91–100 of 133 posts
Earlier quoted context omitted.
Actually the radius is 5mm in the paper, it was nneonneo that got that part wrong.
The wrong part doesn't come from the 5mm, it comes from being orders of magnitude wrong by some other method.
Earlier quoted context omitted.
Holy crap. 125,000RPM for a 5mm disc means the edge is spinning at nearly 9,000mph. On top of that, the g-force would be a = v^2 / r v = 2 * pi * 5mm * 125000/60 s^-1` r = 5mm ...giving 87,000 gees?! I start to wonder if general relativity effects (frame-dragging?) start to become noticeable at that acceleration.
Quick math and google says no: 9,000 MPH = 0.00001342 C Threshold for relativistic effects is .01 C according to this paper: http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/rellim.ht... EDIT: Rereading that paper, they're focused at the particle level, which may or may not make this irrelevant. I know anecdotally that GPS satellites have to take relativity into account. Geostationary satellites move at 1.9 miles p…
I remember doing this with big coat buttons and string when I was a kid.
Not anywhere close to the $0.20 cost of this paper centrifuge, but still a pretty huge savings compared to the $6k-$10k units generally available currently.
[1]: https://www.macfound.org/fellows/965/
[2]: https://en.wikipedia.org/wiki/Foldscope
[3]: https://www.ted.com/talks/manu_prakash_a_50_cent_microscope_...
As usual, what you really want to do is read the paper: http://www.nature.com/articles/s41551-016-0009 This is a well-written and very clear paper. It covers several aspects that went unmentioned in the Gizmodo article, and highlights that although building such a device may be trivial, evaluating and studying it is not. Some highlights: the paper covers how the device was built in detail, including information on th…
Holy crap. 125,000RPM for a 5mm disc means the edge is spinning at nearly 9,000mph. On top of that, the g-force would be a = v^2 / r v = 2 * pi * 5mm * 125000/60 s^-1` r = 5mm ...giving 87,000 gees?! I start to wonder if general relativity effects (frame-dragging?) start to become noticeable at that acceleration.
Fill in the blanks, m/s:
v (in m/s) = pi * D * rpm / 60 (D in m)
3.141593 * 0.01 * 125,000 / 60 = 65.45 (m/s)
v (in km/h) = pi * D * rpm * 60 / 1000 (D in m)
3.141593 * 0.01 * 125,000 * 60 / 1000 = 235.62 (km/h)
Earlier quoted context omitted.
Holy crap. 125,000RPM for a 5mm disc means the edge is spinning at nearly 9,000mph. On top of that, the g-force would be a = v^2 / r v = 2 * pi * 5mm * 125000/60 s^-1` r = 5mm ...giving 87,000 gees?! I start to wonder if general relativity effects (frame-dragging?) start to become noticeable at that acceleration.
Quick math and google says no: 9,000 MPH = 0.00001342 C Threshold for relativistic effects is .01 C according to this paper: http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/rellim.ht... EDIT: Rereading that paper, they're focused at the particle level, which may or may not make this irrelevant. I know anecdotally that GPS satellites have to take relativity into account. Geostationary satellites move at 1.9 miles p…
As usual, what you really want to do is read the paper: http://www.nature.com/articles/s41551-016-0009 This is a well-written and very clear paper. It covers several aspects that went unmentioned in the Gizmodo article, and highlights that although building such a device may be trivial, evaluating and studying it is not. Some highlights: the paper covers how the device was built in detail, including information on th…
> As usual, what you really want to do is read the paper: An aside: If you are not reading Nature you may be missing out on a lot. I would guess the same applies to Science. Only the back half of Nature is actual research papers, which often are indeed very slow going. The other half is science news written clearly - it's fascinating, not a chore at all - and with a level of knowledge and sophistication unmatched els…
Wouldn't want to waste words on silly shit like methods, references, discussions, etc in a CNS paper, would we?
LIGO doesn't even bother sending papers to Nature or science any more. The editors at both are unbearably pompous.
As usual, what you really want to do is read the paper: http://www.nature.com/articles/s41551-016-0009 This is a well-written and very clear paper. It covers several aspects that went unmentioned in the Gizmodo article, and highlights that although building such a device may be trivial, evaluating and studying it is not. Some highlights: the paper covers how the device was built in detail, including information on th…
Holy crap. 125,000RPM for a 5mm disc means the edge is spinning at nearly 9,000mph. On top of that, the g-force would be a = v^2 / r v = 2 * pi * 5mm * 125000/60 s^-1` r = 5mm ...giving 87,000 gees?! I start to wonder if general relativity effects (frame-dragging?) start to become noticeable at that acceleration.
Earlier quoted context omitted.
1. The g-force always acts in one direction: towards the outside of the disc. 2. The diameter of the tube is small. It's nearly 1-D dynamics in there. 3. Very large g-forces only happen at top rotational speeds. When not rotating, the material gets slowly mixed back up, but at the regular (i.e. very slow) diffusion speed. So: separation works always towards the outside + re-mixing is a much slower process = it works…
Yes I understand what you are saying, that the force is going to the outside of the disc, but using even light braking (over minutes or even hours for ultracentrifuging) can disturb a pellet or separation. This is rapidly coming to a complete stop and reversing direction over and over.