#Electrons that stick together, superconduct together The discovery of a surprising feature of superconductivity in an unconventional superconductor by a RIKEN-led research team provides clues about the superconducting mechanism in this material
and thus could aid the search for room-temperature superconductors. Superconductors conduct electricity with zero resistance,
and hence they could potentially revolutionize electric motors, generators and utility grids. However, scientists have yet to discover a material that becomes superconducting at ambient temperature-all known superconductors operate only at cryogenic temperatures,
making them impractical for general applications. Unfortunately, progress toward achieving the goal of room-temperature superconductivity has been hindered by scientistslimited understanding of the fundamental mechanism responsible for the emergence of this remarkable physical phenomenon.
Superconductivity occurs as the result of pairs of electrons binding together in such a way that they act as a single quasiparticle.
In conventional superconductors, which include elemental materials that become superconducting at temperatures very close to absolute zero,
the binding force is provided by vibrations in the atomic lattice through which the electrons travel.
Yet not all superconductors behave this way. In unconventional superconductors that do not fit the conventional model,
this binding force develops in a different manner and various mechanisms have been proposed for it. One such mechanism is the magnetic
or spin fluctuation of the electrons themselves, which binds electrons in pairs through the entanglement of electron spins.
However recent experiments have shown that this mechanism cannot explain the superconducting state in the quintessential unconventional superconductor Cecu2si2.
Inspired by this result, Michi-To Suzuki and Ryotaro Arita from the RIKEN Center for Emergent Matter Science, in collaboration with Hiroaki Ikeda from Ritsumeikan University in Japan, investigated the mechanism of electron pairing in 2si2
from first principles. Their research focused on the unique ultipolebehavior of Cecu2si2. The electrons in Cecu2si2 can interact by entanglement of both spin
and are responsible for superconductivity in Cecu2si2. This kind of electron binding may also be present in the recently discovered class of high-temperature iron-based superconductors. e found that the origin of the unconventional superconductivity in Cecu2si2 is an exotic multipole degree of freedom consisting of entangled spins
and orbitals, says Suzuki. he finding urges us to reconsider the mechanism of superconductivity. c
#Water heals a bioplastic (w/video) A drop of water self-heals a multiphase polymer derived from the genetic code of squid ring teeth,
which may someday extend the life of medical implants, fiber-optic cables and other hard to repair in place objects, according to an international team of researchers."
"What's unique about this plastic is the ability to stick itself back together with a drop of water,
"said Melik Demirel, professor of engineering science and mechanics, Penn State.""There are other materials that are self healing,
but not with water.""A squid ring teeth derived plastic being cut in two and self healing with water and pressure.
Demirel and his team looked at the ring teeth of squid collected around the world--in the Mediterranean, Atlantic, near Hawaii,
the researchers used biotechnology to create the proteins in bacteria. The polymer can then either be molded using heat
or cast by solvent evaporation. The two-part material is a copolymer consisting of an amorphous segment that is soft and a more structured molecular architecture.
The structured portion consists of strands of amino acids connected by hydrogen bonds to form a twisted and/or pleated sheet.
This part also provides strength for the polymer, but the amorphous segment provides the self-healing.
The polymer can either be molded using heat or cast by solvent evaporation. Video: Demirel Lab/Penn State) The researchers created a dog-bone shaped sample of the polymer
and then cut it in half. Using warm water at about 113 degrees Fahrenheit--slightly warmer than body temperature--and a slight amount of pressure with a metal tool,
and go on with operation, saving time and money.""Maybe someday we could apply this approach to healing of wounds or other applications,
"he said.""It would be interesting in the long run to see if we could promote wound healing this way
#New technique lowers cost of energy-efficient embedded computer systems (Nanowerk News) Electrical and computer engineers at North carolina State university have developed a new technique for creating less-expensive,
low-power embedded systems-the computing devices found in everything from thermostats to automobiles.""Using our techniques,
we've been able to create prototype systems with power converters that have a combination of energy efficiency
and low cost that-as far as we've been able to tell-is unmatched by anything currently on the market,
"says Alex Dean, co-author of a paper on the work and an associate professor of electrical and computer engineering at NC State.
An embedded system with common peripherals. To understand the new technique, you have to know a little about embedded systems.
For one thing, they require a power source. And to maximize energy efficiency the system should be designed to operate using the best voltage possible.
Sometimes this means using the lowest voltage needed to run the circuit. At other times, this means raising the voltage slightly
so the system can finish the work sooner, and then going into a low-power sleep mode.
But batteries usually put out power at a voltage level that makes the system operate inefficiently;
often, the battery puts out more voltage than the system needs. To change the voltage to the best level,
a system may use a power converter. The most efficient power converters, called switch-mode power converters, have two parts.
One part consists of"power stage"hardware that controls the storage and flow of power.
"which allows the converter to respond to changes in the embedded system's demand for power
or changes in the flow of energy from the power source, or even provide protection against extreme temperatures and device failures.
The controller can be designed a specifically circuit or a separate processor which runs special control software.
Having a dynamic responsive power converter is also important because it allows the embedded system to be more energy efficient;
the system can go to sleep, then operate quickly, then shut back down -and the power converter can adjust the flow of power accordingly."
and incorporated the power converter software into the embedded system processor. These methods guarantee that the other software on the embedded system's processor will not disturb the power converter's correct operation,
"Dean explains.""This eliminates the need for a separate processor or controller circuit on the power converter itself,
which in turn makes the overall system less expensive.""It also makes the embedded system smaller, lighter and more flexible."
"Because the embedded system software and power converter software are using a shared processor on a single chip,
it gives developers more coordinated control over both the system's functions and related demands those functions may make on the power converter,
"Dean says. The researchers made two prototype converters using the new technique and compared them to dozens of other compatible power converters on the market
-and found that none of the other converters could match the prototypes'combination of low cost and high efficiency."
"Our second-best prototype had 90 percent efficiency-less than 10 percent of the energy was wasted, "Dean says."
"Our best prototype had 95 percent efficiency. And both had component costs of about 50 cents.
"The paper,"Using Real-time System Design Methods to Integrate SMPS Control Software with Application Software"(pdf),
will be presented at the IEEE Energy conversion Congress & Expo being held Sept. 20-24 in Montreal, Canada a
#Turning clothing into information displays Researchers from Holst Centre (set up by TNO and imec), imec and CMST,
imec associated lab at Ghent University, have demonstrated the world first stretchable and conformable thin-film transistor (TFT) driven LED display laminated into textiles.
This paves the way to wearable displays in clothing providing users with feedback. Wearable devices such as healthcare monitors and activity trackers are now a part of everyday life for many people.
Today wearables are separate devices that users must remember to wear. The next step forward will be to integrate these devices into our clothing.
Doing so will make wearable devices less obtrusive and more comfortable encouraging people to use them more regularly and,
hence, increasing the quality of data collected. A key step towards realizing wearable devices in clothing is creating displays that can be integrated into textiles to allow interaction with the wearer. earable devices allow people to monitor their fitness
and health so they can live full and active lives for longer. But to maximize the benefits wearables can offer,
they need to be able to provide feedback on what users are doing as well as measuring it.
By combining imec patented stretch technology with our expertise in active-matrix backplanes and integrating electronics into fabrics
wee taken a giant step towards that possibility, says Edsger Smits, Senior research scientist at Holst Centre.
The conformable display is very thin and mechanically stretchable. A fine-grain version of the proven meander interconnect technology was developed by the CMST lab at Ghent University
and Holst Centre to link standard (rigid) LEDS into a flexible and stretchable display. The LED displays are fabricated on a polyimide substrate
and encapsulated in rubber, allowing the displays to be laminated in to textiles that can be washed.
Importantly, the technology uses fabrication steps that are known to the manufacturing industry enabling rapid industrialization.
Following an initial demonstration at the Society for Information Display Display Week in San jose, USA earlier this year, Holst Centre has presented the next generation of the display at the International Meeting on Information Display
(IMID) in Daegu, Korea, 18-21 august 2015. Smaller LEDS are mounted now on an amorphous indium-gallium-zinc oxide (a-IGZO) TFT backplane that employs a two-transistor
and one capacitor (2t-1c) pixel engine to drive the LEDS. These second-generation displays offer higher pitch and increased, average brightness.
The presentation will feature a 32x32 pixel demonstrator with a resolution of 13 pixels per inch (ppi) and average brightness above 200 candelas per square meter (cd/m2.
Work is ongoing to further industrialize this technology h
#New, ultrathin optical devices shape light in exotic ways Caltech engineers have created flat devices capable of manipulating light in ways that are very difficult
or impossible to achieve with conventional optical components. The new devices are made not of glass,
but rather of silicon nanopillars that are arranged precisely into a honeycomb pattern to create a"metasurface"that can control the paths and properties of passing light waves.
These metasurface devices, described in a paper published online on August 31, 2015, in the journal Nature Nanotechnology("Dielectric metasurfaces for complete control of phase and polarization with subwavelength spatial resolution and high transmission"
could lead to ultracompact optical systems such as advanced microscopes, displays, sensors, and cameras that can be mass-produced using the same photolithography techniques used to manufacture computer microchips."
"Currently, optical systems are made one component at a time, and the components are assembled often manually, "says Andrei Faraon (BS'04), an assistant professor of applied physics and materials science,
and the study's principal investigator.""But this new technology is very similar to the one used to print semiconductor chips onto silicon wafers,
so you could conceivably manufacture millions of systems such as microscopes or cameras at a time.""Seen under a scanning electron microscope,
the new metasurfaces that the team created resemble a cut forest where only the stumps remain.
Each silicon stump, or pillar, has an elliptical cross section, and by carefully varying the diameters of each pillar
Light is an electromagnetic field, and the field of single-color, or monochromatic light oscillates at all points in space with the same frequency but varying relative delays, or phases.
Polarization refers to the trajectory of the oscillations of the electromagnetic field at each point in space.
Manipulating the polarization of light is essential for the operation of advanced microscopes, cameras, and displays;
the control of polarization also enables simple gadgets such as 3-D glasses and polarized sunglasses."
"Scanning electron microscope of a metasurface showing silicon nanopillars on a glass substrate. Tilted view is shown on the right and top view on the left.
A honeycomb pattern is overlaid on the left image. While the same goal can be achieved using an arrangement of multiple conventional optical components such as glass lenses, prisms, spatial light modulators, polarizers,
#Quantum dot solar cell exhibits 30-fold concentration We've achieved a luminescent concentration ratio greater than 30 with an optical efficiency of 82-percent for blue photons,
who is also the Samsung Distinguished Professor of Nanoscience and Nanotechnology at the University of California Berkeley,
and director of the Kavli Energy Nanoscience Institute (ENSI), was the co-leader of this research.
Luminescent solar concentrators featuring quantum dots and photonic mirrors suffer far less parasitic loss of photons than LSCS using molecular dyes as lumophores.
Alivisatos and Ralph Nuzzo of the University of Illinois are the corresponding authors of a paper in ACS Photonics describing this research entitled Quantum dot Luminescent Concentrator Cavity Exhibiting 30-fold Concentration.
The solar energy industry in the United states is soaring with the number of photovoltaic installations having grown from generating 1. 2 gigawatts of electricity in 2008 to generating 20-plus gigawatts today, according to the U s. Department of energy (DOE). Still,
nearly 70-percent of the electricity generated in this country continues to come from fossil fuels. Low-cost alternatives to todays photovoltaic solar panels are needed for the immense advantages of solar power to be realized fully.
One promising alternative has been luminescent solar concentrators (LSCS. Unlike conventional solar cells that directly absorb sunlight and convert it into electricity,
an LSC absorbs the light on a plate embedded with highly efficient light-emitters called lumophores that then re-emit the absorbed light at longer wavelengths, a process known as the Stokes shift.
This re-emitted light is directed to a micro-solar cell for conversion to electricity. Because the plate is much larger than the micro-solar cell,
the solar energy hitting the cell is concentrated highly. With a sufficient concentration factor, only small amounts of expensive III-V photovoltaic materials are needed to collect light from an inexpensive luminescent waveguide.
However the concentration factor and collection efficiency of the molecular dyes that up until now have been used as lumophores are limited by parasitic losses,
imperfect light trapping within the waveguide, and reabsorption and scattering of propagating photons. We replaced the molecular dyes in previous LSC systems with core/shell nanoparticles composed of cadmium selenide (Cdse) cores
and cadmium sulfide (Cds) shells that increase the Stokes shift while reducing photon re-absorption, says Bronstein.
The Cdse/Cds nanoparticles enabled us to decouple absorption from emission energy and volume, which in turn allowed us to balance absorption
and scattering to obtain the optimum nanoparticle, he says. Our use of photonic mirrors that are matched carefully to the narrow bandwidth of our quantum dot lumophores allowed us to achieve waveguide efficiency exceeding the limit imposed by total internal reflection.
In their ACS Photonics paper, the collaborators express confidence that future LSC devices will achieve even higher concentration ratios through improvements to the luminescence quantum yield, waveguide geometry,
and photonic mirror design. The success of this Cdse/Cds nanoparticle-based LSC system led to a partnership between Berkeley Lab, the University of Illinois, Caltech and the National Renewable energy Lab (NREL) on a new solar
concentrator project. At the recent Clean energy Summit held in Las vegas President Obama and Energy secretary Ernest Moniz announced this partnership will receive a $3 million grant for the development of a micro-optical tandem LCS under MOSAIC,
the newest program from DOES ARPA-E. MOSAIC stands for Micro-scale Optimized Solar-cell Arrays with Integrated Concentration.
The LCS work reported in this story was carried out through the U s. Department of energys Energy Frontier Research center program and the National Science Foundation n
#Biodiesel made easier and cleaner with waste-recycling catalyst Researchers at Cardiff University have devised a way of increasing the yield of biodiesel by using the waste left over from its production process.
Using simple catalysis, the researchers have been able to recycle a non-desired by-product produced when biodiesel is formed from vegetable oil,
and convert this into an ingredient to produce even more biodiesel. It is believed this new process will have significant environmental benefits by improving the yield of biodiesel in a sustainable way that doesn't require the use of additional fossil fuels
Fuel suppliers are required also to reduce the greenhouse gas intensity of the EU fuel mix by 6 per cent by 2020 in comparison to 2010.
The work is currently in its early stages and in future studies the researchers will look to optimise the design of the catalyst
Lead author of the study Professor Graham Hutchings, Director of the Cardiff Catalysis Institute, said:"
"Co-author of the study Professor Stuart Taylor, Deputy Director of the Cardiff Catalysis Institute, said:"
which waste is dealt with, and seriously improve the quality of life by reducing carbon emissions from fossil fuels and encourage efficient use of resources."
"Professor Matthew Rosseinsky, Professor of Inorganic chemistry at the University of Liverpool, who was not part of the study,
said:""This paper shows how fundamental catalysis research can develop new mild processes to enhance the sustainability of biodiesel.
As well as offering new opportunities for industry, it will stimulate the search for even better basic catalysts
#Chemical engineers outline new approach to materials design A novel approach that should ignificantly accelerate materials discoveryis the subject of a new article in the Journal of Physical chemistry Letters("Machine-learning-Augmented Chemisorption Model
"The findings reveal a unique model that enables fast and accurate prediction of novel alloy materials for efficient chemical conversions.
Two Virginia Tech chemical engineering faculty members, Luke Achenie and Hongliang Xin, along with Xianfeng Ma and Zheng Li from Xin research group,
authored the article in the peer-reviewed journal. his is the first example of learning from data in catalysis. We anticipate that this new approach will have a huge impact in future materials design,
Catalysts come in multiple forms including: acids, solid metal nanoparticles, and large protein molecules or enzymes in human bodies.
Ninety percent of industrially important chemicals are made using catalysts. It is a major field in applied science;
hence the importance of the new approach by the Virginia Tech chemical engineering members. The mixture of two or more metals with very precise atomic structures and compositions as shown great promise for catalyzing many chemical and electrochemical reactions,
Xin said. In the past, testing of mixed blends of metals has produced novel physical and chemical properties. owever the process is very time-consuming and costly to search for highly optimized alloysusing the conventional approaches, Achenie added.
So that is why Achenie and Xin decided to use existing data to train computer algorithms to make predictions of new materials,
a field called machine learning. This approach captures complex, nonlinear interactions of molecules on metal surfaces through artificial neural networks,
thus allowing arge scale exploration alloy materials space, according to their article. They specifically concentrated on the electrochemical reduction of carbon dioxide on metal electrodes ecause of the current interest in this process for sustainable production of fuels and value added chemicals,
Xin explained. Carbon dioxide (CO2) is a versatile industrial material, used in everything from fire extinguishers to oil recovery to carbonated beverages,
but it is also a major greenhouse gas. Conversion of CO2 to something useful could dramatically reduce its emission into the atmosphere
and help alleviate the global warming problem. With their model and their design approach they have identified a few promising copper multi-metallics with a higher energy conversion efficiency and possibly higher selectivity in carbon dioxide electro-reduction to ethylene,
an extremely useful chemical in industry for making plastics. his study opens a new way for designing metal-based catalysts with complexities, for example, geometry and composition, promoters and poisons, defects,
and nano-effects, Xin said. Source: Virginia Tec i
#Pillared graphene gains strength Rice university researchers discovered that putting nanotube pillars between sheets of graphene could create hybrid structures with a unique balance of strength, toughness and ductility throughout all three dimensions.
Carbon nanomaterials are common now as flat sheets, nanotubes and spheres, and theye being eyed for use as building blocks in hybrid structures with unique properties for electronics,
heat transport and strength. The Rice team is laying a theoretical foundation for such structures by analyzing how the blocksjunctions influence the properties of the desired materials.
Rice materials scientist Rouzbeh Shahsavari and alumnus Navid Sakhavand calculated how various links particularly between carbon nanotubes and graphene, would affect the final hybrid properties in all directions.
They found that introducing junctions would add extra flexibility while maintaining almost the same strength
Their results appear this week in the journal Carbon("Junction configuration-induced mechanisms govern elastic and inelastic deformations in hybrid carbon nanomaterials".
"Carbon nanotubes are rolled-up arrays of perfect hexagons of atoms; graphene is a rolled out sheet of the same.
the way the atoms are arranged can influence all those properties. ome labs are actively trying to make these materials or measure properties like the strength of single nanotubes and graphene sheets,
and quantitatively predict the properties of hybrid versions of graphene and nanotubes. These hybrid structures impart new properties
and functionality that are absent in their parent structures graphene and nanotubes. To that end the lab assembled three-dimensional computer models of illared graphene nanostructures, akin to the boron nitride structures modeled in a previous study to analyze heat transfer between layers. his time we were interested in a comprehensive understanding of the elastic and inelastic properties
of 3-D carbon materials to test their mechanical strength and deformation mechanisms, Shahsavari said. e compared our 3-D hybrid structures with the properties of 2-D stacked graphene sheets and 1-D carbon nanotubes.
Layered sheets of graphene keep their properties in-plane, but exhibit little stiffness or thermal conductance from sheet to sheet,
But pillared graphene models showed far better strength and stiffness and a 42 percent improvement in out-of-plane ductility,
The latter allows pillared graphene to exhibit remarkable toughness along out-of-plane directions, a feature that is not possible in 2-D stacked graphene sheets or 1-D carbon nanotubes,
The researchers calculated how the atomsinherent energies force hexagons to take on or lose atoms to neighboring rings,
Turning the nanotubes in a way that forced wrinkles in the graphene sheets added further flexibility and shear compliance,
When the material did fracture, the researchers found it far more likely for this to happen at the eight-member rings,
That leads to the notion the hybrids can be tuned to fail under particular circumstances. his is the first time anyone has created such a comprehensive atomistic ensto look at the junction-mediated properties of 3-D carbon nanomaterials
Shahsavari said. e believe the principles can be applied to other low-dimensional materials such as boron nitride and molybdenum/tungsten or the combinations thereof. m
based on UNSW Australia research that can predict for the first time which combinations of metals will best form these useful materials.
Just like something from science fiction-think of the Liquid-Metal Man robot assassin (T-1000) in the Terminator films-these materials behave more like glass or plastic than metal.
While still being metals, they become as malleable as chewing gum when heated and can be moulded easily
They are also three times stronger and harder than ordinary metals on average, and are among the toughest materials known."
"They have been described as the most significant development in materials science since the discovery of plastics more than 50 years ago,"says study author, Dr Kevin Laws, from UNSW Australia in Sydney.
Most metals are crystalline when solid, with their atoms arranged in a highly organised and regular manner.
Metallic glass alloys, however, have disordered a highly structure, with the atoms arranged in a non-regular way."
"There are many types of metallic glass, with the most popular ones based on zirconium, palladium, magnesium, titanium or copper.
But until now, discovering alloy compositions that form these materials has required a lengthy process of trial and error in the laboratory,
They have used their model to successfully predict more than 200 new metallic glass alloys based on magnesium
"Metallic glass alloys are expensive to manufacture and to date have only been used in niche products,
such as ejector pins for iphones, watch springs for expensive hand-wound watches, trial medical implants,
They are planned also for use in the next Mars rover vehicle.""But if they become easier and cheaper to make,
they could be used widely in many applications including as exceptionally strong components in personal electronic devices, in space exploration vehicles,
and as hydrogen storage materials in next generation batteries
#3d bone marrow made from silk biomaterials successfully generates platelets (Nanowerk News) Researchers funded by the National Institute of Biomedical Imaging
and Bioengineering at Tufts University and their collaborators have developed successfully a 3-dimensional (3d) tissue-engineered model of bone marrow that can produce functional human platelets outside the body (ex vivo).
Platelets, a key component of the blood that enables clotting, play an essential role in healing,
Failure to produce new bone marrow can be caused by disease, trauma, or some cancer treatments, and can lead to a significantly higher risk of infections,
and the need for blood transfusions. Understanding and reproducing key features of bone marrow formationnd hence, the creation of blood cells and platelets in tissue culture for storage and later useould help in treatment of a variety of medical problems.
The researchers worked to mimic the complex environment where megakaryocytes develop and mature into platelets.
This environment includes endothelial cells (the cells lining the inside of blood vessels) and extracellular matrix (ECM) components,
which provide structural support and signaling to surrounding cells. David Kaplan, Ph d.,professor and Director of the NIH P41 Resource Center on Tissue Engineering, Alessandra Balduini, M d,
. and their collaborators have focused on forming bone marrow models with these components and other growth factors to imitate
and support the formation of functional human platelets. To begin, the researchers knew they would need a structure that could support endothelial cells, ECMS,
and megakaryocytes, without adversely activating the cells or platelets. The team knew from their previous work with silk protein scaffolds that silk is a very biocompatible material that is amenable to many manipulations to customize it for a specific use,
while also avoiding any cell-specific signaling. They formed silk scaffolds of different thicknesses (ranging from 2 to 5 micrometers)
In order to mimic the production environment and microvasculature, the structures through which blood flows, the researchers formed silk sponges around porous silk microtubes.
The wall thickness of the microtubes was kept below 10 micrometers, which helped proplatelets migrate through the walls and release platelets.
By pumping culture media, a solution filled with necessary nutrients, through the microtubes, the researchers mimicked the flow of blood.
In addition, platelets generated ex vivo could be used to help healing in regenerative medicine including recalcitrant ulcers and burns.
The key feature is that the platelets are functional, thus, the system can be used for fundamental and applied studies of the bone marrow. his is an elegant example of how to deconstruct a complex process into its basic elements,
and then build it back up, brick by brick, to give you a basic structure you need for the product you are looking forn this case a human platelet made to order,
Taking this incremental approachdding to the structure one step at a time, this group is making great strides on the path to creating therapeutic quantities of platelets on demand. t
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