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quinta-feira, 6 de novembro de 2014

Google Glass may partially obstruct peripheral vision, study finds

Testing of study participants who wore head-mounted display systems -- Google Glass -- found that the glasses created a partial peripheral vision obstruction, according to a study in the November 5 issue of JAMA.

Interest in wearable head-mounted display systems for general consumers is increasing, with multiple models in production. However, their effect on vision is largely unknown. Peripheral visual field is a main component of vision and essential for daily activities such as driving, pedestrian safety, and sports. Conventional spectacle frames can reduce visual field, sometimes causing absolute blind spots, and head mounted devices have even more pronounced frames, according to background information in the article.

Tsontcho Ianchulev, M.D., M.P.H., of the University of California, San Francisco, and colleagues compared performance on visual field tests with a head-mounted device vs regular eyewear to quantify their effect on visual function. Three healthy individuals with 20/20 best-corrected visual acuity and normal baseline visual fields were tested in April 2014. Participants used a wearable device (Google Glass, Google Inc.), following manufacturer's instructions, for a 60-minute acclimation period. Perimetric visual testing (a measurement of the field of vision) was conducted first with the device, followed by a control frame (regular eyewear) of similar color and temple width.

In addition, to assess how the devices are worn by general consumers, photographs of people wearing the product and facing the camera, obtained from an Internet search, were analyzed. Photographs were assessed for prism position relative to the pupil.

Visual field testing demonstrated significant scotomas (blind spots) in all 3 participants while wearing the device, creating a clinically meaningful visual field obstruction in the upper right quadrant. Defects were induced by the Google Glass frame hardware design only and were not related to a distracting effect of software-related interference.

An analysis of 132 images indicated that many people wear the device near or overlapping their pupillary axis (a line perpendicular to the surface of the cornea, passing through the center of the pupil), which may induce scotomas and interfere with daily function.

The authors note that the study is limited by the small number of participants, who may not be representative of all users, and that a larger sample is needed to identify factors that influence scotoma size and depth.

"Additional studies are needed to understand the effects of these devices on visual function, particularly as their use becomes increasingly common," the authors conclude.

Story Source:

The above story is based on materials provided by The JAMA Network Journals. Note: Materials may be edited for content and length.

Journal Reference:

Tsontcho Ianchulev, Donald S. Minckler, H. Dunbar Hoskins, Mark Packer, Robert Stamper, Ravinder D. Pamnani, Edward Y. Koo. Wearable Technology With Head-Mounted Displays and Visual Function. JAMA, 2014; 312 (17): 1799 DOI: 10.1001/jama.2014.13754

Novel nanofiber-based technology could help prevent HIV/AIDS transmission

Scientists have developed a novel topical microbicide loaded with hyaluronic acid (HA) nanofibers that could potentially prevent transmission of the human immunodeficiency virus (HIV) through the vaginal mucosa. This research is being presented at the 2014 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition, the world's largest pharmaceutical sciences meeting, in San Diego, Nov. 2-6.

HIV is an infectious virus that attacks T lymphocytes, a type of white blood cell that prevents infections and disease. Over time, HIV dramatically depletes the body's T cell population, leaving the body defenseless against opportunistic pathogens. HIV is transmitted through direct contact with blood, semen, pre-seminal fluid, vaginal fluids, rectal fluids, or breast milk from an infected person. According to AIDS.gov, the Center for Disease Control and Prevention estimates that more than 1 million persons aged 13 years and older are living with HIV infection, including 180,900 who are unaware that they have the virus. To date, there is no functional cure for HIV infection/AIDS. Currently available anti-HIV drug delivery methods are formulated as gels and suppositories, but can lack appropriate vaginal retention, are prone to medicine leakage, and may cause uncomfortable wetness.

To address these issues, Bi-Botti Youan, Ph.D and his colleagues from University of Missouri-Kansas City School of Pharmacy developed an anti-HIV drug loaded onto a mucoadhesive hyaluronic acid (HA) nanofiber delivery system. This delivery system is intended to stop HIV transmission through the vaginal mucosa, providing a triggered release upon exposure to semen fluid during sexual intercourse. The researchers used an electrospinning method to prepare the nanofibers loaded with tenofovir, a topical anti-HIV compound. Both semen enzyme-dependent nanofiber degradation and drug release were then measured using chemical and analytical assays. The cytotoxic effects of the nanofibers on human vaginal cells and on the Lactobacilli bacteria (L. crispatus) present in vaginal flora were also assessed.

"The success of vaginal drug delivery systems depends on the length of time that the drug-containing formulation remains at the site of administration (ex. vagina, rectum). The mucoadhesive nanofibers developed in this study could be beneficial by causing much less discomfort and reducing the dosing frequency simultaneously due to their prolonged retention at the target site," said Youan.

The nanofiber-based formulation offers various potential advantages in vaginal drug delivery, including the ability to adapt delivery systems for different medical needs, with no leakage or messiness after their application. Furthermore, this technology could be beneficial in protecting drug molecules against enzymatic and other degradation that can occur in the body. Since human semen is the carrier of HIV virus transmission during male to female intercourse, a semen enzyme-triggered nanofiber delivery system as used in this study has the potential to inactivate or kill the HIV virus prior to exposure and penetration of the vaginal mucosa.

The next stage of Youan's research is to examine the safety and efficacy of the hyaluronic acid-based nanofiber templates. Further in vivo studies will be carried out using animal models to characterize the viral transmission, inhibition, potential biodistribution, pharmacokinetics, vaginal retention time, safety and immunological responses to the nanofibers.

Story Source:

The above story is based on materials provided by American Association of Pharmaceutical Scientists. Note: Materials may be edited for content and length.

High-speed 'label-free' imaging could reveal dangerous plaques

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This image is taken using a new type of medical imaging technology that could diagnose cardiovascular disease by measuring ultrasound signals from molecules exposed to a fast-pulsing laser. The system, called intravascular photoacoustic imaging, takes precise three-dimensional images of plaques lining arteries and identifies deposits that are likely to rupture and cause heart attacks. This cross-sectional view of an artery shows lipids (green) deposited inside the arterial wall. Black and white indicate contrast showing the cross-sectional geometry.

Researchers are close to commercializing a new type of medical imaging technology that could diagnose cardiovascular disease by measuring ultrasound signals from molecules exposed to a fast-pulsing laser.

The system takes precise three-dimensional images of plaques lining arteries and identifies deposits that are likely to rupture and cause heart attacks, said Ji-Xin Cheng (pronounced Jee-Shin), a professor in Purdue University's Weldon School of Biomedical Engineering and Department of Chemistry.

The imaging reveals the presence of carbon-hydrogen bonds making up lipid molecules in arterial plaques that cause heart disease. Research findings are detailed in a paper appearing online in the Nature journal Scientific Reports.

"This allows us to see the exact nature of plaque formation in the walls of arteries so we can define whether plaque is going to rupture," said Michael Sturek, co-author of the paper and a professor and chair of the Department of Cellular & Integrative Physiology at Indiana University School of Medicine. "Some plaques are more dangerous than others, but one needs to know the chemical makeup of the blood vessel wall to determine which ones are at risk of rupturing."

Research in the area has been hindered by the inability to perform high-speed imaging in tissue. The researchers solved the problem by developing a Raman laser using a laser that produces 2,000 pulses per second, each pulse capable of generating an image, representing a 100-fold increase in the imaging speed of the new technology, called intravascular photoacoustic imaging.

"This innovation represents a big step toward advancing this technology to the clinical setting," Cheng said.

The paper was authored by researchers from Purdue, Indiana University School of Medicine, the University of California, Davis, the University of California, Irvine, and startup company Spectral Energy.

The imaging technique is "label free," meaning it does not require samples to be marked with dyes, making it appealing for diagnostic applications.

The technology is being commercialized by the company Vibronix Inc., co-founded by Cheng and Purdue postdoctoral research associate Pu Wang.

The laser, which pulses in the near-infrared range of the spectrum, causes tissue to heat and expand locally, generating pressure waves at the ultrasound frequency that can be picked up with a device called a transducer.

The paper was authored by Wang; USC graduate student Teng Ma; Purdue research scientist Mikhail N. Slipchenko; USC graduate student Shanshan Liang; Purdue graduate student Jie Hui; K. Kirk Shung, director of the Ultrasonic Transducer Resource Center at USC; Sukesh Roy, CEO of Spectral Energy LLC in Dayton, Ohio; Sturek; USC researcher Qifa Zhou; Zhongping Chen, a researcher at UC Irvine; and Cheng.

The system is small enough to be incorporated into an endoscope to put into blood vessels using a catheter, said Cheng.

The near-infrared laser causes enough heating to generate ultrasound but not enough to damage the tissues. The research was conducted with intact pig tissue and will expand to research with live animals and then clinical studies with humans.

Story Source:

The above story is based on materials provided by Purdue University. The original article was written by Emil Venere. Note: Materials may be edited for content and length.

Journal Reference:

Pu Wang, Teng Ma, Mikhail N. Slipchenko, Shanshan Liang, Jie Hui, K. Kirk Shung, Sukesh Roy, Michael Sturek, Qifa Zhou, Zhongping Chen, Ji-Xin Cheng. High-speed Intravascular Photoacoustic Imaging of Lipid-laden Atherosclerotic Plaque Enabled by a 2-kHz Barium Nitrite Raman Laser. Scientific Reports, 2014; 4: 6889 DOI: 10.1038/srep06889

String field theory could be the foundation of quantum mechanics: Connection could be huge boost to string theory

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Artist's abstraction (stock illustration).

Two USC researchers have proposed a link between string field theory and quantum mechanics that could open the door to using string field theory -- or a broader version of it, called M-theory -- as the basis of all physics.

"This could solve the mystery of where quantum mechanics comes from," said Itzhak Bars, USC Dornsife College of Letters, Arts and Sciences professor and lead author of the paper.

Bars collaborated with Dmitry Rychkov, his Ph.D. student at USC. The paper was published online on Oct. 27 by the journal Physics Letters.

Rather than use quantum mechanics to validate string field theory, the researchers worked backwards and used string field theory to try to validate quantum mechanics.

In their paper, which reformulated string field theory in a clearer language, Bars and Rychov showed that a set of fundamental quantum mechanical principles known as "commutation rules'' may be derived from the geometry of strings joining and splitting.

"Our argument can be presented in bare bones in a hugely simplified mathematical structure," Bars said. "The essential ingredient is the assumption that all matter is made up of strings and that the only possible interaction is joining/splitting as specified in their version of string field theory."

Physicists have long sought to unite quantum mechanics and general relativity, and to explain why both work in their respective domains. First proposed in the 1970s, string theory resolved inconsistencies of quantum gravity and suggested that the fundamental unit of matter was a tiny string, not a point, and that the only possible interactions of matter are strings either joining or splitting.

Four decades later, physicists are still trying to hash out the rules of string theory, which seem to demand some interesting starting conditions to work (like extra dimensions, which may explain why quarks and leptons have electric charge, color and "flavor" that distinguish them from one another).

At present, no single set of rules can be used to explain all of the physical interactions that occur in the observable universe.

On large scales, scientists use classical, Newtonian mechanics to describe how gravity holds the moon in its orbit or why the force of a jet engine propels a jet forward. Newtonian mechanics is intuitive and can often be observed with the naked eye.

On incredibly tiny scales, such as 100 million times smaller than an atom, scientists use relativistic quantum field theory to describe the interactions of subatomic particles and the forces that hold quarks and leptons together inside protons, neutrons, nuclei and atoms.

Quantum mechanics is often counterintuitive, allowing for particles to be in two places at once, but has been repeatedly validated from the atom to the quarks. It has become an invaluable and accurate framework for understanding the interactions of matter and energy at small distances.

Quantum mechanics is extremely successful as a model for how things work on small scales, but it contains a big mystery: the unexplained foundational quantum commutation rules that predict uncertainty in the position and momentum of every point in the universe.

"The commutation rules don't have an explanation from a more fundamental perspective, but have been experimentally verified down to the smallest distances probed by the most powerful accelerators. Clearly the rules are correct, but they beg for an explanation of their origins in some physical phenomena that are even deeper," Bars said.

The difficulty lies in the fact that there's no experimental data on the topic -- testing things on such a small scale is currently beyond a scientist's technological ability.

quarta-feira, 5 de novembro de 2014

How a giant impact formed asteroid Vesta's 'belt'

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A massive collision: A high-speed camera recorded a laboratory simulation of colliding heavenly bodies. An analysis of shock propagation suggests what may have caused the tilted canyon-like grooves around the equator of the asteroid Vesta.

Collisions of heavenly bodies generate almost unimaginable levels of energy. Researchers at Brown used NASA's ultra-high-speed cannon and computer models to simulate such a collision on Vesta, the second-largest object in the asteroid belt. Their analysis of the images -- taken at a million frames per second -- shows how Vesta may have gotten the deep grooves that encircle its midsection.

When NASA's Dawn spacecraft visited the asteroid Vesta in 2011, it showed that deep grooves that circle the asteroid's equator like a cosmic belt were probably caused by a massive impact on Vesta's south pole. Now, using a super high-speed cannon at NASA's Ames Research Center, Brown University researchers have shed new light on the violent chain of events deep in Vesta's interior that formed those surface grooves, some of which are wider than the Grand Canyon.

"Vesta got hammered," said Peter Schultz, professor of earth, environmental, and planetary sciences at Brown and the paper's senior author. "The whole interior was reverberating, and what we see on the surface is the manifestation of what happened in the interior."

The research suggests that the Rheasilvia basin on Vesta's south pole was created by an impactor that came in at an angle, rather than straight on. But that glancing blow still did an almost unimaginable amount of damage. The study shows that just seconds after the collision, rocks deep inside the asteroid began to crack and crumble under the stress. Within two minutes major faults reached near the surface, forming deep the canyons seen today near Vesta's equator, far from the impact point.

The research, led by Angela Stickle, a former graduate student at Brown and now a researcher at the Johns Hopkins University Applied Physics Laboratory, will appear in the February issue of the journal Icarus and is now available online.

"As soon as Pete and I saw the images coming down from the Dawn mission at Vesta, we were really excited," Stickle said. "The large fractures looked just like things we saw in our experiments. So we decided to look into them in more detail, and run the models, and we found really interesting relationships."

For the study, the researchers used the Ames Vertical Gun Range, a cannon with a 14-foot barrel used to simulate collisions on celestial bodies. The gun uses gunpowder and compressed hydrogen gas to launch projectiles at blinding speed, up to 16,000 miles per hour. For this latest research, Schultz and his colleagues launched small projectiles at softball-sized spheres made of an acrylic material called PMMA. When struck, the normally clear material turns opaque at points of high stress. By watching the impact with high-speed cameras that take a million shots per second, the researchers can see how these stresses propagate through the material.

The experiments showed that that damage from the impact starts where one would expect: at the impact point. But shortly after, failure patterns begin to form inside the sphere, opposite the point of impact. Those failures grow inward toward the sphere's center and then propagate outward toward the edges of the sphere like a blooming flower.

Using numerical models to scale the lab collision up to the size of Vesta, the second-largest object in the asteroid belt, the researchers showed that the outward-blooming "rosette" of damage extending to the surface is responsible for the troughs that form a belt around Vesta's equator.

The results answer some questions about Vesta's belt that had long been puzzling. Chief among them is the orientation of the belt with respect to the crater. The belt's angle isn't exactly what would be expected if it were caused by the Rheasilvia impact.

"The belt is askew," Schultz said, "as if Vesta were making a fashion statement."

These new experiments suggest that the crooked belt is the result of the angle of impact. An oblique impact causes the damage plane to be tilted with respect the crater. The orientation of Vesta's belt sheds light on the nature of the impact. The researchers conclude that the object that created Rheasilvia came in at an angle less than 40 degrees, traveling at about 11,000 miles per hour.

"Vesta was lucky," Schultz said. "If this collision had been straight on, there would have been one less large asteroid and only a family of fragments left behind."

The research shows that even a glancing blow can have tremendous consequences.

"When big things happen to small bodies," Schultz said, "it shakes them to the core."

Astronomers solve puzzle about bizarre object at center of our galaxy: Enormous black hole drove two binary stars to merge

Telescopes from Hawaii's W.M. Keck Observatory use a powerful technology called adaptive optics, which enabled UCLA astronomers to discover that G2 is a pair of binary stars that merged together, cloaked in gas and dust.

For years, astronomers have been puzzled by a bizarre object in the center of the Milky Way that was believed to be a hydrogen gas cloud headed toward our galaxy's enormous black hole.

Having studied it during its closest approach to the black hole this summer, UCLA astronomers believe that they have solved the riddle of the object widely known as G2.

A team led by Andrea Ghez, professor of physics and astronomy in the UCLA College, determined that G2 is most likely a pair of binary stars that had been orbiting the black hole in tandem and merged together into an extremely large star, cloaked in gas and dust -- its movements choreographed by the black hole's powerful gravitational field. The research is published today in the journal Astrophysical Journal Letters.

Astronomers had figured that if G2 had been a hydrogen cloud, it could have been torn apart by the black hole, and that the resulting celestial fireworks would have dramatically changed the state of the black hole.

"G2 survived and continued happily on its orbit; a simple gas cloud would not have done that," said Ghez, who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics. "G2 was basically unaffected by the black hole. There were no fireworks."

Black holes, which form out of the collapse of matter, have such high density that nothing can escape their gravitational pull -- not even light. They cannot be seen directly, but their influence on nearby stars is visible and provides a signature, said Ghez, a 2008 MacArthur Fellow.

Ghez, who studies thousands of stars in the neighborhood of the supermassive black hole, said G2 appears to be just one of an emerging class of stars near the black hole that are created because the black hole's powerful gravity drives binary stars to merge into one. She also noted that, in our galaxy, massive stars primarily come in pairs. She says the star suffered an abrasion to its outer layer but otherwise will be fine.

Ghez and her colleagues -- who include lead author Gunther Witzel, a UCLA postdoctoral scholar, and Mark Morris and Eric Becklin, both UCLA professors of physics and astronomy -- conducted the research at Hawaii's W.M. Keck Observatory, which houses the world's two largest optical and infrared telescopes.

When two stars near the black hole merge into one, the star expands for more than 1 million years before it settles back down, said Ghez, who directs the UCLA Galactic Center Group. "This may be happening more than we thought. The stars at the center of the galaxy are massive and mostly binaries. It's possible that many of the stars we've been watching and not understanding may be the end product of mergers that are calm now."

Ghez and her colleagues also determined that G2 appears to be in that inflated stage now. The body has fascinated many astronomers in recent years, particularly during the year leading up to its approach to the black hole. "It was one of the most watched events in astronomy in my career," Ghez said.

Ghez said G2 now is undergoing what she calls a "spaghetti-fication" -- a common phenomenon near black holes in which large objects become elongated. At the same time, the gas at G2's surface is being heated by stars around it, creating an enormous cloud of gas and dust that has shrouded most of the massive star.

Witzel said the researchers wouldn't have been able to arrive at their conclusions without the Keck's advanced technology. "It is a result that in its precision was possible only with these incredible tools, the Keck Observatory's 10-meter telescopes," Witzel said.

The telescopes use adaptive optics, a powerful technology pioneered in part by Ghez that corrects the distorting effects of the Earth's atmosphere in real time to more clearly reveal the space around the supermassive black hole. The technique has helped Ghez and her colleagues elucidate many previously unexplained facets of the environments surrounding supermassive black holes.

"We are seeing phenomena about black holes that you can't watch anywhere else in the universe," Ghez added. "We are starting to understand the physics of black holes in a way that has never been possible before."

Lemurs: Gardeners of Madagascar rainforest at risk

A large proportion of trees in Madagascar's rainforest have fruits eaten by lemurs. Lemurs in turn disperse the seeds of their fruit trees throughout the forest with their scat. Such dispersal can play a crucial role for a tree species' ability to regenerate, but effects are poorly understood, especially when there are multiple dispersers.

For the tree, the evolutionary advantage of having animal-dispersed seeds may be that the seeds land well away from their parent trees where survival is low or that seeds are directed into spots where they are the most likely to sprout and survive.

Amy Dunham, an assistant professor of biosciences, and graduate student Onja Razafindratsima set out to detail the symbiotic relationship between fruit-eating lemurs and the trees that feed them through a three-year study in a rainforest in southeastern Madagascar.

Their data from observations, experiments and mathematical models demonstrate that seeds of a common canopy tree have a 300 percent higher chance of sprouting and becoming a sapling when dispersed by lemurs versus simply falling to the ground. One of the three lemur species is particularly good at dropping seeds in spots that are most advantageous for sprouting and survival. Other lemurs are not so selective, but still benefit the tree by moving seeds away from the parent tree. By acting as forest gardeners, these animals give the tree's population a boost.

The study appeared online in the Ecological Society of America journal Ecology.

As part of the study, the researchers followed the seed-dispersal patterns of three of Madagascar's lemur species: the red-fronted brown lemur, the red-bellied lemur and the southern black-and-white ruffed lemur. That meant tracking and observing groups of lemurs as the animals leaped from tree to tree through the forest, dined in the 65-foot-high canopies and dropped their undigested seeds at ground level.

Razafindratsima led the study as part of a thesis project she expects to complete early next year. She built a team of local researchers near Ranomafana National Park, the home of Centre ValBio, a research station founded by Dunham's former Ph.D. adviser, primatologist Patricia Wright.

"We have a team of up to 10 local villagers who are trained to do research," said Razafindratsima, a native of Madagascar. "Their exceptional knowledge of the forest is very important to us when we're trying to track lemurs and identify seeds and seedlings in a forest with over 300 species of trees."

The research team tracked 24 groups of lemurs over a year without the benefit of radio collars, said Razafindratsima, who keeps in touch with her team via phone and Skype when she's at Rice. She said the study sites were as close as a short hike from Centre ValBio and as far as a two-day trek through steep terrain that entailed camping overnight.

In addition to tracking lemurs and their dispersed seeds, the research team spent three years carrying out experiments on seed sprouting and survival. They found that dispersal by lemurs dramatically increased the odds that seeds would take root and survive. In particular, the red-fronted brown lemurs tended to drop seeds away from their parent trees and in places where there were gaps in the canopy. This gave individual seeds the best shot at taking root.

Dunham said trees benefit from the wide dispersal of their seeds, and for some species in Madagascar, lemurs are the primary or only animal that can distribute those seeds. As the largest fruit-eaters in the system, these lemurs swallow seeds that may be too large for other fruit-eating animals, such as birds or bats.

"Seeds away from the parent tree survive better because there's less competition among seedlings," Razafindratsima said. "If they're close by the parent, they may also share the same natural enemies, like soil pathogens and seed predators, so there's higher mortality."

Trees that lose their dispersers will simply drop their seeds to the ground beneath their canopies, where chances of survival are slim, Dunham said. "Lemurs fill an important role as the gardeners for these trees. By ensuring that some seeds land in spots suitable for germination and survival, they increase the ability of these trees to replace themselves"

Dunham hopes the study will contribute to growing efforts to protect lemurs, and therefore the rainforest, which has been impacted in recent years by economic and political instability. She noted grassroots efforts within Madagascar led to the first World Lemur Festival in late October to celebrate and protect the animals and their habitats in Madagascar.

"What got us interested is that frugivorous lemur populations are declining across the island, and we know very little about how these seed dispersers actually affect tree populations," she said. "Once we understand that better, maybe we'll have a better idea of how the community might change if the lemurs disappear.

"If some species suddenly lose their dispersers, but others dispersed by birds or the wind are doing fine, it may change population trajectories and alter which tree species are dominant in a community. To understand what happens when these species are lost, we need to understand their role in the ecosystem," she said.

Putting batteries in a kidsafe coat of armor

A Brigham and Women's Hospital (BWH) led team has developed a simple "coat of armor" to encase small batteries, rendering them harmless if they are ever swallowed. Children, particularly infants and young toddlers, can ingest these batteries, leading to serious damage to their esophagus as well as other gut tissue, and sometimes, death. Such incidents are on the rise, yet up until now, no solutions have been directed at the battery itself. The new work, published online November 3, 2014 in the Proceedings of the National Academy of Sciences, offers a simple, cost-effective fix that if implemented, could dramatically reduce if not eliminate, this unfortunate problem.

"To date, there has been no innovation to address this issue with small batteries," says Jeff Karp, PhD, BWH Division of Biomedical Engineering in the Department of Medicine, Harvard Medical School, Harvard Stem Cell Institute. "To address this challenge we sought to develop something that would render the battery inert, specifically when it was outside of a device."

Each year, roughly 5 billion "button" batteries are produced across the world. These small, disc-shaped batteries power everything from children's toys, hearing aids and laser pointers to remote controls and musical greeting cards. While recent legislation requires battery compartments in children's toys to be secured with screws, many items commonly used by adults contain these batteries in easily accessible formats and their packaging provides no protection. With the proliferation of such gadgets, and the demand for ever-powerful batteries to power them, the problem of accidental ingestion is increasing. In 2013, there were more than 3,000 reported cases of accidental battery ingestion -- the majority in children under age 6.

"Ingested disc batteries require emergent removal from the esophagus," says co-first study author Giovanni Traverso, MB, BCh, PhD, a gastroenterologist at Massachusetts General Hospital and a researcher at MIT. "The swallowing of these batteries is a gastrointestinal emergency given that tissue damage starts as soon as the battery is in contact with the tissue, generating an electric current and leading to a chemical burn."

Karp and his colleagues became aware of this issue in 2010, and decided to apply their collective expertise toward developing a novel solution. "This seemed like a tractable problem that we could make significant headway on in a short period of time, just based on our expertise in materials and devices," says Karp.

Karp, together with first author Bryan Laulicht, PhD, a postdoctoral fellow in Karp's lab, noticed that when a battery sits within a device, there is gentle pressure applied to it, yet when it is outside the device, such force does not exist.

"We set out to create a specialized coating that could switch from an insulator to a conductor when subjected to pressure," said Co-author Robert Langer, Institute Professor from the Harvard-MIT Division of Health Sciences and Technology.

The scientists discovered this unique substance in an unlikely place -- touch screens. Using an off-the-shelf material known as a quantum tunneling composite, they identified a nanoparticle-based coating that, when subjected to pressure, allows an electrical current to pass through. In contrast, it allows no current to run in the absence of such pressure.

They used this material to coat one side of the batteries -- covering the "minus" ends or the anodes. To determine the coating's effectiveness, they teamed up with Traverso, exposing coated and uncoated batteries to gut tissue both in a laboratory dish and in living animals. In all cases, the coated batteries caused no damage while the uncoated batteries, as expected, caused significant damage.

In addition to reducing injuries, this innovation is also likely to be quite cost-effective. "The ultimate cost will depend on the exact composition of the material that is used, but for our current formulation, we're talking cents, not dollars," says Laulicht, first author of the paper.

Now, Karp and his colleagues are working to determine the best route toward manufacturing and scaling up to a sufficiently large number of batteries, and then working with battery manufacturers to get the coated batteries into the hands of consumers.

Story Source:

The above story is based on materials provided by Brigham and Women's Hospital. Note: Materials may be edited for content and length.

Journal Reference:

Bryan Laulicht, Giovanni Traverso, Vikram Deshpande, Robert Langer, and Jeffrey M. Karp. Simple battery armor to protect against gastrointestinal injury from accidental ingestion. PNAS, 2014 DOI: 10.1073/pnas.1418423111

Chemists gain edge in next-gen energy: Flexible film can catalyze production of hydrogen

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A thin, flexible film developed at Rice University shows excellent potential as a hydrogen catalyst or as an energy storage device. The two-dimensional film could be a cost-effective component in such applications as fuel cells.

Rice University scientists who want to gain an edge in energy production and storage report they have found it in molybdenum disulfide.

The Rice lab of chemist James Tour has turned molybdenum disulfide's two-dimensional form into a nanoporous film that can catalyze the production of hydrogen or be used for energy storage.

The versatile chemical compound classified as a dichalcogenide is inert along its flat sides, but previous studies determined the material's edges are highly efficient catalysts for hydrogen evolution reaction (HER), a process used in fuel cells to pull hydrogen from water.

Tour and his colleagues have found a cost-effective way to create flexible films of the material that maximize the amount of exposed edge and have potential for a variety of energy-oriented applications.

The Rice research appears in the journal Advanced Materials.

Molybdenum disulfide isn't quite as flat as graphene, the atom-thick form of pure carbon, because it contains both molybdenum and sulfur atoms. When viewed from above, it looks like graphene, with rows of ordered hexagons. But seen from the side, three distinct layers are revealed, with sulfur atoms in their own planes above and below the molybdenum.

This crystal structure creates a more robust edge, and the more edge, the better for catalytic reactions or storage, Tour said.

"So much of chemistry occurs at the edges of materials," he said. "A two-dimensional material is like a sheet of paper: a large plain with very little edge. But our material is highly porous. What we see in the images are short, 5- to 6-nanometer planes and a lot of edge, as though the material had bore holes drilled all the way through."

The new film was created by Tour and lead authors Yang Yang, a postdoctoral researcher; Huilong Fei, a graduate student; and their colleagues. It catalyzes the separation of hydrogen from water when exposed to a current. "Its performance as a HER generator is as good as any molybdenum disulfide structure that has ever been seen, and it's really easy to make," Tour said.

While other researchers have proposed arrays of molybdenum disulfide sheets standing on edge, the Rice group took a different approach. First, they grew a porous molybdenum oxide film onto a molybdenum substrate through room-temperature anodization, an electrochemical process with many uses but traditionally employed to thicken natural oxide layers on metals.

The film was then exposed to sulfur vapor at 300 degrees Celsius (572 degrees Fahrenheit) for one hour. This converted the material to molybdenum disulfide without damage to its nano-porous sponge-like structure, they reported.

The films can also serve as supercapacitors, which store energy quickly as static charge and release it in a burst. Though they don't store as much energy as an electrochemical battery, they have long lifespans and are in wide use because they can deliver far more power than a battery. The Rice lab built supercapacitors with the films; in tests, they retained 90 percent of their capacity after 10,000 charge-discharge cycles and 83 percent after 20,000 cycles.

"We see anodization as a route to materials for multiple platforms in the next generation of alternative energy devices," Tour said. "These could be fuel cells, supercapacitors and batteries. And we've demonstrated two of those three are possible with this new material."

Co-authors of the paper are Rice graduate students Gedeng Ruan and Changsheng Xiang. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of materials science and nanoengineering and of computer science.

The Peter M. and Ruth L. Nicholas Postdoctoral Fellowship of Rice's Smalley Institute for Nanoscale Science and Technology and the Air Force Office of Scientific Research Multidisciplinary University Research program supported the research.

A future of power outages; what happens when the lights go out?

November 3, 2014

Taylor & Francis

It is impossible to imagine the modern world without electricity. We are dependent on an uninterrupted source of power and when it fails the consequences are devastating. Over the past decade there have been 50 significant power-outage events occurring in 26 countries, and the demand for electricity continues to grow stronger with rapid population growth, compact urban areas and an 'addiction' to electric appliances. In their article "Exergy and the City: The Technology and Sociology of Power (Failure)," Hugh Byrd and Steve Matthewman predict that these blackouts are only a dress rehearsal for a future in which they will appear more frequently and with greater severity.

The authors highlight the frail electrical power system of the 'privileged' West where it is taken for granted that there will be a continued stable supply of electricity for the distant future. Electrical power generation and distribution is more vulnerable than we might assume due to poor investment in infrastructure and many power grids operating close to capacity. Over the past 30 years, the demand for electricity has increased by 25%, while the construction of transmission faculties has fallen. It is argued that it will take large investments in electric utilities to meet future demand.

With our electrical infrastructures under threat, our dependence on electricity and our vulnerability when a blackout occurs are exposed; the economic damage of power outages and quality disturbances are estimated to cost the American economy between $25 and $180 billion per annum, although the indirect costs could be up to five times higher. Blackouts affect the economy and our everyday lives in a number of ways. Without electricity, food provisions are compromised as a lack of refrigeration means food cannot be stored safely, leading to increased risk of food poisoning; security systems fail and the crime rate increases, as it amplifies the opportunity for fraud, theft and exploitation. A lack of power also causes an immediate and prevalent problem for transport systems; traffic lights fail, rail systems come to a stop and air transport becomes compromised due to the loss of communications and unlit runways.

Despite a frail electrical infrastructure and the consequences of blackouts, our dependency on electricity continues to intensify, fuelled in part by consumer 'addictions' to electronic devices, air conditioning and, in the future electric vehicles. Electricity demands will become even greater as our resources become constrained due to the depletion of fossil fuel, a lack of renewable energy sources, peak oil and climate change. As we become more dependent on an uninterrupted supply of electricity for our comfort, security, communication systems, transport, health and food supply…what will happen when the lights go out?

Story Source:

The above story is based on materials provided by Taylor & Francis. Note: Materials may be edited for content and length.

Journal Reference:

Hugh Byrd, Steve Matthewman. Exergy and the City: The Technology and Sociology of Power (Failure). Journal of Urban Technology, 2014; 21 (3): 85 DOI: 10.1080/10630732.2014.940706