Can Traumatic Memories Be Erased?

Can Traumatic Memories Be Erased?

  1:33:00 AM    Science Lover

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Could veterans of war, rape victims and other people who have seen horrific crimes someday have the traumatic memories that haunt them weakened in their brains? In a new study, UCLA life scientists report a discovery that may make the reduction of such memories a reality.

Could veterans of war, rape victims and other people 
who have seen horrific crimes someday have the traumatic 
memories that haunt them weakened in their brains? In a 
new study, UCLA life scientists report a discovery that may 
make the reduction of such memories a reality. "I think we 
will be able to alter memories someday to reduce the trauma 
from our brains," said the study's senior author. 
(Credit: © adimas / Fotolia)

"I think we will be able to alter memories someday to reduce the trauma from our brains," said the study's senior author, David Glanzman, a UCLA professor of integrative biology and physiology and of neurobiology.

The study appears in the April 27 issue of the Journal of Neuroscience.

Glanzman, a cellular neuroscientist, and his colleagues report that they have eliminated, or at least substantially weakened, a long-term memory in both the marine snail known as Aplysia and neurons in a Petri dish. The researchers say they gaining important insights into the cell biology of long-term memory.

They discovered that the long-term memory for sensitization in the marine snail can be erased by inhibiting the activity of a specific protein kinase -- a class of molecules that modifies proteins by chemically adding to them a phosphate (an inorganic chemical), which changes the proteins' structure and activity. The protein kinase is called PKM (protein kinase M), a member of the class known as protein kinase C (PKC), which is associated with memory.

The research has important potential implications for the treatment of post-traumatic stress disorder, as well as drug addiction, in which memory plays an important role, and perhaps Alzheimer's disease and other long-term memory disorders.

"Almost all the processes that are involved in memory in the snail also have been shown to be involved in memory in the brains of mammals," said Glanzman, who added that the human brain is far too complicated to study directly.

PKM is rare in that while most protein kinases have both a catalytic domain, which is the part of the molecule that does its work, and a regulatory domain, akin to an on-off switch that can be used by other signaling pathways to shut off the activity of the kinase, PKM has only the catalytic domain -- not the regulatory domain.

"This means that once PKM is formed, there is no way to shut it off," said Glanzman, who is a member of UCLA's Brain Research Institute. "Once it is activated, PKM's continual activity maintains a memory until PKM degrades."

Glanzman decided to study PKM in the marine snail, which has simple forms of learning and a simple nervous system, so that he could understand in precise detail how PKM's activity maintains a long-term memory, a process that is not well understood.

Glanzman and his colleagues -- researchers Diancai Cai, lead author of the study; Kaycey Pearce; and Shanping Chen, all of whom work in his laboratory -- studied a simple kind of memory called sensitization. If marine snails are attacked by a predator, the attack heightens their sensitivity to environmental stimuli -- a "fundamental form of learning that is necessary for survival and is very robust in the marine snail," Glanzman said.

"The advantage of Aplysia," he said, "is that we know the neurons that produce this reflex; we know where they are in the nervous system."

The scientists removed the key neurons from the snail's nervous system and put them in a Petri dish, thereby recreating in the dish the two-neuron "circuit" -- a sensory neuron and a motor neuron -- that produces the reflex.

"The point is to reduce the problem so we can study on a fundamental biological level how PKM is maintaining long-term memory," Glanzman said.

They succeeded in erasing a long-term memory, both in the snail itself and in the circuit in the dish. They are the first scientists to show that long-term memory can be erased at a connection between just two neurons.

"We found that if we inhibit PKM in the marine snail, we will erase the memory for long-term sensitization," Glanzman said. "In addition, we can erase the long-term change at a single synapse that underlies long-term memory in the snail."

The scientists administered electric shocks to the snails' tails. Following this training, when the scientists gently touched a snail's siphon (an organ in their mid-section used in respiration), the animal responded with a reflexive contraction that lasted about 50 seconds. A week later, when the scientists touched the siphon, the reflex still lasted 30 seconds or more, rather than just the second or two the reflex normally lasts without the shock training. This constituted a long-term memory.

Then, once the marine snail had formed the long-term memory, the scientists injected an inhibitor of PKM into the snail and 24 hours later touched the siphon; the marine snail responded as though it had never received the tail shocks, with a very brief contraction.

"The long-term memory is gone," Glanzman said.

Life scientists agree that learning is due to changes in the synaptic connections, some of which strengthen and some of which weaken, in the brain. This new research opens the door to learning how the changes in synaptic connections are maintained and what role PKM plays in this memory maintenance. Glanzman and his colleagues are now conducting detailed analyses.

During the long-term memory, new synaptic connections grow between the sensory neuron and the motor neuron. If the scientists inhibit PKM, will those synaptic connections disappear?

"We're going to study that," Glanzman said. "Now we can study the cell biology of how PKM maintains long-term memory. Once we know that, we may be able to alter long-term memories. This has implications for psychiatric disorders that are related to memory. Post-traumatic stress disorder is a hyper-induction of a long-term memory that won't go away."

Targeting specific memories

Is there a way to turn the traumatic memory down?

"This is the first step toward figuring that out," Glanzman said. "Even after we know this, we will still need a way to target the memory. We have captured the memory in the dish, but we also have to know where in the brain the memory is."

Does he think it will become possible to target and weaken specific traumatic memories?

"I do," Glanzman said. "Not in the immediate future, but I think we will be able to go into one's brain, identify the location of the memory of a traumatic experience and try to dampen it down. We can do this in culture, and there is no essential difference between the synapse in culture and the synapse in your brain. We have captured the memory in the dish; now we have to figure out a way to target the memories in human brains. Once we know the neural circuit that contains the memory, then we need a selective way to inhibit the activity of PKM in that circuit."

People have different brain circuits -- collections of neurons and synapses that join neurons -- for different memories, Glanzman believes. Scientists may seek to inhibit PKM in a particular circuit. The goal would be to find the brain circuit that is predominantly associated with a traumatic memory and target PKM in that circuit.

If you boost rather than inhibit PKM activity, might that have a beneficial affect for patients with Alzheimer's disease? Alzheimer's disease appears to initially disrupt the synaptic basis of learning, Glanzman said, and PKM might be involved in that disruption.

Just as scientists are seeking to target and kill cancer cells without damaging healthy cells, Glanzman intends to study whether it is possible to weaken only certain synapses associated with traumatic memories, while leaving other memories intact.

"The brain is the most complicated organ in the body," Glanzman said, noting that the brain has many trillions of synapses. "The research is complex, but this is the way we are going to understand how memories in our brains last a lifetime, or at least part of the way. It will take a lot of research, but I think it will be feasible."

Next steps include studying the relationship between PKM and the synapses and how the structure of synapses changes when PKM is inhibited.

"That is going to tell us how long-term memories are maintained," Glanzman said. "This is the first step. The more we know about how long-term memory is induced in the brain and how our memories are maintained in the brain, the more we are going to be able to treat long-term memory loss."

The experiments are very difficult, and Glanzman praised co-authors Cai, Pearce and Chen as "unbelievably skilled."

For 28 years, Glanzman has studied learning and memory in the marine snail, which is substantially larger than its garden variety counterpart and has approximately 20,000 neurons in its central nervous system; humans have approximately 1 trillion. However, the cellular and molecular processes seem to be very similar between the marine snail and humans.

"The fundamental mechanisms of learning and memory are identical, as far as we can tell," Glanzman said.

Glanzman's research is funded by a Senator Jacob Javits Award in the Neurosciences from the National Institute of Neurological Disorders and Stroke (NINDS) and by the National Institute of Mental Health.

The marine snail processes information about its environment and is capable of learning when an environment is safe and when it is not, learning to escape from predators, and learning to identify food. The marine snail is native to California, living in tidal waters off the coast.

Glanzman is also studying learning at the synaptic level in the zebra fish.

In earlier research, Glanzman's team identified a cellular mechanism in the Aplysia that plays an important role in learning and memory. A protein called the NMDA (N-methyl D-aspartate) receptor enhances the strength of synaptic connections in the nervous system and plays a vital role in memory and in certain kinds of learning in the mammalian brain as well. Glanzman's demonstration that the NMDA receptor plays a critical role in learning in the marine snail was entirely unexpected.

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Microsleep: Brain Regions Can Take Short Naps During Wakefulness, Leading to Errors

Microsleep: Brain Regions Can Take Short Naps During Wakefulness, Leading to Errors

  10:28:00 AM    Science Lover

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If you've ever lost your keys or stuck the milk in the cupboard and the cereal in the refrigerator, you may have been the victim of a tired brain region that was taking a quick nap.

A photo of rats with objects introduced into their 
cages to keep them awake. (Credit: Giulio Tononi,
M.D., Ph.D., University of Wisconsin-Madison)

Researchers at the University of Wisconsin-Madison have a new explanation. They've found that some nerve cells in a sleep-deprived yet awake brain can briefly go "off line," into a sleep-like state, while the rest of the brain appears awake.

"Even before you feel fatigued, there are signs in the brain that you should stop certain activities that may require alertness," says Dr. Chiara Cirelli, professor of psychiatry at the School of Medicine and Public Health. "Specific groups of neurons may be falling asleep, with negative consequences on performance."

Until now, scientists thought that sleep deprivation generally affected the entire brain. Electroencephalograms (EEGs) show network brain-wave patterns typical of either being asleep or awake.

"We know that when we are sleepy, we make mistakes, our attention wanders and our vigilance goes down," says Cirelli. "We have seen with EEGs that even while we are awake, we can experience shorts periods of 'micro sleep.' "

Periods of micro sleep were thought to be the most likely cause of people falling asleep at the wheel while driving, Cirelli says.

But the new research found that even before that stage, brains are already showing sleep-like activity that impairs them, she says.

As reported in the current issue of Nature, the researchers inserted probes into specific groups of neurons in the brains of freely-behaving rats. After the rats were kept awake for prolonged periods, the probes showed areas of "local sleep" despite the animals' appearance of being awake and active.

"Even when some neurons went off line, the overall EEG measurements of the brain indicated wakefulness in the rats," Cirelli says.

And there were behavioral consequences to the local sleep episodes.

"When we prolonged the awake period, we saw the rats start to make mistakes," Cirelli says.

When animals were challenged to do a tricky task, such as reaching with one paw to get a sugar pellet, they began to drop the pellets or miss in reaching for them, indicating that a few neurons might have gone off line.

"This activity happened in few cells," Cirelli adds. "For instance, out of 20 neurons we monitored in one experiment, 18 stayed awake. From the other two, there were signs of sleep -- brief periods of activity alternating with periods of silence."

The researchers tested only motor tasks, so they concluded from this study that neurons affected by local sleep are in the motor cortex.

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Neurorobotics Reveals Brain Mechanisms of Self-Consciousness

Neurorobotics Reveals Brain Mechanisms of Self-Consciousness

  12:57:00 AM    Science Lover

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A new study uses creative engineering to unravel brain mechanisms associated with one of the most fundamental subjective human feelings: self-consciousness. The research, published in the April 28 issue of the journal Neuron, identifies a brain region called the temporo-parietal junction (TPJ) as being critical for the feeling of being an entity localized at a particular position in space and for perceiving the world from this position and perspective.

A new study uses creative engineering to unravel brain 
mechanisms associated with one of the most fundamental 
subjective human feelings: self-consciousness. The research 
identifies a brain region called the temporo-parietal junction 
(TPJ) as being critical for the feeling of being an entity 
localized at a particular position in space and for perceiving 
the world from this position and perspective. 
(Credit: © paul prescott / Fotolia)

Recent theories of self-consciousness highlight the importance of integrating many different sensory and motor signals, but it is not clear how this type of integration induces subjective states such as self-location ("Where am I in space?") and the first-person perspective ("From where do I perceive the world?"). Studies of neurological patients reporting out-of-body experiences have provided some evidence that brain damage interfering with the integration of multisensory body information may lead to pathological changes of the first-person perspective and self-location. However, it is still not known how to examine brain mechanisms associated with self-consciousness.

"Recent behavioral and physiological work, using video-projection and various visuo-tactile conflicts showed that self-location can be manipulated in healthy participants," explains senior study author, Dr. Olaf Blanke, from the Ecole Polytechnique Fédérale de Lausanne in Switzerland. "However, so far these experimental findings and techniques do not allow for the induction of changes in the first-person perspective and have not been integrated with neuroimaging, probably because the experimental set-ups require participants to sit, stand, or move. This makes it very difficult to apply and film the visuo-tactile conflicts on the participant's body during standard brain imaging techniques."

Making use of inventive neuroimaging-compatible robotic technology that was developed by Dr. Gassert's group at the Swiss Federal Institute of Technology in Zurich, Dr. Blanke and colleagues studied healthy subjects and employed specific bodily conflicts that induced changes in self-location and first-person perspective while simultaneously monitoring brain activity with functional magnetic resonance imaging. They observed that TPJ activity reflected experimental changes in self-location and first-person perspective. The researchers also completed a large study of neurological patients with out-of-body experiences and found that brain damage was localized to the TPJ.

"Our results illustrate the power of merging technologies from engineering with those of neuroimaging and cognitive science for the understanding of the nature of one of the greatest mysteries of the human mind: self-consciousness and its neural mechanisms," concludes Dr. Blanke. "Our findings on experimentally and pathologically induced altered states of self-consciousness present a powerful new research technology and reveal that TPJ activity reflects one of the most fundamental subjective feelings of humans: the feeling that 'I' am an entity that is localized at a position in space and that 'I' perceive the world from here."

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Solar Power Goes Viral: Researchers Use Virus to Improve Solar-Cell Efficiency

Solar Power Goes Viral: Researchers Use Virus to Improve Solar-Cell Efficiency

  10:02:00 AM    Science Lover

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Researchers at MIT have found a way to make significant improvements to the power-conversion efficiency of solar cells by enlisting the services of tiny viruses to perform detailed assembly work at the microscopic level.

In this diagram, the M13 virus consists of a strand 
of DNA (the figure-8 coil on the right) attached to a 
bundle of proteins called peptides -- the virus coat 
proteins (the corkscrew shapes in the center) which 
attach to the carbon nanotubes (gray cylinders) 
and hold them in place. A coating of titanium 
dioxide (yellow spheres) attached to dye molecules 
(pink spheres) surrounds the bundle. More of the 
viruses with their coatings are scattered across the 
background. (Credit: Matt Klug, Biomolecular 
Materials Group)

In a solar cell, sunlight hits a light-harvesting material, causing it to release electrons that can be harnessed to produce an electric current. The new MIT research, published online in the journal Nature Nanotechnology, is based on findings that carbon nanotubes -- microscopic, hollow cylinders of pure carbon -- can enhance the efficiency of electron collection from a solar cell's surface.

Previous attempts to use the nanotubes, however, had been thwarted by two problems. First, the making of carbon nanotubes generally produces a mix of two types, some of which act as semiconductors (sometimes allowing an electric current to flow, sometimes not) or metals (which act like wires, allowing current to flow easily). The new research, for the first time, showed that the effects of these two types tend to be different, because the semiconducting nanotubes can enhance the performance of solar cells, but the metallic ones have the opposite effect. Second, nanotubes tend to clump together, which reduces their effectiveness.

And that's where viruses come to the rescue. Graduate students Xiangnan Dang and Hyunjung Yi -- working with Angela Belcher, the W. M. Keck Professor of Energy, and several other researchers -- found that a genetically engineered version of a virus called M13, which normally infects bacteria, can be used to control the arrangement of the nanotubes on a surface, keeping the tubes separate so they can't short out the circuits, and keeping the tubes apart so they don't clump.

The system the researchers tested used a type of solar cell known as dye-sensitized solar cells, a lightweight and inexpensive type where the active layer is composed of titanium dioxide, rather than the silicon used in conventional solar cells. But the same technique could be applied to other types as well, including quantum-dot and organic solar cells, the researchers say. In their tests, adding the virus-built structures enhanced the power conversion efficiency to 10.6 percent from 8 percent -- almost a one-third improvement.

This dramatic improvement takes place even though the viruses and the nanotubes make up only 0.1 percent by weight of the finished cell. "A little biology goes a long way," Belcher says. With further work, the researchers think they can ramp up the efficiency even further.

The viruses are used to help improve one particular step in the process of converting sunlight to electricity. In a solar cell, the first step is for the energy of the light to knock electrons loose from the solar-cell material (usually silicon); then, those electrons need to be funneled toward a collector, from which they can form a current that flows to charge a battery or power a device. After that, they return to the original material, where the cycle can start again. The new system is intended to enhance the efficiency of the second step, helping the electrons find their way: Adding the carbon nanotubes to the cell "provides a more direct path to the current collector," Belcher says.

The viruses actually perform two different functions in this process. First, they possess short proteins called peptides that can bind tightly to the carbon nanotubes, holding them in place and keeping them separated from each other. Each virus can hold five to 10 nanotubes, each of which is held firmly in place by about 300 of the virus's peptide molecules. In addition, the virus was engineered to produce a coating of titanium dioxide (TiO2), a key ingredient for dye-sensitized solar cells, over each of the nanotubes, putting the titanium dioxide in close proximity to the wire-like nanotubes that carry the electrons.

The two functions are carried out in succession by the same virus, whose activity is "switched" from one function to the next by changing the acidity of its environment. This switching feature is an important new capability that has been demonstrated for the first time in this research, Belcher says.

In addition, the viruses make the nanotubes soluble in water, which makes it possible to incorporate the nanotubes into the solar cell using a water-based process that works at room temperature.

Prashant Kamat, a professor of chemistry and biochemistry at Notre Dame University who has done extensive work on dye-sensitized solar cells, says that while others have attempted to use carbon nanotubes to improve solar cell efficiency, "the improvements observed in earlier studies were marginal," while the improvements by the MIT team using the virus assembly method are "impressive."

"It is likely that the virus template assembly has enabled the researchers to establish a better contact between the TiO2 nanoparticles and carbon nanotubes. Such close contact with TiO2 nanoparticles is essential to drive away the photo-generated electrons quickly and transport it efficiently to the collecting electrode surface."

Kamat thinks the process could well lead to a viable commercial product: "Dye-sensitized solar cells have already been commercialized in Japan, Korea and Taiwan," he says. If the addition of carbon nanotubes via the virus process can improve their efficiency, "the industry is likely to adopt such processes."

Belcher and her colleagues have previously used differently engineered versions of the same virus to enhance the performance of batteries and other devices, but the method used to enhance solar cell performance is quite different, she says.

Because the process would just add one simple step to a standard solar-cell manufacturing process, it should be quite easy to adapt existing production facilities and thus should be possible to implement relatively rapidly, Belcher says.

The research team also included Paula Hammond, the Bayer Professor of Chemical Engineering; Michael Strano, the Charles (1951) and Hilda Roddey Career Development Associate Professor of Chemical Engineering; and four other graduate students and postdoctoral researchers. The work was funded by the Italian company Eni, through the MIT Energy Initiative's Solar Futures Program.

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Scientists Create Stable, Self-Renewing Neural Stem Cells

Scientists Create Stable, Self-Renewing Neural Stem Cells

  9:35:00 AM    Science Lover

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In a paper published in the April 25 early online edition of the Proceedings of the National Academy of Sciences, researchers at the University of California, San Diego School of Medicine, the Gladstone Institutes in San Francisco and colleagues report a game-changing advance in stem cell science: the creation of long-term, self-renewing, primitive neural precursor cells from human embryonic stem cells (hESCs) that can be directed to become many types of neuron without increased risk of tumor formation.

Depicts cultured, self-renewing primitive neural 
precursors derived from human embryonic stem cells 
using molecule inhibitors. (Credit: UC San 
Diego School of Medicine)

"It's a big step forward," said Kang Zhang, MD, PhD, professor of ophthalmology and human genetics at Shiley Eye Center and director of the Institute for Genomic Medicine, both at UC San Diego. "It means we can generate stable, renewable neural stem cells or downstream products quickly, in great quantities and in a clinical grade -- millions in less than a week -- that can be used for clinical trials and, eventually, for clinical treatments. Until now, that has not been possible."

Human embryonic stem cells hold great promise in regenerative medicine due to their ability to become any kind of cell needed to repair and restore damaged tissues. But the potential of hESCs has been constrained by a number of practical problems, not least among them the difficulty of growing sufficient quantities of stable, usable cells and the risk that some of these cells might form tumors.

To produce the neural stem cells, Zhang, with co-senior author Sheng Ding, PhD, a former professor of chemistry at The Scripps Research Institute and now at the Gladstone Institutes, and colleagues added small molecules in a chemically defined culture condition that induces hESCs to become primitive neural precursor cells, but then halts the further differentiation process.

"And because it doesn't use any gene transfer technologies or exogenous cell products, there's minimal risk of introducing mutations or outside contamination," Zhang said. Assays of these neural precursor cells found no evidence of tumor formation when introduced into laboratory mice.

By adding other chemicals, the scientists are able to then direct the precursor cells to differentiate into different types of mature neurons, "which means you can explore potential clinical applications for a wide range of neurodegenerative diseases," said Zhang. "You can generate neurons for specific conditions like amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), Parkinson's disease or, in the case of my particular research area, eye-specific neurons that are lost in macular degeneration, retinitis pigmentosa or glaucoma."

The new process promises to have broad applications in stem cell research. The same method can be used to push induce pluripotent stem cells (stem cells artificially derived from adult, differentiated mature cells) to become neural stem cells, Zhang said. "And in principle, by altering the combination of small molecules, you may be able to create other types of stem cells capable of becoming heart, pancreas, or muscle cells, to name a few."

The next step, according to Zhang, is to use these stem cells to treat different types of neurodegenerative diseases, such as macular degeneration or glaucoma in animal models.

Funding for this research came, in part, from grants from National Institutes of Health Director's Transformative R01 Program, the National Institute of Child Health and Development, the National Heart, Lung, and Blood Institute, the National Eye Institute, the National Institute of Mental Health, the California Institute for Regenerative Medicine, a VA Merit Award, the Macula Vision Research Foundation, Research to Prevent Blindness, a Burroughs Wellcome Fund Clinical Scientist Award in Translational Research and the Richard and Carol Hertzberg Fund.

Co-authors of the study include Wenlin Li, Yu Zhang, Wanguo Wei, Rajesh Ambasudhan, Tongxiang Lin, Janghwan Kim, Department of Chemistry, The Scripps Research Institute; Woong Sun, Xiaolei Wang, UCSD Institute for Genomic Medicine and Shiley Eye Center, Department of Anatomy, Korea University College of Medicine, Seoul, Korea; Peng Xia, Maria Talantova, Stuart A. Lipton, Del E. Webb Center for Neuroscience, Aging and Stem Cell Research, Sanford-Burnham Medical Research Institute; Woon Ryoung Kim, Department of Anatomy, Korea University College of Medicine, Seoul, Korea.

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Cheaper Hydrogen Fuel Cells: Utility of Non-Precious-Metal Catalysts Documented

Cheaper Hydrogen Fuel Cells: Utility of Non-Precious-Metal Catalysts Documented

  9:21:00 AM    Science Lover

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Los Alamos National Laboratory scientists have developed a way to avoid the use of expensive platinum in hydrogen fuel cells, the environmentally friendly devices that might replace current power sources in everything from personal data devices to automobiles.

Los Alamos National Laboratory scientists have 
developed a way to avoid the use of expensive 
platinum in hydrogen fuel cells, the environmentally 
friendly devices that might replace current power 
sources in everything from personal data devices 
to automobiles. (Credit: Image courtesy of DOE/Los 
Alamos National Laboratory)

In a paper published April 21 in Science, Los Alamos researchers Gang Wu, Christina Johnston, and Piotr Zelenay, joined by researcher Karren More of Oak Ridge National Laboratory, describe the use of a platinum-free catalyst in the cathode of a hydrogen fuel cell. Eliminating platinum -- a precious metal more expensive than gold -- would solve a significant economic challenge that has thwarted widespread use of large-scale hydrogen fuel cell systems.

Polymer-electrolyte hydrogen fuel cells convert hydrogen and oxygen into electricity. The cells can be enlarged and combined in series for high-power applications, including automobiles. Under optimal conditions, the hydrogen fuel cell produces water as a "waste" product and does not emit greenhouse gasses. However, because the use of platinum in catalysts is necessary to facilitate the reactions that produce electricity within a fuel cell, widespread use of fuel cells in common applications has been cost prohibitive. An increase in the demand for platinum-based catalysts could drive up the cost of platinum even higher than its current value of nearly $1,800 an ounce.

The Los Alamos researchers developed non-precious-metal catalysts for the part of the fuel cell that reacts with oxygen. The catalysts -- which use carbon (partially derived from polyaniline in a high-temperature process), and inexpensive iron and cobalt instead of platinum -- yielded high power output, good efficiency, and promising longevity. The researchers found that fuel cells containing the carbon-iron-cobalt catalyst synthesized by Wu not only generated currents comparable to the output of precious-metal-catalyst fuel cells, but held up favorably when cycled on and off -- a condition that can damage inferior catalysts relatively quickly.

Moreover, the carbon-iron-cobalt catalyst fuel cells effectively completed the conversion of hydrogen and oxygen into water, rather than producing large amounts of undesirable hydrogen peroxide. Inefficient conversion of the fuels, which generates hydrogen peroxide, can reduce power output by up to 50 percent, and also has the potential to destroy fuel cell membranes. Fortunately, the carbon- iron-cobalt catalysts synthesized at Los Alamos create extremely small amounts of hydrogen peroxide, even when compared with state-of-the-art platinum-based oxygen-reduction catalysts.

Because of the successful performance of the new catalyst, the Los Alamos researchers have filed a patent for it.

"The encouraging point is that we have found a catalyst with a good durability and life cycle relative to platinum-based catalysts," said Zelenay, corresponding author for the paper. "For all intents and purposes, this is a zero-cost catalyst in comparison to platinum, so it directly addresses one of the main barriers to hydrogen fuel cells."

The next step in the team's research will be to better understand the mechanism underlying the carbon-iron-cobalt catalyst. Micrographic images of portions of the catalyst by researcher More have provided some insight into how it functions, but further work must be done to confirm theories by the research team. Such an understanding could lead to improvements in non-precious-metal catalysts, further increasing their efficiency and lifespan.

Project funding for the Los Alamos research came from the U.S. Department of Energy's Energy Efficiency and Renewable Energy (EERE) Office as well as from Los Alamos National Laboratory's Laboratory-Directed Research and Development program. Microscopy research was done at Oak Ridge National Laboratory's SHaRE user facility with support from the DOE's Office of Basic Energy Sciences.

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Optical Microscope Without Lenses Produces High-Resolution 3-D Images on a Chip

Optical Microscope Without Lenses Produces High-Resolution 3-D Images on a Chip

  8:43:00 AM    Science Lover

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UCLA researchers have redefined the concept of a microscope by removing the lens to create a system that is small enough to fit in the palm of a hand but powerful enough to create three-dimensional tomographic images of miniscule samples.

Lens-free tomographic imaging: Schematic diagram 
of the lens-free tomography setup showing the angles of 
rotation for the light source to illuminate a sample. 
(Credit: Image courtesy of UCLA)

The advance, featured in the early online edition of the journal Proceedings of the National Academy of Sciences, represents the first demonstration of lens-free optical tomographic imaging on a chip, a technique capable of producing high-resolution 3-D images of large volumes of microscopic objects.

"This research clearly shows the potential of lens-free computational microscopy," said Aydogan Ozcan, senior author of the research and an associate professor of electrical engineering at UCLA's Henry Samueli School of Engineering and Applied Science. "Wonderful progress has been made in recent years to miniaturize life-sciences tools with microfluidic and lab-on-a-chip technologies, but until now optical microscopy has not kept pace with the miniaturization trend."

An optical imaging system small enough to fit onto an opto-electronic chip provides a variety of benefits. Because of the automation involved in on-chip systems, scientific work could be sped up significantly, which might have a great impact in the fields of cell and developmental biology. In addition, the small size not only has great potential for miniaturizing systems but also leads to cost savings on equipment.

The optical microscope, invented more than 400 years ago, has tended to grow larger and more complex as it has been modified to image ever-smaller objects with better resolution. To address this lack of progress in miniaturization, Ozcan's research group -- with graduate student Serhan Isikman and postdoctoral scholar Waheb Bishara as lead researchers -- developed the new tomographic microscopy platform through the next evolution of a lens-free imaging technology the group created and has been improving for years.

Ozcan, a researcher at the California NanoSystems Institute at UCLA, makes the analogy that a traditional optical microscope is like a huge set of pipes delivering content, in the form of images, to the user. Over years of development, bottlenecks occur that impede further improvement. Even if one part of the system -- that is, one bottleneck -- is improved, other bottlenecks keep that improvement from being fully realized. Not so with the lens-free system, according to Ozcan.

"Lens-free imaging removes the pipes altogether by utilizing an entirely new design," he said.

The system takes advantage of the fact that organic structures, such as cells, are partially transparent. So by shining a light on a sample of cells, the shadows created reveal not only the cells' outlines but details about their sub-cellular structures as well.

"These details can be captured and analyzed if the shadow is directed onto a digital sensor array," Isikman said. "The end result of this process is an image taken without using a lens."

Ozcan envisions this lens-free imaging system as one component in a lab-on-a-chip platform. It could potentially fit beneath a microfluidic chip, a tool for the precise control and manipulation of sub-millimeter biological samples and fluids, and the two tools would operate in tandem, with the microfluidic chip depositing and subsequently removing a sample from the lens-free imager in an automated, or high-throughput, process.

The platform's 3-D images are created by rotating the light source to illuminate the samples from multiple angles. These multiple angles also allow the system to utilize tomography, a powerful imaging technique. Through the use of tomography, the system is able to produce 3-D images without sacrificing resolution.

"The field of view of lens-based microscopes is limited because the lens focuses on a narrow area of a sample," Bishara said. "A lens-free microscope has both a much larger field of view and depth of field because the imaging is done by the digital sensor array and is not constrained by a lens."

The research was funded by grants from the National Science Foundation, the U.S. Office of Naval Research and the National Institutes of Health and was also supported by the Gates Foundation and the Vodafone Americas Foundation.

For more information on the Ozcan research group, visit http://innovate.ee.ucla.edu/.

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Development in Fog Harvesting Process May Make Water Available to the World’s Poor

Development in Fog Harvesting Process May Make Water Available to the World’s Poor

  11:20:00 PM    Science Lover

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In the arid Namib Desert on the west coast of Africa, one type of beetle has found a distinctive way of surviving. When the morning fog rolls in, the Stenocara gracilipes species, also known as the Namib Beetle, collects water droplets on its bumpy back, then lets the moisture roll down into its mouth, allowing it to drink in an area devoid of flowing water.

Mesh being tested for use on fog-harvesting devices 
by Shreerang Chhatre and colleagues at MIT. 
(Credit: Patrick Gillooly)

What nature has developed, Shreerang Chhatre wants to refine, to help the world's poor. Chhatre is an engineer and aspiring entrepreneur at MIT who works on fog harvesting, the deployment of devices that, like the beetle, attract water droplets and corral the runoff. This way, poor villagers could collect clean water near their homes, instead of spending hours carrying water from distant wells or streams. In pursuing the technical and financial sides of his project, Chhatre is simultaneously a doctoral candidate in chemical engineering at MIT; an MBA student at the MIT Sloan School of Management; and a fellow at MIT's Legatum Center for Development and Entrepreneurship.

Access to water is a pressing global issue: the World Health Organization and UNICEF estimate that nearly 900 million people worldwide live without safe drinking water. The burden of finding and transporting that water falls heavily on women and children. "As a middle-class person, I think it's terrible that the poor have to spend hours a day walking just to obtain a basic necessity," Chhatre says.

A fog-harvesting device consists of a fence-like mesh panel, which attracts droplets, connected to receptacles into which water drips. Chhatre has co-authored published papers on the materials used in these devices, and believes he has improved their efficacy. "The technical component of my research is done," Chhatre says. He is pursuing his work at MIT Sloan and the Legatum Center in order to develop a workable business plan for implementing fog-harvesting devices.

Interest in fog harvesting dates to the 1990s, and increased when new research on Stenocara gracilipes made a splash in 2001. A few technologists saw potential in the concept for people. One Canadian charitable organization, FogQuest, has tested projects in Chile and Guatemala.

Chhatre's training as a chemical engineer has focused on the wettability of materials, their tendency to either absorb or repel liquids (think of a duck's feathers, which repel water). A number of MIT faculty have made advances in this area, including Robert Cohen of the Department of Chemical Engineering; Gareth McKinley of the Department of Mechanical Engineering; and Michael Rubner of the Department of Materials Science and Engineering. Chhatre, who also received his master's degree in chemical engineering from MIT in 2009, is co-author, with Cohen and McKinley among other researchers, of three published papers on the kinds of fabrics and coatings that affect wettability.

One basic principle of a good fog-harvesting device is that it must have a combination of surfaces that attract and repel water. For instance, the shell of Stenocara gracilipes has bumps that attract water and troughs that repel it; this way, drops collects on the bumps, then run off through the troughs without being absorbed, so that the water reaches the beetle's mouth.

To build fog-harvesting devices that work on a human scale, Chhatre says, "The idea is to use the design principles we developed and extend them to this problem."

To build larger fog harvesters, researchers generally use mesh, rather than a solid surface like a beetle's shell, because a completely impermeable object creates wind currents that will drag water droplets away from it. In this sense, the beetle's physiology is an inspiration for human fog harvesting, not a template. "We tried to replicate what the beetle has, but found this kind of open permeable surface is better," Chhatre says. "The beetle only needs to drink a few micro-liters of water. We want to capture as large a quantity as possible."

In some field tests, fog harvesters have captured one liter of water (roughly a quart) per one square meter of mesh, per day. Chhatre and his colleagues are conducting laboratory tests to improve the water collection ability of existing meshes.

FogQuest workers say there is more to fog harvesting than technology, however. "You have to get the local community to participate from the beginning," says Melissa Rosato, who served as project manager for a FogQuest program that has installed 36 mesh nets in the mountaintop village of Tojquia, Guatemala, and supplies water for 150 people. "They're the ones who are going to be managing and maintaining the equipment." Because women usually collect water for households, Rosato adds, "If women are not involved, chances of a long-term sustainable project are slim."

Whatever Chhatre's success in the laboratory, he agrees it will not be easy to turn fog-harvesting technology into a viable enterprise. "My consumer has little monetary power," he notes. As part of his Legatum fellowship and Sloan studies, Chhatre is analyzing which groups might use his potential product. Chhatre believes the technology could also work on the rural west coast of India, north of Mumbai, where he grew up.

Another possibility is that environmentally aware communities, schools or businesses in developed countries might try fog harvesting to reduce the amount of energy needed to obtain water. "As the number of people and businesses in the world increases and rainfall stays the same, more people will be looking for alternatives," says Robert Schemenauer, the executive director of FogQuest.

Indeed, the importance of water-supply issues globally is one reason Chhatre was selected for his Legatum fellowship.

"We welcomed Shreerang as a Legatum fellow because it is an important problem to solve," notes Iqbal Z. Quadir, director of the Legatum Center. "About one-third of the planet's water that is not saline happens to be in the air. Collecting water from thin air solves several problems, including transportation. If people do not spend time fetching water, they can be productively employed in other things which gives rise to an ability to pay. Thus, if this technology is sufficiently advanced and a meaningful amount of water can be captured, it could be commercially viable some day."

Quadir also feels that if Chhatre manages to sell a sufficient number of collection devices in the developed world, it could contribute to a reduction in price, making it more viable in poor countries. "The aviation industry in its infancy struggled with balloons, but eventually became a viable global industry," Quadir adds. "Shreerang's project addresses multiple problems at the same time and, after all, the water that fills our rivers and lakes comes from air."

That said, fog harvesting remains in its infancy, technologically and commercially, as Chhatre readily recognizes. "This is still a very open problem," he says. "It's a work in progress."

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Functioning Synapse Created Using Carbon Nanotubes: Devices Might Be Used in Brain Prostheses or Synthetic Brains

Functioning Synapse Created Using Carbon Nanotubes: Devices Might Be Used in Brain Prostheses or Synthetic Brains

  1:38:00 AM    Science Lover

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Engineering researchers the University of Southern California have made a significant breakthrough in the use of nanotechnologies for the construction of a synthetic brain. They have built a carbon nanotube synapse circuit whose behavior in tests reproduces the function of a neuron, the building block of the brain.

This image shows nanotubes used in synthetic 
synapse and apparatus used to create them. 
(Credit: USC Viterbi School of Engineering)

The team, which was led by Professor Alice Parker and Professor Chongwu Zhou in the USC Viterbi School of Engineering Ming Hsieh Department of Electrical Engineering, used an interdisciplinary approach combining circuit design with nanotechnology to address the complex problem of capturing brain function.

In a paper published in the proceedings of the IEEE/NIH 2011 Life Science Systems and Applications Workshop in April 2011, the Viterbi team detailed how they were able to use carbon nanotubes to create a synapse.

Carbon nanotubes are molecular carbon structures that are extremely small, with a diameter a million times smaller than a pencil point. These nanotubes can be used in electronic circuits, acting as metallic conductors or semiconductors.

"This is a necessary first step in the process," said Parker, who began the looking at the possibility of developing a synthetic brain in 2006. "We wanted to answer the question: Can you build a circuit that would act like a neuron? The next step is even more complex. How can we build structures out of these circuits that mimic the function of the brain, which has 100 billion neurons and 10,000 synapses per neuron?"

Parker emphasized that the actual development of a synthetic brain, or even a functional brain area is decades away, and she said the next hurdle for the research centers on reproducing brain plasticity in the circuits.

The human brain continually produces new neurons, makes new connections and adapts throughout life, and creating this process through analog circuits will be a monumental task, according to Parker.

She believes the ongoing research of understanding the process of human intelligence could have long-term implications for everything from developing prosthetic nanotechnology that would heal traumatic brain injuries to developing intelligent, safe cars that would protect drivers in bold new ways.

For Jonathan Joshi, a USC Viterbi Ph.D. student who is a co-author of the paper, the interdisciplinary approach to the problem was key to the initial progress. Joshi said that working with Zhou and his group of nanotechnology researchers provided the ideal dynamic of circuit technology and nanotechnology.

"The interdisciplinary approach is the only approach that will lead to a solution. We need more than one type of engineer working on this solution," said Joshi. "We should constantly be in search of new technologies to solve this problem."

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Material That If Scratched, You Can Quickly and Easily Fix Yourself, With Light Not Heat

Material That If Scratched, You Can Quickly and Easily Fix Yourself, With Light Not Heat

  11:44:00 AM    Science Lover

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Imagine you're driving your own new car--or a rental car--and you need to park in a commercial garage. Maybe you're going to work, visiting a mall or attending an event at a sports stadium, and you're in a rush. Limited and small available spots and concrete pillars make parking a challenge. And it happens that day: you slightly misjudge a corner and you can hear the squeal as you scratch the side of your car--small scratches, but large anticipated repair costs.

Schematic of optically healing polymers. The specially 
designed polymer molecules that make up the solid 
item can be disassembled by the UV light so that they 
flow and fill in the cracks. When the light is turned off, 
the molecules reassemble themselves and the filled 
cracks become rigid again. (Credit: Zina Deretsky, 
National Science Foundation, after Burnworth et al., 
Nature, April 21, 2011)

Now imagine that that you can repair these unsightly scratches yourself--quickly, easily and inexpensively. . . . or that you can go through a car wash that can detect these and other more minor scratches and fix them as the car goes through the washing garage. Fantasy? Not exactly. Not anymore. Not according to a new discovery detailed in the April 21 issue of the journal Nature, and depicted in a short video interview and simulation: http://www.youtube.com/watch?v=h-fka0wfY8w

A team of researchers in the United States and Switzerland have developed a polymer-based material that can heal itself with the help of a widely used type of lighting. Called "metallo-supramolecular polymers," the material is capable of becoming a supple liquid that fills crevasses and gaps left by scrapes and scuffs when placed under ultraviolet light for less than a minute and then resolidifying.

"This is ingenious and transformative materials research," said Andrew Lovinger, polymers program director in NSF's Division of Materials Research. "It demonstrates the versatility and power of novel polymeric materials to address technological issues and serve society while creating broadly applicable scientific concepts."

The team involves researchers at Case Western Reserve University in Cleveland, Ohio, led by Stuart J. Rowan; the Adolphe Merkle Institute of the University of Fribourg in Switzerland, led by Christoph Weder; and the Army Research Laboratory at Aberdeen Proving Ground in Maryland, led by Rick Beyer.

The scientists envision widespread uses in the not-so-distant future for re-healable materials like theirs, primarily as coatings for consumer goods such as automobiles, floors and furniture. While their polymers are not yet ready for commercial use, they acknowledge, they now have proved that the concept works. And with that, what happens next is up to the market place. Necessity, the mother of invention, will expand the possibilities for commercial applications.

"These polymers have a Napoleon Complex," explains lead author Stuart Rowan, a professor of macromolecular engineering and science and director of the Institute for Advanced Materials at Case Western Reserve University. "In reality they're pretty small but are designed to behave like they're big by taking advantage of specific weak molecular interactions."

"Our study is really a fundamental research study," said Christoph Weder, a professor of polymer chemistry and materials and the director of the Adolphe Merkle Institute. "We tried to create materials that have a unique property matrix, that have unique functionality and that in principle could be very useful."

Specifically, the new materials were created by a mechanism known as supramolecular assembly. Unlike conventional polymers, which consist of long, chain-like molecules with thousands of atoms, these materials are composed of smaller molecules, which were assembled into longer, polymer-like chains using metal ions as "molecular glue" to create the metallo-supramolecular polymers.

While these metallo-supramolecular polymers behave in many ways like normal polymers, when irradiated with intense ultraviolet light the assembled structures become temporarily unglued. This transforms the originally solid material into a liquid that flows easily. When the light is switched off, the material re-assembles and solidifies again; its original properties are restored.

Using lamps such as those dentists use to cure fillings, the researchers repaired scratches in their polymers. Wherever they waved the light beam, the scratches filled up and disappeared, much like a cut that heals and leaves no trace on skin. While skin's healing process can be represented by time-lapse photography that spans several days or weeks, self-healing polymers heal in just seconds.

In addition, unlike the human body, durability of the material does not seem to be compromised by repeated injuries. Tests showed the researchers could repeatedly scratch and heal their materials in the same location.

Further, while heat has provided a means to heal materials for a long time, the use of light provides distinct advantages, says Mark Burnworth, a graduate student at Case Western Reserve University. "By using light, we have more control as it allows us to target only the defect and leave the rest of the material untouched."

The researchers systematically investigated several new polymers to find an optimal combination of mechanical properties and healing ability. They found that metal ions that drive the assembly process via weaker chemical interactions serve best as the light-switchable molecular glue.

They also found the materials that assembled in the most orderly microstructures had the best mechanical properties. But, healing efficiency improved as structural order decreased.

"Understanding these relationships is critical for allowing us improve the lifetime of coatings tailored to specific applications, like windows in abrasive environments" Beyer said.

And what's next? According to Rowan, "One of our next steps is to use the concepts we have shown here to design a coating that would be more applicable in an industrial setting."

Film director and art curator Aaron Rose was at least partially right when he said, "In the right light, at the right time, everything is extraordinary." Self-healing polymers certainly are extraordinary.

The research was funded by the Army Research Office of the U.S. Army Research Laboratory, the U.S. National Science Foundation, and the Adolphe Merkle Foundation.

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Microsoft Browser Would Offer Personalization along with Privacy Protection

Microsoft Browser Would Offer Personalization along with Privacy Protection

  10:28:00 AM    Science Lover

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Today, many websites ask users to take a devil's deal: share personal information in exchange for receiving useful personalized services. New research from Microsoft, which will be presented at the IEEE Symposium on Security and Privacy in May, suggests the development of a Web browser and associated protocols that could strengthen the user's hand in this exchange. Called RePriv, the system mines a user's behavior via a Web browser but controls how the resulting information is released to websites that want to offer personalized services, such as a shopping site that automatically knows users' interests.

An experimental system would tighten the
limits on information provided to websites.

Today, many websites ask users to take a devil's deal: share personal information in exchange for receiving useful personalized services. New research from Microsoft, which will be presented at the IEEE Symposium on Security and Privacy in May, suggests the development of a Web browser and associated protocols that could strengthen the user's hand in this exchange. Called RePriv, the system mines a user's behavior via a Web browser but controls how the resulting information is released to websites that want to offer personalized services, such as a shopping site that automatically knows users' interests.

"The browser knows more about the user's behavior than any individual site," says Ben Livshits, a researcher at Microsoft who was involved with the work. He and colleagues realized that the browser could therefore offer a better way to track user behavior, while it also protects the information that is collected, because users won't have to give away as much of their data to every site they visit.

The RePriv browser tracks a user's behavior to identify a list of his or her top interests, as well as the level of attention devoted to each. When the user visits a site that wants to offer personalization, a pop-up window will describe the type of information the site is asking for and give the user the option of allowing the exchange or not. Whatever the user decides, the site doesn't get specific information about what the user has been doing—instead, it sees the interest information RePriv has collected.

Livshits explains that a news site could use RePriv to personalize a user's view of the front page. The researchers built a demonstration based on the New York Times website. It reorders the home page to reflect the user's top interests, also taking into account data collected from social sites such as Digg that suggests which stories are most popular within different categories.

Livshits admits that RePriv still gives sites some data about users. But he maintains that the user remains aware and in control. He adds that cookies and other existing tracking techniques sites already collect far more user data than RePriv supplies.

The researchers also developed a way for third parties to extend RePriv's capabilities. They built a demonstration browser extension that tracks a user's interactions with Netflix to collect more detailed data about that person's movie preferences. The extension could be used by a site such as Fandango to personalize the movie information it presents—again, with user permission.

"There is a clear tension between privacy and personalized technologies, including recommendations and targeted ads," says Elie Bursztein, a researcher at the Stanford Security Laboratory, who is developing an extension for the Chrome Web browser that enables more private browsing. "Putting the user in control by moving personalization into the browser offers a new way forward," he says.

"In the medium term, RePriv could provide an attractive interface for service providers that will dissuade them from taking more abusive approaches to customization," says Ari Juels, chief scientist and director of RSA Laboratories, a corporate research center.

Juels says RePriv is generally well engineered and well thought out, but he worries that the tool goes against "the general migration of data and functionality to the cloud." Many services, such as Facebook, now store information in the cloud, and RePriv wouldn't be able to get at data there—an omission that could hobble the system, he points out.

Juels is also concerned that most people would be permissive about the information they allow RePriv to release, and he believes many sites would exploit this. And he points out that websites with a substantial competitive advantage in the huge consumer-preference databases they maintain would likely resist such technology. "RePriv levels the playing field," he says. "This may be good for privacy, but it will leave service providers hungry." Therefore, he thinks, big players will be reluctant to cooperate with a system like this.

Livshits argues that some companies could use these characteristics of RePriv to their advantage. He says the system could appeal to new services, which struggle to give users a personalized experience the first time they visit a site. And larger sites might welcome the opportunity to get user data from across a person's browsing experience, rather than only from when the user visits their site. Livshits believes they might be willing to use the system and protect user privacy in exchange.

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