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How to make graphene in a kitchen blender

Nature Newsblog - 6 hours 26 min ago

Atomic resolution, scanning transmission electron microscope image of part of a nanosheet of shear exfoliated graphene. Credit: CRANN/SuperSTEM

Don’t try this at home. No really, don’t: it almost certainly won’t work and you won’t be able to use your kitchen blender for food afterwards. But buried in the supplementary information of a research paper published today is a domestic recipe for producing large quantities of clean flakes of graphene.

The carbon sheets are the world’s thinnest, strongest material, both electrically conductive and flexible, and tipped to transform everything from touchscreen displays to water treatment. Many researchers – including Jonathan Coleman at Trinity College Dublin – have been chasing ways to make large amounts of good-quality graphene flakes.

In Nature Materials, a team led by Coleman (and funded by the UK-based firm Thomas Swan) describe how they took a high-power (400 watt) kitchen blender and added half a litre of water, 10 to 25 mls of detergent, and 20 to 50 grams of graphite powder (found in pencil leads). They turned the machine on for 10 to 30 minutes. The result, the team reports: a large number of micrometre-sized flakes of graphene, suspended in the water.

Coleman adds, hastily, that the recipe involves a delicate balance of surfactant and graphite, which he has not yet disclosed (a barrier that dissuaded me from trying it out; he is preparing a detailed kitchen recipe for later publication). And in his laboratory, centrifuges, electron microscopes, and spectrometers were also used to separate out the graphene and test the outcome. In fact, the kitchen-blender recipe was added late in the study as a bit of a gimmick – the main work was done first with an industrial blender (pictured).

Five litres of suspended graphene (in an industrial blender). Credit: CRANN.

Still, he says, the example shows just how simple is his new method for making graphene in industrial quantities. Thomas Swan has scaled the (patented) process up into a pilot plant and, says commercial director Andy Goodwin, hopes to be making a kilogram of graphene a day by the end of this year, sold as a dried powder and as a liquid dispersion from which it may be sprayed onto other materials.

“It is a significant step forward towards cheap and scalable mass production,” says Andrea Ferrari, an expert on graphene at the University of Cambridge, UK. “The material is of a quality close to the best in the literature, but with production rates apparently hundreds of times higher.”

The flakes are not as high-quality as those that the winners of the 2010 Nobel Prize in Chemistry, Andre Geim and Kostya Novoselov from Manchester University, famously isolated by using Scotch Tape to peel off single sheets from graphite. Nor are they as large as the metre-scale graphene sheets that firms today grow atom by atom from a vapour.  But outside of high-end electronics applications, smaller flakes suffice: the real question is how to make lots of them.

Though hundreds of tons of graphene are already being produced each year — and you can easily buy some online — their quality is variable. Many of the flakes in store are full of defects or smothered with chemicals, affecting their conductivity and other properties, and are tens or hundreds of layers thick. “Most of the companies are selling stuff that I wouldn’t even call graphene,” says Coleman.

The blender technique produces small flakes some four or five layers thick on average, but apparently without defects – meaning high electrical conductivity. Coleman thinks the blender induces shear forces in the liquid sufficient to prise off sheets of carbon atoms from the graphite chunks (“as if sliding cards from a deck”, he explains).

Kitchen blenders aren’t the only way to produce reasonably high-quality flakes of graphene. Ferrari still thinks that using ultrasound to rip graphite apart could give better materials in some cases. And Xinliang Feng, from the Max Planck Institute for Polymer Research in Mainz, Germany, says that his recent publication, in the Journal of the American Chemical Society, reports a way to produce higher-quality, fewer-layer graphene at higher rates by electrochemical means. (Coleman points out that Thomas Swan have taken the technique far beyond what is reported in the paper).

As for applications: “the graphene market isn’t one size fits all,” says Coleman, but the researchers report testing it as the electrode materials in solar cells and batteries. He suggests that the flakes could also be added as a filler into plastic drinks bottles – where their added strength reduces the amount of plastic needed, and their ability to block the passage of gas molecules such as oxygen and carbon dioxide maintains the drink’s shelf life.

In another application altogether, a small amount added to rubber produces a band whose conductivity changes as it stretches – in other words, a sensitive strain sensor. Thomas Swan’s commercial manager, Andy Goodwin, mentions flexible, low-cost electronic displays; graphene flakes have also been suggested for use in desalination plants, and even condoms.

In each case, it’s yet to be proven that the carbon flakes really outperform other options – but the new discoveries for mass-scale production mean that we should soon find out. At the moment, an array of firms is competing for different market niches, but Coleman predicts a thinning-out as a few production techniques dominate. “There are many companies making and selling graphene now: there will be many fewer in 5 years’ time,” he says.

Categories: General, News

In sex-reversed cave insects, females have the penises

Biology News - Thu, 2014-04-17 20:39


This shows the female penis of N. aurora. Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but related species in the genus Neotrogla, are the first example of an animal with sex-reversed genitalia.

Categories: Biology News, General

Some immune cells defend only 1 organ

Biology News - Thu, 2014-04-17 20:38

Scientists have uncovered a new way the immune system may fight cancers and viral infections. The finding could aid efforts to use immune cells to treat illness.

Categories: Biology News, General

What’s in a name? Emmett Reid Dunn and the Oedipus salamanders

Ernst Mayr Library Blog - Thu, 2014-04-17 15:07

When scientists describe a new animal species, they give it a name, according to rules of the ICZN, the International Code of Zoological Nomenclature.   Species names can honor a person or the place where the animal lives, or reflect the personality of the describer, as in the case of the beetle Gelae donut (Miller and Wheeler 2004).  Emmet Reid Dunn (1894-1956), who earned his PhD at Harvard under Thomas Barbour, expressed his sense of humor when naming salamanders.  Dunn’s 1921 dissertation on the Plethodontidae was expanded and published in 1926 as The Salamanders of the Family Plethodontidae.   Of the eight Oedipus salamanders that Dunn described there, two stand out: Oedipus rex and Oedipus complex.

Because names change as scientific knowledge advances, both of these names have been revised into ordinariness.   In 1944, E.H. Taylor reassigned the species within the genus Oedipus to eight separate genera, including Oedipina(Keferstein 1868) and the new genus Pseudoeurycea.

Below are references for the type descriptions, the Taylor 1944 and the Encyclopedia of Life entries for both.   The new names are more accurate, but not as clever!

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Oedipus rex, sp.nov. described by E.R. Dunn in 1921.

Common name, Royal False Brook Salamander.

E.R. Dunn, “Two new Central American salamanders”, Proceedings of the Biology Society of Washington vol. 34, pg. 143-146 (1921)

EOL record for Pseudoeurycea rex:   http://eol.org/pages/1019116/overview

Pseudoeurycea rex © 2006 Sean Michael Rovito Source: CalPhotos

 

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E.H. Taylor, “The genera of Plethodont Salamanders in Mexico, Pt. 1.”, Univ. of Kansas Science Bulletin vol. 30, pg. 189-232 (1944).

Oedipus complex, sp.nov. described by E.R. Dunn in 1924.

Common name, Gamboa worm salamander.

E.R. Dunn, “New Amphibians from Panama”, Occasional Papers of the Boston Society of Natural History vol. 5, pg 93-95 (1924).

EOL record for Oedipina complex:  http://eol.org/pages/2815206/overview/

Oedipina complex © STRI

 

 

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