Grain boundaries are the interfaces between the small crystals that make up nearly every material in our physical world. Understanding grain boundaries is essential because they dictate the most important characteristics of a material. Want to make steel corrosion resistant? The key is in the grain boundaries because they are the pathways for corrosive elements. Scientists at BYU, in collaboration with a scientist at Cambridge (UK), recently developed a machine learning approach predicting grain boundary properties. Not only can it make predictions, but the design of the machine learning model also makes it explanatory---It can identify the "physics reason" why some grain boundaries are good, and some are bad.
This demonstration illustrates the power of a wave focusing technique called time reversal acoustics. A vibration speaker and a laser Doppler vibrometer are used to knock over one targeted Lego figure among many placed on an aluminum plate. BYU researchers (Brian Anderson and students) use this technique to locate and characterize cracks in structures, to deliver private communications, and many other potential applications. Click the title link and watch a video of the demo.
Every technology is intimately related to a particular materials set. The steam engines that powered the industrial revolution in the eighteenth century were made of steel and, information and communication technologies are underpinned by silicon. Once a material is chosen for a given technology, it gets locked with it because of the investments associated with establishing large-scale production lines. This means that changing the materials set in an established technology is a rare event and must be considered as a revolution. Computational materials discovery can play an important role in fueling such revolutions
A recent article that appeared in the Astronomical Journal (Joner and Hintz, 2015, AJ, 150, 204), established a new photometric system based on a pair of filter functions used to measure the strength of the H-alpha line in stars. The paper presented H-alpha and H-beta indices for 136 field and cluster stars that were observed with the 1.2-meter telescope at the Dominion Astrophysical Observatory during an 11 year period. The indices were determined from spectro-photometry of the thousands of spectra exposures. The figure to the left shows a relation for normal main sequence stars between the new H-alpha index and the more than 60 year old H-beta index. Color-color plots like this one are useful in surveys to detect objects of astrophysical interest that display emission features of various strengths. These extreme objects are easily seen in a color-color plot. One High Mass X-ray Binary recently observed for a followup study was located at (0.87,1.87) in the color-color plot.
Nanoparticles of gamma-alumina obtained from a novel synthetic solvent-deficient method show promise as improved industrial catalyst-supports. X-ray PDF analysis reveals that they are born with a high concentration of defects that locally resemble boehmite. As the nanoparticles are annealed to successively higher temperatures, the boehmite-like defects heal gradually rather than disappearing in an abrupt phase transition, which explains several previously misunderstood of properties of the gamma phase.
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Cameron Olsen, Jacob Embley, Kameron Hansen, Andrew Henrichsen, Ryan Peterson, John Colton, and Richard Watt recently published an article titled "Tuning Ferritin’s band gap through mixed metal oxide nanoparticle formation" in Nanotechnology. Click on the image above to read it.
The Crown of the Sun: During a total solar eclipse, the Sun's extensive outer atmosphere, or corona, is an inspirational sight. Streamers and shimmering features visible to the eye span a brightness range of over 10,000 to 1, making them notoriously difficult to capture in a single photograph....
This photograph and Description come from NASA's Astronomy Picture of the Day web site.