Home | Community | Message Board

Sporeworks
This site includes paid links. Please support our sponsors.


Welcome to the Shroomery Message Board! You are experiencing a small sample of what the site has to offer. Please login or register to post messages and view our exclusive members-only content. You'll gain access to additional forums, file attachments, board customizations, encrypted private messages, and much more!

Shop: PhytoExtractum Buy Bali Kratom Powder   Unfolding Nature Unfolding Nature: Being in the Implicate Order   North Spore Cultivation Supplies

Jump to first unread post Pages: 1
InvisibleDiploidM
Cuban


Folding@home Statistics
Registered: 01/09/03
Posts: 19,274
Loc: Rabbit Hole
The Physics of Coffee Rings
    #14938494 - 08/17/11 05:14 PM (12 years, 8 months ago)



A lot of simple things in science turn out to be quite complicated. Take, for example, coffee: You may have noticed that a spilled drop of coffee doesn't dry as a brown blob, but rather as a clear blob with a dark ring around the edge.

It's taken physicists more than a decade to figure out why this effect, known technically as "the coffee ring effect," happens. But now they think they have an answer.

The scientists who cracked the problem weren't initially studying the coffee ring effect at all. Peter Yunker and his colleagues at the University of Pennsylvania were studying how different-shaped particles — like spheres, egg-shaped, or even more elongated particles — pack together when the liquid they are in evaporates.

So first they looked at what happened when liquids with spherical particles evaporated; these formed a ring like coffee does.

"But when we evaporated the drop with the elongated particles, instead of forming a ring, they were spread out across the entire area covered by the drop," Yunker says.

This was the aha moment: Maybe it was the shape of the particles that were responsible for the coffee ring effect. Coffee does have particles in it, but Yunker didn't know whether they were spherical or not.

So he did what any good scientist would do: "We went down to the building coffee machine, put 35 cents in, got a cup of coffee, went back upstairs to the microscope, put it on a slide, took a look, and, at least on the micron scale, the particles that we saw were spherical in shape," he says.

Deforming The Drop

That might be enough proof for most people. But Yunker wanted to look at the effect in conditions he could control precisely, like the size of the particles and their exact shape. So he decided to make particles that could easily be manipulated.

"Our particles were made from polystyrene, so they're just plastic particles," he says.

Sure enough, when he let a drop of liquid with round particles in it evaporate, it formed a ring. When he tried it with elongated particles, he saw no ring. So why did the shape make a difference?

"When an elongated particle reaches the surface of the drop, it deforms the surface," Yunker says. Deforming the surface of the drop seems to be the key. "When spheres reach the surface of the drop, their shape does not induce the same deformation."

Without the deformation, the particles travel to the edge of the drop and form a ring. With the deformation that the elliptical particles cause, there's no ring. (You can see this effect in the video at the bottom of this page.)

Results of the study (which was not sponsored by Starbucks) appear in the journal Nature.

From Coffee To Printers

Arjun Yodh, director of the Laboratory for Research on the Structure of Matter at the University of Pennsylvania, was a co-author of the paper.

"At some level it was a curiosity, but then, actually, there's a lot of interesting physics about why it happens," Yodh says. And there are practical applications that go beyond coffee. "A lot of times when you're drying something, you'd rather make it uniform than to make it all congregate to the edge."

Think of a thin film of paint or ink from an inkjet printer — you don't want darker edges around each letter in a document.

Joan Curry, a chemist at the University of Arizona, says the new research appears to have solved that problem. "They found a variable that they can tweak — apparently it's not too hard to do — and they can change whether this film is uniform or not."
Shape Matters

This video, produced by the University of Pennsylvania, shows what the coffee ring effect looks like under a microscope. Watch how round particles speed out to the edges while elongated particles stay in place as the liquid dries. Some of the footage has been sped up 25 times.

NPR


--------------------
Republican Values:

1) You can't get married to your spouse who is the same sex as you.
2) You can't have an abortion no matter how much you don't want a child.
3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer.

4) We need a smaller, less-intrusive government.

Extras: Filter Print Post Top
Offlinejohnalden
Registered: 04/07/11
Posts: 26
Last seen: 12 years, 3 months
Re: The Physics of Coffee Rings [Re: Diploid]
    #14950357 - 08/20/11 12:02 AM (12 years, 8 months ago)

Really Nice information you shared here. Thanks


--------------------
Swiss Replica Watches

Extras: Filter Print Post Top
Offlineiglowmyc
Stranger


Registered: 08/04/11
Posts: 17
Last seen: 5 years, 3 months
Re: The Physics of Coffee Rings [Re: johnalden]
    #14980317 - 08/26/11 02:43 AM (12 years, 8 months ago)

i will never drink coffee again with thinking about particles now

Extras: Filter Print Post Top
OfflineHumility
Working on it
 User Gallery


Registered: 10/07/08
Posts: 6,745
Last seen: 7 years, 2 months
Re: The Physics of Coffee Rings [Re: iglowmyc]
    #14981030 - 08/26/11 09:13 AM (12 years, 8 months ago)

This is actually pretty interesting.

Thanks for sharing!!


--------------------

Extras: Filter Print Post Top
InvisibleDiploidM
Cuban


Folding@home Statistics
Registered: 01/09/03
Posts: 19,274
Loc: Rabbit Hole
Re: The Physics of Coffee Rings [Re: Humility]
    #14981087 - 08/26/11 09:33 AM (12 years, 8 months ago)

There are some cool time-lapse micrograph videos of the process happening at the link. The particles look almost alive, like a flock of birds or schooling fish.


--------------------
Republican Values:

1) You can't get married to your spouse who is the same sex as you.
2) You can't have an abortion no matter how much you don't want a child.
3) You can't have a certain plant in your possession or you'll get locked up with a rapist and a murderer.

4) We need a smaller, less-intrusive government.

Extras: Filter Print Post Top
OfflineHumility
Working on it
 User Gallery


Registered: 10/07/08
Posts: 6,745
Last seen: 7 years, 2 months
Re: The Physics of Coffee Rings [Re: Diploid]
    #14981525 - 08/26/11 11:24 AM (12 years, 8 months ago)

Thanks for pointing out the vid.  I missed the part about spherical vs. ovoid particles and how surfactant can change the behavior of differently shaped particles.


--------------------

Extras: Filter Print Post Top
OfflineBillahat
Orbital
Male


Folding@home Statistics
Registered: 07/03/11
Posts: 115
Loc: Space
Last seen: 10 years, 9 months
Re: The Physics of Coffee Rings [Re: Humility]
    #14981582 - 08/26/11 11:36 AM (12 years, 8 months ago)

Hmm.. very interesting, great post.


--------------------
::DEMAPPING & REMAPPING::

     

Extras: Filter Print Post Top
Offlinesnoot
look alive ∞
Male User Gallery

Folding@home Statistics
Registered: 01/30/05
Posts: 9,644
Loc: 45º parallel Flag
Last seen: 20 hours, 15 minutes
Re: The Physics of Coffee Rings [Re: Billahat]
    #14993901 - 08/28/11 09:58 PM (12 years, 8 months ago)

Cool I was reading about this before, cool to see the video. Pretty fascinating/


--------------------



I am incapable of conceiving infinity, and yet I do not accept finity.
- Simone de Beauvoir -

Extras: Filter Print Post Top
OfflineIdiot
I Am Moron!
Male User Gallery

Registered: 11/27/05
Posts: 6,554
Loc: 41.90231, 12.45390 Flag
Last seen: 28 days, 5 hours
Re: The Physics of Coffee Rings [Re: snoot]
    #15025815 - 09/03/11 11:56 PM (12 years, 8 months ago)

I wonder if you can change the shape of the particles in real time and cause some sort of locomotion.


--------------------

Customize your Shroomery experience!
Do not argue with an idiot. He will drag you down to his level and beat you with experience.

Extras: Filter Print Post Top
OfflineThe24HourMC
Master Of Ceremonies
Male User Gallery


Registered: 10/16/09
Posts: 7,704
Loc: Gone
Last seen: 9 years, 3 months
Re: The Physics of Coffee Rings [Re: snoot]
    #15028668 - 09/04/11 04:01 PM (12 years, 8 months ago)

wow. I was wondering about this just today.


--------------------


My Baby In MCLA


Fuckin Shit

Fuck that stay high

Extras: Filter Print Post Top
Jump to top Pages: 1

Shop: PhytoExtractum Buy Bali Kratom Powder   Unfolding Nature Unfolding Nature: Being in the Implicate Order   North Spore Cultivation Supplies


Similar ThreadsPosterViewsRepliesLast post
* New maglev style launch-ring could send sattelites into orbit DNKYD 1,029 4 10/06/06 09:15 PM
by Catalysis
* The Oh-My-God Particle
( 1 2 all )
DiploidM 3,626 23 03/28/05 11:15 AM
by cybrbeast
* String Theory and Quantum Physics.
( 1 2 all )
ergot 5,222 24 01/03/04 01:02 AM
by MarioNett
* 20 light-year wide particle accelerator spotted by astronomers MarioNett 2,190 18 04/16/05 11:06 AM
by Aeolus1369
* What is a wave/particle? Gomp 1,249 11 04/07/06 10:41 AM
by ChuangTzu
* Anyone who claims they understand quantum physics.......
( 1 2 all )
bit_slice 5,454 30 02/05/09 05:10 PM
by Annom
* Ring Tones Adults Can't Hear (LMAO!)
( 1 2 all )
DiploidM 1,888 25 06/22/06 06:35 AM
by Seuss
* Rings TheDudeAbides 310 0 02/22/06 08:01 PM
by TheDudeAbides

Extra information
You cannot start new topics / You cannot reply to topics
HTML is disabled / BBCode is enabled
Moderator: trendal, automan, Northerner
1,089 topic views. 0 members, 0 guests and 2 web crawlers are browsing this forum.
[ Show Images Only | Sort by Score | Print Topic ]
Search this thread:

Copyright 1997-2024 Mind Media. Some rights reserved.

Generated in 0.025 seconds spending 0.007 seconds on 14 queries.