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.
What do precision laser metrology and broadband femtosecond lasers have to do with each other? Plenty! This marriage was the reason Ted Haensch and Jan Hall shared the 2005 Nobel Prize in Physics. Part of that experiment has been reproduced at BYU, and it has been used to correct a serious spectroscopy error in atomic ytterbium. This work was published in Phys. Rev. A 94, 052511 (2016).
The figure shows two different integration "grids," a standard rectangular grid versus an contour-by-contour grid. The Materials Simulation Group (msg.byu.edu) is exploring competing schemes for speeding up the integration of electron bands in materials. An important part of "first-principles" materials calculations involves integrating over the occupied electron states, the so-called "band energy integration." This is the primary source of error in first-principles calculations of solids. Improving this integration would have a dramatic impact on computational simulations of metallic systems.
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Mike Joner and Eric Hintz et al. recently published an article titled "Discovery and Photometric Analysis of the δ Scuti Variable TYC 2168-132-1" in The Journal of the American Association of Variable Star Observers. Click on the image above to read it.
Curiosity Rover Takes Selfie on Mars : Yes, but have you ever taken a selfie on Mars? The Curiosity rover on Mars has. This selfie was compiled from many smaller images -- which is why the mechanical arm holding the camera is not visible....
This photograph and Description come from NASA's Astronomy Picture of the Day web site.