Navigation Links
Penn physicists undo the 'coffee ring effect'
Date:8/18/2011

PHILADELPHIA A team of University of Pennsylvania physicists has shown how to disrupt the "coffee ring effect" the ring-shaped stain of particles leftover after coffee drops evaporate by changing the particle shape. The discovery provides new tools for engineers to deposit uniform coatings.

The research was conducted by professor Arjun Yodh, director of the Laboratory for Research on the Structure of Matter; doctoral candidates Peter Yunker and Matthew Lohr; and postdoctoral fellow Tim Still, all of the department of Physics and Astronomy in Penn's School of Arts and Sciences.

Their research will be published in the journal Nature on August 18.

"The coffee ring effect is very common in everyday experience," Yunker said. "To avoid it, scientists have gone to great lengths designing paints and inks that produce an even coating upon evaporation. We found that the effect can be eliminated simply by changing the shape of the particle."

The edges of a water drop sitting on a table or a piece of paper, for example, are often "pinned" to the surface. This means that when the water evaporates, the drop can't shrink in circumference but instead flattens out. That flattening motion pushes water and anything suspended in it, such as coffee particles, to its edges. By the time the drop fully evaporates, most of the particles have reached the edge and are deposited on the surface, making a dark ring.

University of Chicago physicists Sidney Nagel, Thomas Witten and their colleagues wrote an influential paper about this process in 1997, which focused mainly on suspended spherical particles, but it was not until the Yodh team's recent experiments that the surprising role played by suspended particle shape was discovered.

Yodh's team used uniformly sized plastic particles in their experiments. These particles were initially spherical but could be stretched into varying degrees of eccentricity, to ensure
'/>"/>

Contact: Evan Lerner
elerner@upenn.edu
215-573-6604
University of Pennsylvania
Source:Eurekalert

Page: 1 2 3

Related biology technology :

1. McGill physicists find a new state of matter in a transistor
2. U of T physicists squeeze light to quantum limit
3. Physicists discover important step for making light crystals
4. Nanophysicists find unexpected magnetic effect
5. NYU physicists find way to explore microscopic systems through holographic video
6. Physicists at UC Santa Barbara make discovery in quantum mechanics
7. U-M physicists create first atomic-scale map of quantum dots
8. Physicists capture first images of atomic spin
9. UBC, Max Planck formalize partnership among worlds top quantum physicists
10. UC Riverside physicists pave the way for graphene-based spin computer
11. Rice physicists discover ultrasensitive microwave detector
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:9/15/2014)... , Sept. 15, 2014 ... on revolutionizing the treatment of cancer through the ... cells, announced that, together with the Asbestos Disease ... Cancer Institute New South Wales (NSW) Premier,s Award ... four recipients are the hospitals that will be ...
(Date:9/15/2014)... can go downhill fast when a patient has sepsis, ... in a patient,s blood -- often too fast for ... human spleen and developed by a team at Harvard,s ... the way doctors treat sepsis. , "Even with ... intensive care units at least 30 percent of the ...
(Date:9/15/2014)... Bioptigen announced today the ... for the optical device metrology and pre-clinical ophthalmic research ... for Contact Lens Metrology is designed for non-destructive, ... contact lens, IOL structures, and donor tissues. ... lens immersed in a hydration bath (saline), automated segmentation ...
(Date:9/15/2014)... DUBLIN , Sept. 15, 2014 Research ... "Whole Exome Sequencing Market by Product, by Services, by Technology, ... their offering. Whole Exome Sequencing (WES) is ... the genome, i.e. the exon. The exome, which is the ... of the total genome and is actually converted into proteins ...
Breaking Biology Technology:EnGeneIC Named a Recipient of the Cancer Institute NSW Premier's Award for Excellence in Translational Cancer Research 2EnGeneIC Named a Recipient of the Cancer Institute NSW Premier's Award for Excellence in Translational Cancer Research 3Blood-cleansing biospleen device developed for sepsis therapy 2Blood-cleansing biospleen device developed for sepsis therapy 3Blood-cleansing biospleen device developed for sepsis therapy 4Bioptigen Introduces Deep Imaging OCT System for Contact Lens Metrology 2Global Whole Exome Sequencing (Systems, Kits, Library Preparation, Target Enrichment) Market by Product, by Services, by Technology, by Application - Forecast to 2018 2Global Whole Exome Sequencing (Systems, Kits, Library Preparation, Target Enrichment) Market by Product, by Services, by Technology, by Application - Forecast to 2018 3
... study, only 25 percent of online marketers track their ... at the Jupitermedias 2004 Search Engine Strategies Conference in ... who create pay-per-click campaigns set them up and let ... ,According to the study, active online marketers often track ...
... Inc., can continue to sell advertising to competitors of ... ads, a federal district court in Virginia has ruled. ... and lucrative part of Googles business. In the third ... came from keyword advertising, also called sponsored links. ...
... about using biomass and enzymes to produce hydrogen fuel, ... Badger AgVest in Lake Delton last Thursday. ... brought to the conference by the AgVest group, which ... doesn't make specific recommendations, AgVest tries to hook up ...
Cached Biology Technology:How to make pay-per-click ad campaigns pay off 2Google wins first battle in trademark war 2Investors hear about new agricultural technology 2
(Date:9/16/2014)... the "molecular brakes" that time the generation of important ... "hair cells" translate sound waves into electrical signals that ... sounds. If the arrangement of the cells is disordered, ... research will be published in The Journal of ... and Hey2 act as brakes to prevent hair cell ...
(Date:9/16/2014)... we inherit certain traits from our parents that are ... genes play out by taking certain drugs or better ... a team of researchers at the Boston University School ... epigenetics research. , Epigenetics regulates gene expression in ... proteins, which prevent permanent mutations or alterations within the ...
(Date:9/16/2014)... has its own bacterial identity. That,s the conclusion of ... who studied the genetic fingerprints of bacteria on 57 ... "This study demonstrates for the first time that host ... strategies possess very different microbial communities on their leaves," ... researcher in the UO,s Institute of Ecology and Evolution ...
Breaking Biology News(10 mins):Hey1 and Hey2 ensure inner ear 'hair cells' are made at the right time, in the right place 2Epigenetic drugs: A hope to treat cancer resistance and reduce cancer relapse? 2Epigenetic drugs: A hope to treat cancer resistance and reduce cancer relapse? 3Microbiome research shows each tree species has a unique bacterial identity 2
... The ongoing dance between a virus and ... human adenoviruses typically cause mild infections, recent reports have ... fatal, human infections. Researchers from the Massachusetts ... for Public Health, School of Systems Biology, George Mason ...
... balls that can zap pain and lung tumors to ... physicians will present the latest research on cutting-edge treatments ... Meeting April 13󈝾 at the Ernest N. Morial Convention ... the theme "IR Reaching Out" and delivers education, resources ...
... have identified a new potential therapeutic target for lowering ... to statins. Scientists in the lab of ... action of a gene responsible for transporting a protein ... remove cholesterol from the blood in mice. Trapping the ...
Cached Biology News:Society of Interventional Radiology: 38th Annual Scientific Meeting 2U-M researchers find new way to clear cholesterol from the blood 2
... PP1, purified Formulation: 0.15M NaCl, ... 0.1mM MnCl2, 1mM MgCl2, 1mM EGTA, ... dephosphorylation of proteins Purification: DEAE chromatography, ... and gel filtration chromatography Quality Assurance: ...
... Endothelin-1 (human, porcine) Endogenous potent ... ETA receptor and modulates vascular tonus. ET-1, ... three distinct endothelin genes. ET-2 and ET-3 ... two and six amino acids, respectively. All ...
Human sVCAM-1/CD106 ELI-PAIR Kit...
HNF-1 Purified Anti-Mouse, Anti-Rat, Anti-Rabbit, Anti-Human clone 2, Isotype Mouse IgG 1 , 50 µg Consult technical datasheet for details....
Biology Products: