Navigation Links
Answer to saliva mystery has practical impact
Date:6/11/2010

Researchers at Rice University, Purdue University and the Massachusetts Institute of Technology have solved a long-standing mystery about why some fluids containing polymers -- including saliva -- form beads when they are stretched and others do not.

The findings are published online this week in the journal Nature Physics.

Study co-author Matteo Pasquali, professor in chemical and biomolecular engineering at Rice, said the study answers fundamental scientific questions and could ultimately lead to improvements as diverse as ink-jet printing, nanomaterial fiber spinning and drug dispensers for "personalized medicine."

Co-author Osman Basaran, Purdue's Burton and Kathryn Gedge Professor of Chemical Engineering, said, "Any kindergartner is familiar with this beading phenomenon, which you can demonstrate by stretching a glob of saliva between your thumb and forefinger. The question is, 'Why does this beading take place only in some fluids containing polymers but not others?'"

Pasquali said, "In answering the question about why some fluids do this and others do not, we are addressing everyday processes that apply to fiber and droplet formation, not just in multibillion-dollar industrial plants but also in fluids produced in living cells."

Saliva and other complex "viscoelastic" fluids like shaving cream and shampoo contain long molecules called polymers. When a strand of viscoelastic fluid is stretched, these polymers can cause a line of beads to form just before the strand breaks.

Pasquali said the explanation for why some viscoelastic fluids form beads and others do not was decades in the making. The origins of the work can be traced to Pasquali's and Basaran's doctoral research adviser, L.E. "Skip" Scriven of the University of Minnesota. Pasquali said Scriven worked out the basics of the competition between capillary, inertial and viscous forces in flows during the 1970s and 1980s. In the mid-1990s, during his doctoral research at Minnesota, Pasquali expanded on Scriven's earlier work to include the effects of viscoelasticity, which originates in liquid microstructures and nanostructures. Finally, Pasquali's former doctoral student, Pradeep Bhat, the lead author of the new study, took up the mantle nine years ago as a Ph.D. student in Pasquali's lab and continued working on the problem for the past three years as a postdoctoral researcher in Basaran's lab at Purdue.

Bhat, Basaran and Pasquali found that a key factor in the beading mechanism is fluid inertia, or the tendency of a fluid to keep moving unless acted upon by an external force.

Other major elements are a fluid's viscosity; the time it takes a stretched polymer molecule to "relax," or snap back to its original shape when stretching is stopped; and the "capillary time," or how long it would take for the surface of the fluid strand to vibrate if plucked.

"It turns out that the inertia has to be large enough and the relaxation time has to be small enough to form beads," Bhat said.

The researchers discovered that bead formation depends on two ratios: the viscous force compared with inertial force and the relaxation time compared with the capillary time.


'/>"/>

Contact: David Ruth
druth@rice.edu
713-348-6327
Rice University
Source:Eurekalert

Related biology news :

1. Microbes answer more questions collectively
2. U of I researchers say foliar fungicides may not be the answer for hail-damaged corn
3. Microbial answer to plastic pollution?
4. An answer to another of lifes big questions
5. Bubble physicist counts bubbles in the ocean to answer questions about climate, sound, light
6. Studying hair of ancient Peruvians answers questions about stress
7. Are sterile mosquitoes the answer to malaria elimination?
8. Avoiding dangerous climate change: Is geo-engineering the answer?
9. Critical Zone Observatory seeks to answer climate change questions
10. All tied up: Tethered protein provides long-sought answer
11. Researcher looks for answers about unique disease-resistant gene
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/16/2017)... CeBIT 2017 - Against identity fraud with DERMALOG solutions "Made in ... ... combined in one project, multi-biometric solutions provide a crucial contribution against identity fraud. (PRNewsFoto/Dermalog Identification ... Used combined in one project, multi-biometric solutions provide a ... ...
(Date:3/9/2017)... FRANCISCO and MOUNTAIN VIEW, Calif. ... , "Eating Well Made Simple," and 23andMe , ... help guide better food choices.  Zipongo can now provide ... their food preferences, health goals and biometrics, but also ... certain food choices. Zipongo,s personalized food decision ...
(Date:3/6/2017)... MATEO, Calif. , March 6, 2017 /PRNewswire/ ... marketing and sales technology, today announced Predictive Sales ... solution for infusing actionable sales intelligence into Salesforce. ... to automatically enable their sales organizations with deep ... messages that allow for intelligent engagement. Predictive Sales ...
Breaking Biology News(10 mins):
(Date:4/26/2017)... ... April 26, 2017 , ... Led ... phase I clinical trials comes to Tampa, San Francisco and Boston in 2017. ... representing FDA regulated organizations such as Pfizer Inc., Teva Pharmaceuticals, Advaxis, Inc., Ocular ...
(Date:4/26/2017)... , April 26, 2017  Genisphere LLC, provider ... has signed a collaborative and sponsored research agreement ... Silvia Muro . The overall goal of the ... of various 3DNA designs and formulations after ... diseases of the vasculature as well as inflammatory ...
(Date:4/25/2017)... (PRWEB) , ... April 25, 2017 , ... ... Piedmont Physical Medicine & Rehabilitation, P.A. , proudly announced today that acclaimed physiatrist ... commence his duties on May 15, 2017. , Dr. Terzella completed his residency ...
(Date:4/21/2017)... COLORADO (PRWEB) , ... April 21, 2017 , ... ... Awards recognized outstanding manufactures in 10 categories with over 30 nominees and well ... in Manufacturing presented the new award and the event was hosted by CompanyWeek ...
Breaking Biology Technology: