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ANU scientists have successfully bent light beams around an object on a two dimensional metal surface, opening the door to faster and cheaper computer chips working with light.
The international team, including three members from the Research School of Physics and Engineering at ANU, have successfully demonstrated that a tiny beam of light on a flat surface can be bent around an obstacle, and course-correct itself on the other side of that obstacle. It’s the world’s first two-dimensional demonstration of so-called ‘Airy beams’. Their paper on the subject will be published in this month’s Physical Review Letters.
“Students in science class learn that light rays travel along straight trajectories and that it can’t go around corners,” said ANU team member Professor Yuri Kivshar.
“Recently it was discovered that small beams of light can be bent in a laboratory setting, diffracting much less than a regular beam. These rays of light are called ‘Airy Beams,’ and named after the English astronomer Sir George Biddell Airy, who studied light in rainbows.
“Our team has demonstrated that these beams can also be bound on the flat surface of a chip. We also observed a fascinating property of these beams – the so-called self-healing phenomenon, where the wave recovers after passing through surface defects,” he said.
Fellow ANU team member Dr Dragomir Neshev says that this demonstration offers potential in a number of areas.
“This discovery offers some exciting possible applications, particularly in the area of communications technology where it could allow us a cheap way to manipulate light on a chip,” he said. -
The 2011 Nobel Prize in chemistry was awarded to Dan Schechtman for his discovery of quasicrystals, materials that do not have the regular lattice structure of crystalline solids. Schechtman produced quasicrystals in the laboratory in 1982, but until 2008 nobody had found a naturally occurring quasicrystal. Now researchers in Italy and the United States have examined the rock that contained these natural quasicrystals and determined it may actually be part of a meteorite.
Normal crystalline solids have atoms or molecules arranged in cubes, hexagons, or other regular repeating patterns. Quasicrystals exhibit different symmetries that never precisely repeat: pentagons, icosahedrons, and so forth. Schechtman and researchers after him produced these quasi-periodic lattices by melting materials under high pressure, then cooling them quickly in a process known as quenching.
In 2008, Luca Bindi of the Museo di Storia Naturale in Firenze, Italy approached Paul Steinhardt at Princeton University to investigate a curious rock collected in eastern Russia during the late 1970s. The researchers (including Bindi, Steinhardt, Nan Yao, and Peter Lu) found it contained naturally occurring quasicrystal grains—the first ever identified.
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Organic polymers can be used to create materials with very distinct properties (both good and bad). For example, thermoset materials resist heat and solvents, making them extremely durable and allowing them to be used in the oven. The downside is that, once they’re made, that’s it—no recycling. Thermoplastics are stable below a set temperature, but they can be melted, allowing them to be remade into new materials. Unfortunately, they don’t hold up very well to solvents.
Now, researchers are saying they’ve created a third option, one that acts like a thermoplastic at high temperatures but can hold up to most solvents. The material’s secret? An embedded catalyst that allows chemical bonds to constantly rearrange. The material’s desired properties can be tuned based on the polymer it’s made from and how much catalyst remains. (via New, recyclable plastic lets you weld pieces together with a hairdryer)
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A well-known method of making heat sinks for electronic devices is a process called sintering, in which powdered metal is formed into a desired shape and then heated in a vacuum to bind the particles together. But in a recent experiment, some students tried sintering copper particles in air and got a big surprise.
Instead of the expected solid metal shape, what they found was a mass of particles that had grown long whiskers of oxidized copper. “It was sort of serendipitous,” says Kripa Varanasi, d’Arbeloff Assistant Professor of Mechanical Engineering at MIT. “We got this crazy stuff, particles covered in nanowires,” he says.
The resulting process could turn out to be an important new method for manufacturing structures that span a range of sizes down to a few nanometers (billionths of a meter) in size. “You go in one step from solid spherical powder to very complex structures,” says Christopher Love, a mechanical engineering graduate student who is lead author on the paper. “The process is very simple, and the structures are durable,” he says. These new structures could be used for managing the flow of heat in various applications ranging from powerplants to the cooling of electronics.
Not only were the particles covered with fine wires, but the abundance of the wires turned out to be dependent on the size of the original copper particles. “We are the first to observe a size-dependent oxidation in copper,” Varanasi says. That means researchers can easily synthesize porous structures at various scales, in bulk, by selecting the particles they start out with: Particles smaller than a certain size sinter, while larger particles grow nanowires.
The discovery is reported in a paper being published in the journal RSC Nanoscale. In addition to Varanasi and Love, the paper’s authors are mechanical engineering graduate student J. David Smith and postdoc Yuehua Cui of the Laboratory for Manufacturing and Productivity.
Such hierarchical structures can be very effective for thermal management, cooling everything from microprocessors to the boilers of huge powerplants. They might even prove useful in engineered geothermal power, which holds great promise as a system for providing clean, renewable power. Because the resulting structures are so easily controlled, “you can optimize them to control phenomena taking place at different length and time scales,” Varanasi says.
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“This wall sculpture is made of and about the transition metal element Manganese (Mn). The centre of the piece represents the beautiful symmetry that is the electron shell –the orbit of the electrons around the atom nucleus. Manganese is found as a free element in the Earth’s crust, so I’ve contrasted the scientific view of the element with the energy and textures of rock formations.
This piece was constructed using stoneware clay, textured on the potter’s wheel, and hand-built. Manganese dioxide in powdered form was applied to the surface and fused to the clay in a kiln firing to 1260°C ” -Niamh Harte
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Diamond particles discovered in candle flames
Candle flames contain millions of tiny diamond particles, a university professor has discovered.
Dr Wuzong Zhou, of St Andrews University, found about 1.5 million diamond nanoparticles are created in a candle flame every second it burns.
The diamond particles are burned away in the process.
But the chemistry professor said the discovery could lead to research into how diamonds could be created more cheaply.
Dr Zhou used a new sampling technique to remove particles from the centre of the flame, which is believed to have never been done, and found it contained all four known forms of carbon.
He said: “This was a surprise, because each form is usually created under different conditions.
“This will change the way we view a candle flame forever.”
(via BBC News)
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The electromagnetic force has gotten a little stronger, gravity a little weaker, and the size of the smallest “quantum” of energy is now known a little better. The National Institute of Standards and Technology (NIST) has posted the latest internationally recommended values of the fundamental constants of nature.
The constants, which range from relatively famous (the speed of light) to the fairly obscure (Wien frequency displacement law constant) are adjusted every four years in response to the latest scientific measurements and advances. These latest values arrive on the verge of a worldwide vote this fall on a plan to redefine the most basic units in the International System of Units (SI), such as the kilogramand ampere, exclusively in terms of the fundamental constants.
The values are determined by the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants, an international group that includes NIST members. The adjusted values reflect some significant scientific developments over the last four years.
(via The constants they are a changin’: NIST posts latest adjustments to fundamental figures)
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This seems a lot easier than having to re-grow your jawbone in your abdomen, but it’s really a question of scale.
There was a time when people who lost teeth as adults were simply out of luck. When we developed dentures and dental implants, the situation improved for those who are dentally deficient. But dentures are uncomfortable, and the procedure for installing dental implants is rather barbaric. Researchers at Columbia University Medical Center have devised a new method for regrowing missing teeth in adults – right in their own mouths.
The technique, developed by Dr. Jeffrey Mao, involves placing a tooth “scaffolding” made of natural materials in the patient’s mouth and directing stem cells to develop into a new, healthy tooth. By growing a real tooth right in the patient’s mouth, the patient’s healing time is greatly reduced when compared to that required after dental implants, and the chance of rejection by the patient’s body is almost eliminated
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Water-Air Interface Barely There
Where sea meets sky, there are lots of water molecules with an identity crisis. About a quarter of the H2O in water’s uppermost layer can’t decide whether to be liquid or gas: One hydrogen atom stays in the drink while the other pokes up, vibrating in the air.
This layer of molecular ambiguity is extremely thin and has little or no effect on the water below it, new data reported June 9 in Nature show. Right beneath the liquid’s surface, water molecules go about their business just as if the air weren’t there.
That may seem like a dull discovery, but the find is important, says Pavel Jungwirth of the Academy of Sciences of the Czech Republic in Prague, who wrote a commentary on the work in the same issue of Nature. “In some ways this is a negative result,” Jungwirth says. “Sometimes a negative result can be very positive.”
Insights into the behavior of water molecules at this superthin surface layer may give scientists a better understanding of the bonding and behavior of pollutants or other compounds intermingling at the surface. The new data might also improve models of water’s interactions with the atmosphere and within cells, says physical chemist Dennis Hore of University of Victoria in British Columbia, who was not involved in the study.
The finding that water molecules with one hydrogen waving in the air have little effect on the arrangement of all the H2O below refutes an idea that’s been bandied about for ages — that water molecules in bulk below will fall into lockstep, organizing themselves into orderly layers, says Jungwirth.
“After the first layer, it’s all over,” he says. “A lot of people still subscribe to this long-range idea. But this shows very clearly that you don’t have long-range order in water.”
(Source: sciencenews.org)
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New elastic polymer self-heals in just one minute
Self-healing polymers are extremely sought after by scientists, as they have many useful—not to mention lucrative—applications. Back in 2009, we reported a polyurethane-based polymeric material that heals itself in roughly an hour when exposed to UV light. That particular polymer, made by Biswajit Ghosh and Marek W. Urban, would be useful as a protective coating for phones, cars, etc. It worked based on the principle of having a reactive chemical component that would split open when physically damaged to create two reactive ends that can then covalently link together under UV light to repair itself.
In a recent issue of Nature, Mark Burnworth and his colleagues report a different type of self-healing material, one that can repair itself in about a minute under UV light.
(via Ars Technica)
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Atomic bonding
In January 1999, scientists from Arizona State University produced the first-ever real-time images of atomic bonding. The team used x-ray scattering and electron diffraction techniques to capture direct images of the electronic bonds that hold together atoms of oxygen and copper in a compound called cuprite.
In this image—which is real and not a computer simulation—you can see the dumbbell-shaped clouds of electrons that are shared between copper and oxygen atoms in cuprite (Cu20).
This image represents the first time the covalent bonds between atoms have ever been “seen” in cuprite. The invisible nuclei of the copper atoms are at the center of the dumbbells. Nuclei of the oxygen atoms are at the center and corners of the superimposed cube. The fuzzy green clouds are less-defined electron clouds representing covalent bonds between the copper atoms.
Source: NSF
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Not just a funny website about science, this is possibly the funniest fucking website concerning science I’ve ever read.
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What Happens When You Mix Every Single Element Together at Once?
The entire periodic table mixed together is one of those awesome what if scenarios so out there that not even scientists know for sure. Their guess? Anything from “a quark-gluon plasma” (!) to “flaming plutonium.” Do not try at home!
Luckily, you could never try this at home, as NYU theoretical chemist Mark Tuckerman says attempting to fuse all of the known elements would require “118 [Large Hadron Colliders]-one to accelerate each element.” Sounds a bit pricy! And even then, the results would be fleeting. Quark-gluon plasma, the cosmic stuff theorized to have existed immediately after the Big Bang, “would last for a fraction of a second before degrading.” Bummer.
Part of the reason it’s so hard to predict what would go down is due to the unpredictably reactive nature of the elements. Random stuff happens depending on which elements happen to be closer to which. “You could run this experiment 100 times and get 100 different combinations,” says Tuckerman. One hundred experiments! One hundred and eighteen Large Hadron Colliders! And to what end, besides some split second primordial plasma?
If you tried combining powdered forms of all 118 elements in a sealed container, it wouldn’t be pretty—”All hell would break loose,” says John Stanton, director of the Institute for Theoretical Chemistry at the University of Texas. “Flaming plutonium is a very bad thing. Inhaling airborne radioactive material can cause rapid death.” But after some temporary terror and waves of flaming radioactive chaos, it’d get pretty boring—just a bunch of lame old carbon monoxide and carbon dioxide. A lot of the elements wouldn’t even react. “Thermodynamics wins again,” Stanton smirks. Damn you, laws of the physical world!
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Why Life Is Physics, Not Chemistry
The idea that life boils down to chemistry is being usurped by a much more ambitious idea, says two of the world’s leading biophysicists.
One of the more important examples in 20th centruy science is that biology is the result of evolution, not the other way round. By that way if thinking, evolution is a process, an algorithm even; albeit one with unimaginable power. Exploit evolution and there is little you cannot achieve.
In recent years, computer scientists have begun to exploit evolution’s amazing power. One thing they have experienced time and time again is evolution’s blind progress. Put a genetic algorithm to work and it will explore the evolutionary landscape, looking for local minima. When it finds one, there is no knowing whether it is the best possible solution of whether it sits within touching distance of an evolutionary abyss that represents a solution of an entirely different order of magnitude.
That hints at the possibility that life as it has evolved on Earth is but a local minima in a vast landscape of evolutionary possibilities. If that’s the case, biologists are studying a pitifully small fraction of something bigger. Much bigger.
Today, we get an important insight into this state of affairs thanks to a fascinating paper by Nigel Goldenfeld and Carl Woese at the University of Illinois. Goldenfeld is a physicist by training while Woese, also a physicist, is one of the great revolutionary figures in biology. In the 1970s, he defined a new kingdom of life, the Archae, and developed a theory of the origin of life called the RNA world hypothesis, which has gained much fame or notoriety depending on your viewpoint.
Together they suggest that biologists need to think about their field in a radical new way: as a branch of condensed matter physics. Their basic conjecture is that life is an emergent phenomena that occurs in systems that are far out of equilibrium. If you accept this premise, then two questions immediately arise: what laws describe such systems and how are we to get at them.
Goldenfeld and Woese say that biologists’ closed way of thinking on this topic is embodied by the phrase: all life is chemistry. Nothing could be further from the truth, they say.
They have an interesting analogy to help press their case: the example of superconductivity…According to Goldenfeld and Woese, life is like superconductivity. It is an emergent phenomenon and we need to understand the fundamental laws of physics that govern its behaviour. Consequently, only a discipline akin to physics can reveal such laws and biology as it is practised today does not fall into this category.
(Via/Tip of the hat to unknownskywalker)
(Source: technologyreview.com)
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![Designer optoelectronics - quantum mechanics for new materials
European researchers have combined computer modelling of quantum mechanics and precision fabrication processes to create novel transparent conductive oxides made to order for a wide range of scientific and consumer applications.
Imagine specifying exactly how you want a new material to behave, handing those specs to an engineer, and getting back a brand-new material with exactly the qualities you need.
That’s what the EU-funded project NATCO (for Novel Advanced Transparent Conductive Oxides) set out to do. They designed and developed novel transparent conductive oxides (TCOs) to exacting specifications by applying quantum mechanics to predict a material’s optical and electronic properties, fabricating it, and checking their results experimentally.
The results? Completely new TCOs with a wide range of potential applications in sensors, solar cells, smart windows, and dozens of other scientific, commercial and consumer products.
“In the field of optoelectronics, there’s a great need to find better and less costly materials,” says Guy Garry, coordinator of the NATCO project. “The route we took was first to make calculations to find the best way to get the properties that we needed. When we fabricated these materials, we found that their properties were the same as we had calculated.”
This rational design process - using first principles to calculate the conductivity and transparency of novel materials before fabricating them - allowed the researchers to develop new TCOs with enhanced performance rapidly and efficiently.
“We were able to make these calculations very quickly, which allowed us to enhance existing properties and find new properties,” says Dr Garry.
Brand new optoelectronic material
TCOs - materials that combine transparency and conductivity, qualities that are not usually found together - have multiple applications. As sensors, photovoltaics, light emitting devices and electronically controllable films, they are found in scientific instruments, DVDs, digital cameras, mobile phones, computer displays and hundreds of other products.
Until recently, most TCOs relied on a material called ITO, an oxide of indium which is doped - slightly modified - by the addition of a small quantity of tin. ITOs have proved useful, but, Dr Garry says, suffer from two drawbacks. Their transparency is not very good, especially in the near-infrared range, and indium is in short supply and very expensive.
The NATCO team decided to explore a completely different material, strontium cuprate doped with varying amounts of barium. Copper, barium and strontium are far more abundant and much less expensive than indium.
Extensive calculations applying quantum mechanics predicted that, by doping strontium cuprate with a few percent by weight of barium, the researchers could create precisely the materials they wanted, combining good electrical conductivity and optical transparency.
Fabricating the new materials was a challenge. At first the materials were fabricated in the form of bulk ceramics and then, for actual applications, thin layers were deposited on suitable substrates.
In the end, the researchers settled on two deposition techniques - pulsed laser deposition (PLD) and metal organic chemical deposition (MOCVD).
In PLD, a burst of laser light vaporises the material to be deposited, creating a thin film on a glass or silicon surface. It allows precise control, but can’t be used on large surfaces.
MOCVD uses organic chemistry to create gasses that deposit the desired material onto a surface. It is a more complicated procedure, but has the advantage of being able to be scaled up to coat large surfaces.
Once they had fabricated the materials, the researchers could test how well their electrical and optical properties matched the predicted values. “This was the first time that this kind of work was done on TCOs,” says Dr Garry.
Multiple applications in the works
Today, one of the most promising applications of NATCO’s new TCOs is in the area of exquisitely sensitive biosensors. These devices, with the tongue-twisting title of Elecro-Chemical Optical Waveguide Light-mode Spectroscopy Sensors, are fabricated by the Hungarian consortium partner MicroVacuum. They work by measuring how light is bent as it passes through a very thin optical wave guiding layer.
When target molecules bind to the surface of the detector, they change the TCO´s refractive index, which in turn changes how light passes through the waveguide. Applying a varying electric field through the layer provides further information about the molecules.
“We got very good results on these devices using our strontium cuprate materials,” says Dr Garry. He foresees a wide range of applications for these sensors, especially in the area of proteomics.
The project’s commercial and academic partners are pursuing other applications for NATCO’s designer TCOs, including more efficient solar cells, smart windows, novel light sources, and materials to modulate laser light.
For Dr Garry, the results of the project’s first-principles modelling and precision fabrication approach are so encouraging that he plans to apply them to more challenging problems.
“We’d like to use this route to study more complicated materials,” he says. “For example, to look at ferro-electricity to see why some materials with the same structure are ferro-electric while others are not.”
More information: NATCO project - http://www.trt.tha … co/index.htm
Provided by ICT Results (news : web)
[Source: Phys.Org]](http://25.media.tumblr.com/tumblr_l7ymuoMaBs1qzy64do1_250.jpg)
Designer optoelectronics - quantum mechanics for new materials
European researchers have combined computer modelling of quantum mechanics and precision fabrication processes to create novel transparent conductive oxides made to order for a wide range of scientific and consumer applications.
Imagine specifying exactly how you want a new material to behave, handing those specs to an engineer, and getting back a brand-new material with exactly the qualities you need.
That’s what the EU-funded project NATCO (for Novel Advanced Transparent Conductive Oxides) set out to do. They designed and developed novel transparent conductive oxides (TCOs) to exacting specifications by applying quantum mechanics to predict a material’s optical and electronic properties, fabricating it, and checking their results experimentally.
The results? Completely new TCOs with a wide range of potential applications in sensors, solar cells, smart windows, and dozens of other scientific, commercial and consumer products.
“In the field of optoelectronics, there’s a great need to find better and less costly materials,” says Guy Garry, coordinator of the NATCO project. “The route we took was first to make calculations to find the best way to get the properties that we needed. When we fabricated these materials, we found that their properties were the same as we had calculated.”
This rational design process - using first principles to calculate the conductivity and transparency of novel materials before fabricating them - allowed the researchers to develop new TCOs with enhanced performance rapidly and efficiently.
“We were able to make these calculations very quickly, which allowed us to enhance existing properties and find new properties,” says Dr Garry.
Brand new optoelectronic material
TCOs - materials that combine transparency and conductivity, qualities that are not usually found together - have multiple applications. As sensors, photovoltaics, light emitting devices and electronically controllable films, they are found in scientific instruments, DVDs, digital cameras, mobile phones, computer displays and hundreds of other products.
Until recently, most TCOs relied on a material called ITO, an oxide of indium which is doped - slightly modified - by the addition of a small quantity of tin. ITOs have proved useful, but, Dr Garry says, suffer from two drawbacks. Their transparency is not very good, especially in the near-infrared range, and indium is in short supply and very expensive.
The NATCO team decided to explore a completely different material, strontium cuprate doped with varying amounts of barium. Copper, barium and strontium are far more abundant and much less expensive than indium.
Extensive calculations applying quantum mechanics predicted that, by doping strontium cuprate with a few percent by weight of barium, the researchers could create precisely the materials they wanted, combining good electrical conductivity and optical transparency.
Fabricating the new materials was a challenge. At first the materials were fabricated in the form of bulk ceramics and then, for actual applications, thin layers were deposited on suitable substrates.
In the end, the researchers settled on two deposition techniques - pulsed laser deposition (PLD) and metal organic chemical deposition (MOCVD).
In PLD, a burst of laser light vaporises the material to be deposited, creating a thin film on a glass or silicon surface. It allows precise control, but can’t be used on large surfaces.
MOCVD uses organic chemistry to create gasses that deposit the desired material onto a surface. It is a more complicated procedure, but has the advantage of being able to be scaled up to coat large surfaces.
Once they had fabricated the materials, the researchers could test how well their electrical and optical properties matched the predicted values. “This was the first time that this kind of work was done on TCOs,” says Dr Garry.
Multiple applications in the works
Today, one of the most promising applications of NATCO’s new TCOs is in the area of exquisitely sensitive biosensors. These devices, with the tongue-twisting title of Elecro-Chemical Optical Waveguide Light-mode Spectroscopy Sensors, are fabricated by the Hungarian consortium partner MicroVacuum. They work by measuring how light is bent as it passes through a very thin optical wave guiding layer.
When target molecules bind to the surface of the detector, they change the TCO´s refractive index, which in turn changes how light passes through the waveguide. Applying a varying electric field through the layer provides further information about the molecules.
“We got very good results on these devices using our strontium cuprate materials,” says Dr Garry. He foresees a wide range of applications for these sensors, especially in the area of proteomics.
The project’s commercial and academic partners are pursuing other applications for NATCO’s designer TCOs, including more efficient solar cells, smart windows, novel light sources, and materials to modulate laser light.
For Dr Garry, the results of the project’s first-principles modelling and precision fabrication approach are so encouraging that he plans to apply them to more challenging problems.
“We’d like to use this route to study more complicated materials,” he says. “For example, to look at ferro-electricity to see why some materials with the same structure are ferro-electric while others are not.”
More information: NATCO project - http://www.trt.tha … co/index.htm
Provided by ICT Results (news : web)
[Source: Phys.Org]
