Cars inch forward slowly in traffic jams, but molecules, when jammed up, can move extremely fast.
New research by Northwestern University researchers finds that water molecules traveling through tiny carbon nanotube pipes do not flow continuously but rather intermittently, like stop-and-go traffic, with unexpected results.
“Previous molecular dynamics simulations suggested that water molecules coursing through carbon nanotubes are evenly spaced and move in lockstep with one another,” said Seth Lichter, professor of mechanical engineering at Northwestern’s McCormick School of Engineering and Applied Science. “But our model shows that they actually move intermittently, enabling surprisingly high flow rates of 10 billion molecules per second or more.”
The research is described in an Editor’s Choice paper, “Solitons Transport Water through Narrow Carbon Nanotubes,” published January 27 in the journal Physical Review Letters.
The findings could resolve a quandary that has baffled fluid dynamics experts for years. In 2005, researchers — working under the assumption that water molecules move through channels in a constant stream — made a surprising discovery: water in carbon nanotubes traveled 10,000 times faster than predicted.
The phenomenon was attributed to a supposed smoothness of the carbon nanotubes’ surface, but further investigation uncovered the counterintuitive role of their inherently rough interior.
Lichter and post-doctoral researcher Thomas Sisan performed new simulations with greater time resolution, revealing localized variations in the distribution of water along the nanotube. The variations occur where the water molecules do not line up perfectly with the spacing between carbon atoms — creating regions in which the water molecules are unstable and so propagate exceedingly easily and rapidly through the nanotube.
Nanochannels are found in all of our cells, where they regulate fluid flow across cell membranes. They also have promising industrial applications for desalinating water. Using the newly discovered fluid dynamics principles could enable other applications such as chemical separations, carbon nanotube-powered batteries, and the fabrication of quantum dots, nanocrystals with potential applications in electronics.
Megan Fellman | EurekAlert!
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Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...
Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.
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The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
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With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
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For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
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