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Nanoscale optical switch breaks miniaturization barrier

Nanoscale optical switch breaks miniaturization barrier | Research | Scoop.it

An ultra-fast and ultra-small optical switch has been invented that could advance the day when photons replace electrons in the innards of consumer products ranging from cell phones to automobiles.

The new optical device can turn on and off trillions of times per second. It consists of individual switches that are only one five-hundredths the width of a human hair (200 nanometers) in diameter. This size is much smaller than the current generation of optical switches and it easily breaks one of the major technical barriers to the spread of electronic devices that detect and control light: miniaturizing the size of ultrafast optical switches.

The new device was developed by a team of scientists from Vanderbilt University, University of Alabama-Birmingham, and Los Alamos National Laboratory and is described in the Mar. 12 issue of the journal Nano Letters.

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A New Way to Tune X-ray Laser Pulses

A New Way to Tune X-ray Laser Pulses | Research | Scoop.it

A new system at SLAC National Accelerator Laboratory's X-ray laser narrows a rainbow spectrum of X-ray colors to a more intense band of light, creating a much more powerful way to view fine details in samples at the scale of atoms and molecules.

“It’s like going from regular television to HDTV,” said Norbert Holtkamp, SLAC deputy director and leader of the lab's Accelerator Directorate.

Designed and installed at SLAC's Linac Coherent Light Source (LCLS) in collaboration with Lawrence Berkeley National Laboratory and Switzerland’s Paul Scherrer Institute, it is the world’s first “self-seeding” system for enhancing lower-energy or "soft" X-rays.

Scientists had to overcome a series of engineering challenges to build it, and it is already drawing international interest for its potential use at other X-ray free-electron lasers.

"Because this system delivers more intense soft X-ray light at the precise energy we want for experiments, we can make measurements at a far faster rate," said Bill Schlotter, an LCLS staff scientist. "It will open new possibilities, from exploring exotic materials and biological and chemical samples in greater detail to improving our view of the behavior of atoms and molecules.”

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Patterns of particles generated by surface charges

Patterns of particles generated by surface charges | Research | Scoop.it

Tuning the material structure at the nanoscale level can be really hard to achieve – but what if we had small particles, which assemble all by themselves, creating the required structure? At the Vienna University of Technology (TU Wien), the phenomenon of self-assembly is being investigated by studying inhomogeneously charged particles. Depending on different parameters, they can form gel-like or crystal-like structures. This kind of self-assembly holds great promise for nanotechnology.

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Diagnosing diseases in real time with smartphones

Diagnosing diseases in real time with smartphones | Research | Scoop.it

Smartphones are capable of giving us directions when we're lost, sending photos and videos to our friends in mere seconds, and even helping us find the best burger joint in a three-mile radius. But University of Houston researchers are using smartphones for another very important function: diagnosing diseases in real time.

The researchers are developing a disease diagnostic system that offers results that could be read using only a smartphone and a $20 lens attachment.

The system is the brainchild of Jiming Bao, assistant professor of electrical and computer engineering, and Richard Willson, Huffington-Woestemeyer Professor of Chemical and Biomolecular Engineering. It was created through grants from the National Institutes of Health and The Welch Foundation, and was featured in February in ACS Photonics.

This new device, like essentially all diagnostic tools, relies on specific chemical interactions that form between something that causes a disease – a virus or bacteria, for example – and a molecule that bonds with that one thing only, like a disease-fighting antibody. A bond that forms between a strep bacteria and an antibody that interacts only with strep, for instance, can support an ironclad diagnosis.

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Phosphorene introduced as graphene alternative

Phosphorene introduced as graphene alternative | Research | Scoop.it

Phosphorus has joined carbon as the only elements to be separated into sheets each a single atom thick,researchers announced March 7 at a meeting of the American Physical Society. The newly fabricated ultrathin material, dubbed phosphorene, could prove superior to its popular carbon counterpart for use in next-generation electronics.

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Too many electrons at the lithiation front in silicon are a problem

Too many electrons at the lithiation front in silicon are a problem | Research | Scoop.it

Ubiquitous but frustrating, lithium-ion batteries fade because the materials lose their structure in response to charging and discharging. This structural change is closely related to the formation of electron-rich regions within the electrode, according to scientists at Pacific Northwest National Laboratory (PNNL), the University of Electronic Science and Technology of China, Northwestern University, and Rensselaer Polytechnic Institute. The team used experiments and molecular simulations to show that the electron-rich region causes silicon bonds to break. The bond breakage transforms crystalline silicon into an amorphous alloy of lithium and silicon.

"It was absolutely unclear what was going on, although a lot of papers described how inserting lithium ions into materials leads to amorphization," said Dr. Fei Gao, a chemical physicist and a corresponding author on the study. "We propose that local electron-rich conditions induce amorphization."

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Boron gets a nano refresh: Scientists find stable 2D structures with unique properties

Boron gets a nano refresh: Scientists find stable 2D structures with unique properties | Research | Scoop.it

The National Nanotechnology Initiative defines nanotechnology as the understanding and control of matter at the nanoscale, at dimensions of approximately 1 and 100 nanometers, where unique phenomena enable novel applications. Nanotechnology is taking the world by storm, revolutionizing the materials and devices used in many applications and products. That's why a finding announced by Xiang-Feng Zhou and Artem R. Oganov, Group of Theoretical Crystallography in the Department of Geosciences, are so significant.

The paper, "Semimetallic Two-Dimensional Boron Allotrope with Massless Dirac Fermions," was published on February 27 in Physical Review Letters. The lead author is Oganov's postdoc at Stony Brook, Xiang-Feng Zhou, who is also an Associate Professor at Nankai University in Tianjin, China.

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Engineering team increases power efficiency for future computer processors

Engineering team increases power efficiency for future computer processors | Research | Scoop.it

Have you ever wondered why your laptop or smartphone feels warm when you're using it? That heat is a byproduct of the microprocessors in your device using electric current to power computer processing functions—and it is actually wasted energy.

Now, a team led by researchers from the UCLA Henry Samueli School of Engineering and Applied Science has made major improvements in computer processing using an emerging class of magnetic materials called "multiferroics," and these advances could make future devices far more energy-efficient than current technologies.

With today's device microprocessors, electric current passes through transistors, which are essentially very small electronic switches. Because current involves the movement of electrons, this process produces heat—which makes devices warm to the touch. These switches can also "leak" electrons, making it difficult to completely turn them off. And as chips continue to get smaller, with more circuits packed into smaller spaces, the amount of wasted heat grows.

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Researchers use atomic layer deposition to grow bimetallic nanoparticles

Researchers use atomic layer deposition to grow bimetallic nanoparticles | Research | Scoop.it

Since the dawn of the Bronze Age, people have appreciated the advantages of using alloys rather than single metals to make better materials. Recently, scientists have discovered a recipe for making tiny two-metal structures that could similarly expand the forefront of materials science.

Bimetallic nanoparticles – tiny grains a few dozen to hundreds of atoms in size – hold tremendous promise as catalysts for a number of different applications, according to Jeffrey Elam, a chemist at the U.S. Department of Energy's Argonne National Laboratory. However, until now researchers lacked a precise and flexible general method for creating them.

According to Elam, traditional methods lack the precision to make a batch of purely bimetallic nanoparticles. Instead, they produce a mixture of both bimetallic and monometallic nanoparticles, and these different nanoparticles have different chemical properties.

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Metal nanotubes make for better batteries

Metal nanotubes make for better batteries | Research | Scoop.it

Researchers in the US have taken an important step towards understanding exactly how single-walled carbon nanotubes (SWCNTs) boost the performance of lithium-ion batteries. The team found that metallic SWCNTs are able to accommodate more lithium atoms than semiconducting SWCNTs, which could lead to better performance. The research also reveals how semiconducting SWCNTs could be made to take up more lithium. The work could have a broad practical impact because lithium-ion batteries are used in a range of portable electronic devices.

SWCNTs are frequently employed as additives in lithium-ion batteries to improve the lifetime of the battery and its charge and discharge rates. However, SWCNTs come in two electronic flavours – metallic and semiconducting – and it was not clear whether both types were boosting performance or if one flavour was responsible for the bulk of the improvement.

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Superabsorbing Design May Lower Manufacturing Cost of Thin Film Solar Cells

Superabsorbing Design May Lower Manufacturing Cost of Thin Film Solar Cells | Research | Scoop.it

Researchers from North Carolina State University have developed a “superabsorbing” design that may significantly improve the light absorption efficiency of thin film solar cells and drive down manufacturing costs.

The superabsorbing design could decrease the thickness of the semiconductor materials used in thin film solar cells by more than one order of magnitude without compromising the capability of solar light absorption.

“State-of-the-art thin film solar cells require an amorphous silicon layer that is about 100 nanometers (nm) thick to capture the majority of the available solar energy,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and senior author of a paper describing the work. “The structure we’re proposing can absorb 90 percent of available solar energy using only a 10 nm thick layer of amorphous silicon.

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Nanocatalysts for Fuel Cells Exceed Targets Set for 2017

Nanocatalysts for Fuel Cells Exceed Targets Set for 2017 | Research | Scoop.it

Researchers at the U.S. Department of Energy (DOE) Lawrence Berkeley National Laboratory and Argonne National Laboratory (ANL) have developed bimetallic nanocatalysts that are an order of magnitude higher in activity than the 2017 target set for fuel cells by the U.S. Department of Energy (DOE).

This development marks a very long effort by researchers around the world to find some way to apply nanomaterials to fuel cells. 

One weak point of fuel cells that nanomaterials could exploit was thought to be the platinum that is used as a catalyst in the system's anode  for oxidizing hydrogen and turning it into protons and electrons. Of course, platinum is a precious metal and was seen as a cost point in the fuel cell. However, it’s not been entirely clear that the cost of platinum catalysts has been a major factor in slowing the adoption of fuel cells.

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Physicists solve 20-year-old debate surrounding glassy surfaces

Physicists solve 20-year-old debate surrounding glassy surfaces | Research | Scoop.it

University of Waterloo physicists have succeeded in measuring how the surfaces of glassy materials flow like a liquid, even when they should be solid.

A series of simple and elegant experiments were the solution to a problem that has been plaguing condensed matter physicists for the past 20 years.

Understanding the mobility of glassy surfaces has implications for the design and manufacture of thin-film coatings and also sets practical limits on how small we can make nanoscale devices and circuitry.

The work is the culmination of a project carried out by a research team led by Professor James Forrest and doctoral student Yu Chai from the University of Waterloo as well as researchers from École Superieure de Physique et de Chimie Industrielles in France and McMaster University.

Their groundbreaking work was published in the prestigious scientific journal, Science, this week.

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Graphene-like iron made in the lab - physicsworld.com

Graphene-like iron made in the lab - physicsworld.com | Research | Scoop.it

Atom-thick layers of iron have been made in the tiny holes of a perforated piece of free-standing graphene. The work was done by an international team, which has also done calculations that suggest the new material has some potentially useful exotic properties, such as a large magnetic moment. However, the team believes the 2D structure becomes thermodynamically unstable when it is more than 12 atoms wide: a problem that would have to be overcome before the material could be put to work in practical applications such as magnetic data storage.

At first glance, a free-standing 2D metal seems impossible. This is because the bonding between atoms in a metal is mediated by conduction electrons, which are free to move in any direction. As a result, metals tend to have 3D crystal structures and no tendency to form planar sheets. This is unlike crystalline carbon, which is held together by highly directional covalent bonds that allow free-standing atom-thick sheets of graphene to exist. While single epitaxial layers of metal atoms can be created on a substrate, these are not true 2D materials because the atoms are bonded to the underlying structure.

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Nanomolecular origami boxes hold big promise for energy storage

Nanomolecular origami boxes hold big promise for energy storage | Research | Scoop.it

If you think your origami skills can't be beat – try this: (1) use the world's thinnest material, (2) make the origami fold and unfold itself, and (3) pack into your miniscule origami box enough hydrogen atoms to exceed future U.S. goals for hydrogen energy storage devices. Researchers from the University of Maryland have done all three. 

Graphene is the world's thinnest material, just one atom thick. Mechanical engineers Shuze Zhu and Teng Li have found that they can make tiny squares of graphene fold into a box, which will open and close itself in response to an electric charge.

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Atomically Thin Solar Cells

Atomically Thin Solar Cells | Research | Scoop.it

It does not get any thinner than this: The novel material graphene consists of only one atomic layer of carbon atoms and exhibits very special electronic properties. As it turns out, there are other materials too, which can open up intriguing new technological possibilities if they are arranged in just one or very few atomic layers. Researchers at the Vienna University of Technology have now succeeded for the first time in creating a diode made of tungsten diselenide. Experiments show that this material may be used to create ultrathin flexible solar cells. Even flexible displays could become possible.

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Scientists build thinnest-possible LEDs to be stronger, more energy efficient

Scientists build thinnest-possible LEDs to be stronger, more energy efficient | Research | Scoop.it

Most modern electronics, from flat-screen TVs and smartphones to wearable technologies and computer monitors, use tiny light-emitting diodes, or LEDs. These LEDs are based off of semiconductors that emit light with the movement of electrons. As devices get smaller and faster, there is more demand for such semiconductors that are tinier, stronger and more energy efficient. 

University of Washington scientists have built the thinnest-known LED that can be used as a source of light energy in electronics. The LED is based off of two-dimensional, flexible semiconductors, making it possible to stack or use in much smaller and more diverse applications than current technology allows.

"We are able to make the thinnest-possible LEDs, only three atoms thick yet mechanically strong. Such thin and foldable LEDs are critical for future portable and integrated electronic devices," said Xiaodong Xu, a UW assistant professor in materials science and engineering and in physics.

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Bone Replacements and Heart Monitors Spur Health Revolution in Open Source 3D Printing

Bone Replacements and Heart Monitors Spur Health Revolution in Open Source 3D Printing | Research | Scoop.it

The evolution of 3D printing has moved quickly and it is now poised to alter every aspect of our lives and health. Thousands of Europeans are enjoying 3D-printed metal orthopaedic implants to support or replace missing bones and, in the US, thousands more have benefited from 3D printing used by dentists. Most people that need hearing aids have custom 3D-printed devices comfortably resting in their ears now.

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Observed live with X-ray laser: Electricity controls magnetism

Observed live with X-ray laser: Electricity controls magnetism | Research | Scoop.it

Researchers from ETH Zurich and the Paul Scherrer Institute PSI demonstrate how the magnetic structure can be altered quickly in novel materials. The effect could be used in efficient hard drives of the future. 

Data on a hard drive is stored by flipping small magnetic domains. Researchers from the Paul Scherrer Institute PSI and ETH Zurich have now changed the magnetic arrangement in a material much faster than is possible with today's hard drives. The researchers used a new technique where an electric field triggers these changes, in contrast to the magnetic fields commonly used in consumer devices. This method uses a new kind of material where the magnetic and electric properties are coupled. Applied in future devices, this kind of strong interaction between magnetic and electric properties can have numerous advantages. For instance, an electrical field can be generated more easily in a device than a magnetic one. In the experiment, the changes in magnetic arrangement took place within a picosecond (a trillionth of a second) and could be observed with x-ray flashes at the American x-ray laser LCLS. The flashes are so short that you can virtually see how the magnetisation changes from one image to the next - similar to how we are able to capture the movement of an athlete with a normal camera in a series of images with a short exposure time. In future, such experiments should also be possible at PSI's new research facility, the x-ray laser SwissFEL.

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Researchers discover new group of quasicrystals

Researchers discover new group of quasicrystals | Research | Scoop.it

A team of researchers working at the university of Notre Dame has discovered a whole new group of quasicrystals. In their paper published in the journalNature, the team describes how they accidently created a new kind of quasicrystal as part of a series of experiments designed to learn more about electron distribution in ferrocenecarboxylic acids.

Quasicrystals are groups of molecules bonded together in structures that resemble crystals in that they are organized, but unlike crystals, the structures are not nearly as uniform. In fact, they are quite the opposite—though they are locally symmetric, they lack any sort of long distance periodicity. Because of their chaotic nature, quasicrystalstend to feel slippery to the touch, which is why they have been used to coat the surface of non-stick frying pans. The first quasicrystal was made, also by accident, in 1982, by Daniel Shechtman (who later won a Nobel prize for his work). Since then many more of them have been made in various labs, (one was even found to exist in a meteorite) though most of them have had one thing in common, they were all formed from two or three metal alloys.

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Graphene Flakes Bring Higher Efficiencies to Polymer Solar Cells

Graphene Flakes Bring Higher Efficiencies to Polymer Solar Cells | Research | Scoop.it

The hunt by researchers for applications of graphene in photovoltaics has been, for the most part, limited to serving as a replacement to indium tin oxide (ITO), which is used as the transparent electrodes in organic solar cells. That started to change last year when researchers started to look at the potential of graphene in the conversion and conduction layers of solar cells.

Now researchers at the University of Cincinnati are experimenting withadding a small amount of graphene flakes to polymer-blend bulk-heterojunction (BHJ) solar cells and are finding that it improves the conversion efficiency of the cells significantly. The semiconducting part of a BHJ solar cells is made from two different materials—an electron donor and an acceptor. Light forms excitons at their interface, which separate into holes and the electrons producing a voltage. In the work performed by the Cincinnati researchers, they have discovered that they can increase the ratio of electron donors to electron acceptors to boost the energy absorbed by the cell.

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Researchers create stable 2-D electron gas in strontium titanate, open door to new kind of electronics

Researchers create stable 2-D electron gas in strontium titanate, open door to new kind of electronics | Research | Scoop.it

Usually, microelectronic devices are made of silicon or similar semiconductors. Recently, the electronic properties of metal oxides have become quite interesting. These materials are more complex, yet offer a broader range of possibilities to tune their properties. An important breakthrough has now been achieved at the Vienna University of Technology: a two dimensional electron gas was created in strontium titanate. In a thin layer just below the surface electrons can move freely and occupy different quantum states.

Strontium titanate is not only a potential future alternative to standard semiconductors, it could also exhibit interesting phenomena, such as superconductivity, thermoelectricity or magnetic effects that do not occur in the materials that are used for today's electronic devices.

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Using colour for clues

Using colour for clues | Research | Scoop.it

The ability to locate and count small numbers of impurity atoms could lead to advances in modern electronics and optical fiber communication networks.

In research published today inPhysical Review Letters, physicists from Monash University, the University of Melbourne and TU Graz, Austria, show a method called spectrum imaging can be used to measure atom concentrations at atomic resolution. 

By using spectrum images to visualise where atoms are and how they are bonded, scientists will gain further insight into the properties of new materials. Spectrum imaging provides a digital image encoding this complex information through colour.

Co-author Dr Scott Findlay, of Monash University’s School of Physics, said the technique could be a useful tool to characterise new materials.

“When probed with an electron beam, atoms give that beam an energy spectrum in a way that is like adding colour. Distinct atomic species add distinctive colours,” Dr Findlay said.

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GE and partners developing undersea pipeline x-ray technology

GE and partners developing undersea pipeline x-ray technology | Research | Scoop.it

General Electric and partners BP and marine engineering company Oceaneering have jointly adapted existing medical x-ray machines to crawl along undersea pipelines looking for cracks or other problems.

GE is of course a world leader in x-ray technology, mostly for medical applications. Other uses are for scanning pipes and other structures (airplane wings, bridge supports, etc.). Until now, however, there has not been a way to use existing x-ray devices to scan pipelines sitting on the floor of the ocean for defects (they don't actually sit on the ocean floor, they are held slightly above it). In this new effort, researchers from the company's healthcare and oil and gas subsidiaries, along with the outside partners began with an existing medical x-ray machine, then modified it to be able to withstand the brutal environment that exists at the bottom of an ocean (300 atmospheres of pressure and 40 degree temperatures, for example). There is also the saltwater and constant motion of underwater currents to deal with.

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A step closer to a photonic future

A step closer to a photonic future | Research | Scoop.it

The future of computing may lie not in electrons, but in photons – that is, in microprocessors that use light instead of electrical signals. But these so-called photonic devices are typically built using customized methods that make them difficult and expensive to manufacture.
Now, engineers have demonstrated that low power photonic devices can be fabricated using standard chip-making processes. They have achieved what the researchers dub a major milestone in photonic technology. The work will be presented at this year's OFC Conference and Exposition, being held March 9-13 in San Francisco.
The two new devices – a modulator and a tunable filter – are as energy-efficient as some of the best devices around, the researchers say, and were built using a standard IBM advanced Complementary Metal-Oxide Semiconductor (CMOS) process – the same chip-making process used to build many commercially available chips, some of which are found in Sony's Playstation 3 and also in Watson, the supercomputer that won Jeopardy! in 2011.
"As far as we know, we're the first ones to get silicon photonics natively integrated into an advanced CMOS process and to achieve energy efficiencies that are very competitive with electronics," said Mark Wade of the University of Colorado, Boulder, who will present his team's work at OFC. Wade's co-authors include researchers from the Massachusetts Institute of Technology and the University of California, Berkeley.

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