Friday 6 September 2013

Scientists use DNA to assemble a transistor from graphene

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Graphene is a sheet of carbon atoms arrayed in a honeycomb pattern, just a single atom thick. It could be a better semiconductor than silicon -- if we could fashion it into ribbons 20 to 50 atoms wide. Could DNA help?

via Science Daily

Scientists use DNA to assemble a transistor from graphene

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(Phys.org) —Graphene is a sheet of carbon atoms arrayed in a honeycomb pattern, just a single atom thick. It could be a better semiconductor than silicon – if we could fashion it into ribbons 20 to 50 atoms wide. Could DNA help?



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Debris flows on Arctic sand dunes are similar to dark dune spot-seepage flows on Mars

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Scientists have demonstrated that frozen water in the form of snow or frost can melt to form debris flows on sunward-facing slopes of sand dunes in the Alaskan arctic at air temperatures significantly below the melting point of water. The debris flows consist of sand mixed with liquid water that cascade down steep slopes.

via Science Daily

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Interstellar Poster-Map - High Frontier solitaire

Here's a great poster featuring a beautiful image from deep space


Updated Aug 2013. This map, together with the High Frontier Colonization boardgame and free rules available by writing phileklund@gmail.com, enables you to travel to all the stars within a dozen light years with a starship of your design and a crew of your choice. This can be a "post-script" to a multi-player Colonization Game, or as a solitaire game. To journey to the stars, you will need a good starship engine, the right team of humans and robot supports, and enough fuel “decatanks” (i.e. fuel tanks ten times normal mass) to speed up to cruising speed and then to slow to a dead stop at the destination. Your pilots have the special ability to brake the starship without using fuel, by drogue braking at gas giants, heliopause bow shock surfing on the Local Interstellar Cloud (LIC), using antimatter-fueled beam-core rockets, or using interplanetary magnetic fields. Your scientists dream up new ideas, which your engineers make into reality using 3D printers and nano-configuration refineries. Your engineers also repair dust and radiation damage, while your entrepreneurs keep the passengers sane with products and services. Marriages help reduce stress and provide for the next generation. Raygun crew are able to beam-push ultralight probes, either to potential destinations or back to Earth for help. Spacewalkers fix punctured radiators and land on planets to explore them. However the passengers both age and accumulate stress, and can mutiny if not aligned with the politics. Radiation can interfere with reproduction and increase cancer enough to turn your starship into a ghost ship.
Click to customize with size, paper type etc.
via Zazzle Astronomy market place

Shining a little light changes metal into semiconductor

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By blending their expertise, two materials science engineers at Washington University in St. Louis changed the electronic properties of new class of materials—just by exposing it to light.



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Hubble catches a spiral in the air pump

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(Phys.org) —Lying more than 110 million light-years away from Earth in the constellation of Antlia (The Air Pump) is the spiral galaxy IC 2560, shown here in an image from NASA/ESA Hubble Space Telescope. At this distance it is a relatively nearby spiral galaxy, and is part of the Antlia cluster—a group of over 200 galaxies held together by gravity. This cluster is unusual; unlike most other galaxy clusters, it appears to have no dominant galaxy within it.



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Physicists find enhanced fluctuations in nanomagnets

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NYU physicists have discovered that nanomagnets—a billionth of a meter in size—with a preferred up or down magnetization are sensitive to heating or cooling, more than expected.



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Iron in the sun: A greenhouse gas for X-ray radiation

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(Phys.org) —Scientists from the Heidelberg Max Planck Institute for Nuclear Physics (MPIK) in cooperation with DESY (Hamburg) at the synchrotron PETRA III have investigated for the first time X-ray absorption of highly charged iron ions. A transportable ion trap developed at MPIK was used for generation and storage of the ions. The high-precision measurements provide important new insight into the role of highly charged ions in astrophysical plasmas, e. g. for radiation transport inside stars.



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NASA to Share the Universe with Instagram Users through Its Images

NASA is launching an official Instagram profile that will take its fans on an out-of-this-world journey through images of Earth and beyond.

via NASA Breaking News

http://www.nasa.gov/press/2013/september/nasa-to-share-the-universe-with-instagram-users-through-its-images

Europe completes second instrument for James Webb Space Telescope

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Europe has completed the Near-Infrared Spectrograph, one of two instruments it is contributing to the international James Webb Space Telescope, a space observatory set for launch on an Ariane 5 rocket in 2018.




via ESA Space Science

http://www.esa.int/Our_Activities/Space_Science/Europe_completes_second_instrument_for_James_Webb_Space_Telescope

Ultrafast graphene circuits

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Graphene - gamechanger, or just hype?


Not so long ago, some started to think that graphene will never live up to its promise as a radical technology changer, because it seemed that it's been such a long time since it was discovered and hyped up, and no real graphene electronic devices have been shown. The hype was becoming apparent already in 2010, following the Nobel prize awarded for the discovery of the material, and Professor Geim had to come out with statements of caution in the media on several occasions. Even as the Graphene Flagship (which Graphenea is part of) was awarded a billion euros, Professor Andrea Ferrari of Cambridge University stressed the amount of work that still needs to be done before graphene goes commercial. Even so, the hype kept rising.


Gapless graphene


A part of the reason for the apparent dissonance in the expectations of the public and those of the experts was the lack of a band gap in graphene. A band gap is a range of energies which charge-carrying electrons in a material cannot occupy, leading to a pronounced difference in the behaviour of electrons below the gap to those above the gap. Namely, electrons below the energy band gap are fixed to their positions and do not carry any current. Those above the gap have enough energy to move around, making the entire material conductive. Materials that possess a band gap are called semiconductors, the most famous of the class being the ubiquitous silicon.


The absence of a band gap in graphene makes all its electrons mobile. While zooming mobile electrons are great for carrying electricity and showing off a range of spectacular scientific breakthroughs, the inability to switch the current off stands in stark contrast to the requirements of the traditional transistor, the basic element of electronic circuit logic. All internal circuits in consumer electronic devices operate on the principle of bits, on the exchange of "0"s and "1"s the sequence of which encodes the relevant information. Modern circuits incorporate billions of semiconductor transistors, constantly flipping between the conducting and insulating state. Graphene just isn't able to do that. Or is it?


Graphene transistors are real


Already back in February, reports showed up of a new class of graphene transistors. How was it done? By bombarding a part of a graphene sheet with helium ions, that part of the sheet is strongly modified by introducing defects. The ion-irradiated part acquires a much larger density of charge carriers than the rest of the sheet, creating an insulating region. The insulating region prevents current flow between the electrodes of the device. Now defaulting to the "0" state, the graphene transistor can be made to conduct current again by applying an electric field to the pristine parts of the graphene. The field is applied with an additional pair of electronic gates.


The result was an interesting proof of principle, and was not the first nor the last that appeared around the same time. All the effort, however, was plagued by the resultant low quality of the graphene switch. The graphene that was exposed to ions or other types of chemicals would always have a dramatically reduced ability to conduct electrons, compared to the untreated case. Also, the switching efficiency was always poor compared to what we're used to from silicon. So the partial success of the first graphene transistors was more food for the sceptics.



Figure: Printed circuits are about to become fast and flexible. Source: sxc.hu.


Just some months later, we are seeing a rise of advanced graphene electronic devices. Less than two weeks ago, researchers at MIT demonstrated a novel way of increasing the charge carrier concentration in graphene. Chlorine gas was introduced to a graphene surface in a controlled way, so to not damage the sheet in the process. Teams led by Mildred Dresselhaus and our scientific adviser Tomas Palacios, modified the graphene surface with chlorine plasma in a reactive ion etcher, a plasma-inducing chamber with tightly controlled conditions. After careful tweaking of the process, they were able to retain the high charge carrier mobility of 1500 cm2/V, commonly obtained in untreated graphene. The process uniformly coats graphene with the chlorine, with coverage up to 45% of the surface area. Theory predicts that at 50% coverage, the all-important band gap will emerge in graphene. Just 5% more, and we could have graphene transistors comparable to those made of silicon - except they would be ultrathin, transparent, printable, and flexible.


A new kind of graphene logic


Nearly simultaneously, researchers at the University of California, Riverside, have come up with a new approach to graphene transistors. Instead of modifying the graphene, Alexander Balandin and colleagues have chosen to modify the logic. The team uses regular band gap-less graphene, and utilizes the material's unique property of negative differential resistance. With negative resistance, under some conditions, the electrical current increases with decreasing the applied voltage. Biasing parts of the graphene sheet into the "negative" regime and other part normally, a new type of transistor was achieved. This time scientists did not stop at showing the proof of principle, but rather went all the way to showing a logic gate made from graphene. At operating speeds predicted to be up to 400 GHz, the approach could usher in a new era of graphene information processing.


Graphene has its share of hype and overselling, however it is important to note that research is still proceeding at an incredible pace, with the scientific landscape radically changing every few months. Although much remains to be done to fulfil all the promise that this wonderful material holds, the research and industry communities are working diligently towards a common goal - new graphene-enabled technologies.




via Graphenea

Astro-Love iPhone 4/4s Case

Here's a great product from Zazzle featuring an astronomy case. Maybe you'd like to see your name on it? Click to personalize and see what it's like!

here's a cool design that is sure to work out for you. It was created by Abriceaux,
another talented artist from the Zazzle community!


Love is eternal just as space is never-ending. Connect your iPhone 4/4s to the stars with this beautiful case!* *NOT actually capable of connecting your iPhone to the stars.

»visit the Abriceaux store for more designs and products like this
The Zazzle Promise: We promise 100% satisfaction. If you don't absolutely love it, we'll take it back!

Interstellar winds buffeting our solar system have shifted direction

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Scientists have discovered that the particles streaming into the solar system from interstellar space have likely changed direction over the last 40 years.

via Science Daily

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Powerful jets discovered blowing material out of galaxy

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Astronomers using a worldwide network of radio telescopes have found strong evidence that a powerful jet of material propelled to nearly light speed by a galaxy's central black hole is blowing massive amounts of gas out of the galaxy. This process, they said, is limiting the growth of the black hole and the rate of star formation in the galaxy, and thus is a key to understanding how galaxies develop.

via Science Daily

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Phoenix on Christmas Tree Cluster, backdrop Samsung Galaxy S3 Cover


Galaxies, Stars and Nebulae series A gorgeous mobile phone cover with a stylized Rising Phoenix featuring a colour image of the region known as NGC 2264 - an area of sky that includes the sparkling blue baubles of the Christmas Tree star cluster and the Cone Nebula.

It was created from data taken through four different filters (B, V, R and H-alpha) with the Wide Field Imager at ESO's La Silla Observatory, 2400 m high in the Atacama Desert of Chile in the foothills of the Andes.

The image shows a region of space about 30 light-years across.

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Image codes: xmastrclst phnx

ESO/J. Emerson/VISTA www.eso.org
Reproduced under the Creative Commons Attribution 3.0 Unported license.
via Zazzle Astronomy market place

Carina Nebula - Our Awesome Universe Galaxy S3 Case


Galaxies, Stars and Nebulae series A fantastic astronomy photograph showing a panoramic view of the WR 22 and Eta Carinae regions of the Carina Nebula.

The picture was created from images taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.

It's a stunning, mind-blowing, fantastic image that reveals a little of the wonder that is our universe.

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image code: crnneb

ESO/J. Emerson/VISTA www.eso.org
Reproduced under the Creative Commons Attribution 3.0 Unported license.
via Zazzle Astronomy market place

IBEX spacecraft measures changes in the direction of interstellar winds buffeting our solar system

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Neutral interstellar atoms are flowing into the solar system from a different direction than previously observed.

via Science Daily

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