Materials Prediction Scores a Hit


 Figure 1

 The energetics of predicting materials. A schematic free energy landscape for different crystallographic configurations is given by the blue line. Note the small difference in energy between various structures compared with the total energy of a crystal demanding high computational accuracy. The application of pressure as done by Gou et al. will modify the energy landscape (red curve), potentially stabilizing new structures. The ground state (such as superconductivity, magnetism, or other forms of order) for a given structure is determined at even lower energy scales, as depicted in the inset. The addition of strong electronic correlations in some materials will further modify the landscape over large energy scales up to 10eV, making predictions even more challenging.

Had the great American philosopher Yogi Berra been a condensed matter physicist, he might have said “It’s difficult to make predictions, especially about superconductivity.” Predictions about a material’s structure and even more so its function have been goals of materials research for a long time, but the track record for predicting that a given compound will superconduct is notoriously bad [1]. Fortunately, advances in the fidelity and resolution of electronic structure calculations are beginning to change this trend [2]. In fact, the White House’s Materials Genome Initiative [3] represents a recognition that with recent advances in computational capability and materials models, such breakthroughs are possible and, in fact, likely probable. In a paper in Physical Review Letters, Huiyang Gou at the University of Bayreuth, Germany, and colleagues [4] describe a success story in the search for predictability. They report the observation of superconductivity in iron tetraboride (FeB4) at approximately 3 kelvin (K). Not only did they find superconductivity where electronic structure calculations told them to look, they used high-pressure synthesis techniques to discover a compound that wasn’t readily apparent in nature. Further, the resulting compound, orthorhombic FeB4, turns out to be very mechanically hard as well as superconducting, thus possessing two desirable traits.

Most attempts to predict superconductivity invoke the physicist Bernd Matthias [5]. In the 1950s–1970s Matthias articulated a number of empirical “rules” that anticipated a large number of superconducting materials based on crystal structure and the number of valence electrons per atom. However, these rules were clearly based on intuition and not predictive theory. The experimental discovery that cuprates, magnesium diboride (MgB2), and more recently, iron pnictides all superconduct drove home the reality that serendipity was still the best materials discovery engine. However, that reality is beginning to evolve.

Why is it so difficult to predict new superconducting materials? One issue is the difficulty predicting the structural stability of a compound, that is, whether the binding energy between atoms is large enough to keep them stuck together in a particular configuration. Electronic structure calculations provide the total energy for a crystal, which is on the order of 105 electron volts per atom (eV/atom) (see Fig. 1). However, the stability with respect to competing phases is typically as small as 10-2 eV/atom, thus demanding incredibly high accuracy of the calculations. Furthermore, calculations are typically performed at T=0K in ideal crystals, while the thermal energy at which the crystals are synthesized and the energy scale created by defects can easily shift the relative total energies of competing phases by similar amounts. Another factor is that superconductivity is a very low-energy instability of the electronic structure. For a superconductor with a transition temperature Tc of 3K, as discovered by Gou et al., this amounts to an energy scale of 10-4eV. Few predictive models (yet) have accuracy at the parts per billion level covered by these energy scales.

Advanced electronic structure calculations for predictions have increased effectiveness due to the relative accessibility and availability of high-pressure techniques. Recent discoveries demonstrate that surprises still exist at high pressure [6]. We now know that a dozen or so additional elements superconduct at elevated pressure even though they are normal materials under ambient conditions, including calcium at 220 gigapascals (with Tc=29K, the highest Tc for an elemental superconductor). More broadly, materials science has been transformed by our ability to apply sufficient pressure to tune structural energetics on this scale to make new states of matter available.

In 2010, Kolmogorov, a coauthor of the present study, and colleagues predicted additional phases in the iron–boron (Fe-B) binary phase diagram that had yet to be observed [7]. They used a high-throughput search method coupled to an evolutionary algorithm to identify new structures for which superconductivity was theoretically evaluated. Subsequently, Bialon et al. suggested that the stability of iron tetraboride (FeB4) would be enhanced under pressure, and predicted the material’s hardness [8]. In the present manuscript, Gou et al. confirmed that FeB4 can be synthesized under pressure, and furthermore, that it possess the two novel predicted properties: superconductivity and high incompressibility. In addition, though not definitive, Gou et al. obtained preliminary data that superconductivity is phonon mediated like other conventional superconductors.

While the paper by Gou et al. gives promise that theory may finally be able to guide experimentalists where to look for conventional superconductors, it’s important to remember that the predicted Tc was 5 times too large in a structure that couldn’t be synthesized at ambient pressure. Further, the situation remains much more challenging for unconventional superconductors such as the cuprates, pnictides, heavy fermion materials, and organics. The biggest issue is that strong electronic correlations alter the electronic structure in these materials over an energy scale of order 1–10eV. While modern electronic structure calculations such as dynamical mean-field theory are making progress in understanding these effects, we currently lack the ability to reliably identify an additional superconducting instability on this strongly correlated background. How these electronic correlations modify the ability to compute structural stability of compounds also remains an open question. Given that superconductivity emerges in strongly correlated systems in ways we least expect it [9], future searches would be aided by guidance on where to find such correlations and competing electronic instabilities.

Gou et al. provide an encouraging step in the quest for materials by design, but one can also hope that this is a harbinger of even more and better things to come. Leveraging advanced computational capabilities and associated materials algorithms, together with synthetic techniques that allow broader access to phase space, including metastable materials, holds the exciting potential of delivering on the vision of the Materials Genome Initiative. We look forward to this, bearing in mind the quote attributed to Yogi Berra: “It’s difficult to make predictions, especially about the future.”

Acknowledgment

Our work in this area has been supported by the Department of Energy’s Office of Basic Energy Sciences Division of Materials Science and Engineering.

References

  1. I. I. Mazin, “Superconductivity Gets an Iron Boost,” Nature 464, 183 (2010).
  2. R. Akashi and R. Arita, “Development of Density-Functional Theory for a Plasmon-Assisted Superconducting State: Application to Lithium Under High Pressures,” Phys. Rev. Lett. 111, 057006 (2013).
  3. Materials Genome Initiative for Global Competitiveness, http://www.whitehouse.gov/blog/2011/06/24/materials-genome-initiative-renaissance-american-manufacturing.
  4. H. Gou et al., “Discovery of a Superhard Iron Tetraboride Superconductor,” Phys. Rev. Lett. 111, 157002 (2013).
  5. B. T. Matthias, T. H. Geballe, and V. B. Compton, “Superconductivity,” Rev. Mod. Phys. 35, 1 (1963).
  6. M. Sakata, Y. Nakamoto, K. Shimizu, T. Matsuoka, and Y. Ohishi, “Superconducting state of Ca-VII below a critical temperature of 29 K at a pressure of 216 GPa,” Phys. Rev. B 83, 220512(R) (2011).
  7. A. N. Kolmogorov, S. Shah, E. R. Margine, A. F. Bialon, T. Hammerschmidt, and R. Drautz, “New Superconducting and Semiconducting Fe-B Compounds Predicted with an Ab Initio Evolutionary Search,” Phys. Rev. Lett. 105, 217003 (2010).
  8. A. F. Bialon, T. Hammerschmidt, R. Drautz, S. Shah, E. R. Margine, and A. N. Kolmogorov, “Possible Routes for Synthesis of New Boron-Rich Fe–B and Fe1-xCrxB4 Compounds,” Appl. Phys. Lett. 98, 081901 (2011).
  9. Z. Fisk, H. R. Ott, and J. D. Thompson, “Superconducting materials: What the record tells us,” Philos. Mag. 89, 2111 (2009).
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Indian Surgeon Helping Polio Patients Take First Steps.


India is getting close to marking its third year without a new recorded polio case, setting the stage for the country to be officially declared polio-free in January. While much has been done to immunize infants against the disease, millions of people are living with polio, unable to live a normal life.

But one surgeon is working to change that.

At one of New Delhi’s oldest hospitals, in the only designated polio ward in all of India, patients like Abida Khatoon have only one goal.

“I can stand and walk,” Khatoon said. “I just need a little help, and soon I won’t need that as well. Soon, I will be able to walk on my own.”

It took two months of surgery and rehabilitation at St. Stephen’s Hospital for Khatoon to achieve her life-long dream of being able to walk.

She and other young women in this eight-bed ward credit Dr. Mathew Varghese, an orthopedic surgeon who has devoted his entire career to restoring mobility and dignity to those left crippled by the poliovirus that invades the brain and spinal cord, causing paralysis.

“All these girls have been crawling, except for this one, all the others have been crawling,” Varghese said. “The other muscles are very weak. They have never had the opportunity to stand on their two feet. For the first time in their lives – like this girl is paralyzed at six months — she has never been able to stand on her two feet.”

As India gets closer to officially being declared polio-free, the effect of the massive immunization effort can be seen in the hospital, with Varghese now mostly treating people in their early twenties as opposed to young children some two decades ago.

In 1990, New Delhi alone saw 3,000 new polio cases. Now that number is zero.The trend is reflected here at this polio ward, where at its peak it saw 600 patients annually. Now that number is down to fewer than 200.

Rotary International has been on the frontline of India’s polio eradication efforts and helps fund reconstructive surgeries at St. Stephen’s. Former Rotary President Rajendra Saboo saw the need to give polio patients a second chance at a normal life during a trip to a village in the northern Indian state of Uttar Pradesh.

“Then another child came, also crawling,” said Saboo. “And I said ‘what is happening to these children?’ They seem to have been struck by polio. And the villagers said, ‘no, no, no, just forget them, they are dust.’”

But Rotary and Varghese did not forget them. Patients hear about the ward and travel to New Delhi from across India in hopes of correcting bent legs and feet. No one is turned away.

After weeks in the hospital, 19-year-old Abida Khartoon is getting ready to go home to her village in Uttar Pradesh.

“If I had only met Dr. Varghese earlier, I wouldn’t have had as much hardship in life,” she said. “My hands wouldn’t be so calloused [from using them to get around]. Because of him, I am doing better,” she said tearfully.

But Khartoon is not the only one brought to tears. When asked what this surgeon’s dream is — the answer was simple.

“My dream,” he asked, trying to choke back his own tears. “This ward should be empty. No polio.”

read the fill story:

http://m.voanews.com/a/1766219.html#b10g16f20b13

Bee-friendly plants put to the test


Honeybee on lavender (c) Science Photo Library

Researchers have used an experimental garden to put pollinator-friendly plants to the test.

The University of Sussex scientists counted the number of insects visiting the plants in their garden.

They say their findings show that insect-friendly plants are just as pretty, cheap and easy to grow as less pollinator-friendly varieties.

Their results are published in the Journal of Functional Ecology.

PhD student Mihail Garbuzov used 32 different varieties of popular garden plants. These included some nectar-rich and highly scented plants he thought would be attractive to insects and some that seemed to be less attractive.

While the small-scale study did not produce an exhaustive list of the best plants for pollinating insects, the team says the data has put a number on just how many more pollinators the right plants can attract.

Mr Garbuzov told the BBC: “Some of the best plants attracted approximately 100 times as many insects as the worst.

“And the plants that are attractive to insects are not more expensive, and they’re just as pretty.”

The researchers wrote in their paper that there was “great scope for making gardens and parks more insect friendly” by selecting the right plants.

Tips for insect-friendly gardening are already available from a variety of sources, but the researchers say they are largely based on “opinion and general experience”.

The aim of this study, said Prof Francis Ratnieks, from the University of Sussex, was to “put that advice on a firmer scientific footing, by gathering information about the actual number of insects visiting the flowers to collect nectar or pollen”.

Counting bees

Honeybee on a flower (c) Ethel M Villalobos
  • Bees have different colour-detection systems from humans, and can see the world in ultraviolet. This helps them to detect the flowers they pollinate and take nectar from.
  • Pollination is essential for agriculture, as well as the reproduction of non-food flowers and plants. According to the UN Food and Agriculture Organization, pollinators including bees, birds and bats are involved in more than a third of the world’s crop production.
  • Honeybees evolved to make honey as a food source for the colony. Selective breeding of European honeybees by humans has produced colonies that make excess honey for us to harvest.

The researchers gathered their data simply by visiting each of the patches of flowers every day over two summers and counting the number of insects on the flowers.

Their results did lead them to make some horticultural recommendations – they found that borage, lavender, marjoram and open-flower dahlias varieties were very good for insects.

The colourfully named bowles mauve everlasting wallflower was also very attractive to pollinators, while the least attractive flowering plant for insects was the very popular geranium.

Marjoram, the researchers say, was probably the best “all-rounder”, attracting honey bees, bumble bees, other bees, hover flies, and butterflies.

Borage was the best for honey bees and lavender and open-flowered dahlias were most attractive to bumblebees.

The team put a number of varieties of lavender to the test and found that highly bred hybrids, including some with novel colours – such as white or pink – that have been carefully bred into the plants proved the most attractive to insects.

Dr Nigel Raine, from Royal Holloway University of London, commented that with bee populations declining across the world, “we can all give bees a helping hand by planting the right flowers to give them the nectar and pollen they need”.

“This study highlights that it’s important for bee-friendly gardeners to choose what you plant with care,” he added.

“Gardeners and town planners should think carefully about the mixture of flowers they plant to ensure food is available for a wide range of bees and other important insect pollinators.

“It’s also important to cater for the needs of the rarer species and provide food at times when there might be fewer wild flowers in bloom.”

In another prior study, a team from the University of California San Diego used this ‘taste test’ to work out if bees are able to detect the scent of a flower. If the bee detects a floral scent, it will stick out its tongue.

Underwater wi-fi given test run.


University of Buffalo underwater wi-fi testing team
The team dropped two 40lb (18kg) sensors into a lake near Buffalo

Researchers have tested an “underwater wi-fi” network in a lake in an attempt to make a “deep-sea internet”.

The team, from the University of Buffalo, New York, said the technology could help detect tsunamis, offering more reliable warning systems.

They aim to create an agreed standard for underwater communications, to make interaction and data-sharing easier.

Unlike normal wi-fi, which uses radio waves, the submerged network technology utilises sound waves.

Radio waves are able to penetrate water, but with severely limited range and stability. Sound waves provide a better option – as demonstrated by many aquatic species such as whales and dolphins.

Wireless communication underwater has been possible for some time, but the problem lies in getting separate systems used by different organisations to communicate with each other.

The US National Oceanic and Atmospheric Administration (NOAA), for instance, uses acoustic waves to send data from tsunami sensors on the sea floor to buoys on the surface.

However due to infrastructure differences, this data cannot be shared quickly with other information gathered by the US Navy.

‘Unprecedented ability’

Therefore, the University of Buffalo team is attempting to create a shared standard.

“A submerged wireless network will give us an unprecedented ability to collect and analyse data from our oceans in real time,” said Tommaso Melodia, lead researcher.

“Making this information available to anyone with a smartphone or computer, especially when a tsunami or other type of disaster occurs, could help save lives.”

The test was carried out at Lake Erie, near Buffalo. The research team dropped two 40lb (18kg) sensors into the water – and were then able to use a laptop to transmit information to them.

In future, the team hopes the sensors could be used to help detect and solve environmental issues. With a shared standard, different research groups with varied equipment could potentially combine their data gathering efforts with greater ease, and in real-time.

More details of the team’s work will be presented at a conference for underwater networking to be held in Taiwan next month.

Man In India Who Claims That He Has Not Eaten or Drunk Any Liquid In 70 Years Examined By Scientists | MyScienceAcademy


Doctors and experts are baffled by an Indian man who claims not to have eaten or drunk anything for 70 years – but is still in perfect health.

A team of scientists and doctors in Sterling Hospital, in the western Indian city of Ahmedabad, are studying the claims of Prahlad Jani, a local holy man, who is over 70 years old.

He claims to have been blessed by a goddess when he was 8-years-old, which has enabled him to survive without sustenance and that he derives energy through meditation.

Most people can live without food for several weeks, with the body drawing on its fat and protein stores. But the average human can survive for only three to four days without water.

watch the small video clip.

URL: http://www.youtube.com/watch?v=FGF7EY2Ucm8

The New Deadliest Substance Known to Man Is Top Secret (For Now)


Scientists recently discovered a new type of botulinum toxin (a.k.a. botox) that they believe is the deadliest substance known to man. Because they’ve yet to discover an antitoxin, researchers won’t publish the details of gene sequence due to security concerns—a first for the scientific community. Thank God.

When scientists say this stuff is deadly, they mean it. It takes an injection of just 2 billionths of a gram or inhaling 13 billionths of a gram to kill an adult. A spoonful of the stuff in a city’s water supply could be catastrophic. The toxin, which comes from the bacterium Clostridium botulinum, blocks the chemical that makes nerves work, causing botulism and death by paralysis. In a comment accompanying a newly published journal article on the new botox, Stanford Medical School professor David Relman said the substance posed “an immediate and unusually serious risk to society.”

You’d be right to wonder: If this stuff is so dangerous, why do we have it in the first place? Well, it’s not manmade if that’s what you’re thinking. Before this new discovery, there were seven known branches on the botulinum family tree, but researchers recently found an eighth type of toxin in stool samples of an infant with botulism. It just so turns out that eighth type, known as type H, is the deadliest substance in the world. Scientists are withholding the genetic sequence so that terrorists, for instance, can’t synthesize it and do something terrible. Terrorists do like botox, too. It was one of these toxins that the Japanese cult Aum Shinrikyo tried to release in downtown Tokyo in the 1990s.

Despite the somewhat sensational nature of this latest discovery, everything is okay for now. This is, however, a rude reminder of how scientific discoveries can always be twisted into weapons of warfare. Unless we keep them secret, that is.

Estimate doubled for vCJD carriers


CJD diseased brain tissue

Twice as many Britons as previously thought could be carrying the human form of “mad cow” disease, variant CJD.

Researchers believe one in 2,000 people in the UK is a carrier of the disease linked to eating contaminated beef.

Their estimate in the BMJ comes from studying more than 32,000 samples of human tissue removed during appendix operations carried out between 2000 and 2012 at 41 hospitals.

It remains unclear if any of these carriers will ever develop symptoms.

Early predictions of a vCJD epidemic didn’t come to fruition.

To date, here have been 177 UK deaths from vCJD. Most of these occurred in the late 90s and early 2000s. There has been only one death in the last two years.

The rare, fatal disease progressively attacks the brain.

“Start Quote

Will these people develop disease and can they transmit it? There are many questions we still do not know the answers to”

Lead researcher Prof Sebastian Brandner

But it appears that relatively few who catch the infectious agent that causes the disease develop symptoms. People can be “silent” carriers for decades and not even know it.

The BMJ research identified 16 such carriers out of the thousands of appendix tissue samples studied.

Experts say many vital questions remain unanswered.

Since the link between vCJD and bovine spongiform encephalopathy (BSE), known as mad cow disease, was discovered in 1996, there have been strict controls to prevent meat from infected cattle from entering the food chain.

However, the average time it takes for the symptoms of vCJD to occur after initial infection is still unclear.

Preventing spread

This means people exposed to infected meat before the food controls were introduced continue to develop variant CJD, and may spread it to others.

Experience tells us that the disease could be transmitted from human to human via blood – in the UK, there have been three reported cases of vCJD associated with a blood transfusion.

Blood donor services take measures to ensure blood is not infected but there is no test to screen for vCJD, although scientists are working on this.

And there is currently no cure for the disease.

Prof Sebastian Brandner of University College London, who led the BMJ research, said: “We do not know what will happen.

“Will these people develop disease and can they transmit it? There are many questions we still do not know the answers to.”

Prof Richard Knight, director of the National CJD Research and Surveillance Unit in Edinburgh, said the answers might not be known for decades.

In the meantime, surveillance was key, he said.

“You can see from the data available that its likely that we will get a secondary or tertiary wave of disease but its likely that these further waves will be small.

“Future clinical cases will be pretty small in number,” he added.

Dr Graham Jackson, of the MRC Prion Unit at UCL Institute of Neurology, said: “Given the high levels of infection indicated by this research, it is now crucial we establish how many people in the UK harbour that infection in their bloodstream in order to adequately assess the risks of transmission through contaminated blood donations.

“Studies to develop new blood tests for CJD must remain a priority to assist with screening and protecting the UK blood supply.”

3D printing ‘entering the metal age’


3D printing ‘entering the metal age’ http://www.bbc.co.uk/news/science-environment-24528306

The growth of global immunisation.


http://www.bbc.co.uk/news/health-24519949

Mystery of the world’s most-kissed woman


Mystery of the world’s most-kissed woman.
http://www.bbc.co.uk/news/magazine-24534069