Graphene Aerogel Takes World's Lightest Material Crown 198
cylonlover writes "Not even a year after it claimed the title of the world's lightest material, aerographite has been knocked off its crown by a new aerogel made from graphene. Created by a research team from China's Zhejiang University in the Department of Polymer Science and Engineering lab headed by Professor Gao Chao, the ultra-light aerogel has a density of just 0.16 mg/cm3, which is lower than that of helium and just twice that of hydrogen."
Density calculation? (Score:4, Interesting)
I'm assuming that the 'density' figure given is a 'weight of graphene in a given volume' one, rather than one that includes the gasses occupying the pores/cells of the material?
It would be quite shocking indeed if something largely saturated in nitrogen and oxygen were less dense than helium...
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I suspect you're right.
OTOH, how strong is it? Graphene is supposed to be tough stuff. If it could be used to trap hydrogen and keep it from burning it might be very useful (eg. replace all water-ships with airships).
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At the density levels we are talking about here, I'd assume that the surface area is absolutely enormous(particularly per unit weight) so normally-negligible things like gases absorbed onto the surface might become a significant factor, as well as those mechanically trapped within the pores.
Re:Density calculation? (Score:5, Informative)
OTOH, how strong is it? Graphene is supposed to be tough stuff.
I have no idea how strong graphene areogel is, but I have handled silica aerogel and it is extremely fragile. It it difficult to handle it without accidentally fracturing it. My daughter used a disk of aerogel as in insulator in her school science project last year, and we had to buy three disks ($30 each) because they kept breaking. I hope graphene aerogel is stonger.
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TFA says it's "very strong and extremely elastic, bouncing back after being compressed". The application they project is swabbing up oil spills, but there have to be lots and lots of other applications out there.
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I have handled silica aerogel and it is extremely fragile. It it difficult to handle it without accidentally fracturing it. ... I hope graphene aerogel is stronger.
Accoring to TFA: The result is a material the team claims is very strong and extremely elastic, bouncing back after being compressed.
So this stuff appears to be much more robust than silica aerogels, which are rigid and brittle, and not elastic in the least. That should give it many more practical applications.
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Now THAT would be fascinating... First "charge" a piece of the graphene aerogel with hydrogen, then bring it out into the air and try to light one corner with a match or small torch. I'll bet that the mechanical structure is delicate enough that the match or torch would trigger the release of some hydrogen, which would then burn. The interesting part would be if that flame triggered a cascade or just died out, and if a cascade were triggered, how fast it would be, and how much the carbon would participat
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Yeah, interesting material but in no way the lightest. If the holes in the material count to its volume, you can get lower density with a big balloon.
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a functional pseudo-vacuum balloon that doesn't collapse under atmospheric pressure.
Now that would change the world.
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If you had a membrane that could withstand the pressure
I think the thought here is that the aerogel would provide the rigidity that the membrane lacks.
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If it's rigid you don't need any hydrogen, that's the point.
1 liter of *nothing* is lighter than 1 liter of hydrogen. We don't have a material (that I know of anyway) that can both support the 1 atmosphere pressure difference of the inside and the outside of a large enough to be useful surface area while also not weighing so much that it's pointless.
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It would be preferable to use something that reacts less easily with oxygen than hydrogen, in many cases.
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Good luck convincing anyone that hydrogen airships are safe.
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FTFY
Most people don't care about why it is now safe, they just remember "Oh the Humanity"
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People get in hot air balloons all the time, despite their rather dismal safety record. Hot air is not viable for airships.
There are currently three possible lift gases for airships: hydrogen, helium, and water vapour. Hydrogen is out for safety reasons, helium will be too expensive, and steam is difficult because the airship has to be really large to avoid too much heat loss.
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Area scales square, volume scales cube... all you need do it make it really, really big. Aside from the issue of the gel itsself not being strong enough, of course.
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Yeah, but to do that, you need really big carbon atoms, and they're still hard to build... ;-)
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design a custom, stable, spherical molecule.
assemble atom by atom in a vacuum
with a large enough volume, and thin enough walls, you could have a permanent 'helium' balloon
Aerogel vs. M&Ms (Score:3)
I still remember the first time I learned about aerogel. The picture had a column of Aerogel about the size of a double-height coke can on one side of a balance and 3 M&Ms on the other side that weighed more.
Re:Aerogel vs. M&Ms (Score:5, Informative)
The insulative properties [wikimedia.org] are also pretty dramatic. There is another picture floating around with some crayons in place of the flower. That little stunt might not work as well with carbon aerogels as it does with silica ones, though...
Re:Aerogel vs. M&Ms (Score:4, Interesting)
Given that all aerogels are extremely tenuous foams, I would strongly suspect that all of them are pretty good insulators(even if one were made of a very good conductor of heat, like silver, there is just so little solid and so much trapped-gas-pocket that good insulation is to be suspected). However, if the aerogel is made of a material that burns in oxygen, the same combination of a tiny amount of solid with plenty of gas probably results in a very swift burn once you get it started.
I'd suspect that a carbon aerogel would be only slightly worse as an insulator than a silica one; but I wouldn't try taking a blowtorch to it(except to see what happens...)
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It's more impressive when you do it the other way around: http://upload.wikimedia.org/wikipedia/commons/thumb/e/ea/Aerogelbrick.jpg/568px-Aerogelbrick.jpg [wikimedia.org]
Enter the new airship age ... (Score:5, Insightful)
Make a bag around it. Remove the air. We have an airship with the lift somewhere between H and He.
So how strong is the aerogel? How big a bag can we make and have it support atmospheric pressure on the other side? That will really determine the lift efficiency.
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You still have the weather issues that make airships impractical and now your lifting agent costs billions per fill. That is just the first two problems.
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Because cutting edge materials never get cheaper when a valid use is found for them and they start getting produced on industrial, economical scales.
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I'm sure all the operators who fly airships daily would be interested to hear why you think it's impractical to do what they are doing.
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Which ones are those?
All the ones I know of are used only for advertising and pleasure cruising due to these limitations.
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And horatio, there are more things on heaven and earth, than you- I- or any one man will ever think of
the best you can hope to do, is appreciate a reasonable smidgeon of one percent
Humans are endlessly variable, and there are a lot of us.
http://en.wikipedia.org/wiki/Zeppelin_NT [wikipedia.org]
"The Zeppelin NT ("Neue Technologie", German for new technology) is a class of helium-filled airships being manufactured since the 1990s by the German company Zeppelin Luftschifftechnik GmbH (ZLT) in Friedrichshafen.[1] The initial mo
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Those are only for advertising and pleasure cruises.
This is because of the inherent stability issues that lighter than air craft all face.
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I'm pretty sure that they already know, and don't care why it's impractical. After all, if it was practical, they'd be more common than airplanes, which they are not.
Well the cost of helium, and the explosiveness of hydrogen, are pretty good reasons why they're impractical. If graphene aerogel could remove these issues than the question is if there's additional impracticalities.
My guess would be weather (having that large a profile makes it too hard to stay on course with wind), carrying capacity, and speed.
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In a world without wind - perhaps. Not in this one, though.
An airship that can sink (Score:2)
The second problem is actually the main problem, IMHO. It is not like this kind of lifting agent is going to leak out if the hull is damaged by bad weather, or expand uncontrollably if ship ascends too abruptly.
The hull is damaged, air might leak in and make the structure heavier. The is short of design makes airship rather similar to ships and submarines that move through water. In the event of damage the worry isn't that the contained material (air in the case of ships and submarines) will leak out. The problems is that the outside material (water in the case of ships/submarines, air in the case of a aerogel filled airships) will leak in.
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Probably about 1/1000 as strong as it would have to be to withstand atmospheric pressure. That's *IF* you could remove all the encapsulated air, which of course you couldn't.
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That's *IF* you could remove all the encapsulated air, which of course you couldn't
I believe this is quite possible following the aerogel production process. Once the supercritical compound is "drained" out it, the aerogel would basically be at vacuum.
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You know those storage bags that you suck the air out of with a vacuum so they take up less space? Imagine putting a sponge in one, and sucking out all the air. It would end up flat as a pancake, which is probably the same way a bag of areogel would look under those conditions.
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... except a sponge is not a rigid structure, unlike aerogel.
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When something is described as "extremely elastic, bouncing back after being compressed" then it's unlikely to be all that rigid...
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I am (perhaps incorrectly) under the assumption that aerogels are rigid. [wikipedia.org]
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So how strong is the aerogel? How big a bag can we make and have it support atmospheric pressure on the other side? That will really determine the lift efficiency.
As an ultralight foam, it has strength, but very little. You can order aerogel samples online - I did a year or two ago (glass aerogel, not graphene). It's extremely brittle and has almost no impact strength, but it has sufficient strength to be made useful. You could conceivably do what you suggest and create a bag of it, then isolate it from the exterior surface or any surface that might see impact damage. It could certainly be made to work if you had enough time, money, and talented minds.
The problem is,
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Make a bag around it. Remove the air. We have an airship with the lift somewhere between H and He.
Using a vacuum gives you little additional buoyancy. Air has a density of about 1.2 kg/m^3. Hydrogen has a density of about 0.09 kg/m^3. So a cubic meter of vacuum has a buoyancy of 1.2 kg/m^3, and a cubic meter of H has a buoyancy of 1.11 kg/m^3. So a vacuum will only give you about 8% more lift than using hydrogen, and about 16% more than using helium. The expense and hassle of maintaining a vacuum is unlikely to be worth the gain.
What ever happened to precision of speech? (Score:5, Informative)
Obviously not 'lightest', but 'least dense'. Sheesh, editors - do your JOB! The /. title should be "Silly folk at Gizmag confuse mass with density when describing world's least dense solid.'
Re:What ever happened to precision of speech? (Score:4, Funny)
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Which makes me think...
It might not be appropriate to consider aerogels "solid" in the "3D solid" sense. It might be better to consider aerogels to be a real and physical example of a "factal solid," and I wouldn't care to attempt to assign the fractional dimensionality to such a thing. But aerogels seem to have the essential characteristics of the "space-filling" shapes described in fractal literature.
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Obviously not 'lightest', but 'least dense'.
You've just got to apply a correction factor. Ask yourself whether it is the lightest material per kilogram...
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Lightest per kilogram? A have a feather and a gold brick that are both exactly 1kg/kg.
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The absolute terms 'light' and 'heavy' are not shorthand for relative terms relating to density. If you don't include the volume of a substance when describing something as 'light' or 'heavy', you can't beat a single neutrino - it's possibly the 'lightest*' substance in absolute terms of only mass. 'Light' and 'low density' are not the same thing. Notice that mass (g) and density (g/cm^3) don NOT depend on gravity, only mass and volume. Sintered depleted uranium is (relatively) low density, but very heavy.
A
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I think you've got it backwards. As you say words in English that end in -er are relative - they have no use without comparing things. Words like big and small, hot and cold are relative as well, but the comparison is usually implied. ("That dog is big" [as compared to other dogs]). Words that end in -est are absolutes - "That is the tallest dog", meaning there is no other dog that is taller.
Also I think you are confusing 'substance' and 'object' - a single neutrino is not a substance, it is an object. Wat
Density (Score:2, Interesting)
" the ultra-light aerogel has a density of just 0.16 mg/cm3, which is lower than that of helium and just twice that of hydrogen."
Picture in the article shows a chunk of the stuff being supported by a blade of grass. If the density's lower than that of helium, why isn't it floating away instead of sitting there like a thing that's denser than the atmosphere around it?
Re:Density (Score:5, Informative)
The density is measured including its interior space. In reality the interior space is filled with air and its realtive weight is the carbon structure alone.
To make it float you would have to find a way to seal off the interior structure and remove the air from that.
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The density is measured including its interior space. In reality the interior space is filled with air and its realtive weight is the carbon structure alone. To make it float you would have to find a way to seal off the interior structure and remove the air from that.
I don't understand that. If the inner air "cavities" are connected to the outside and thus have the outside air's vertical pressure gradient, they should exert the same buoyant force / upward "lift" on the carbon structure, or not?
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If the density's lower than that of helium, why isn't it floating away
Bad journalism ...
being repeated verbatim by an idiot slashdot submitters
then not being deleted by idiot slashdot editors
then being voted up in the firehose by equally stupid readers.
On a "tech" site, with three separate links in the editorial chain, you'd think that it would have been spotted, but nooooooo.
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Because the material is extremely porous, and is saturated with ambient air.
In a vacuum, the material should float.
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In a vacuum, the material should float.
What would it be displacing in a vacuum? Paging @Archimedes.
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Just to clarify, you would need to seal the outer surface, and pull a vacuum on the internal volume of the material. Then, assuming that the sealing coating didn't weigh too much, the stuff should float.
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Yay, you finally said it right!
I am just imagining (like everyone else) 3D printers of this stuff that create rigid blimp sections which are assembled (interlocking) and provide a permanent no-gas lighter-than-air rigid support structure. You only need to maintain vacuum, which is far more easy and desirable than having to lug a fixed amount of compressed buoyant gas around.
14 psi (Score:2)
You are also assuming that the outside air pressure wouldn't crush it down to a density that would make it sink.
I would be really surprised if you could just evacuate the stuff and make it float. Some day we'll use evacuated carbon nanostructures for lighter than air, but I don't think we're there yet.
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Why would it float in a vacuum?
Now that *WOULD* be magically ground breaking tech ;)
Carbon is awesome (Score:3)
Can be used to make the hardest or lightest stuff on the planet.
Carbon's reputation is however spoiled by a couple of Oxygen a-holes that like to latch on to it, stupid no good Oxygen.
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howdy AC,
i can't stand it! i hafta post this link ...
Facts About Dihydrogen Monoxide
- http://www.dhmo.org/facts.html [dhmo.org]
the idea that there are actually _several_ such sites adds to the giggle factor. [*grin*]
take care,
lee
OK, explain this to me, someone... (Score:2)
This stuff is lighter than helium (presumably at standard pressure and temperature) and yet not buoyant in air. That presumably means it's air-permeable in much the same way that a cellulose sponge is water permeable? In that case, in what sense is it lighter than helium? If you enclosed a volume of this stuff in a gas-tight membrane it would presumably be buoyant in air, but that - it seems to me - would surely be because vacuum is lighter than air?
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Yes. Depending on the actual strength and other factors you may be able to make it lighter than air by sealing it into an air-tight membrane of some sort and removing all of the air. If it retains its structure it would then be lighter than air.
Brief Kings (Score:5, Funny)
Graphene Aerogel Takes World's Lightest Material Crown
A crown should weigh heavy on a ruler's brow, lest he forget the weight of his responsibility.
I don't quite get it (Score:5, Interesting)
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What defines solid? There's lots of things that are "solid" but filled with holes; think pumice or a brick. Molecules are mostly empty space, as are atoms themselves. It's not necessarily any sillier to think of aerogel as being solid than it is to think of pumice being solid. If you want to draw the line, it's always going to be arbitrary
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And how do you make one dimensional graphene fibres?
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Because if you were to slice it in half, this graphene aerogel would be the exact same density and consistency all the way through, at every single molecular point inside of it.
I really doubt it, otherwise it would not be a gel [wikipedia.org], it would be a solution or a cristal (definition of a gel implies: have porous inner surface to trap the liquid)
Transparent aluminum? (Score:2)
But it will take years to figure out the dynamics of this matrix.
Dumb question? (Score:2)
Here's my stupid question: if it's less dense than helium, and about 1/10 that of nitrogen (1.6 mg/cm3)...why is it pictured *sitting* on anything? Why doesn't it float away?
If, as I suspect, it's porous and it's being measured as 'less dense' than He only because they are taking the actual mass/OUTER VOLUME...well, that's not actual density is it? If so, then by this method my portable dog kennel (made of STEEL) is only an order of magnitude more dense than oxygen.
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It doesn't float away because it's filled with air. If it were filled with nothing (i.e., a vacuum) it should float away.
It's very reasonable to think about the overall density of something. Think about a boat - a boat floats because it is overall less dense than water it displaces.
Material? (Score:2)
This thing seems to consist mainly of air. Doesn't that stretch the definition of "material" quite a bit? If I create a 10-foot wireframe cube consisting of just 12 thin aluminium stiffeners, and define the whole interior of the thing as part of the "material", that's gonna have a pretty low density too.
"density" .... really? (Score:2)
I can change the density of hydrogen or helium by heating it up, or compressing it.
If I wanted hydrogen to be less dense than whatever aerogel, I just need to move the hydrogen to a bigger bottle.
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Will helium readily flow through it?
Its density does not mean it is not too porous to prevent everything else from flowing through, or tight enough to significantly restrict the flow of the gasses you want.
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Wouldn't the use of the world "Aerogel" sorta indicate that we're talking about a solid?
Or even the term "Material" in context...I mean..using this line of thought you're using, a vaccume is technically lighter, I mean, you didn't specify the lightest 'gas' after all.
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Vacuum is a gas in the eyes of Christian fundamentalists. Just like Atheism is a religion, not collecting stamps is a hobby, and off is a TV channel.
Re:I'd believe it if you added the word "solid" (Score:4, Funny)
I like "off"; there's less re-runs than the other channels.
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And helium. And a lot of other gasses. The aerogel only stays puffed up because it's got air in it. If you're going to be fair you have to count that as part of the density.
Re:I'd believe it if you added the word "solid" (Score:4, Interesting)
Well, it should be possible to make it less squishy (carbon makes diamonds, after all). Cover it with some other graphene variant in low pressure, and one just might manage to make a lighter-than-air solid. I'd avoid the torch, though.
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I don't think an elemental gas counts as a "material."
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This is why no one under the age of 32 today has any fundamental understanding of the English language. ... This is why they put their punctuation inside of quotation marks even when the punctuation is not part of the thing being quoted...
Funny, APA, MLA, and the Chicago Manual of Style all recommend putting the period inside the quotation at the end of the sentence even if the original quotation does not have a period. And my copy of the Chicago Manual of Style is older than 32 years. Not that I put much effort into writing random forum posts and I'm sure I make plenty of mistakes. But if one were to try to argue technically about what is the correct approach, at best you can argue it is a stylistic choice. Otherwise, you are going agai
Re:I'd believe it if you added the word "solid" (Score:4, Informative)
The convention in the United States for decades has been to places periods inside the quotation marks. All others are based on the actual quote. The Chicago Manual of Style, as one of many, recommends this, but most guides point out that the British style placing anything not part of the quote outside of the quotation marks is acceptable but may be seen as unusual to American readers--of all ages.
Quotation marks (Score:2)
The convention in the United States for decades has been to places periods inside the quotation marks. All others are based on the actual quote. The Chicago Manual of Style, as one of many, recommends this, but most guides point out that the British style placing anything not part of the quote outside of the quotation marks is acceptable but may be seen as unusual to American readers--of all ages.
Although putting periods inside quotation marks is recommended by various manuals of style and others recommend putting them outside, I believe that both approaches are misguided
Clarity should be the primary concern in language. Quotation marks are used to indicate that the current passage is repeating something verbatim from another source. It is most accurate to include punctuation inside quotation marks if that punctuation is repeated verbatim. In that case, they are punctuating the original. If they
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You are correct that I am a product of 1990's (and 2000's) US public schooling. Not everyone is born into wealth and able to be privately educated.
Despite your implication that my education was inferior, I am able to join a discussion and offer my opinion without attacking participants for little to no reason. I invite you to reflect on what that means in the context of your own education...
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X0563511, did you know that hydrogen is made up of matter, and is thus a material?
On the other side, spelling doesn't matter nowadays, thus your post is immaterial for the context of /.
"eat healthy" (Score:2)
This is why they say someone who eats a healthy diet "eats healthy" instead of "eats healthily".
"I like to eat Italian." => "I like to eat Italian food."
"I like to eat healthy." => "I like to eat healthy food."
So could you please clarify your claim that "to eat healthy" is not valid English?
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Your argument is completely retarded. Helium is also an element and it BEAT helium.
See, that's the problem with mud-slinging - sometimes, a wee bit of that mud comes right back at you.
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Lead is less dense than osmium because of the way their atoms exist in their crystal structures.
"As far as use as a construction and engineering material, the vast majority of the time people don't care how many atoms there are and instead care about something that comes back to the volume."
Not always so in say, chemical or nuclear engineering. But for larger scale applications that is fair enough and you did say the "vast majority." But nothing I said is
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Ridiculous.
Nobody said anything about graphene molecules having less mass than hydrogen atoms (except you).
What was said (in TFA) was that the graphene aerogel is lighter than helium, which has the plain meaning that a given volume of the aerogel has less mass than the same volume of hydrogen.
(BTW, hydrogen around the earth usually comes in the form of H2 molecules, not si
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They're all away, buying low-cost items at the dollar store.
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How is it made?
Freeze-casting [wikipedia.org]: take the material, form a gel with a solvent that has a triple point, freeze the gel, sublimate the solvent.
Graphene oxide [graphene-supermarket.com] is hydrophilic, one may try it at home using water. Use a jewelry ultrasonic cleaner to form the gel and your freezer for freeze-drying the gel. As it may take a while to have all the water sublimating, perhaps trying to freeze-cast it as band rather than a bulky form may help. Note: I didn't try it myself (yet)