In a uniform cylinder, both the mobility and the diffusion coefficient of the particle are independent of the driving force. This is not true, however, when the cylinder diameter varies. Constrictions provide periodic entropic barriers, which slow down drift and diffusion when the driving force is weak. This research examined two types of cylinders.
In the first, a tube consisted of sequential spherical compartments connected by small circular openings. The driving force suppressed the slowdown due to the constrictions. The particle subjected to a strong driving force showed no change in effective diffusion coefficient or mobility as a result of the periodic restrictions. In a tube of cylindrical chambers, however, the results were dramatically different. Under a strong driving force, mobility decreased while the diffusion coefficient became extremely large due to intermittency that occurred in the particle transitions between openings connecting neighboring compartments.
While author Alexander Berezhkovskii of the National Institutes of Health acknowledges that the original idea for the project was inspired by devices that deliver drugs locally in small amounts, he looks at the research as a quest for a broader understanding. “Nature is very complicated because of geometry, but we are looking for something simple that underlies the complexity,” he says.
The article, "Drift and diffusion in a tube of periodically varying diameter. Driving force induced intermittency" by Alexander Berezhkovskii et al will appear in the Journal of Chemical Physics. See: http://jcp.aip.org/
Journalists may request a free PDF of this article by contacting firstname.lastname@example.org.ABOUT THE JOURNAL OF CHEMICAL PHYSICS
Jason Socrates Bardi | Newswise Science News
Physicists Design Ultrafocused Pulses
27.07.2017 | Universität Innsbruck
CCNY physicists master unexplored electron property
26.07.2017 | City College of New York
Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.
Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...
Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers
Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...
Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.
At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
26.07.2017 | Event News
21.07.2017 | Event News
19.07.2017 | Event News
27.07.2017 | Life Sciences
27.07.2017 | Life Sciences
27.07.2017 | Health and Medicine