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2 graphene layers are better than one

Energy of electrons in graphene in the tight-b...

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Researchers at the National Institute of Standards and Technology (NIST) have shown that the electronic properties of two layers of graphene vary on the nanometer scale. The surprising new results reveal that not only does the difference in the strength of the electric charges between the two layers vary across the layers, but they also actually reverse in sign to create randomly distributed puddles of alternating positive and negative charges. Reported in Nature Physics,* the new measurements bring graphene a step closer to being used in practical electronic devices. Graphene, a single layer of carbon atoms, is prized for its remarkable properties, not the least of which is the way it conducts electrons at high speed. However, the lack of what physicists call a band gap—an energetic threshold that makes it possible to turn a transistor on and off—makes graphene ill-suited for digital electronic applications.

Researchers have known that bilayer graphene, consisting of two stacked graphene layers, acts more like a semiconductor when immersed in an electric field.

According to NIST researcher Nikolai Zhitenev, the band gap may also form on its own due to variations in the sheets’ electrical potential caused by interactions among the graphene electrons or with the substrate (usually a nonconducting, or insulating material) that the graphene is placed upon.

NIST fellow Joseph Stroscio says that their measurements indicate that interactions with the disordered insulating substrate material causes pools of electrons and electron holes (basically, the absence of electrons) to form in the graphene layers. Both electron and hole “pools” are deeper on the bottom layer because it is closer to the substrate. This difference in “pool” depths, or charge density, between the layers creates the random pattern of alternating charges and the spatially varying band gap.

Manipulating the purity of the substrate could give researchers a way to finely control graphene’s band gap and may eventually lead to the fabrication of graphene-based transistors that can be turned on and off like a semiconductor.

Still, as shown in the group’s previous work**, while these substrate interactions open the door to graphene’s use as a practical electronic material, they lower the window on speed. Electrons do not move as well through substrate-mounted bilayer graphene; however, this may likely be compensated for by engineering the graphene/substrate interactions.

Stroscio’s team plans to explore further the role that substrates may play in the creation and control of band gaps in graphene by using different substrate materials. If the substrate interactions can be reduced far enough, says Stroscio, the exotic quantum properties of bilayer graphene may be harnessed to create a new quantum field effect transistor.

Source: National Institute of Standards and Technology (NIST)

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Quantum fluctuations are key in superconductors

  • New experiments on a recently discovered class of iron-based superconductors suggest that the ability of their electrons to conduct electricity without resistance is directly connected with the magnetic properties of those electrons. Results of the experiments appear in the Jan. 8 issue of Physical Review Letters. The tests, which were carried out by a team of U.S. and Chinese physicists, shed light on the fundamental nature of high-temperature superconductivity, said Rice physicist Qimiao Si, a co-author on the study.
  • If better understood, high-temperature superconductors could be used to revolutionize electric generators, MRI scanners, high-speed trains and other devices.
  • In the study, scientists from Rice University, the University of Tennessee, Oak Ridge National Laboratory (ORNL), the National Institute of Standards and Technology (NIST), the Chinese Academy of Sciences’ Institute of Physics and Renmin University in Beijing examined several iron-arsenide compounds. These are the “undoped” parents of the iron “pnictides” (pronounced: NICK-tides), a class of materials that were found to be high-temperature superconductors in 2008.
  • The experiments set out to test theoretical predictions that Si and collaborators published in the Proceedings of the National Academy of Sciences last March. They predicted that varying the size of some atoms in the parent compounds could allow physicists to tune the material’s quantum fluctuations. These types of fluctuations can create tipping points called magnetic “quantum critical points,” a state that exists when a material is at the cusp of transitioning from one quantum phase to another.
  • Using neutron-scattering facilities at NIST and ORNL, the team bombarded the materials with neutrons to decipher their structural and magnetic properties. The tests, which supported Si’s theoretical predictions, determined that the strength of magnetic order in the materials was reduced when arsenic atoms were replaced with slightly smaller phosphorus atoms.
  • “We found the first direct evidence that a magnetic quantum critical point exists in these materials,” Si said.
  • The results were made possible by the efforts of Nanlin Wang, a physicist from the Chinese Academy of Sciences’ Institute of Physics, and his research group. They created a series of samples with varying amounts of phosphorous substituting for arsenic.
  • The discovery of high-temperature superconductivity in copper-oxide ceramics in 1986 led physicists to realize that quantum effects in electronic materials were far more complex than anticipated. One of these effects is quantum criticality. Criticality occurs near a tipping point that a material goes through when it changes phases. Many phase changes — like ice melting into water — occur because of thermal fluctuations. But quantum criticalities and quantum phase changes arise solely from quantum fluctuations.
  • “Our finding of a quantum critical point in iron pnictides opens the door for new avenues of research into this important class of materials,” said University of Tennessee/ORNL physicist Pengcheng Dai, a neutron scattering specialist.
  • Si said, “The evidence from this study bolsters the hypothesis that high-temperature superconductivity in the iron pnictides originates from electronic magnetism. This should be contrasted to conventional low-temperature superconductivity, which is caused by ionic vibrations.”
  • SourceRice University

Magnet lab research suggests novel superconductor

Superconductivity has perplexed, astounded and inspired scientists ever since it was discovered in 1911. Now, in the latest of a century of surprises, researchers at the National High Magnetic Field Laboratory at Florida State University have discovered unusual properties in a novel superconducting material that point to an entirely new kind of superconductor. Frank Hunte, a postdoctoral associate at the lab’s Applied Superconductivity Center (ASC), working with David Larbalestier, Alex Gurevich and Jan Jaroszynski, and colleagues in David Mandrus’ group at Oak Ridge National Laboratory in Tennessee, discovered surprising magnetic properties in the new superconductors that suggest they may have very powerful applications Ñ from improved MRI machines and research magnets to a new generation of superconducting electric motors, generators and power transmission lines. The research also adds to the long list of mysteries surrounding superconductivity, providing evidence that the new materials, which scientists are calling “doped rare earth iron oxyarsenides,” develop superconductivity in quite a new way, as detailed in the latest issue of the prestigious journal Nature.
Though research on this substance is very much in its early stages, scientists are talking excitedly of “promise” and “potential.”
“What one would like is a greater selection of superconductors, operating at higher temperatures, being cheaper, possibly being more capable of being made into round wires,” said Larbalestier, director of the ASC. “Iron and arsenic, both inherently cheap materials, are key constituents of this totally new class of superconductors. We’re just fascinated. It’s superconductivity in places you never thought of.”
Superconductivity can be thought of as “frictionless” electricity. In conventional electricity, heat is generated by friction as electrons (electric charge carriers) collide with atoms and impurities in the wire. This heating effect is good for appliances such as toasters or irons, but not so good for most other applications that use electricity. In superconductors, however, electrons glide unimpeded between atoms without friction. If scientists and engineers ever harness this phenomenon at or near room temperature in a practical way, untold billions of dollars could be saved on energy costs.
That’s a big if. Superconductivity, though promising, is still impractical in routine engineering use because it requires a very cold environment attainable only with the help of expensive cryogens such as liquid helium or liquid nitrogen. Past discoveries have helped scientists inch their way up the thermometer, from superconductors requiring minus 452 degrees Fahrenheit (or 4.2 Kelvin) to newer materials that superconduct at around minus 200 degrees F (138 K) Ñ still frigid, but substantially warmer and more practical.
Early this year, Japanese scientists who had been developing iron-based superconducting compounds for several years finally tweaked the recipe just right with a pinch of arsenic. The result: a superconductor, also featuring oxygen and the rare earth element lanthanum, performing at a promising minus 413 degrees F (26 K). The presence of iron in the material was another scientific stunner: Because it’s ferromagnetic, iron stays magnetized after exposure to a magnetic field, and any current generates such a field. As a rule, magnetism’s effect on superconductivity is not to enhance it, but to kill it.
Teams of scientists quickly got busy synthesizing and studying various iron oxyarsenides. Larbalestier, eager to get in on the research, secured a sample from colleagues at Oak Ridge. His objective: Put it in the magnet lab’s 45-tesla Hybrid magnet to see how high a magnetic field the new material could tolerate. (Tesla is a unit of magnetic field strength; the Earth’s magnetic field is one twenty thousandth of a tesla.)
Hunte and his colleagues thought the world-record Hybrid magnet would be more than sufficient to test the field tolerance limits of the new material. They thought wrong: The iron oxyarsenide kept superconducting all the way up to 45 tesla, far past the point at which other superconductors become normal conductors.
A high tolerance for magnetic field is one of three key properties researchers hope for in superconductors. Also desirable are the abilities to operate at relatively high temperatures and in the presence of high electrical currents. Superconductors are used to make MRI and research magnets, and now they are being tested in a new generation of superconducting electric motors, generators, transformers and power transmission lines. Today, the most powerful superconducting magnet generates a field of about 26 tesla. If a superconductor could be found that tolerates a higher current and field, it may make possible more powerful magnets, opening up vast new research areas to scientists and power applications.
Hunte’s experiment yielded other tantalizing findings. Although scientists discovered half a century ago that superconducting electrons enter the “Cooper pair” state, pairing with opposite spin and momentum, magnetism was always thought to break such pairs. Now the archetypal magnetic atom, iron, is a key part of this new class of high temperature superconductors. Scientists have yet another puzzle to probe.
“So far,” said Hunte, “based on both theoretical calculations and what we’re seeing from the experiments, it seems likely that this is a completely different mechanism for superconductivity.”
Hunte is quick to say the group’s research barely scratches the surface.
“The field is completely open. No one knows where this is going to go,” Hunte said. “If it’s found that these materials can support high current densities, then they could be tremendously useful.”

Source: Florida State University

Human-powered drill for clean water By Engineering Student

The drill was created for a year-long engineering capstone project that has students solving real engineering problems with real clients. The team created the drill for WHOLives.org, a nonprofit dedicated to providing clean water, better health and more opportunities to people living in impoverished communities. The organization is currently focusing its drilling efforts on Tanzania, but it has plans to expand its operations to other countries. The project is also co-sponsored by the Ira A. Fulton College of Engineering and Technology.

The drill uses no gears or customized parts, and it can easily be taken apart, transported in the bed of a truck and reassembled within an hour.
The drill can be operated by four people. Three spin the wheel that turns the bit, and the fourth lifts the bit up and down when necessary to punch through tough spots. A water pump system removes the dirt from the six-inch-wide hole.
“At the beginning of the year we had a meeting with the sponsor, and he said that very rarely do you get an opportunity to work on a project that can change millions of lives,” said Nathan Toone, one of the student engineers who worked on the drill. “You forget that sometimes when you’re in the middle of working and setbacks and frustrations, but it’s really good to see it pay off. It has definitely paid off.”

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An Augmented Reality Game for Camera Projector Phones

With the miniaturization of projection technology the integration of tiny projection units, normally referred to as pico projectors, into mobile devices is not longer fiction. Integrated pico pro jectors in mobile devices could make mobile projection ubiquitous within the next few years. Mobile phones with integrated pico pro jectors soon will have the ability to project large-scale information onto any surfaces in the real world. By doing so the interaction space of the mobile device can be expanded to physical ob jects in the environment and this can support interaction concepts that are not even possible on modern desktop computers today. In this video, we explore the possibilities of camera projector phones with a mobile adaption of the Playstation 3
game LittleBigPlanet. The camera projector unit is used to augment the hand drawings of a user with an overlay displaying physical interaction of virtual ob jects with the real world. Players can sketch a 2D world on a sheet of paper or use an existing physical configuration of ob jects and let the physics engine simulate physical procedures in this world to achieve game goals.

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Augmented Reality Head Mounted Display Concept


Using this system, you can affectation aeronautics and AR agreeable while your buzz is in your pocket.
“Most antecedent head-mounted displays accept been large, accoutrement both eyes. But now, we’ve acclimated technology from Olympus to accomplish the affectation actual baby and light. This is a abundant beforehand in agreement of technology. And from now on, DOCOMO will coact with Olympus to enhance the architecture of the head-mounted display, so it can be agitated and beat after attractive strange. We’re giving this audience to advance how the affectation could be acclimated in aggregate with a DOCOMO adaptable phone.”
The new technology uses a attenuate prism alleged an Optical Bar. This creates two ablaze paths to the pupil, one bringing pictures to the eye and the added bringing ablaze from outside, accomplishing apparent pictures. This arrangement makes the eyes actual compact, with no ablaze loss, giving bright, bright pictures.
“The abstraction is to accept a affectation accoutrement an breadth of 18 cm one beat ahead. The admeasurement of the affectation creates the consequence that you’ve put a adaptable buzz into it, with a 3.7 inch or 4 inch screen.”
“The head-mounted affectation uses an Earth’s alluring acreage sensor to ascertain direction, so users can acclimatize themselves aloof by axis their head, rather than their accomplished body. So we’ve congenital in an appliance where, if you face right, the affectation shows advice about shops on your right, and if you face left, it shows advice about shops on your left. If you attending up, there aren’t any shops, but there is the sky, so the affectation shows a acclimate forecast.”

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ARScope From The University of Tokyo

The Tachi-Kawakami Laboratory from the University of Tokyo alien new interface technology alleged ARScope at the Digital Content Expo 2008. ARScope is an interface acclimated to accomplish alloyed absoluteness application Augmented Reality. ARScope uses automatic technology to action a graphical angel ascribe by a camera and activity it in the advanced through a arch army projector. This technology differs from the arch army affectation that has been broadly acclimated in the accomplished because a projector is acclimated to activity an angel assimilate an article in the absolute world, so a basic angel can be superimposed on a absolute apple object. This technology differs from the arch army displays acclimated in the accomplished because it uses a projector to activity an angel assimilate a absolute apple object. The different affection of this technology is that it can be acclimated to blanket a basic angel on a absolute apple object.

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Gearturbine Project Atypical InFlow Thermodynamic Technology

The Gearturbine comes from the contemporary ecological essential global needs of a efficient power plant fueled motor engine.

-Power thrust by bar (tube); air, sea, land, power generation, work application.

-Have the same simple basic system of the “Aelopilie” Heron´s Steam Turbine device from Alexandria,

10-70 AD) one thousand nine hundred years ago. Because; the circular dynamic motion, with 2/Two Opposites power (polar position) lever, and is feeds from his axis center.

http://gearturbine.260mb.com/


*Gearturbine

A typical fueled turbine engine, state of the art. New thermodynamic technology. Top system.

-With Retrodynamic dextrogiro vs levogiro phenomenon effect. / Rotor-RPM VS InFlow / front to front “Collision-interaction” – inflow vs blades surface/(gear). Technical unique dynamic motion mode.

-Form-function wide cilindrical shape / continue kinetic inertia, positive tendence dynamic mass motion

-Non-waste parasitic looses system for: cooling, lubrication & combustion.

-Combustion 2Two (Inside dynamic) continue circular flames (like 2two opposite rockets, (at the same axis)).

-2 Two (very) long captive compression inflow propulsion conduits. start at were ends, in perfect shape balance.

-4 Turbos (rotary & translation motion) inside active.

-Mechanical direct 2two planetary gears thurst, inside in a bigger shell, total lever, polar position. (Big torque) (like the Ying Yang simbol concept).

-3 stages of inflow turbo compression before combustion; 1)1-Turbine, 2)2-Turbos 3)2-Turbos.

*The most innovative power plant engine project today. Higher efficient % percentage. Next trend wave toward global technological coming change.

Patent; Dic 1991 IMPI Mexico #197187 / Carlos Barrera. – Individual Designer – Inventor and project owner. / All Rights Reserved. Monterrey, NL, Mexico.

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Compact Fuel Cell Charger – Aquafairy AF-M3000

At FC Expo 2011, Aquafairy exhibited the AF-M3000, a compact fuel cell for charging smartphones. This product will be released in April.
“It’s called a fuel cell, but it’s actually a generator, producing electricity using hydrogen and oxygen as fuel. It’s a ubiquitous generator, providing power anywhere that doesn’t have an AC supply. In particular, we’ve developed this fuel cell to match the specifications for charging mobile devices like smartphones.”
The power output is about 3 W, and the capacity is about 3-4 W-h, so actual running time is about 90 minutes. The module weighs 128 g and the fuel cartridge weighs 17 g.
“In concrete terms, this product can charge a smartphone that’s run out of power back up to 60% capacity. And it can charge an ordinary cellphone up to full capacity.”
“A feature of our fuel cells is that they produce hydrogen on demand. The hydrogen is released from the hydrogen source material, and reacts with oxygen in the air to generate electricity. The hydrogen source produces hydrogen when water is added. The water and the cartridge are for one use only.”
This product is currently manufactured in a limited quantity. Consequently, the module costs 25,000 yen and the cartridges cost 500 yen each.
“This price is beyond the reach of ordinary consumers, so the next step will be to start mass production. We’d like to provide the module for less than 10,000 yen and the cartridges for less than 200 yen each.”
From now on, Aquafairy plans to develop fuel cells for other devices as well as smartphones.
“As this version is for smartphones, it’s slightly large, but a version for regular cellphones only could be made smaller by using four cells instead of the current eight. We’re also considering a larger version that delivers more power, for digital cameras, video cameras, and notebook PCs. As we’re a venture, we can’t release both types at once, so we’d like to decide on our next step by seeing what feedback we get from presenting this here.”
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Retractable Mobile Solar Power System

Řezy solárního panelu.

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At PV Expo 2011, OS exhibited a retractable solar power system, the GSR-110B.
This product was achieved by using retractable technology developed by OS for projector screens, and flexible amorphous solar cells from Fuji Electric Systems. It’s intended to power communication equipment in an emergency.

“One of these units delivers 40 W of power. The solar panel itself delivers 16 W, and there’s a 24 W battery built into the unit. So a total of 16 W plus 24 W can be output from the unit’s 12v socket.”

The unit weighs just 3 kg, so it can be carried easily and set up right away. Apart from emergencies, it can be used as a power source for leisure activities, such as camping, and for mobile equipment at events.

“This unit can power a netbook PC for about two hours. Two units can also be used together, to deliver 80 W. But you do need to bear in mind that the power output depends on the weather.”

The sheet operates smoothly; it can be pulled out, retracted, and stopped like a roller blind.

“We think there’s an especially big market for this unit overseas, so that’s what we’re focusing on right now. We think this product will be particularly useful in areas that don’t have grid power.”

This mobile solar unit started shipping in January 2011. It’s priced around 60,000 yen, and OS plans to sell 10,000 units in the first year.

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Oyster – the New Wave Power System

Aquamarine Power, a company located in Edinburg, recently presented its latest invention - a new typewave power system, which it plans to install in the subaquatic off the coast of Orkney Islands. The company named its latest invention Oyster. The system features an on-shore base, which, according to Aquamarine Power, is easier to sustain than commonly used wave power systems. In addition the system has the ability to function at shallow depth, which makes it more reliable than the systems working far out at sea.
The company claims that each Oyster unit can generatefrom 300 to 600kw of electricity, which means that a commercial farm that has ten Oysters will be able to produce green energy to about 3,000 homes. The production of electricity using the power of waves is becoming more popular, with an increasing number of companies taking advantage of the motion of the ocean.
The latest invention from the Edinburg-based company is somewhat different from other systems, mainly because it takes advantage of hydraulics in order to bring high-pressure water to shore, where the pressure is transformed into electricity. Here’s how it works: when the underwater oscillator with pistons is turned on by the waves, it starts pumping water through a pipeline to shore, where generators transform the water into electricity – check the links at the bottom of the story.
The power is delivered constantly thanks to the fact that the system is located at a depth of about 12 to 16 meters. It is worth mentioning that at such depths the seas are more consistent. In addition, engineers thought of creating a system that would run silently. It does not use oil or other toxic stuff, which means it doesn’t affect the ocean life. Currently the Oyster is in the development stage. Its developers hope one day to introduce Oyster to the coast of other countries, including Spain, Portugal, Ireland, UK, US, South Africa, Australia and Chile.
According to the calculations carried out by Carbon Trust, the system will be able to save about 500 tons of CO2 each year.
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Inventors Turn Trees Into Street Lights

A team of Taiwanese researchers discovered that trees emit a luminous reddish glow when gold nanoparticlesare placed on their leaves.
Surely using trees instead of street light is an ingenious idea. This would not only considerably reduce electricity costs, but would also lower greenhouse gas emissions, especially in megapolises.
It would be interesting to know that the team made the discovery by accident. Scientists were looking for a way to make high-efficiency lighting similar to LED technology. At the same time they had the goal of creating the new type of lighting without making use of toxic chemicals like phosphor powder.
They alien gold nanoparticles into the leaves of the Bacopa caroliniana plants, appropriately inducing the chlorophyll them to accomplish a red emission, letters Electro IQ.
“In the future, bio-LED could be acclimated to accomplish roadside copse bright at night. This will save activity and blot CO2 as the bio-LED brilliance will account the chloroplast to conduct photosynthesis,” said Dr. Yen-Hsun Su.
The analysis was awful accepted by the Royal Society of Chemistry, which is the better European alignment for advancing the actinic sciences. The abstraction can now be begin in the account Nanoscale
From Physics Great site infoniac.com
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