Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

’Armored’ bubbles can exist in stable non-spherical shapes

15.12.2005


Coating of tightly packed particles on bubble surface supports stresses to stabilize shape

Researchers at Harvard University have demonstrated that gas bubbles can exist in stable non-spherical shapes without the application of external force. The micron- to millimeter scale peapod-, doughnut- and sausage-shaped bubbles, created by coating ordinary gas bubbles with a tightly packed layer of tiny particles and then fusing them, are described this week on the web site of the journal Nature.

"Particles have been used to stabilize emulsions and foams for over 100 years," says lead author Anand Bala Subramaniam, a research associate in Harvard’s Division of Engineering and Applied Sciences who conducted much of the work before receiving his undergraduate degree from Harvard College last June. "However, we’ve demonstrated that not only are particles useful for making bubbles last longer, they fundamentally alter the properties of these bubbles. Instead of behaving like a fluid surface that flows to balance unequal stresses, the ’armor’ of particles on the surface of the bubbles actually supports the unequal stresses inherent in non-spherical shapes."



Surface tension gives all bubbles and drops their perfectly spherical shape by minimizing the surface area for a given volume. Ordinarily if two bubbles are fused, the product is a larger but still spherical bubble. But when particles are strongly anchored to the bubble surface and the bubbles are fused, a stable sausage shape is produced.

"The bubble wants to reduce its surface area by going back to a spherical shape, but the strong anchoring of the particles on the surface prevents their expulsion," Bala Subramaniam says. "The particles end up tightly packed, and eventually push against each other strongly, allowing the bubble surface to carry forces to support a non-spherical shape."

Although the particles are jammed, they are not bonded to each other, Bala Subramaniam adds. It is this absence of permanent bonds that allowed the researchers to reshape and remold the initially sausage-shaped bubbles into peapods, disks and donuts.

The phenomenon of irregularly shaped bubbles has been observed in nature; air bubbles in impure ocean water are often non-spherical, their shapes distorted by surface dirt. The concepts of jamming and non-spherical shapes may also be useful for understanding other systems such as biological membranes. Bala Subramaniam and his colleagues have found particle jamming on surfaces to be a general phenomenon compatible with a wide range of particle coatings, including polystyrene, polymethylmethacrylate, gold and zirconium oxide. Both particle and bubble size can vary widely, with the largest armored bubbles roughly 10,000 times the size of the smallest.

"We have provided a general explanation of why these non-spherical bubbles can be observed," says co-author Howard A. Stone, Bala Subramaniam’s advisor and the Vicky Joseph Professor of Engineering and Applied Mathematics at Harvard. "Bubbles are engineered into many consumer products. The ability to alter the shapes of bubbles and liquid drops in products like ice cream or shaving foams or creams may provide a means to alter the consistency or texture of these products. The non-spherical bubbles could also find use as vessels for delivering drugs, vitamins or flavors."

Steve Bradt | EurekAlert!
Further information:
http://www.harvard.edu

More articles from Life Sciences:

nachricht Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University

nachricht Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>