Saturday, 29 June 2013

Google tests balloons to beam internet from near space

Google tests balloons to beam internet from near space

Google is launching balloons into near space to provide internet access to buildings below on the ground.
About 30 of the superpressure balloons are being launched from New Zealand from where they will drift around the world on a controlled path.
Attached equipment will offer 3G-like speeds to 50 testers in the country.
Access will be intermittent, but in time the firm hopes to build a big enough fleet to offer reliable links to people living in remote areas.
It says that balloons could one day be diverted to disaster-hit areas to aid rescue efforts in situations where ground communication equipment has been damaged.
But one expert warns that trying to simultaneously navigate thousands of the high-altitude balloons around the globe's wind patterns will prove a difficult task to get right.
Airborne for months
Google calls the effort Project Loon and acknowledges it is "highly experimental" at this stage.


Each balloon is 15m (49.2ft) in diameter - the length of a small plane - and filled with lifting gases. Electronic equipment hangs underneath including radio antennas, a flight computer, an altitude control system and solar panels to power the gear.
Google aims to fly the balloons in the stratosphere, 20km (12 miles) or more above the ground, which is about double the altitude used by commercial aircraft and above controlled airspace.
Google says each should stay aloft for about 100 days and provide connectivity to an area stretching 40km in diameter below as they travel in a west-to-east direction.
The firm says the concept could offer a way to connect the two-thirds of the world's population which does not have affordable net connections.
"It's pretty hard to get the internet to lots of parts of the world," Richard DeVaul, chief technical architect at Google[x] - the division behind the scheme - told the BBC.
"Just because in principle you could take a satellite phone to sub-Saharan Africa and get a connection there, it doesn't mean the people have a cost-effective way of getting online.


"The idea behind Loon was that it might be easier to tie the world together by using what it has in common - the skies - than the process of laying fibre and trying to put up cellphone infrastructure."
'Low risk'
Project Loon antenna
Special antennas have been fitted to the homes of test volunteers in New Zealand
Previous proposals to provide connectivity from the upper atmosphere suggested floating high-altitude platforms that stayed in one place and were tethered to the ground.
Google rejected this idea as it involved fighting the winds, meaning the equipment would have to be large, expensive and limited to a fixed area.
But using free-floating balloons introduces another problem: how to ensure they are where they are supposed to be.
"We didn't want them to go just wherever the winds took them, we wanted them to go where the internet is needed on the ground," said Mr DeVaul.
"You have to cause them to move up or down just a little bit through the stratosphere to catch the appropriate wind - which is how we steer them.
"So we have to choreograph a whole ballet of this fleet, and that requires some impressive computing science and a whole lot of computing power."


The balloons will communicate with Google's "mission control" where computer servers will carry out the calculations needed to keep them on track, monitored by a small number of engineers.
The software makes adjustments to each balloon's altitude to take advantage of forecast wind conditions, and nudges the balloons up or down to find a more favourable stream when the predictions are not accurate.
Project Loon balloon

Since the equipment is dependent on solar power, the algorithms must also ensure there is enough charge left in the batteries to allow them to carry on working as they travel through the night.
At the end of their working life, the software initiates a controlled descent so that the kit can be recovered by teams of locally-based employees.
"They have aviation transponders on them and we're in constant contact with civil aviation authorities while the balloons are going up and coming down," Mr DeVaul added.
"They have flashing lights and radar reflectors, so as far as aviation hazards go these Loon balloons present very low risk to aircraft.
"And they also pose low risk to anybody on the ground because even in the unlikely scenario that one suddenly and unexpectedly fails, they have parachutes that are automatically deployed."
Project Loon graphicGoogle says the balloons should not pose a threat to commercial aircraft
A group of about 50 testers based in Christchurch and Canterbury, New Zealand, have had special antennas fitted to their properties to receive the balloons' signals.
Google now plans to partner with other organisations to fit similar equipment to other buildings in countries on a similar latitude, so that people in Argentina, Chile, South Africa and Australia can also take part in the trial.
Tough challenge
The search firm is not the first to pursue such an idea. An Arizona-based firm, Space Data, already provides blimp-based radio repeaters to the US Air Force to allow it to extend communications coverage.


Another Orlando-based firm, World Surveillance Group, sells similar equipment to the US Army and other government agencies.
However, they typically remain airborne for up to a few days at a time rather than for months, and are not as wide-ranging. One expert cautioned that Google might find it harder to control its fleet than it hoped.
"The practicalities of controlling lighter-than-air machines are well known because of the vagaries of the weather," said Prof Alan Woodward, visiting professor at the University of Surrey's department of computing.
Project Loon balloon
Project Loon balloons are made of plastic just 3mm (0.1in) thick
"It's going to take a lot of effort to make these things wander in an autonomous way and I think it may take them a little longer to get right than they might believe."

What are superpressure balloons?

Superpressure balloons are made out of tightly sealed plastic capable of containing highly pressurised lighter-than-air gases.
The aim is to keep the volume of the balloon relatively stable even if there are changes in temperature.
This allows them to stay aloft longer and be better at maintaining a specific altitude than balloons which stretch and contract.
In particular it avoids the problem of balloons descending at night when their gases cool.
The concept was first developed for the US Air Force in the 1950s using a stretched polyester film called Mylar.
The effort resulted in the Ghost (global horizontal sounding technique) programme which launched superpressure balloons from Christchurch, New Zealand to gather wind and temperature data over remote regions of the planet.
Over the following decade 88 balloons were launched, the longest staying aloft for 744 days.
More recently, Nasa has experimented with the technology and suggested superpressure balloons could one day be deployed into Mars's atmosphere.
source:http://www.bbc.co.uk

Can silver promote the colonization of bacteria on medical devices?

Can silver promote the colonization of bacteria on medical devices?

Biomaterials are increasingly being used to replace human organs and tissues. Since biomaterials are susceptible to microbial colonization, silver is often added to reduce the adhesion of bacteria to biomaterials and prevent infections. However, a recent study by researchers in Portugal suggests that – in one material – increasing levels of silver may indirectly promote bacterial adhesion.
Published in the journal Science and Technology of Advanced Materials, the study examined how surface properties affect the adhesion of Staphylococcus epidermidis bacteria to silver-titanium carbonitride (Ag-TiCN) coatings used for hip implant applications.
Can silver promote the colonization of bacteria on medical devices?
SEM micrographs of S. epidermidis IE186 adhered to Ag-TiCN coatings after 2 h and 24 h period of contact: adhesion and biofilm formation to Ag/Ti = 0 a1) and a2) respectively; to Ag/Ti = 0.37 b1) and b2) respectively; to Ag/Ti = 0.62 c1) and c2) respectively. (C) I. Carvalho et al. Sci.

Normally found on human skin and mucous membranes, Staphyloccus epidermidis is one of the main pathogens associated with prosthetic device infections. A nanocomposite thin film, titanium carbonitride is non-toxic to  and features excellent wear resistance, high hardness and good corrosion resistance.
Previous studies have shown that the adhesion of bacteria to biomaterials can be affected by the surface properties of bacteria, the surface properties of the material, and environmental conditions. In this study, Isabel Carvalho and her colleagues found that as the silver content of Ag-TiCN films increased from 0 to 15 percent, the surface roughness of the films decreased from 39 nm to 7 nm, while the hydrophobicity of the surface increased.
In addition, the study found that surfaces that were less rough and more hydrophobic were associated with greater . This suggests that increasing levels of silver in Ag-TiCN thin films may promote bacterial adhesion via a hydrophobic effect


Read more at: http://phys.org/news

Tiny Nanocubes Help Scientists Tell Left from Right

Tiny Nanocubes Help Scientists Tell Left from Right

June 28, 2013 — In chemical reactions, left and right can make a big difference. A "left-handed" molecule of a particular chemical composition could be an effective drug, while its mirror-image "right-handed" counterpart could be completely inactive. That's because, in biology, "left" and "right" molecular designs are crucial: Living organisms are made only from left-handed amino acids. So telling the two apart is important-but difficult.
Electron microscopy "maps" of octahedral gold nanoparticles surrounded by cubic silver shells. Attaching a biomolecule (e.g., DNA) to these nanoparticles strengthens a signal representing a difference between left- and right-handed molecules' response to light by 100 times, and pushes it toward the visible range of the electromagnetic spectrum. (Credit: Image courtesy of Brookhaven National Laboratory)
Now, a team of scientists at the U.S. Department of Energy's Brookhaven National Laboratory and Ohio University has developed a new, simpler way to discern molecular handedness, known as chirality. They used gold-and-silver cubic nanoparticles to amplify the difference in left- and right-handed molecules' response to a particular kind of light. The study, described in the journal Nano Letters, provides the basis for a new way to probe the effects of handedness in molecular interactions with unprecedented sensitivity.
"Our discovery and methods based on this research could be extremely useful for the characterization of biomolecular interactions with drugs, probing protein folding, and in other applications where stereometric properties are important," said Oleg Gang, a researcher at Brookhaven's Center for Functional Nanomaterials and lead author on the paper. "We could use this same approach to monitor conformational changes in biomolecules under varying environmental conditions, such as temperature-and also to fabricate nano-objects that exhibit a chiral response to light, which could then be used as new kinds of nanoscale sensors."
The scientists knew that left- and right-handed chiral molecules would interact differently with "circularly polarized" light-where the direction of the electrical field rotates around the axis of the beam. This idea is similar to the way polarized sunglasses filter out reflected glare unlike ordinary lenses.
Other scientists have detected this difference, called "circular dichroism," in organic molecules' spectroscopic "fingerprints"-detailed maps of the wavelengths of light absorbed or reflected by the sample. But for most chiral biomolecules and many organic molecules, this "CD" signal is in the ultraviolet range of the electromagnetic spectrum, and the signal is often weak. The tests thus require significant amounts of material at impractically high concentrations.
The team was encouraged they might find a way to enhance the signal by recent experiments showing that coupling certain molecules with metallic nanoparticles could greatly increase their response to light (see:http://www.bnl.gov/newsroom/news.php?a=11157). Theoretical work even suggested that these so-called plasmonic particles-which induce a collective oscillation of the material's conductive electrons, leading to stronger absorption of a particular wavelength-could bump the signal into the visible light portion of the spectroscopic fingerprint, where it would be easier to measure.
The group experimented with different shapes and compositions of nanoparticles, and found that cubes with a gold center surrounded by a silver shell are not only able to show a chiral optical signal in the near-visible range, but even more striking, were effective signal amplifiers. For their test biomolecule, they used synthetic strands of DNA-a molecule they were familiar with using as "glue" for sticking nanoparticles together.
When DNA was attached to the silver-coated nanocubes, the signal was approximately 100 times stronger than it was for free DNA in the solution. That is, the cubic nanoparticles allowed the scientists to detect the optical signal from the chiral molecules (making them "visible") at 100 times lower concentrations.
"This is a very large optical amplification relative to what was previously observed," said Fang Lu, the first author on the paper.
The observed amplification of the circular dichroism signal is a consequence of the interaction between the plasmonic particles and the "exciton," or energy absorbing, electrons within the DNA-nanocube complex, the scientists explained.
"This research could serve as a promising platform for ultrasensitive sensing of chiral molecules and their transformations in synthetic, biomedical, and pharmaceutical applications," Lu said.
"In addition," said Gang, "our approach offers a way to fabricate, via self-assembly, discrete plasmonic nano-objects with a chiral optical response from structurally non-chiral nano-components. These chiral plasmonic objects could greatly enhance the design of metamaterials and nano-optics for applications in energy harvesting and optical telecommunications."
This research was conducted at the Center for Functional Nanomaterials and funded by the DOE Office of Science and by the National Science Foundation.

Brain's 'Garbage Truck' May Hold Key to Treating Alzheimer's

Brain's 'Garbage Truck' May Hold Key to Treating Alzheimer's and Other Disorders

June 27, 2013 — In a perspective piece appearing today in the journal Science, researchers at University of Rochester Medical Center (URMC) point to a newly discovered system by which the brain removes waste as a potentially powerful new tool to treat neurological disorders like Alzheimer's disease. In fact, scientists believe that some of these conditions may arise when the system is not doing its job properly.
Scientists point to a newly discovered system by which the brain removes waste as a potentially powerful new tool to treat neurological disorders like Alzheimer's disease. In fact, scientists believe that some of these conditions may arise when the system is not doing its job properly. (Credit: © James Steidl / Fotolia)
"Essentially all neurodegenerative diseases are associated with the accumulation of cellular waste products," said Maiken Nedergaard, M.D., D.M.Sc., co-director of the URMC Center for Translational Neuromedicine and author of the article. "Understanding and ultimately discovering how to modulate the brain's system for removing toxic waste could point to new ways to treat these diseases."
The body defends the brain like a fortress and rings it with a complex system of gateways that control which molecules can enter and exit. While this "blood-brain barrier" was first described in the late 1800s, scientists are only now just beginning to understand the dynamics of how these mechanisms function. In fact, the complex network of waste removal, which researchers have dubbed the glymphatic system, was only first disclosed by URMC scientists last August in the journal Science Translational Medicine.
The removal of waste is an essential biological function and the lymphatic system -- a circulatory network of organs and vessels -- performs this task in most of the body. However, the lymphatic system does not extend to the brain and, consequently, researchers have never fully understood what the brain does its own waste. Some scientists have even speculated that these byproducts of cellular function where somehow being "recycled" by the brain's cells.
One of the reasons why the glymphatic system had long eluded comprehension is that it cannot be detected in samples of brain tissue. The key to discovering and understanding the system was the advent of a new imaging technology called two-photon microscopy which enables scientists to peer deep within the living brain. Using this technology on mice, whose brains are remarkably similar to humans, Nedergaard and her colleagues were able to observe and document what amounts to an extensive, and heretofore unknown, plumbing system responsible for flushing waste from throughout the brain.
The brain is surrounded by a membrane called the arachnoid and bathed in cerebral spinal fluid (CSF). CSF flows into the interior of the brain through the same pathways as the arteries that carry blood. This parallel system is akin to a donut shaped pipe within a pipe, with the inner ring carrying blood and the outer ring carrying CSF. The CSF is draw into brain tissue via a system of conduits that are controlled by a type support cells in the brain known as glia, in this case astrocytes. The term glymphatic was coined by combining the words glia and lymphatic.
The CSF is flushed through the brain tissue at a high speed sweeping excess proteins and other waste along with it. The fluid and waste are exchanged with a similar system that parallels veins which carries the waste out of the brain and down the spine where it is eventually transferred to the lymphatic system and from there to the liver, where it is ultimately broken down.
While the discovery of the glymphatic system solved a mystery that had long baffled the scientific community, understanding how the brain removes waste -- both effectively and what happens when this system breaks down -- has significant implications for the treatment of neurological disorders.
One of the hallmarks of Alzheimer's disease is the accumulation in the brain of the protein beta amyloid. In fact, over time these proteins amass with such density that they can be observed as plaques on scans of the brain. Understanding what role the glymphatic system plays in the brain's inability to break down and remove beta amyloid could point the way to new treatments. Specifically, whether certainly key 'players' in the glymphatic system, such as astrocytes, can be manipulated to ramp up the removal of waste.
"The idea that 'dirty brain' diseases like Alzheimer may result from a slowing down of the glymphatic system as we age is a completely new way to think about neurological disorders," said Nedergaard. "It also presents us with a new set of targets to potentially increase the efficiency of glymphatic clearance and, ultimately, change the course of these conditions."

Thursday, 27 June 2013

Brain Fibers

Brain Fibers

Researchers at the University of Pittsburgh hope the new imaging technique will help them identify neural connections broken by traumatic brain injuries and other neurological disorders.
A high definition fiber-tracking (HDFT) map of a million brain fibers.
(Credit: Walt Schneider Laboratory)
When a 32-year-old man crashed his all-terrain vehicle without wearing a helmet, he slipped into a coma for three weeks. Though his initial CT scans revealed bleeding and swelling, and an MRI scan a week into the coma revealed bruising and swelling in the same area, neurosurgeons had no way of knowing precisely how the man would be affected if he did come out of his coma.
Three weeks later, the man awoke without the ability to move his left leg, arm, or hand. Only then were doctors able to begin planning rehabilitation.
Fortunately for the patient, a novel imaging technique called High Definition Fiber Tracking(HDFT)--developed by a team at the University of Pittsburgh--has helped identify which of his neural pathways were disrupted, according toWalter Schneider, the professor of psychology and neurosurgery who led the team that developed the tech at Pitt's Learning Research and Development Center.
Courtesy of the Laboratory of Neuro Imaging at UCLA and Martinos Center for Biomedical Imaging at MGH, Consortium of the Human Connectome Project – www.humanconnectomeproject.org

HDFT, which the team reports on this monthin a case study in the Journal of Neurosurgery, runs computer algorithms on data collected from MRI scans to view the brain's fiber tracts, each of which contains millions of connections.
"We can virtually dissect 40 major fiber tracts in the brain to find damaged areas and quantify the proportion of fibers lost relative to the uninjured side of the brain or to the brains of healthy individuals," Schneider reports in a school release. "Now, we can clearly see breaks and identify which parts of the brain have lost connections."
HDFT collects data from 257 directions; the state-of-the-art imaging technique called diffusion tensor imaging (DTI), by comparison, uses 51. Researchers took both types of scans of the patient at four and 10 months post-injury, but only the HDFT method revealed a lesion in a motor fiber pathway that would explain left-sided weakness and extensive fiber breaks in the region that controls his left hand.
The patient, by the way, eventually regained movement in his left leg and arm but continued to struggle to use his wrist and fingers at the 10-month mark.
While the Pitt neurosurgeons have used HDFT to map approaches to remove tumors and other abnormalities, they say much work remains to evaluate and ultimately validate HDFT as a new imaging standard. Still, they hope to some day use the fiber tracking to identify breaks that might explain not only motor problems but also memory loss and personality changes that can occur with traumatic brain injuries.

Polymer Coatings a Key Step Toward Oral Delivery of Protein-Based Drugs

Polymer Coatings a Key Step Toward Oral Delivery of Protein-Based Drugs

June 27, 2013 — For protein-based drugs such as insulin to be taken orally rather than injected, bioengineers need to find a way to shuttle them safely through the stomach to the small intestine where they can be absorbed and distributed by the bloodstream. Progress has been slow, but in a new study, researchers report an important technological advance: They show that a "bioadhesive" coating significantly increased the intestinal uptake of polymer nanoparticles in rats and that the nanoparticles were delivered to tissues around the body in a way that could potentially be controlled.
Edith Mathiowitz: "The distribution [of orally delivered protein-based medicines] in the body can be somehow controlled with the type of polymer that you use." (Credit: Mike Cohea/Brown University)
"The results of these studies provide strong support for the use of bioadhesive polymers to enhance nano- and microparticle uptake from the small intestine for oral drug delivery," wrote the researchers in the Journal of Controlled Release, led by corresponding author Edith Mathiowitz, professor of medical science at Brown University.
Mathiowitz, who teaches in Brown's Department of Molecular Pharmacology, Physiology, and Biotechnology, has been working for more than a decade to develop bioadhesive coatings that can get nanoparticles to stick to the mucosal lining of the intestine so that they will be taken up into its epithelial cells and transferred into the bloodstream. The idea is that protein-based medicines would be carried in the nanoparticles.
In the new study, which appeared online June 21, Mathiowitz put one of her most promising coatings, a chemical called PBMAD, to the test both on the lab bench and in animal models. Mathiowitz and her colleagues have applied for a patent related to the work, which would be assigned to Brown University.
In prior experiments, Mathiowitz and her group have shown not only that PBMAD has bioadhesive properties, but also that it withstands the acidic environment of the stomach and then dissolves in the higher pH of the small intestine.
Adhere, absorb, arrive
The newly published results focused on the question of how many particles, whether coated with PBMAD or not, would be taken up by the intestine and distributed to tissues. For easier tracking throughout the body, Mathiowitz's team purposely used experimental and control particles made of materials that the body would not break down. Because they were "non-erodible" the particles did not carry any medicine.
The researchers used particles about 500 nanometers in diameter made of two different materials: polystyrene, which adheres pretty well to the intestine's mucosal lining, and another plastic called PMMA, that does not. They coated some of the PMMA particles in PBMAD, to see if the bioadhesive coating could get PMMA particles to stick more reliably to the intestine and then get absorbed.
First the team, including authors Joshua Reineke of Wayne State University and Daniel Cho of Brown, performed basic benchtop tests to see how well each kind of particles adhered. The PBMAD-coated particles proved to have the strongest stickiness to intestinal tissue, binding more than twice as strongly as the uncoated PMMA particles and about 1.5 times as strongly as the polystyrene particles.
The main experiment, however, involved injecting doses of the different particles into the intestines of rats to see whether they would be absorbed and where those that were taken up could be found five hours later. Some rats got a dose of the polystyrene particles, some got the uncoated PMMA and some got the PBMAD-coated PMMA particles.
Measurements showed that the rats absorbed 66.9 percent of the PBMAD-coated particles, 45.8 percent of the polystyrene particles and only 1.9 percent of the uncoated PMMA partcles.
Meanwhile, the different particles had very different distribution profiles around the body. More than 80 percent of the polystyrene particles that were absorbed went to the liver and another 10 percent went to the kidneys. The PMMA particles, coated or not, found their way to a much wider variety of tissues, although in different distributions. For example, the PBMAD-coated particles were much more likely to reach the heart, while the uncoated ones were much more likely to reach the brain.
Pharmaceutical potential
The apparent fact that the differing surface properties of the similarly sized particles had such distinct distributions in the rats' tissues after the same five-hour period suggests that scientists could learn to tune particles to reach specific parts of the body, essentially targeting doses of medicines taken orally, Mathiowitz said.
"The distribution in the body can be somehow controlled with the type of polymer that you use," she said.
For now, she and her group have been working hard to determine the biophysics of how the PBMAD-coated particles are taken up by the intestines. More work also needs to be done, for instance to demonstrate actual delivery of protein-based medicines in sufficient quantity to tissues where they are needed.
But Mathiowitz said the new results give her considerable confidence.
"What this means now is that if I coat bioerodible nanoparticles correctly, I can enhance their uptake," she said. "Bioerodible nanoparticles are what we would ultimately like to use to deliver proteins. The question we address in this paper is how much can we deliver. The numbers we saw make the goal more feasible."
Another frontier for the delivery of nanoparticles is devising a safe method to make nanoparticles, Mathiowitz said, but, "we have already developed safe and reproducible methods to encapsulate proteins in tiny nanoparticles without compromising their biological activity."
In addition to Reineke, Cho, and Mathiowitz, other authors on the paper are Yu-Ting Liu Dingle, Stacia Furtado, Bryan Laulicht, Danya Lavin, and Peter M. Cheifetz, all of Brown University during the research.

Making Hydrogenation Greener: Using Iron as Catalyst for Widely Used Chemical Process, Replacing Heavy Metals

Making Hydrogenation Greener: Using Iron as Catalyst for Widely Used Chemical Process, Replacing Heavy Metals

June 27, 2013 — Researchers from McGill University, RIKEN (The Institute of Physical and Chemical Research, Wako, Japan) and the Institute for Molecular Science (Okazaki, Japan) have discovered a way to make the widely used chemical process of hydrogenation more environmentally friendly -- and less expensive.
Hydrogenation is a chemical process used in a wide range of industrial applications, from food products, such as margarine, to petrochemicals and pharmaceuticals. The process typically involves the use of heavy metals, such as palladium or platinum, to catalyze the chemical reaction. While these metals are very efficient catalysts, they are also non-renewable, costly, and subject to sharp price fluctuations on international markets.
Because these metals are also toxic, even in small quantities, they also raise environmental and safety concerns. Pharmaceutical companies, for example, must use expensive purification methods to limit residual levels of these elements in pharmaceutical products. Iron, by contrast, is both naturally abundant and far less toxic than heavy metals.
Previous work by other researchers has shown that iron nanoparticles -- tiny pieces of metallic iron -- can be used to activate the hydrogenation reaction. Iron, however, has a well-known drawback: it rusts in the presence of oxygen or water. When rusted, iron nanoparticles stop acting as hydrogenation catalysts. This problem, which occurs with so much as trace quantities of water, has prevented iron nanoparticles from being used in industry.
In research published today in the journal Green Chemistry, scientists from McGill, RIKEN, and the Institute for Molecular Science report that they have found a way to overcome this limitation, making iron an active catalyst in water-ethanol mixtures containing up to 90% water.
The key to this new method is to produce the particles directly inside a polymer matrix, composed of amphiphilic polymers based on polystyrene and polyethylene glycol. The polymer acts as a wrapping film that protects the iron surface from rusting in the presence of water, while allowing the reactants to reach the water and react.
This innovation enabled the researchers to use iron nanoparticles as catalyst in a flow system, raising the possibility that iron could be used to replace platinum-series metals for hydrogenation under industrial conditions.
"Our research is now focused on achieving a better understanding of how the polymers are protecting the surface of the iron from water, while at the same time allowing the iron to interact with the substrate," says Audrey Moores, an assistant professor of chemistry at McGill and co-corresponding author of the paper.
The results stem from an ongoing collaboration between McGill and RIKEN, one of Japan's largest scientific research organizations, in the fields of nanotechnology and green chemistry. Lead author Reuben Hudson, a doctoral student at McGill, worked on the project at the RIKEN Center for Sustainable Resource Science and at the Institute for Molecular Science in Japan. Co-authors of the paper are Prof. Chao-Jun Li of McGill, Dr. Go Hamasaka and Dr. Takao Osako of the Institute for Molecular Science, Dr. Yoichi M.A. Yamada of Riken and Prof. Yasuhiro Uozumi of Riken and the Institute for Molecular Science.
"The approach we have developed through this collaboration could lead to more sustainable industrial processes," says Prof. Uozumi. "This technique provides a system in which the reaction can happen over and over with the same small amount of a catalytic material, and it enables it to take place in almost pure water -- the green solvent par excellence."
Funding for the research was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Foundation for Innovation (CFI), the Canada Research Chairs, the Fonds de recherche du Qu├ębec -- Nature et technologies, the Riken-McGill Fund, the Japan Society for the Promotion of Science (JSPS), and the Japan Science and Technology Agency (JST).

Organic electronics: Imaging defects in solar cells

Organic electronics: Imaging defects in solar cells

Researchers at Ludwig-Maximilians-Universitaet in Munich have developed a new method for visualizing material defects in thin-film solar cells.

Organic electronics: Imaging defects in solar cells
Experimental setup used to map defect densities in organic thin films. A pulsed laser beam is used to raster-scan the material of interest, which is assembled in a field-effect geometry, allowing changes in current flow to be detected. The yellow zones indicate sites at which the defect density is particularly high. Source: Christian Westermeier

An LMU research team led by Bert Nickel has, for the first time, succeeded in functionally characterizing the active layer in organic thin-film solar cells using  for localized  of the material. The findings are reported in the scientific journal "Advanced Materials". "We have developed a method in which the material is raster-scanned with a laser, while the focused beam is modulated in different ways, by means of a rotating attenuator for instance. This enables us to map directly the  of defects in , a feat which has not previously been achieved," explains Christian Westermeier, who is first author of the new study.
Solar cells can convert sunlight into electrical power by exploiting light's capacity to excite molecules, producing  and positively charged "holes". How long it takes for these charge carriers to be extracted by the electrodes is in turn dependent on the detailed structure of the cell's active layer. Defects in the regular arrangement of the atoms act as temporary traps for charge carriers, and thus reduce the size of the usable current that can be produced. The new mapping method allows researchers to detect the changes in current flow associated with localized excitation of defects by laser light. In the utilized experimental geometry a metallic back contact serves as the gating electrode. By applying a voltage to this gate, the traps present in the  can be filled or emptied in a controllable manner via the so-called field effect. By modulating the frequency of the laser light the temporal dynamics of trap states can be determined.
The study revealed that in pentacene, an organic semiconductor, the defects tend to be concentrated at certain positions. "It would be interesting to know what is special about the surface layer at these hot spots. What produces defects at these sites? They could be due to chemical contaminants or to irregularities in the alignment of the molecules," says Bert Nickel, who is also a member of the Nanosystems Initiative Munich (NIM), a Cluster of Excellence.
Nickel and his colleagues chose the pentacene for their experiments because it is the most conductive material presently available for the manufacture of organic semiconductors. In the present study, they looked at a thin pentacene layer in which the majority of  are positively charged holes. In subsequent work, they plan to investigate complete solar cells, which consist of a hole-conducting film in direct contact with an electron-conducting layer.


Read more at: http://phys.org

Wednesday, 26 June 2013

Pharaoh's curse: Why that ancient Egyptian statue moves on its own

Pharaoh's curse: Why that ancient Egyptian statue moves on its own

An ancient Egyptian statue appears to have started moving on its own, much to the amazement of scientists and museum curators.
The statue of Neb-Senu, believed to date to 1800 B.C., is housed in the Manchester Museum in England — at least for now. But if the statue keeps moving, there's no telling where it will end up.
"I noticed one day that it had turned around," museum curator Campbell Price told the Manchester Evening News. "I thought it was strange because it is in a case and I am the only one who has a key.
"I put it back, but then the next day it had moved again," Price said. "We set up a time-lapse video and, although the naked eye can't see it, you can clearly see it rotate." [In Photos: Ancient Egyptian Skeletons Unearthed]
The 10-inch (25-centimeter) statue was acquired by the museum in 1933, according to the New York Daily News. The video clearly shows the artifact slowly turning counterclockwise during the day, but remaining stationary at night.
This daytime movement led British physicist Brian Cox to suggest that the statue's movement is due to the vibration created by museum visitors' footsteps. "Brian thinks it's 'differential friction,' where two surfaces — the stone of the statuette and glass shelf it is on — cause a subtle vibration, which is making the statuette turn," Price said.
"But it has been on those surfaces since we have had it and it has never moved before," Price said. "And why would it go around in a perfect circle?"
Magnetism or friction?
On his blog, Price also speculates that the statue "was carved of steatite and then fired [which] may imply that it is now vulnerable to magnetic forces." Steatite, also known as soapstone, is a soft stone often used for carving.
Oddly, the statue turns 180 degrees to face backward, then turns no more. This led some observers to wonder if the statue moves to show visitors the inscription on its back, which asks for sacrificial offerings "consisting of bread, beer, oxen and fowl."
None of the proposed explanations satisfies Price. "It would be great if someone could solve the mystery," he said.
Paul Doherty, senior scientist at the Exploratorium in San Francisco, says the statue's movement isn't caused by any supernatural force, but probably by something quite ordinary: vibrational stick-slip friction, sometimes called stick-slip vibration.
As Doherty told LiveScience, if the glass shelf on which the statue rests vibrates even slightly, "the vibrating glass moves the statue in the same direction," causing it to turn around.
An everyday example can occur when someone uses an electric blender on a kitchen countertop: The vibration of the blender can cause a nearby coffee cup to "walk" across the countertop.
What makes it stop?
But why would the statue stop moving after turning 180 degrees? Doherty believes the statue stops turning because it's asymmetrically weighted: "One side of the statue has more weight than the other side," he said. After turning around on the shelf, the statue's uneven bottom reaches a more stable position and stops turning.
Besides the footsteps of passing museum visitors, the source of the stick-slip vibration "could be some trolley that goes by during the day, or a train that passes during the day," Doherty said.

Tuesday, 25 June 2013

How NASA Revealed Sun's Hottest Secret in 5-Minute Spaceflight

How NASA Revealed Sun's Hottest Secret in 5-Minute Spaceflight

While many NASA space telescopes soar in orbit for years, the agency's diminutive Hi-C telescope tasted space for just 300 seconds, but it was enough time to see through the sun's secretive atmosphere.
Designed to observe the hottest part of the sun — its corona — the small High-Resolution Coronal Imager (Hi-C) launched on a suborbital rocket that fell back to Earth without circling the planet even once. The experiment revealed never-before-seen "magnetic braids" of plasma roiling in the sun's outer layers, NASA announced today (Jan. 23)
"300 seconds of data may not seem like a lot to some, but it's actually a fair amount of data, in particular for an active region" of the sun, Jonathan Cirtain, Hi-C mission principal investigator at NASA's Marshall Space Flight Center in Huntsville, Ala., said during a NASA press conference today.The solar telescope snapped a total of 165 photos during its mission, which lasted 10 minutes from launch to its parachute landing.
Hi-C launched from White Sands Missile Range in New Mexico atop a sounding rocket in July 2012. The mission cost a total of $5 million — a relative bargain for a NASA space mission, scientists said. The experiment was part of NASA's Sounding Rocket Program, which launches about 20 unmanned suborbital research projects every year. [NASA's Hi-C Photos: Best View Ever of Sun's Corona]
Magnetic Braids on the Sun
While NASA already has telescopes in orbit constantly monitoring the whole surface of the sun, such as the Solar Dynamics Observatory (SDO), the Hi-C mission allowed scientists to focus in on a smaller region than SDO is able to.
"SDO has a global view of the sun," Newmark said. "What this research does is act like a microscope and it zooms in on the real fine structure that's never been seen before."
The next step, the researchers said, is to design a follow-up instrument to take advantage of the new telescope technology tested out by Hi-C, to observe for a longer period of time on an orbital mission.
"Now we've proven it exists, so now we can go study it," said Karel Schrijver, a senior fellow at the Lockheed Martin Advanced Technology Center in Palo Alto, Calif., where the instrument was built.

Supermoon Captured: The Best Shots of Biggest Full Moon in 2013

Supermoon Captured: The Best Shots of Biggest Full Moon in 2013


Skypark Moon

Picture of supermoon in Marina Bay Sands Skypark, Singapore


The Moon in Pune

Picture of the supermoon over Pune, India

Giant Yellow Moon

Picture of the June 23 supermoon over the Old Fortress of Corfu in Greece

Coastal Moon

Picture of the supermoon over Coverack, a fishing village in England

Bay Area Moon

Picture of the full moon over the Bay Bridge in San Francisco, California


source:http://news.nationalgeographic.com



Efficient Production Process for Coveted Nanocrystals

Efficient Production Process for Coveted Nanocrystals

June 25, 2013 — A formation mechanism of nanocrystalline cerium dioxide (CeO2), a versatile nanomaterial, has been unveiled by scientists from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of New South Wales in Sydney, Australia.
Ce(IV) dimers and trimers form in aqueous solution nanometer-sized cer dioxide crystals (CeO2). The size of the nanocrystals is in the order of two to three nanometers. (Credit: A. Ikeda-Ohno)The research results were published in the scientific journal Chemistry -- A European Journal. This finding potentially simplifies and alleviates the existing synthetic processes of nanocrystalline CeO2 production.
Nanocrystalline CeO2 particles are widely used, for example, in catalysts for hazardous gas treatment, in electrodes for solid oxide fuel cells, in polishing materials for advanced integrated circuits, in sunscreen cosmetics, and in such medical applications as artificial superoxide dismutase. Current industrial syntheses of nanocrystalline CeO2 are based on sol-gel processes followed by thermal treatment and/or the addition of accelerant reagents. Any further improvement of the synthetic strategy for CeO2 nanocrystals requires a better understanding of the mechanisms involved in their formation at the atomic scale.
Dr. Atsushi Ikeda-Ohno from the University of New South Wales, Australia, together with Dr. Christoph Hennig from the HZDR opted for a sophisticated multi-spectroscopic approach that combines dynamic light scattering and synchrotron-based X-ray techniques. These complex investigations involved the use of two world-leading synchrotron facilities of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France and SPring-8 in Hyogo, Japan.
Live Monitoring
For the first time ever, the scientists were able to perform an in-situ observation of nanocrystal evolution. So far, little has been known of the formation mechanism of metal nanocrystals; mainly because appropriate analytical techniques were lacking. The most widely used techniques for metal nanocrystal research are electron microscopy and X-ray diffraction. They are powerful enough to visualize the appearance of nanocrystals and to acquire their lattice information, but they are not applicable to the solution state where the evolution of metal nanocrystals occurs. "To probe the formation of nanocrystalline CeO2 in an aqueous solution, we combined different spectroscopic techniques, including dynamic light scattering, synchrotron X-ray absorption spectroscopy, and high energy X-ray scattering," says Dr. Atsushi Ikeda-Ohno.
The information the researchers obtained is fundamental to simplifying and alleviating the synthetic process of CeO2 nanocrystals. They revealed that uniformly sized nanoparticles of CeO2 can be produced simply by pH adjustment of tetravalent cerium (Ce(IV)) in an aqueous solution without subsequent physical/chemical treatment such as heating or adding accelerant chemicals. The produced CeO2 crystals have a uniform particle size of 2 -- 3 nanometers, irrespective of the preparation conditions (e.g. pH and type of pH adjustment). This particle size is exactly in the range which is interesting for industrial applications. A key finding is that mononuclear Ce(IV) solution species do not result in nano-sized CeO2 crystals. The prerequisite is the presence of oligomeric Ce(IV) solution species, such as dimers or trimers.
"We're indeed very glad that our multi-spectroscopic approach is also applicable to any other research on metal nanocrystals. That's why this study contributes to an emerging research area on metal nanocrystals in a broader context," says Dr. Christoph Hennig. "And the HZDR's own measuring station at the ESRF provides the best possible opportunities for this research area of metal nanocrystals which directly contributes to industrial applications."

Video Game Tech Used to Steer Cockroaches On Autopilot

Video Game Tech Used to Steer Cockroaches On Autopilot

June 25, 2013 — North Carolina State University researchers are using video game technology to remotely control cockroaches on autopilot, with a computer steering the cockroach through a controlled environment. The researchers are using the technology to track how roaches respond to the remote control, with the goal of developing ways that roaches on autopilot can be used to map dynamic environments -- such as collapsed buildings.
North Carolina State University researchers are using video game technology to remotely control cockroaches on autopilot, with a computer steering the cockroach through a controlled environment. (Credit: Alper Bozkurt)
The researchers have incorporated Microsoft's motion-sensing Kinect system into an electronic interface developed at NC State that can remotely control cockroaches. The researchers plug in a digitally plotted path for the roach, and use Kinect to identify and track the insect's progress. The program then uses the Kinect tracking data to automatically steer the roach along the desired path. 
The program also uses Kinect to collect data on how the roaches respond to the electrical impulses from the remote-control interface. This data will help the researchers fine-tune the steering parameters needed to control the roaches more precisely.
"Our goal is to be able to guide these roaches as efficiently as possible, and our work with Kinect is helping us do that," says Dr. Alper Bozkurt, an assistant professor of electrical and computer engineering at NC State and co-author of a paper on the work.
"We want to build on this program, incorporating mapping and radio frequency techniques that will allow us to use a small group of cockroaches to explore and map disaster sites," Bozkurt says. "The autopilot program would control the roaches, sending them on the most efficient routes to provide rescuers with a comprehensive view of the situation."
The roaches would also be equipped with sensors, such as microphones, to detect survivors in collapsed buildings or other disaster areas. "We may even be able to attach small speakers, which would allow rescuers to communicate with anyone who is trapped," Bozkurt says.
Bozkurt's team had previously developed the technology that would allow users to steer cockroaches remotely, but the use of Kinect to develop an autopilot program and track the precise response of roaches to electrical impulses is new.
The interface that controls the roach is wired to the roach's antennae and cerci. The cerci are sensory organs on the roach's abdomen, which are normally used to detect movement in the air that could indicate a predator is approaching -- causing the roach to scurry away. But the researchers use the wires attached to the cerci to spur the roach into motion. The wires attached to the antennae send small charges that trick the roach into thinking the antennae are in contact with a barrier and steering them in the opposite direction.
The paper, "Kinect-based System for Automated Control of Terrestrial Insect Biobots," will be presented at the Remote Controlled Insect Biobots Minisymposium at the 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society July 4 in Osaka, Japan. Lead author of the paper is NC State undergraduate Eric Whitmire. Co-authors are Bozkurt and NC State graduate student Tahmid Latif. The research was supported by the National Science Foundation.

Ancient Egyptian statue moving in a Manchester museum?

Ancient Egyptian statue moving in a Manchester museum?

We’re very familiar with moving statues in Ireland and now a Manchester museum is encountering the same ‘problem’. It seems a 4,000 year old statue from Egypt has decided to start moving, rotating 180 degrees over the course of a few days.
Statue move
The entire process was captured on film (see below) and the statue definitely appears to be move.
Theories range from the plausible (gentle vibrations caused by traffic noise) to the more far-fetched (the statue itself wishing the visitors to the Manchester Musuem to read the inscription on the back).
The statue, known as Neb-Senu, has been in the museum for over 80 years but it began moving in February according to the museum’s Egyptologist Campbell Price.
In April they set up a camera and over three days captured the movement. They have now posted the clip online looking for help in solving the mystery.
Whatever the reason, we suspect that the museum is certainly set to have a busy summer.

Testing Artificial Photosynthesis: Fully Integrated Microfluidic Test-Bed for Solar-Driven Electrochemical Energy Conversion Systems

Testing Artificial Photosynthesis: Fully Integrated Microfluidic Test-Bed for Solar-Driven Electrochemical Energy Conversion Systems

June 10, 2013 — With the daily mean concentrations of atmospheric carbon dioxide having reached 400 parts-per-million for the first time in human history, the need for carbon-neutral alternatives to fossil fuel energy has never been more compelling. With enough energy in one hour's worth of global sunlight to meet all human needs for a year, solar technologies are an ideal solution. However, a major challenge is to develop efficient ways to convert solar energy into electrochemical energy on a massive-scale. A key to meeting this challenge may lie in the ability to test such energy conversion schemes on the micro-scale.
In this microfluidic test-bed, a chemically inert wall (red) separates anode from cathode and the channels in which O2 and H2 are generated by splitting water molecules. Protons (H+) are conducted from one channel to the other via a membrane cap (Nafion®) that also prevents the intermixing of the O2 and H2 product streams. (Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory)
Berkeley Lab researchers, working at the Joint Center for Artificial Photosynthesis (JCAP), have developed the first fully integrated microfluidic test-bed for evaluating and optimizing solar-driven electrochemical energy conversion systems. This test-bed system has already been used to study schemes for photovoltaic electrolysis of water, and can be readily adapted to study proposed artificial photosynthesis and fuel cell technologies.
"We've demonstrated a microfluidic electrolyzer for water splitting in which all functional components can be easily exchanged and tailored for optimization," says Joel Ager, a staff scientist with Berkeley Lab's Materials Sciences Division. "This allows us to test on a small scale strategies that can be applied to large scale systems."
Ager is one of two corresponding authors of a paper in the journalPhysical Chemistry Chemical Physics (PCCP) titled "Integrated microfluidic test-bed for energy conversion devices." Rachel Segalman, also with Berkeley Lab's Materials Sciences Division is the other corresponding author. Other co-authors are Miguel Modestino, Camilo Diaz-Botia, Sophia Haussener and Rafael Gomez-Sjoberg.
For more than two billion years, nature has employed photosynthesis to oxidize water into molecular oxygen. An artificial version of photosynthesis is regarded as one of the most promising of solar technologies. JCAP is a multi-institutional partnership led by the California Institute of Technology (Caltech) and Berkeley Lab with operations in Berkeley (JCAP-North) and Pasadena (JCAP-South). The JCAP mission is to develop an artificial version of photosynthesis through specialized membranes made from nano-engineered materials that can do what nature does only much more efficiently and for the purpose of producing storable fuels such as hydrogen or hydrocarbons (gasoline, diesel, etc.).
"The operating principles of artificial photosynthetic systems are similar to redox flow batteries and fuel cells in that charge-carriers need to be transported to electrodes, reactants need to be fed to catalytic centers, products need to be extracted, and ionic transport both from the electrolyte to catalytic centers and across channels needs to occur," Ager says. "While there have been a number of artificial photosynthesis demonstrations that have achieved attractive solar to hydrogen conversion efficiencies, relatively few have included all of the operating principles, especially the chemical isolation of the cathode and anode."
The microfluidic test-bed developed by Ager and his colleagues at JCAP-N allows for different anode and cathode materials to be integrated and electrically accessed independently through macroscopic contacts patterned in the outside of the microfabricated chip. The transport of charge-carriers occurs through an ion conducting polymer membrane, and electrolysis products can be evolved and collected in separated streams. This general design provides selective catalysis at the cathode and anode, minimization of cross-over losses, and managed transport of the reactants. Virtually any photoelectrochemical component, including those made of earth-abundant elements, can be incorporated into the test-bed.
Says Modestino, the lead author of the PCCP paper, "In our experimental realization of the design, a series of 19 parallel channels were fabricated in each device, with a total active area of eight square millimeters. As the microfabricated chips are relatively easy to make, we can readily change dimensions and materials to optimize performance."
This research was supported by the DOE Office of Science.