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Graphene
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MIT teams finding many uses for graphene, the newest form of carbon
In a blown-up image from a scanning tunnelling microscope, it looks just like an endless sheet of chicken wire: a simple flat sheet made up of a lattice of hexagons. But this nanoscopic material called graphene, first generally acknowledged to exist just five years ago, turns out to have a variety of unique, and potentially very useful, characteristics -- ones several MIT researchers are actively trying to better understand and turn into real-world applications.

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Carbon isotope measurements
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Title: Carbon isotope measurements in the Solar System
Authors: Paul M. Woods
(Version v2)

I make publicly available my literature study into carbon isotope ratios in the Solar System, which formed a part of Woods & Willacy (2009). As far as I know, I have included here all measurements of 12C/13C in Solar System objects (excluding those of Earth) up to and including 6 February 2009. Full references are given. If you use the any of the information here, please reference the paper Woods & Willacy (2009) and this publication.

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RE: Carbon
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A new form of carbon material, potentially lighter and stronger than conventional carbon fibres, has been discovered by researchers in China and the United States.
Huisheng Peng of Tongji University in Shanghai and his colleagues have found that a carbon vapour, made by heating ethylene and paraffin oil, will condense into tubes of pure carbon tens of micrometres wide and up to several centimetres long.

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Carbon balloon
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Using a single layer of carbon, just one atom thick, New York-based researchers have created the worlds thinnest balloon.
Cornel University researchers, who are behind this work, say that the fabric they used for making the balloon is leak-proof to even the tiniest airborne molecules.
They say that this balloon may find use in "aquariums" smaller than a red blood cell, through which scientists could peer at molecules.

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Graphene
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Graphene is the strongest material in the world, according to new experiments done by researchers at Columbia University in the US. The secret to the material's extraordinary strength, says the team, lies in the robustness of the covalent carbon-carbon bond and the fact that the graphene monolayers tested were defect-free.

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Experiment finds graphenes missing pi.
Physicists in the US claim to have solved the mystery of the missing pi, which has confounded physicists studying the conductivity of graphene

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As thin as it gets: the carbon membranes recently created by Max Planck scientists are only one atom thick. For electrons, such membranes are almost completely transparent - using an electron microscope, scientists may thus be able to examine absorbed individual molecules on the membranes, and image the atomic structure of complex biological molecules. Such ultra-thin membranes may also be used to filter out gases

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'World's Thinnest Material' Created
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One-atom thick material to revolutionise the scientific world
Scientists have created the world's thinnest material which they predict will revolutionise medical research and electronics.
The new material, created by physicists at Manchester University and the Max-Planck Institute in Germany, is just one atom thick and is expected to be used for a wide variety of scientific research.

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RE: Carbon
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A new way of producing one-atom-thick layers of carbon with exceptional properties has been created, U.S. scientists reported on Wednesday.

The so-called "graphene-based sheets" can be mixed into polymers, glasses and ceramics, to produce novel composite materials with useful thermal, electrical and mechanical properties, said the scientists from the Northwestern University.
These findings were published in the July 20 edition of the journal Nature.
One-atom-thick carbon layers have shown remarkable strength and stiffness, but when these carbon layers pile up into bulk graphite, they become fragile. Scientists have found that there are only weak bonds between the carbon layers in bulk graphite.
Until now, it was not possible to extract individual carbon layers and to embed them as a filler material in materials such as polymers by a scalable route. But the Northwestern team said a chemical treatment would help peel carbon layers off bulk graphite.
A polystyrene-graphene composite has been formed using this method, according to the team led by Rod Ruoff, a professor at Northwestern University.
The material exhibits special properties: when graphene is 0.1 percent in the composite, it shows the lowest reported electrical conductivity value for any carbon-based composite; but when graphene concentration reaches 1 percent, the material has good conductivity.
Such graphite-based composite may be used in various industries, and the researchers believe their process will lead to discoveries of new materials in the future.
According to the U.S. Geological Survey, there are some 1 million tons of graphite sold annually around the world, and roughly 800 million tons of untapped natural graphite to be used in the future,

"Our bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications" the researchers wrote in the journal.

Source: Xinhua

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Most of the carbon supporting life on Earth was forged by red giant stars that never exploded, say astronomers in Michigan and Sweden. These stars cast the carbon into space when they blew off their outer atmospheres and became white dwarfs.

Carbon, nitrogen, and oxygen--atomic numbers 6, 7, and 8--are three of the most abundant elements in the universe. All are vital for human life. Astronomers already know that most of the nitrogen in Earth's atmosphere arose in stars that did not explode, whereas the oxygen you breathe came from stars that did explode. But carbon's origin is less clear: some studies place its birth in stars that later exploded, while other studies say just the opposite.

Now Thomas Bensby of the University of Michigan and Sofia Feltzing of Lund Observatory in Sweden have concluded that most of the Earth's carbon came from stars that died gently. By using the European Southern Observatory's 3.6-meter telescope on La Silla in Chile, the astronomers measured the carbon abundances of 51 F- and G-type main-sequence stars near the Sun. All the stars belong to the Galaxy's disk, the component that harbours the Sun and most of the Milky Way's other stars. The astronomers observed a near-infrared spectral line at a wavelength of 8727 angstroms that arises from neutral carbon atoms.
By comparing the carbon abundances with the stars' abundances of other elements, Bensby and Feltzing determined how fast carbon entered the Galaxy's disk. This rate reveals whether the carbon came from exploding or nonexploding stars--because the former have much shorter lives. Stars that explode as supernovae are usually born with more than 8 times the Sun's mass. During their lives, these high-mass stars shine so brightly that they burn through their fuel supply fast; thus, they explode soon after birth, hurling elements into space. In contrast, stars with less mass live longer, so the elements they created took longer to enter the Galaxy.

Bensby and Feltzing find that carbon entered the Galaxy's disk slowly--much more slowly than oxygen, the elemental hallmark of the high-mass stars that explode. Instead, the astronomers say, carbon enriched the Milky Way's disk at about the same rate as iron and yttrium, two elements that entered the Galaxy slowly. Only the carbon in the Galaxy's oldest stars, such as those in its halo, came mostly from massive stars, because the halo formed so long ago that less massive stars hadn't yet died.

"This kind of data is very important. It's very difficult to compute the stellar-evolution models for this element, so there's still a lot of debate about the amount of carbon that each star of a given mass throws off. Bensby and Feltzing did a very careful abundance analysis, so as to minimize the uncertainties" - Cristina Chiappini of the Astronomical Observatory of Trieste, Italy.

The carbon's evolution is especially troublesome for theorists to model.
The new work has implications beyond the Milky Way.

"Understanding carbon, nitrogen, and oxygen is very important. They are often observed in other galaxies. If you want to interpret other galaxies, you'd better be sure of how the evolution of these elements goes" - Cristina Chiappini.

The best place to gain that understanding is right here in the Milky Way.

The stars that created the carbon in the Milky Way's disk did so when they were red giants like Aldebaran and Arcturus. The red giants fused three helium-4 nuclei to make carbon-12, the most abundant isotope of the element. Some of this carbon seeped into the red giants' atmospheres. The red giants then cast off the carbon-enriched atmospheres, forming planetary nebulae such as the Ring Nebula in Lyra--beautiful bubbles of expanding gas that surround dying stars.

As the stars cast off their atmospheres, they metamorphosed from red giants to white dwarfs. Dim and unspectacular, old white dwarfs nevertheless represent the remains of the stars that made the carbon in diamonds, the carbon in pencil "lead," and most importantly the carbon that forms the basis of terrestrial life.

Bensby and Feltzing will publish their work in a future issue of Monthly Notices of the Royal Astronomical Society.

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