft and Twente in the Netherlands proposed an innovative approach for the design of the exoskeleton and its control. The exoskeletonis designed to be sufficiently robust to bear the weight of a 100 kg adult and powerful enough to recover balance from external causes of instability such as the user’s own torso movements during walking or a gentle push from the back or side. Compared to other exoskeletons developed to date it is relatively light, weighing less than 30 kg without batteries, and, because a final version of the system should be self-powered, it is designed to minimise energy consumption.

The Mindwalker researchers achieved energy efficiency through the use of springs fitted inside the joints that are capable of absorbing and recovering some of the energy otherwise dissipated during walking, and through the development of an efficient strategy for controlling the exoskeleton.

Most exoskeletons are designed to be balanced when stationary or quasi-static and to move by little steps inside their ground stability perimeter, an approach known as ‘Zero moment point’, or ZMP. Although this approach is commonly used for controlling humanoid robots, when applied to exoskeletons, it makes them heavy and slow – and usually requires users to be assisted by a walking frame, sticks or some other support device when they move.

Alternatively, a more advanced and more natural control strategy can replicate the way humans actually walk, with a controlled loss of balance in the walking direction.

‘This approach is called “Limit-cycle walking” and has been implemented using model predictive control to predict the behaviour of the user and exoskeleton and for controlling the exoskeleton during the walk. This was the approach investigated in Mindwalker,’ Mr Ilzkovitz says.

To train users to control the exoskeleton, researchers from Space Applications Services developed a virtual-reality training platform, providing an immersive environment in which new users can safely become accustomed to using the system before testing it out in a clinical setting, and, the team hope, eventually using it in everyday life.

By the end of this year, tests with able-bodied trial users will be completed. The system will then be transferred to the Foundation Santa Lucia for conducting a clinical evaluation until May 2013 with five to 10volunteers suffering from spinal cord injuries. These trials will help identify shortcomings and any areas of performance improvement, the project coordinator says.

In the meantime, the project partners are continuing research on different components for a variety of potential applications. The project coordinator notes, for example, that elements of the system could be adapted for the rehabilitation of stroke victims or to develop easy-to-use exoskeletons for elderly people for mobility support.

Space Applications Services, meanwhile, is also exploring applications of the Mindwalker technology to train astronauts and help them rebuild muscle mass after spending long periods of time in zero-gravity environments.

There’s more about the European Commission’s Seventh Programme-funded Mindwalker project here.

Parallel with these developments in Europe, Miguel Nicolelis of Duke University has stated that he will have a working exoskeleton (Walk Again Project)  for the kickoff by a paraplegic individual for the opening of the World Cup (soccer/football) in Brazil in 2014. I mentioned Nicolelis and his work most recently in a Mar. 4, 2013 posting.

Taken together, this research which strongly suggests that people can perceive prostheses as being part of their bodies and exoskeletons that are powered by the wearer’s thoughts, we seem to be edging closer to a world where machines and humans become one.

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Posted in human enhancement, space exploration | No Comments »

Brain-to-brain communication, organic computers, and BAM (brain activity map), the connectome

Monday, March 4th, 2013

Miguel Nicolelis, a professor at Duke University, has been making international headlines lately with two brain projects. The first one about implanting a brain chip that allows rats to perceive infrared light was mentioned in my Feb. 15, 2013 posting. The latest project is a brain-to-brain (rats) communication project as per a Feb. 28, 2013 news release on EurkAlert,

Researchers have electronically linked the brains of pairs of rats for the first time, enabling them to communicate directly to solve simple behavioral puzzles. A further test of this work successfully linked the brains of two animals thousands of miles apart—one in Durham, N.C., and one in Natal, Brazil.

The results of these projects suggest the future potential for linking multiple brains to form what the research team is calling an “organic computer,” which could allow sharing of motor and sensory information among groups of animals. The study was published Feb. 28, 2013, in the journal Scientific Reports.

“Our previous studies with brain-machine interfaces had convinced us that the rat brain was much more plastic than we had previously thought,” said Miguel Nicolelis, M.D., PhD, lead author of the publication and professor of neurobiology at Duke University School of Medicine. “In those experiments, the rat brain was able to adapt easily to accept input from devices outside the body and even learn how to process invisible infrared light generated by an artificial sensor. So, the question we asked was, ‘if the brain could assimilate signals from artificial sensors, could it also assimilate information input from sensors from a different body?’”

Ben Schiller in a Mar. 1, 2013 article for Fast Company describes both the latest experiment and the work leading up to it,

First, two rats were trained to press a lever when a light went on in their cage. Press the right lever, and they would get a reward–a sip of water. The animals were then split in two: one cage had a lever with a light, while another had a lever without a light. When the first rat pressed the lever, the researchers sent electrical activity from its brain to the second rat. It pressed the right lever 70% of the time (more than half).

In another experiment, the rats seemed to collaborate. When the second rat didn’t push the right lever, the first rat was denied a drink. That seemed to encourage the first to improve its signals, raising the second rat’s lever-pushing success rate.

Finally, to show that brain-communication would work at a distance, the researchers put one rat in an cage in North Carolina, and another in Natal, Brazil. Despite noise on the Internet connection, the brain-link worked just as well–the rate at which the second rat pushed the lever was similar to the experiment conducted solely in the U.S.

The Duke University Feb. 28, 2013 news release, the origin for the news release on EurekAlert, provides more specific details about the experiments and the rats’ training,

To test this hypothesis, the researchers first trained pairs of rats to solve a simple problem: to press the correct lever when an indicator light above the lever switched on, which rewarded the rats with a sip of water. They next connected the two animals’ brains via arrays of microelectrodes inserted into the area of the cortex that processes motor information.

One of the two rodents was designated as the “encoder” animal. This animal received a visual cue that showed it which lever to press in exchange for a water reward. Once this “encoder” rat pressed the right lever, a sample of its brain activity that coded its behavioral decision was translated into a pattern of electrical stimulation that was delivered directly into the brain of the second rat, known as the “decoder” animal.

The decoder rat had the same types of levers in its chamber, but it did not receive any visual cue indicating which lever it should press to obtain a reward. Therefore, to press the correct lever and receive the reward it craved, the decoder rat would have to rely on the cue transmitted from the encoder via the brain-to-brain interface.

The researchers then conducted trials to determine how well the decoder animal could decipher the brain input from the encoder rat to choose the correct lever. The decoder rat ultimately achieved a maximum success rate of about 70 percent, only slightly below the possible maximum success rate of 78 percent that the researchers had theorized was achievable based on success rates of sending signals directly to the decoder rat’s brain.

Importantly, the communication provided by this brain-to-brain interface was two-way. For instance, the encoder rat did not receive a full reward if the decoder rat made a wrong choice. The result of this peculiar contingency, said Nicolelis, led to the establishment of a “behavioral collaboration” between the pair of rats.

“We saw that when the decoder rat committed an error, the encoder basically changed both its brain function and behavior to make it easier for its partner to get it right,” Nicolelis said. “The encoder improved the signal-to-noise ratio of its brain activity that represented the decision, so the signal became cleaner and easier to detect. And it made a quicker, cleaner decision to choose the correct lever to press. Invariably, when the encoder made those adaptations, the decoder got the right decision more often, so they both got a better reward.”

In a second set of experiments, the researchers trained pairs of rats to distinguish between a narrow or wide opening using their whiskers. If the opening was narrow, they were taught to nose-poke a water port on the left side of the chamber to receive a reward; for a wide opening, they had to poke a port on the right side.

The researchers then divided the rats into encoders and decoders. The decoders were trained to associate stimulation pulses with the left reward poke as the correct choice, and an absence of pulses with the right reward poke as correct. During trials in which the encoder detected the opening width and transmitted the choice to the decoder, the decoder had a success rate of about 65 percent, significantly above chance.

To test the transmission limits of the brain-to-brain communication, the researchers placed an encoder rat in Brazil, at the Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), and transmitted its brain signals over the Internet to a decoder rat in Durham, N.C. They found that the two rats could still work together on the tactile discrimination task.

“So, even though the animals were on different continents, with the resulting noisy transmission and signal delays, they could still communicate,” said Miguel Pais-Vieira, PhD, a postdoctoral fellow and first author of the study. “This tells us that it could be possible to create a workable, network of animal brains distributed in many different locations.”

Will Oremus in his Feb. 28, 2013 article for Slate seems a little less buoyant about the implications of this work,

Nicolelis believes this opens the possibility of building an “organic computer” that links the brains of multiple animals into a single central nervous system, which he calls a “brain-net.” Are you a little creeped out yet? In a statement, Nicolelis adds:

We cannot even predict what kinds of emergent properties would appear when animals begin interacting as part of a brain-net. In theory, you could imagine that a combination of brains could provide solutions that individual brains cannot achieve by themselves.

That sounds far-fetched. But Nicolelis’ lab is developing quite the track record of “taking science fiction and turning it into science,” says Ron Frostig, a neurobiologist at UC-Irvine who was not involved in the rat study. “He’s the most imaginative neuroscientist right now.” (Frostig made it clear he meant this as a complement, though skeptics might interpret the word less charitably.)

The most extensive coverage I’ve given Nicolelis and his work (including the Walk Again project) was in a March 16, 2012 post titled, Monkeys, mind control, robots, prosthetics, and the 2014 World Cup (soccer/football), although there are other mentions including in this Oct. 6, 2011 posting titled, Advertising for the 21st Century: B-Reel, ‘storytelling’, and mind control.  By the way, Nicolelis hopes to have a paraplegic individual (using technology Nicolelis is developing for the Walk Again project) kick the opening soccer/football to the 2014 World Cup games in Brazil.

While there’s much excitement about Nicolelis and his work, there are other ‘brain’ projects being developed in the US including the Brain Activity Map (BAM), which James Lewis notes in his Mar. 1, 2013 posting on the Foresight Institute blog,

A proposal alluded to by President Obama in his State of the Union address [Feb. 2013] to construct a dynamic “functional connectome” Brain Activity Map (BAM) would leverage current progress in neuroscience, synthetic biology, and nanotechnology to develop a map of each firing of every neuron in the human brain—a hundred billion neurons sampled on millisecond time scales. Although not the intended goal of this effort, a project on this scale, if it is funded, should also indirectly advance efforts to develop artificial intelligence and atomically precise manufacturing.

As Lewis notes in his posting, there’s an excellent description of BAM and other brain projects, as well as a discussion about how these ideas are linked (not necessarily by individuals but by the overall direction of work being done in many labs and in many countries across the globe) in Robert Blum’s Feb. (??), 2013 posting titled, BAM: Brain Activity Map Every Spike from Every Neuron, on his eponymous blog. Blum also offers an extensive set of links to the reports and stories about BAM. From Blum’s posting,

The essence of the BAM proposal is to create the technology over the coming decade
to be able to record every spike from every neuron in the brain of a behaving organism.
While this notion seems insanely ambitious, coming from a group of top investigators,
the paper deserves scrutiny. At minimum it shows what might be achieved in the future
by the combination of nanotechnology and neuroscience.

In 2013, as I write this, two European Flagship projects have just received funding for
one billion euro each (1.3 billion dollars each). The Human Brain Project is
an outgrowth of the Blue Brain Project, directed by Prof. Henry Markram
in Lausanne, which seeks to create a detailed simulation of the human brain.
The Graphene Flagship, based in Sweden, will explore uses of graphene for,
among others, creation of nanotech-based supercomputers. The potential synergy
between these projects is a source of great optimism.

The goal of the BAM Project is to elaborate the functional connectome
of a live organism: that is, not only the static (axo-dendritic) connections
but how they function in real-time as thinking and action unfold.

…

The European Flagship Human Brain Project will create the computational
capability to simulate large, realistic neural networks. But to compare the model
with reality, a real-time, functional, brain-wide connectome must also be created.
Nanotech and neuroscience are mature enough to justify funding this proposal.

I highly recommend reading Blum’s technical description of neural spikes as understanding that concept or any other in his post doesn’t require an advanced degree. Note: Blum holds a number of degrees and diplomas including an MD (neuroscience) from the University of California at San Francisco and a PhD in computer science and biostatistics from California’s Stanford University.

The Human Brain Project has been mentioned here previously. The  most recent mention is in a Jan. 28, 2013 posting about its newly gained status as one of two European Flagship initiatives (the other is the Graphene initiative) each meriting one billion euros of research funding over 10 years. Today, however, is the first time I’ve encountered the BAM project and I’m fascinated. Luckily, John Markoff’s Feb. 17, 2013 article for The New York Times provides some insight into this US initiative (Note: I have removed some links),

The Obama administration is planning a decade-long scientific effort to examine the workings of the human brain and build a comprehensive map of its activity, seeking to do for the brain what the Human Genome Project did for genetics.

The project, which the administration has been looking to unveil as early as March, will include federal agencies, private foundations and teams of neuroscientists and nanoscientists in a concerted effort to advance the knowledge of the brain’s billions of neurons and gain greater insights into perception, actions and, ultimately, consciousness.

…

Moreover, the project holds the potential of paving the way for advances in artificial intelligence.

What I find particularly interesting is the reference back to the human genome project, which may explain why BAM is also referred to as a ‘connectome’.

ETA Mar.6.13: I have found a Human Connectome Project Mar. 6, 2013 news release on EurekAlert, which leaves me confused. This does not seem to be related to BAM, although the articles about BAM did reference a ‘connectome’. At this point, I’m guessing that BAM and the ‘Human Connectome Project’ are two related but different projects and the reference to a ‘connectome’ in the BAM material is meant generically.  I previously mentioned the Human Connectome Project panel discussion held at the AAAS (American Association for the Advancement of Science) 2013 meeting in my Feb. 7, 2013 posting.

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Posted in human enhancement, medicine, nanotechnology | No Comments »

Silver nanoparticles, water, the environment, and toxicity

Thursday, February 28th, 2013

I am contrasting two very different studies on silver nanoparticles in water and their effect on the environment to highlight the complex nature of determining the risks and environmental effects associated with nanoparticles in general. One piece of research suggests that silver nanoparticles are less dangerous than other commonly used forms of silver while the other piece raises some serious concerns.

A Feb. 28, 2013 news item on Nanowerk features research about the effects that silver nanoparticles have on aquatic ecosystems (Note: A link has been removed),

According to Finnish-Estonian joint research with data obtained on two crustacean species, there is apparently no reason to consider silver nanoparticles more dangerous for aquatic ecosystems than silver ions.

The results were reported in the journal Environmental Science and Pollution Research late last year (“Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus”). Jukka Niskanen has utilised the same polymerisation and coupling reactions in his doctoral dissertation studying several hybrid nanomaterials, i.e. combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles. Niskanen will defend his doctoral thesis at the University of Helsinki in April.

The University of Helsikinki Feb. 28, 2013 press release written by Minna Merilainen and which originated the new item provides details about the research,

“Due to the fact that silver in nanoparticle form is bactericidal and also fungicidal and also prevents the reproduction of those organisms, it is now used in various consumer goods ranging from wound dressing products to sportswear,” says Jukka Niskanen from the Laboratory of Polymer Chemistry at the University of Helsinki, Finland.A joint study from the University of Helsinki and the National Institute of Chemical Physics and Biophysics (Tallinn, Estonia), Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus, shows that silver nanoparticles are apparently no more hazardous to aquatic ecosystems than a water-soluble silver salt. The study compared the ecotoxicity of silver nanoparticles and a water-soluble silver salt.

“Our conclusion was that the environmental risks caused by silver nanoparticles are seemingly not higher than those caused by a silver salt. However, more research is required to reach a clear understanding of the safety of silver-containing particles,” Niskanen says.

Indeed, silver nanoparticles were found to be ten times less toxic than the soluble silver nitrate - a soluble silver salt used for the comparison.

The bioavailability of silver varies in different test media

To explain this phenomenon, the researchers refer to the variance in the bioavailability of silver to crustaceans in different tested media.

University lecturer Olli-Pekka Penttinen from the Department of Environmental Sciences of the University of Helsinki goes on to note that the inorganic and organic compounds dissolved in natural waters (such as humus), water hardness and sulfides have a definite impact on the bioavailability of silver. Due to this, the toxicity of both types of tested nanoparticles and the silver nitrate measured in the course of the study was lower in natural water than in artificial fresh water.

The toxicity of silver nanoparticles and silver ions was studied using two aquatic crustaceans, a water flea (Daphnia magna) and a fairy shrimp ( Thamnocephalus platyurus). Commercially available protein-stabilised particles and particles coated with a water-soluble, non-toxic polymer, specifically synthesised for the purpose, were used in the study. First, the polymers were produced utilising a controlled radical polymerization method. Synthetic polymer-grafted silver particles were then produced by attaching the water-soluble polymer to the surface of the silver with a sulfur bond.

Jukka Niskanen has utilised such polymerisation and coupling reactions in his doctoral dissertation. Polymeric and hybrid materials: polymers on particle surfaces and air-water interfaces, studying several hybrid nanomaterials , i.e., combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles....

It was previously known from other studies and research results that silver changes the functioning of proteins and enzymes. It has also been shown that silver ions can prevent the replication of DNA. Concerning silver nanoparticles, tests conducted on various species of bacteria and fungi have indicated that their toxicity varies. For example, gram-negative bacteria such as Escherichia coli are more sensitive to silver nanoparticles than gram-positive ones (such as Staphylococcus aureus). The difference in sensitivity is caused by the structural differences of the cell membranes of the bacteria. The cellular toxicity of silver nanoparticles in mammals has been studied as well. It has been suggested that silver nanoparticles enter cells via endocytosis and then function in the same manner as in bacterial cells, damaging DNA and hindering cell respiration. Electron microscope studies have shown that human skin is permeable to silver nanoparticles and that the permeability of damaged skin is up to four times higher than that of healthy skin.

While this Finnish-Estonian study suggests that silver nanoparticles do not have a negative impact on the tested crustaceans in an aquatic environment, there’s a study from Duke University suggests that silver nanoparticles in wastewater which is later put to agricultural use may cause problems. From the Feb. 27, 2013 news release on EurekAlert,

In experiments mimicking a natural environment, Duke University researchers have demonstrated that the silver nanoparticles used in many consumer products can have an adverse effect on plants and microorganisms.

…

The main route by which these particles enter the environment is as a by-product of water and sewage treatment plants. [emphasis] The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting “sludge,” which is then spread on the land surface as a fertilizer.

…

The researchers found that one of the plants studied, a common annual grass known as Microstegium vimeneum, had 32 percent less biomass in the mesocosms treated with the nanoparticles. Microbes were also affected by the nanoparticles, Colman [Benjamin Colman, a post-doctoral fellow in Duke's biology department and a member of the Center for the Environmental Implications of Nanotechnology (CEINT)] said. One enzyme associated with helping microbes deal with external stresses was 52 percent less active, while another enzyme that helps regulate processes within the cell was 27 percent less active. The overall biomass of the microbes was also 35 percent lower, he said.

“Our field studies show adverse responses of plants and microorganisms following a single low dose of silver nanoparticles applied by a sewage biosolid,” Colman said. “An estimated 60 percent of the average 5.6 million tons of biosolids produced each year is applied to the land for various reasons, and this practice represents an important and understudied route of exposure of natural ecosystems to engineered nanoparticles.”

“Our results show that silver nanoparticles in the biosolids, added at concentrations that would be expected, caused ecosystem-level impacts,” Colman said. “Specifically, the nanoparticles led to an increase in nitrous oxide fluxes, changes in microbial community composition, biomass, and extracellular enzyme activity, as well as species-specific effects on the above-ground vegetation.”

As previously noted, these two studies show just how complex the questions of risk and nanoparticles can become.  You can find out more about the Finish-Estonian study,

Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus by  Irina Blinova, Jukka Niskanen, Paula Kajankari, Liina Kanarbik, Aleksandr Käkinen, Heikki Tenhu, Olli-Pekka Penttinen, and Anne Kahru. Environmental Science and Pollution Research published November 11, 2012 online

The publisher offers an interesting option for this article. While it is behind a paywall, access is permitted through a temporary window if you want to preview a portion of the article that lies beyond the abstract.

Meanwhile here’s the article by the Duke researchers,

Low Concentrations of Silver Nanoparticles in Biosolids Cause Adverse Ecosystem Responses under Realistic Field Scenario by Benjamin P. Colman, Christina L. Arnaout, Sarah Anciaux, Claudia K. Gunsch, Michael F. Hochella Jr, Bojeong Kim, Gregory V. Lowry,  Bonnie M. McGill, Brian C. Reinsch, Curtis J. Richardson, Jason M. Unrine, Justin P. Wright, Liyan Yin, and Emily S. Bernhardt. PLoS ONE 2013; 8 (2): e57189 DOI: 10.1371/journal.pone.0057189

This article is open access as are all articles published by the Public Library of Science (PLoS) journals.

For anyone interested in the Duke University/CEINT mesocosm project, I made mention of it in an Aug. 15, 2011 posting.

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Posted in agriculture, environment, nanotechnology, risk, water | 1 Comment »

‘Touching’ infrared light, if you’re a rat followed by announcement of US FDA approval of first commercial artificial retina (bionic eye)

Friday, February 15th, 2013

Researcher Miguel Nicolelis and his colleagues at Duke University have implanted a neuroprosthetic device in the portion of a rat’s brain related to touch that allows the rats to see infrared light. From the Feb. 12, 2013 news release on EurekAlert,

Researchers have given rats the ability to “touch” infrared light, normally invisible to them, by fitting them with an infrared detector wired to microscopic electrodes implanted in the part of the mammalian brain that processes tactile information. The achievement represents the first time a brain-machine interface has augmented a sense in adult animals, said Duke University neurobiologist Miguel Nicolelis, who led the research team.

The experiment also demonstrated for the first time that a novel sensory input could be processed by a cortical region specialized in another sense without “hijacking” the function of this brain area said Nicolelis. This discovery suggests, for example, that a person whose visual cortex was damaged could regain sight through a neuroprosthesis implanted in another cortical region, he said.

Although the initial experiments tested only whether rats could detect infrared light, there seems no reason that these animals in the future could not be given full-fledged infrared vision, said Nicolelis. For that matter, cortical neuroprostheses could be developed to give animals or humans the ability to see in any region of the electromagnetic spectrum, or even magnetic fields. “We could create devices sensitive to any physical energy,” he said. “It could be magnetic fields, radio waves, or ultrasound. We chose infrared initially because it didn’t interfere with our electrophysiological recordings.”

Interestingly, the research was supported by the US National Institute of Mental Health (as per the news release).

The researchers have more to say about what they’re doing,

“The philosophy of the field of brain-machine interfaces has until now been to attempt to restore a motor function lost to lesion or damage of the central nervous system,” said Thomson, [Eric Thomson] first author of the study. “This is the first paper in which a neuroprosthetic device was used to augment function—literally enabling a normal animal to acquire a sixth sense.”

Here’s how they conducted the research,

The mammalian retina is blind to infrared light, and mammals cannot detect any heat generated by the weak infrared light used in the studies. In their experiments, the researchers used a test chamber that contained three light sources that could be switched on randomly. Using visible LED lights, they first taught each rat to choose the active light source by poking its nose into an attached port to receive a reward of a sip of water.

After training the rats, the researchers implanted in their brains an array of stimulating microelectrodes, each roughly a tenth the diameter of a human hair. The microelectrodes were implanted in the cortical region that processes touch information from the animals’ facial whiskers.

Attached to the microelectrodes was an infrared detector affixed to the animals’ foreheads. The system was programmed so that orientation toward an infrared light would trigger an electrical signal to the brain. The signal pulses increased in frequency with the intensity and proximity of the light.

The researchers returned the animals to the test chamber, gradually replacing the visible lights with infrared lights. At first in infrared trials, when a light was switched on the animals would tend to poke randomly at the reward ports and scratch at their faces, said Nicolelis. This indicated that they were initially interpreting the brain signals as touch. However, over about a month, the animals learned to associate the brain signal with the infrared source. They began to actively “forage” for the signal, sweeping their heads back and forth to guide themselves to the active light source. Ultimately, they achieved a near-perfect score in tracking and identifying the correct location of the infrared light source.

To ensure that the animals were really using the infrared detector and not their eyes to sense the infrared light, the researchers conducted trials in which the light switched on, but the detector sent no signal to the brain. In these trials, the rats did not react to the infrared light.

Their finding could have an impact on notions of mammalian brain plasticity,

A key finding, said Nicolelis, was that enlisting the touch cortex for light detection did not reduce its ability to process touch signals. “When we recorded signals from the touch cortex of these animals, we found that although the cells had begun responding to infrared light, they continued to respond to whisker touch. It was almost like the cortex was dividing itself evenly so that the neurons could process both types of information.

This finding of brain plasticity is in contrast with the “optogenetic” approach to brain stimulation, which holds that a particular neuronal cell type should be stimulated to generate a desired neurological function. Rather, said Nicolelis, the experiments demonstrate that a broad electrical stimulation, which recruits many distinct cell types, can drive a cortical region to adapt to a new source of sensory input.

All of this work is part of Nicolelis’ larger project ‘Walk Again’ which is mentioned in my March 16, 2012 posting and includes a reference to some ethical issues raised by the work. Briefly, Nicolelis and an international team of collaborators are developing a brain-machine interface that will enable full mobility for people who are severely paralyzed. From the news release,

The Walk Again Project has recently received a $20 million grant from FINEP, a Brazilian research funding agency to allow the development of the first brain-controlled whole body exoskeleton aimed at restoring mobility in severely paralyzed patients. A first demonstration of this technology is expected to happen in the opening game of the 2014 Soccer World Cup in Brazil.

Expanding sensory abilities could also enable a new type of feedback loop to improve the speed and accuracy of such exoskeletons, said Nicolelis. For example, while researchers are now seeking to use tactile feedback to allow patients to feel the movements produced by such “robotic vests,” the feedback could also be in the form of a radio signal or infrared light that would give the person information on the exoskeleton limb’s position and encounter with objects.

There’s more information including videos about the work with infrared light and rats at the Nicolelis Lab website.  Here’s a citation for and link to the team’s research paper,

Perceiving invisible light through a somatosensory cortical prosthesis by Eric E. Thomson, Rafael Carra, & Miguel A.L. Nicolelis. Nature Communications Published 12 Feb 2013 DOI: 10.1038/ncomms2497

Meanwhile, the US Food and Drug Administraton (FDA) has approved the first commercial artificial retina, from the Feb. 14, 2013 news release,

The U.S. Food and Drug Administration (FDA) granted market approval to an artificial retina technology today, the first bionic eye to be approved for patients in the United States. The prosthetic technology was developed in part with support from the National Science Foundation (NSF).

The device, called the Argus® II Retinal Prosthesis System, transmits images from a small, eye-glass-mounted camera wirelessly to a microelectrode array implanted on a patient’s damaged retina. The array sends electrical signals via the optic nerve, and the brain interprets a visual image.

The FDA approval currently applies to individuals who have lost sight as a result of severe to profound retinitis pigmentosa (RP), an ailment that affects one in every 4,000 Americans. The implant allows some individuals with RP, who are completely blind, to locate objects, detect movement, improve orientation and mobility skills and discern shapes such as large letters.

The Argus II is manufactured by, and will be distributed by, Second Sight Medical Products of Sylmar, Calif., which is part of the team of scientists and engineers from the university, federal and private sectors who spent nearly two decades developing the system with public and private investment.

Scientists are often compelled to do research in an area inspired by family,

“Seeing my grandmother go blind motivated me to pursue ophthalmology and biomedical engineering to develop a treatment for patients for whom there was no foreseeable cure,” says the technology’s co-developer, Mark Humayun, associate director of research at the Doheny Eye Institute at the University of Southern California and director of the NSF Engineering Research Center for Biomimetic MicroElectronic Systems (BMES). …”

There’s also been considerable government investment,

The effort by Humayun and his colleagues has received early and continuing support from NSF, the National Institutes of Health and the Department of Energy, with grants totaling more than $100 million. The private sector’s support nearly matched that of the federal government.

“The retinal implant exemplifies how NSF grants for high-risk, fundamental research can directly result in ground-breaking technologies decades later,” said Acting NSF Assistant Director for Engineering Kesh Narayanan. “In collaboration with the Second Sight team and the courageous patients who volunteered to have experimental surgery to implant the first-generation devices, the researchers of NSF’s Biomimetic MicroElectronic Systems Engineering Research Center are developing technologies that may ultimately have as profound an impact on blindness as the cochlear implant has had for hearing loss.”

Leaving aside controversies about cochlear implants and the possibility of such controversies with artificial retinas (bionic eyes), it’s interesting to note that this device is dependent on an external camera,

The researchers’ efforts have bridged cellular biology–necessary for understanding how to stimulate the retinal ganglion cells without permanent damage–with microelectronics, which led to the miniaturized, low-power integrated chip for performing signal conversion, conditioning and stimulation functions. The hardware was paired with software processing and tuning algorithms that convert visual imagery to stimulation signals, and the entire system had to be incorporated within hermetically sealed packaging that allowed the electronics to operate in the vitreous fluid of the eye indefinitely. Finally, the research team had to develop new surgical techniques in order to integrate the device with the body, ensuring accurate placement of the stimulation electrodes on the retina.

“The artificial retina is a great engineering challenge under the interdisciplinary constraint of biology, enabling technology, regulatory compliance, as well as sophisticated design science,” adds Liu.  [Wentai Liu of the University of California, Los Angeles] “The artificial retina provides an interface between biotic and abiotic systems. Its unique design characteristics rely on system-level optimization, rather than the more common practice of component optimization, to achieve miniaturization and integration. Using the most advanced semiconductor technology, the engine for the artificial retina is a ‘system on a chip’ of mixed voltages and mixed analog-digital design, which provides self-contained power and data management and other functionality. This design for the artificial retina facilitates both surgical procedures and regulatory compliance.”

The Argus II design consists of an external video camera system matched to the implanted retinal stimulator, which contains a microelectrode array that spans 20 degrees of visual field. [emphasis mine] …

“The external camera system-built into a pair of glasses-streams video to a belt-worn computer, which converts the video into stimulus commands for the implant,” says Weiland [USC researcher Jim Weiland], “The belt-worn computer encodes the commands into a wireless signal that is transmitted to the implant, which has the necessary electronics to receive and decode both wireless power and data. Based on those data, the implant stimulates the retina with small electrical pulses. The electronics are hermetically packaged and the electrical stimulus is delivered to the retina via a microelectrode array.”

You can see some footage of people using artificial retinas in the context of Grégoire Cosendai’s TEDx Vienna presentation. As I noted in my Aug. 18, 2011 posting where this talk and developments in human enhancement are mentioned, the relevant material can be seen at approximately 13 mins., 25 secs. in Cosendai’s talk.

Second Sight Medical Devices can be found here.

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Natural and engineered nanoparticles in an Orion magazine podcast & in a NanoBosc machinima piece

Friday, February 8th, 2013

The Jan. 16, 2013 Orion magazine podcast discussion (more about that later) regarding safety and engineered and natural nanoparticles arose from an article (worth reading) by Heather Millar in the magazine’s January/February 2013 issue, Pandora’s Boxes.

For anyone familiar with the term ‘Pandora’s box’, Millar’s and the magazine’s bias is made clear immediately, nanoparticles are small and threatening. From the Pandora’s box Wikipedia essay,

Today, the phrase “to open Pandora’s box” means to perform an action that may seem small or innocuous, but that turns out to have severe and far-reaching consequences. [emphases mine]

Millar’s article is well written and offers some excellent explanations. For example, there’s this from Pandora’s Boxes,

So chemistry and physics work differently if you’re a nanoparticle. You’re not as small as an atom or a molecule, but you’re also not even as big as a cell, so you’re definitely not of the macro world either. You exist in an undiscovered country somewhere between the molecular and the macroscopic. Here, the laws of the very small (quantum mechanics) merge quirkily with the laws of the very large (classical physics). Some say nanomaterials bring a third dimension to chemistry’s periodic table, because at the nano scale, long-established rules and groupings don’t necessarily hold up.

Then, she has some dodgier material,

Yet size seems to be a double-edged sword in the nanoverse. Because nanoparticles are so small, they can slip past the body’s various barriers: skin, the blood-brain barrier, the lining of the gut and airways. Once inside, these tiny particles can bind to many things. They seem to build up over time, especially in the brain. Some cause inflammation and cell damage. Preliminary research shows this can harm the organs of lab animals, though the results of some of these studies are a matter of debate.

Some published research has shown that inhaled nanoparticles actually become more toxic as they get smaller. Nano–titanium dioxide, one of the most commonly used nanoparticles (Pop-Tarts, sunblock), has been shown to damage DNA in animals and prematurely corrode metals. Carbon nanotubes seem to penetrate lungs even more deeply than asbestos. [emphases mine]

I think it’s worth ‘unpacking’ these two paragraphs, so here goes.  Slipping past the body’s barriers is a lot more difficult than Millar suggests in the first paragraph. My July 4, 2012 posting on breakthough research  where they penetrated the skin barrier includes this comment from me,

After all the concerns  about nanosunscreens and nanoparticles penetrating the skin raised by civil society groups, the Friends of the Earth in particular, it’s interesting to note that doctors and scientists consider penetration of the skin barrier to be extremely difficult. Of course, they seem to have solved [as of July 2012] that problem which means the chorus of concerns may rise to new heights.

I had a followup in my Oct.3, 2012 posting titled, Can nanoparticles pass through the skin or not?, suggesting there’s still a lot of confusion about this topic even within the scientific community.

Moving on to the other ‘breaches’. As I recall, there was a recent  (Autumn 2012?) nanomedicine research announcement that the blood-brain barrier was breached by nanoparticles. I haven’t yet encountered any mention of breaching the gut and I mention lungs in my next paragraph where I discuss carbon nanotubes.

As for that second paragraph, it’s an example of scaremongering. ‘Inhaled nanoparticles become more toxic as their size decreases’—ok. Why mention nano-titanium oxide in pop tarts and sunblocks, which are not inhaled, in the followup sentence? As for the reference to DNA damage and corroded metals further on, this is straight out of the Friends of the Earth literature which often cites research in a misleading fashion including those two pieces.  There is research supporting part of Millar’s statement about carbon nanotubes—provided they are long and multiwalled. In fact, as they get shorter, the resemblance to asbestos fibers in the lungs or elsewhere seems to disappear as per my Aug 22, 2012 posting and my Jan. 16, 2013 posting.

You don’t need to read the article before listening to the fascinating Jan. 16, 2013 Orion magazine podcast with Millar (reading portions of her article) and expert guests, Mark Wiesner from Duke University and director of their Center for Environmental Implications of Nano Technology (CEINT was first mentioned in my April 15, 2011 posting), Ronald Sandler from Northeastern University and author of Nanotechnology: The Social And Ethical Issues, and Jaydee Hanson, policy director for the International Center for Technology Assessment.

The discussion between Wiesner, Sandler, and Hanson about engineered and natural nanoparticles is why I’ve called the podcast fascinating. Hearing these experts ‘fence’ with each other highlights the complexities and subtleties inherent in discussions about emerging technologies (nano or other) and risk. Millar did not participate in that aspect of the conversation and I imagine that’s due to the fact that she has only been researching this area for six months while the other speakers all have several years worth experience individually and, I suspect, may have debated each other previously.

At the risk of enthusing too much about naturally occurring nanoparticles, I’m mentioning, again (my Feb. 1, 2013 posting), the recently published book by Nanowiki, Nanoparticles Before Nanotechnology, in the context of the stunning visual images used to illustrate the book. I commented previously about them and Victor Puntes of the Inorganic Nanoparticles Group at the Catalan Institute of Nanotechnology (ICN) and one of the creators of this imagery, kindly directed me to a machinima piece (derived from the NanoBosc Second Life community) which is the source for the imagery. Here it is,

NanoBosc from Per4mance MetaLES ..O.. on Vimeo.

Happy Weekend!

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No more boat scraping with new coating from Duke University

Thursday, January 31st, 2013

There’s a lot of interest in finding ways to discourage bacteria from growing on various surfaces, for example, Sharklet, which is based on nanostructures on sharkskin, is a product being developed for hospitals (my Feb. 10, 2011 posting) and there are polymers that ‘uninvite’ bacteria at the University of Nottingham (my Aug. 13, 2012 posting).

A Jan. 31, 2013 news item on Nanowerk highlights the latest work being done at Duke University,

Duke University engineers have developed a material that can be applied like paint to the hull of a ship and will literally be able to dislodge bacteria, keeping it from accumulating on the ship’s surface. This buildup on ships increases drag and reduces the energy efficiency of the vessel, as well as blocking or clogging undersea sensors.

The team’s research was published online,

Bioinspired Surfaces with Dynamic Topography for Active Control of Biofouling by Phanindhar Shivapooja, Qiming Wang, Beatriz Orihuela, Daniel Rittschof, Gabriel P. López1, Xuanhe Zhao. Advanced Materials, Article first published online: 6 JAN 2013, DOI: 10.1002/adma.201203374

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

The article is behind a paywall but the abstract is freely available,

Dynamic change of surface area and topology of elastomers is used as a general, environmentally friendly approach for effectively detaching micro- and macro-fouling organisms adhered on the elastomer surfaces. Deformation of elastomer surfaces under electrical or pneumatic actuation can debond various biofilms and barnacles. The bio-inspired dynamic surfaces can be fabricated over large areas through simple and practical processes. This new mechanism is complementary with existing materials and methods for biofouling control.

Duke University’s Jan. 31, 2013 news release by Richard Merritt, which originated the news item, provides more detail from the researchers,

“We have developed a material that ‘wrinkles,’ or changes it surface in response to a stimulus, such as stretching or pressure or electricity,” said Duke engineer Xuanhe Zhao, assistant professor in Duke’s Pratt School of Engineering. “This deformation can effectively detach biofilms and other organisms that have accumulated on the surface.”

…

Zhao has already demonstrated the ability of electric current to deform, or change, the surface of polymers.

…

The researchers tested their approach in the laboratory with simulated seawater, as well as on barnacles. These experiments were conducted in collaboration with Daniel Rittsch of the Duke University Marine Lab in Beaufort, N.C.

Keeping bacteria from attaching to ship hulls or other submerged objects can prevent a larger cascade of events that can reduce performance or efficiency. Once they have taken up residence on a surface, bacteria often attract larger organisms, such as seaweed and larva of other marine organisms, such as worms, bivalves, barnacles or mussels.

There are other ways to introduce efficiencies in marine transp0rtation as per my June 27, 2012 posting about Zyvex Marine and its new composites which will make for lighter vessels.

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Using carbon nanotubes to treat neural injuries?

Tuesday, December 11th, 2012

It’s more usual to hear about toxicology when discussing carbon nanotubes (CNTs) and health but recent work from Duke University Medical Center suggests that CNTs could be used in therapeutic treatments for neural injuries. From the Dec. 10,2012 news item on ScienceDaily,

A nanomaterial engineered by researchers at Duke can help regulate chloride levels in nerve cells that contribute to chronic pain, epilepsy, and traumatic brain injury.

The findings, published online Dec. 10, 2012, in the journal Small, were demonstrated in individual nerve cells as well as in the brains of mice and rats, and may have future applications in intracranial or spinal devices to help treat neural injuries.

The Dec. 10, 2012 news release from Duke Medicine News and Communications discusses carbon nanotubes and the applications they are usually associated with,

Carbon nanotubes are a nanomaterial with unique features, including mechanical strength and electrical conductivity. These characteristics, along with their tiny size, make them appealing to researchers in technology and medicine alike.

In a world of shrinking computers and smartphones, carbon nanotubes have been tapped as a solution for improving microchips. They outpace silicon microchips in size and performance, meeting a demand for smaller, faster devices. For people with nerve injury and certain neurological disorders, devices coated with or entirely made of carbon nanotubes could offer a new avenue for improving treatment options.

“Carbon nanotubes hold great promise for an array of applications, and we are only beginning to see their enormous potential,” said lead author Wolfgang Liedtke, M.D., PhD, associate professor of medicine and neurobiology at Duke. “Their exceptional mechanical and electrical properties make them ideal for developing devices that interface with nervous tissues. However, the precise mechanisms behind carbon nanotubes and their effect on neurons remain elusive.”

One of the Duke researchers actually developed a new kind of carbon nanotube for this research (from the Duke news release),

Not all carbon nanotubes are the same. Jie Liu, PhD, George Barth Geller Professor of Chemistry at Duke University and senior author of the study, developed specific carbon nanotubes that are extraordinarily pure. Termed few-walled carbon nanotubes, they have superior properties to their commercially-available counterparts.

Duke researchers initially set out to gauge if carbon nanotubes had toxic or adverse effects on living tissue. Studying neurons cultured from rodents, representing a “cerebral cortex in a dish,” they found the opposite. Exposing the cells to carbon nanotubes appeared to have a nourishing effect on the neurons, making them bigger and stronger.

“Previous studies have looked at the behavior of carbon nanotubes on neurons. However, the impurity in the nanotubes significantly affected the results. After we developed pure few-walled carbon nanotubes in our lab, we discovered that nanotubes actually accelerated the growth of the neuronal cells significantly,” said Liu.

Here’s what happens in some cases of neural injury and the impact that few-walled carbon nanotubes might have on future therapeutics (from the Duke news release),

Neural circuits can be corrupted by elevated chloride within neurons. A number of diseases involve such neural circuit damage, including chronic pain, epilepsy, and traumatic brain injury.

Low levels of chloride within neurons are maintained by a chloride transporter protein called KCC2, which functions by churning chloride ions out of the cell. In mature neurons, there is no back-up for this function.

The immature neurons cultured in Liedtke’s laboratory had high levels of chloride, but as the cells matured, their chloride levels dropped as KCC2 increased. When the neurons were exposed to carbon nanotubes, the cells matured much faster, and the chloride levels dropped more quickly. Researchers learned that younger cells exposed to carbon nanotubes produced more KCC2 protein.

“Carbon nanotubes enhanced the regulation of chloride in neurons to normal levels. These changes are of enormous significance to the cell,” Liedtke said.

The increase in KCC2 protein was also connected to a rise in calcium in the neurons. The increased calcium levels activated a protein found in the brain called CaMKII which signals a neuron to make more KCC2.

Similar results were observed in the brains of mice, as the carbon nanotubes prompted an increase in activity of the KCC2 gene, suggesting that the few-walled carbon nanotubes influence gene regulation of KCC2.

These findings may lead to the development of a new generation of neural engineering devices using carbon nanotubes. Existing devices that modulate the function of nerve cells use electrical systems that date back several decades.

“We hope that carbon nanotubes will work as well in injured nerves as they did in our study of developing neurons,” Liedtke continued. “The use of carbon nanotubes is just in its infancy, and we are excited to be part of a developing field with so much potential.”

Naturally (sarcasm alert), the researchers have done this (from the Duke news release),

Liedtke and Liu have filed a preliminary patent application for the few-walled carbon nanotubes used in this research. [emphasis mine]

How how many new therapies will be developed (or even researched) if the materials needed for the research are patented?

For anyone who’s interested in the paper, here’s a citation and link (from the ScienceDaily news item),

Wolfgang Liedtke, Michele Yeo, Hongbo Zhang, Yiding Wang, Michelle Gignac, Sara Miller, Ken Berglund and Jie Liu. Highly Conductive Carbon Nanotube Matrix Accelerates Developmental Chloride Extrusion in Central Nervous System Neurons by Increased Expression of Chloride Transporter KCC2. Small, 10 DEC 2012 DOI: 10.1002/smll.201201994

This paper is behind a paywall.

It should be mentioned that ScienceDaily offers a choice of citation formats, APA or MLA. This citation is in APA format.

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Monkeys, mind control, robots, prosthetics, and the 2014 World Cup (soccer/football)

Friday, March 16th, 2012

The idea that a monkey in the US could control a robot’s movements in Japan is stunning. Even more stunning is the fact that the research is four years old. It was discussed publicly in a Jan. 15, 2008 article by Sharon Gaudin for Computer World,

Scientists in the U.S. and Japan have successfully used a monkey’s brain activity to control a humanoid robot — over the Internet.

This research may only be a few years away from helping paralyzed people walk again by enabling them to use their thoughts to control exoskeletons attached to their bodies, according to Miguel Nicolelis, a professor of neurobiology at Duke University and lead researcher on the project.

“This is an attempt to restore mobility to people,” said Nicolelis. “We had the animal trained to walk on a treadmill. As it walked, we recorded its brain activity that generated its locomotion pattern. As the animal was walking and slowing down and changing his pattern, his brain activity was driving a robot in Japan in real time.”

This video clip features an animated monkey simulating control of  a real robot in Japan (the Computational Brain Project of the Japan Science and Technology Agency (JST) in Kyoto partnered with Duke University for this project),

I wonder if the Duke researchers or communications staff thought that the sight of real rhesus monkeys on treadmills might be too disturbing. While we’re on the topic of simulation, I wonder where the robot in the clip actually resides. Quibbles about the video clip aside, I have no doubt that the research took place.

There’s a more recent (Oct. 5, 2011) article, about the work being done in Nicolelis’ laboratory at Duke University, by Ed Yong for Discover Magazine (mentioned previously described in my Oct. 6, 2011 posting),

This is where we are now: at Duke University, a monkey controls a virtual arm using only its thoughts. Miguel Nicolelis had fitted the animal with a headset of electrodes that translates its brain activity into movements. It can grab virtual objects without using its arms. It can also feel the objects without its hands, because the headset stimulates its brain to create the sense of different textures. Monkey think, monkey do, monkey feel – all without moving a muscle.
And this is where  Nicolelis wants to be in three years: a young quadriplegic Brazilian man strolls confidently into a massive stadium. He controls his four prosthetic limbs with his thoughts, and they in turn send tactile information straight to his brain. The technology melds so fluidly with his mind that he confidently runs up and delivers the opening kick of the 2014 World Cup.

This sounds like a far-fetched dream, but Nicolelis – a big soccer fan – is talking to the Brazilian government to make it a reality.

According to Yong, Nicolelis has created an international consortium to support the Walk Again Project. From the project home page,

The Walk Again Project, an international consortium of leading research centers around the world represents a new paradigm for scientific collaboration among the world’s academic institutions, bringing together a global network of scientific and technological experts, distributed among all the continents, to achieve a key humanitarian goal.

The project’s central goal is to develop and implement the first BMI [brain-machine interface] capable of restoring full mobility to patients suffering from a severe degree of paralysis. This lofty goal will be achieved by building a neuroprosthetic device that uses a BMI as its core, allowing the patients to capture and use their own voluntary brain activity to control the movements of a full-body prosthetic device. This “wearable robot,” also known as an “exoskeleton,” will be designed to sustain and carry the patient’s body according to his or her mental will.

In addition to proposing to develop new technologies that aim at improving the quality of life of millions of people worldwide, the Walk Again Project also innovates by creating a complete new paradigm for global scientific collaboration among leading academic institutions worldwide. According to this model, a worldwide network of leading scientific and technological experts, distributed among all the continents, come together to participate in a major, non-profit effort to make a fellow human being walk again, based on their collective expertise. These world renowned scholars will contribute key intellectual assets as well as provide a base for continued fundraising capitalization of the project, setting clear goals to establish fundamental advances toward restoring full mobility for patients in need.

It’s the exoskeleton described on the Walk Again Project home page that Nicolelis is hoping will enable a young Brazilian quadriplegic to deliver the opening kick for the 2014 World Cup (soccer/football) in Brazil.

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