In extremely cold helium, downward flow into a “drain” forms a vortex that obeys the law of quantum mechanics, not classical mechanics (as with, say, water). Sometimes two vortexes interact and violently separate. Computer simulations suggest that after the vortexes pull apart, they develop ripples called “Kelvin waves” to quickly get rid of the energy. Now, for the first time, researchers have visual evidence that this actually happens.
Researchers at NIST have devised an idea for determining the 3-D shape of features as small as 10-nm wide. The model-based method compares data from scanning electron microscope images with stored entries in a library of 3-D shapes to find a match and to determine the shape of the sample. The work provides a powerful new way to characterize nanostructures.
Far beneath the surface of the ocean, deep currents act as conveyer belts, channeling heat, carbon, oxygen and nutrients around the globe. A new study by the Univ. of Pennsylvania’s Irina Marinov and Raffaele Bernardello and colleagues from McGill Univ. has found that recent climate change may be acting to slow down one of these conveyer belts, with potentially serious consequences for the future of the planet’s climate.
Biophysicists at Rice Univ. have used a miniscule machine, a protease called an FtsH-AAA hexameric peptidase, as a model to test calculations that combine genetic and structural data. Their goal is to solve one of the most compelling mysteries in biology: how proteins perform the regulatory mechanisms in cells upon which life depends.
Researchers at North Carolina State Univ. have developed the equivalent of GPS directions for future plant scientists to understand how plants adapt to the environment and to improve plants’ productivity and biofuel potential. Two articles published in The Plant Cell offer a step-by-step approach for studying plant traits, drawing on comprehensive, quantitative research on lignin formation in black cottonwood.
U.K. scientists have succeeded in measuring how the surfaces of glassy materials flow like a liquid, even when they should be solid. A series of simple and elegant experiments were the solution to a problem that has been plaguing condensed matter physicists for the past 20 years. The finding has implications for thin-film coating designs.
So-called extremely low-volatility organic compounds, which are produced by plants, have been detected for the first time during field and laboratory experiments in Finland and Germany. The results may help to explain discrepancies between observations and theories about how volatile organic compounds produced by vegetation are converted into atmospheric aerosol. This in turn should improve existing climate models.
When deciding what materials to use in building something, determining how those materials respond to stress and strain is often the first task. A material’s macroscopic, or bulk, properties in this area is generally the product of what is happening on a microscopic scale. When stress causes a material’s constituent molecules to rearrange in a way such that they can't go back to their original positions, it is known as plastic deformation.
Technical staff at Westinghouse Electric Company LLC, supported by a light water reactor research team at Oak Ridge National Laboratory, have used a new core simulator to analyze its AP1000 advanced pressurized water reactor. The testing focused on modeling the startup conditions and its “neutronics”: the behavior of neutrons in a reactor core.
The Arctic isn't nearly as bright and white as it used to be because of more ice melting in the ocean, and that's turning out to be a global problem, a new study says. With more dark, open water in the summer, less of the sun's heat is reflected back into space. So the entire Earth is absorbing much more heat than expected.
The heroes and villains in animated films tend to be on opposite ends of the moral spectrum. But they’re often similar in their hair, which is usually extremely rigid or straight and swings to and fro. It’s rare to see an animated character with bouncy, curly hair, since computer animators don’t have a simple mathematical means for describing it. That is, until now.
Shape is thought to play an important role in the effectiveness of cells grown to repair or replace damaged tissue in the body. To help design new structures that enable cells to "shape up," researchers at NIST have come up with a way to measure, and more importantly, classify, the shapes cells tend to take in different environments.
For more than two years, researchers have been investigating melanopsin, a retina pigment capable of sensing light changes in the environment, informing the nervous system and synchronizing it with the day/night rhythm. They have found that this pigment is potentially more sensitive to light than its more famous counterpart rhodopsin, the pigment that allows night vision.
A team of physicists have used statistical mechanics and mathematical modeling to shed light on something known as epigenetic memory, which allows an organism to create a biological memory of some variable condition, such as quality of nutrition or temperature. The model highlights the "engineering" challenge a cell must constantly face during molecular recognition.
Oil and gas remain primary power sources for both personal and industrial use worldwide. Extraction of these fuel resources from underground reservoirs involves complex geomechanical processes, and can result in subsidence of the ground over a reservoir. Since this occurrence can have an impact on the environment and affect the operability of extraction equipment, it needs to be accurately predicted and kept within safe limits.
Researchers at Tyndall National Institute in Ireland have produced the first ever atom-by-atom simulation of nanoscale film growth by atomic layer deposition (ALD), a thin-film technology used in the production of silicon chips. The accomplishment required the acquisition of the complete set of hundreds of ALD reactions at the quantum mechanical level.
The concept of a hypersonic aircraft that takes off from the runway and doesn’t need a rest, inspection or repair is still a unbuilt dream, but Univ. of Cincinnati researchers are developing the validation metrics that could help predict the success or failure of such a model before it is even built, as test data becomes available from component, to sub-system, to the completely assembled air vehicle.
Water resource management efforts have given rise to several computer models dealing with hydrology, public policy, chemistry and more. Jonathan Goodall, associate professor of civil and environmental engineering at the Univ. of Virginia, is working to design an integrated computer modeling system that will seamlessly connect all the different models, enabling everyone involved in the water resources field to see the big picture.
According to a study by Pacific Northwest National Laboratory, China can build its way to a more energy efficient future by improving the rules regulating these structures like houses, apartments and retail stores. The scientists created a unique model that projects how much energy can be saved with changes to China's building energy codes, and those savings were significant.
Rice Univ. scientists have created a way to interpret interactions among pairs of task-oriented proteins that relay signals. The goal is to learn how the proteins avoid crosstalk and whether they can be tuned for better performance. Each cell contains thousands of these two-component signaling proteins, which often act as sensors and trigger the cell to act.
Scientists at the Univ. of Liverpool have shown that deep sea fault zones could transport much larger amounts of water from the Earth’s oceans to the upper mantle than previously thought. They have estimated that over the age of the Earth, the Japan subduction zone alone could transport the equivalent of up to three and a half times the water of all the Earth’s oceans to its mantle.
As part of his PhD, postdoctoral research fellow Dr. Daniel Tune in Australia has designed a computer modelling system that shows which combination of carbon nanotubes absorb the most sunlight, therefore providing the most energy. In 2011, researchers in the U.S. successfully fabricated a solar cell using carbon nanotubes, but there are more than 70 different types of carbon nanotube that could be used in such solar cells.
A new model by a team of researchers may shed new understanding on the phenomenon known as discontinuous shear thickening (DST), in which the resistance to stirring takes a sudden jump. Easily observed in a “kitchen experiment” by mixing together equal amounts of cornstarch and water, DST occurs because concentrated suspensions of hard particles in a liquid respond differently than normal fluids to shear forces.
Plasmonic nanostructures are of great current interest as chemical sensors or imaging agents because they can detect the emission of light at a different wavelength than the excitation light. Researchers have struggled with how to interpret this resonant secondary light emission. Recent work that models the emission as Raman scattering from electron-hole pairs, however, has shown a way to predict emission outcome.
New model calculations indicate that the extreme density of the base of the thickened primary crust caused it to subside vertically, or “drip”, into Earth's mantle during the Archean eon, which began about 4 billion years ago. In contrast, the movements of today's tectonic plates involve largely lateral movements with oceanic lithosphere recycled in subduction zones.