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Dhahran, Saudi Arabia

King Abdullah University of Science and Technology is a public research university located in Thuwal, Saudi Arabia.KAUST was founded in 2009 and focuses exclusively on graduate education and research, using English as the official language of instruction. It offers programs in Biological and Environmental science and Engineering; Computer, Electrical, and Mathematical science and Engineering; and Physical science and Engineering. It was recently announced that KAUST has one of the fastest growing research and citation records in the world right now. Wikipedia.

Josserand C.,CNRS Jean Le Rond dAlembert Institute | Thoroddsen S.T.,King Abdullah University of Science and Technology
Annual Review of Fluid Mechanics | Year: 2016

A drop hitting a solid surface can deposit, bounce, or splash. Splashing arises from the breakup of a fine liquid sheet that is ejected radially along the substrate. Bouncing and deposition depend crucially on the wetting properties of the substrate. In this review, we focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of not only liquid inertia, viscosity, and surface tension, but also the surrounding gas. The gas cushions the initial contact; it is entrapped in a central microbubble on the substrate; and it promotes the so-called corona splash, by lifting the lamella away from the solid. Particular attention is paid to the influence of surface roughness, natural or engineered to enhance repellency, relevant in many applications. © Copyright 2016 by Annual Reviews. All rights reserved. Source

Harb M.,King Abdullah University of Science and Technology
Journal of Physical Chemistry C | Year: 2013

We report a systematic study on the optoelectronic properties of Se-modified anatase TiO2 investigated by DFT (including the perturbation theory approach DFPT) within the screened coulomb hybrid HSE06 formalism to guarantee accurate band gap and electronic excitation predictions. Various selenium species at substitutional sites for O or Ti, at interstitial sites, as well as at mixed substitutional/interstitial sites are studied. Among the explored structures, Ti(1-2x)O2Se2x (containing Se4+ species), TiO(2-x)Sex (containing Se2- species), and TiO(2-x)Se2x (containing Se2 2- species) reveal significant enhanced visible-light optical absorption spectra with new absorption features appearing at 500, 600, and 690 nm, respectively. Our calculated spectra are found to be in good agreement with those obtained in available experimental works. The band gap narrowing in these materials originates from incorporation of newly occupied electronic levels within 0.5-1.5 eV above the original valence band of TiO 2, leading to new narrowed band gaps of 2.5, 2.0, and 1.8 eV respectively. Our calculations also reveal suitable band positions of Ti (1-2x)O2Se2x and TiO(2-x)Se x for overall water splitting, whereas TiO(2-x)Se 2x shows an unsuitable valence band position for the oxygen evolution reaction. In contrast, the localized electronic character of the new occupied states on the Se 4p orbitals and only on the O 2p orbitals linked to the Se species makes the holes mobility limited in this material and the recombination rate of charge carriers greatly increased in the bulk. © 2013 American Chemical Society. Source

Wu Y.,King Abdullah University of Science and Technology
Optics Express | Year: 2014

Accidental degeneracy in a photonic crystal consisting of a square array of elliptical dielectric cylinders leads to both a semi-Dirac point at the center of the Brillouin zone and an electromagnetic topological transition (ETT). A perturbation method is deduced to affirm the peculiar linear-parabolic dispersion near the semi-Dirac point. An effective medium theory is developed to explain the simultaneous semi-Dirac point and ETT and to show that the photonic crystal is either a zero-refractive-index material or an epsilon-near-zero material at the semi-Dirac point. Drastic changes in the wave manipulation properties at the semi-Dirac point, resulting from ETT, are described.©2014 Optical Society of America. Source

Moise A.R.,University of Kansas | Al-Babili S.,King Abdullah University of Science and Technology | Wurtzel E.T.,City University of New York
Chemical Reviews | Year: 2014

Carotenoid synthesis is based on the analysis of the phenotype of several mutant strains of tomato lacking carotenoid synthetic genes. Carotenoids are tetraterpenes derived through the condensation of the five-carbon (C5) universal isoprenoid precursors isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). A recently developed concept that could explain the role of the poly-cis pathway in carotenoid synthesis is that the intermediates of this pathway have additional physiological roles that extend beyond serving as precursors of lycopene. This concept is based on the analysis of the phenotype of several mutant strains of tomato lacking carotenoid synthetic genes. The feedback regulation of early carotenoid synthetic genes in response to a block in upstream metabolism represents a paradigm shift in our understanding of the mechanism and regulation of carotenoid synthesis and of metabolic regulation in general. The molecular details of a signaling pathway that regulates carotenogenesis in response to the levels of carotenoid precursors are still unclear. Source

Alkhalifah T.,King Abdullah University of Science and Technology
Geophysics | Year: 2011

Parameter estimation in an inhomogeneous anisotropic medium offers many challenges; chief among them is the trade-off between inhomogeneity and anisotropy. It is especially hard to estimate the anisotropy anellipticity parameter τ in complex media. Using perturbation theory and Taylor's series, I have expanded the solutions of the anisotropic eikonal equation for transversely isotropic (TI) media with a vertical symmetry axis (VTI) in terms of the independent parameter τ from a generally inhomogeneous elliptically anisotropic medium background. This new VTI traveltime solution is based on a set of precomputed perturbations extracted from solving linear partial differential equations. The traveltimes obtained from these equations serve as the coefficients of a Taylor-type expansion of the total traveltime in terms of τ. Shanks transform is used to predict the transient behavior of the expansion and improve its accuracy using fewer terms. A homogeneous medium simplification of the expansion provides classical nonhyperbolic moveout descriptions of the traveltime that are more accurate than other recently derived approximations. In addition, this formulation provides a tool to scan for anisotropic parameters in a generally inhomogeneous medium background. A Marmousi test demonstrates the accuracy of this approximation. For a tilted axis of symmetry, the equations are still applicable with a slightly more complicated framework because the vertical velocity and δ are not readily available from the data. © 2011 Society of Exploration Geophysicists. Source

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