The microscopic mechanism leading to stabilization of cubic and tetragonal forms of zirconia (ZrO2) is analyzed by means of a self-consistent tight-binding model. Using this model, energies and structures of zirconia containing different vacancy concentrations are calculated, equivalent in concentration to the charge compensating vacancies associated with dissolved yttria (Y2O3) in the tetragon...

Understanding the temporal and spatial variability in a crop yield is viewed as one of the key steps in the implementation of precision agriculture practices. Therefore, a study on a center pivot irrigated 23.5 ha field in Saudi Arabia was conducted to assess the variability in alfalfa yield using Landsat-8 imagery and a hay yield monitor data. In addition, the study was designed to also explor...

A series of neutral cubic nickel(II)-imidazolate Ni8L12X4 cages were prepared by rational choices of substituents and anions with solvothermal subcomponent self-assembly technology. Both substituents and halide anions play a critical role in the formation and stabilization of cubic cages. Changing one of the factors in the reaction will switch the final structure to a Ni14L24 rhombic dodecahedr...

When a mixture of two kinds of grains differing in size and shape is poured in a vertical two-dimensional cell, the mixture spontaneously stratifies in alternating layers of small and large grains, whenever the large grains are more faceted than the small grains. Otherwise, the mixture spontaneously segregates in different regions of the cell when the large grains are more rounded than the smal...

Experimental evidences are presented showing unusually large and highly anisotropic vibrations in the "simple cubic" (SC) unit cell adopted by calcium over a broad pressure ranging from 30-90 GPa and at temperature as low as 40 K. X-ray diffraction patterns show a preferential broadening of the (110) Bragg reflection indicating that the atomic displacements are not isotropic but restricted to t...

The growth of GaN films on silicon or sapphire substrates has not been straightforward due to their large mismatch ('13%). SiC is structurally the closest material to GaN (especially cubic form) and has a small lattice mismatch (3.5%) between SiC and GaN, and therefore can be useful as the substrate for GaN. Single-crystal wafers of cubic SiC and GaN, however, are hard to obtain and have not be...

It is proved that, if F (x) be a cubic polynomial with integral coefficients having the property that F (n) is equal to a sum of two positive integral cubes for all sufficiently large integers n, then F (x) is identically the sum of two cubes of linear polynomials with integer coefficients that are positive for sufficiently large x. A similar result is proved in the case where F (n) is merely a...