King Abdullah University of Science and Technology

About: King Abdullah University of Science and Technology is a education organization based out in Jeddah, Saudi Arabia. It is known for research contribution in the topics: Membrane & Catalysis. The organization has 6221 authors who have published 22019 publications receiving 625706 citations. The organization is also known as: KAUST.

Design and volume optimization of space structures

Abstract: We study the design and optimization of statically sound and materially efficient space structures constructed by connected beams. We propose a systematic computational framework for the design of space structures that incorporates static soundness, approximation of reference surfaces, boundary alignment, and geometric regularity. To tackle this challenging problem, we first jointly optimize node positions and connectivity through a nonlinear continuous optimization algorithm. Next, with fixed nodes and connectivity, we formulate the assignment of beam cross sections as a mixed-integer programming problem with a bilinear objective function and quadratic constraints. We solve this problem with a novel and practical alternating direction method based on linear programming relaxation. The capability and efficiency of the algorithms and the computational framework are validated by a variety of examples and comparisons.

Bias-voltage dependence of perpendicular spin-transfer torque in asymmetric MgO-based magnetic tunnel junctions

Abstract: Spin-transfer torque allows the magnetization of nanopillar devices to be switched electrically. Incorporating asymmetries into the design of such a device generates a linear out-of-plane torque component that could help prevent the unwanted spontaneous reversal of the nanopillar’s magnetization. Spin-transfer torque1,2 (STT) allows the electrical control of magnetic states in nanostructures3,4,5. The STT in magnetic tunnel junctions (MTJs) is of particular importance owing to its potential for device applications6,7. It has been demonstrated8,9,10,11 that the MTJ has a sizable perpendicular STT ( , field-like torque), which substantially affects STT-driven magnetization dynamics. In contrast to symmetric MTJs where the bias dependence of is quadratic8,9,10,12,13, it is theoretically predicted that the symmetry breaking of the system causes an extra linear bias dependence11. Here, we report experimental results that are consistent with the predicted linear bias dependence in asymmetric MTJs. The linear contribution is quite significant and its sign changes from positive to negative as the asymmetry is modified. This result opens a way to design the bias dependence of the field-like term, which is useful for device applications by allowing, in particular, the suppression of the abnormal switching-back phenomena.

The temperature-dependent microstructure of PEDOT/PSS films: insights from morphological, mechanical and electrical analyses

Abstract: Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) is a widely used conductive polymer in the field of flexible electronics The ways its microstructure changes over a broad range of temperatures remain unclear This paper describes microstructure changes at different temperatures and correlates the microstructure with its physical properties (mechanical and electrical) We used High-Angle Annular Dark-Field Scanning Electron Microscopy (HAADF-STEM) combined with electron energy loss spectroscopy (EELS) to determine the morphology and elemental atomic ratio of the film at different temperatures These results together with the Atomic Force Microscopy (AFM) analysis provide the foundation for a model of how the temperature affects the microstructure of PEDOT/PSS Moreover, dynamic mechanical analysis (DMA) and electrical characterization were performed to analyze the microstructure and physical property correlations

Microbiology of the Red Sea (and other) deep-sea anoxic brine lakes

Abstract: The Red Sea harbours approximately 25 deep-sea anoxic brine pools. They constitute extremely unique and complex habitats with the conjugation of several extreme physicochemical parameters rendering them some of the most inhospitable environments on Earth. After 50 years of research mostly driven by chemists, geophysicists and geologists, the microbiology of the brines has been receiving increased interest in the last decade. Recent molecular and cultivation-based studies have provided us with a first glimpse on the enormous biodiversity of the local microbial communities, the identification of several new taxonomic groups, and the isolation of novel extremophiles that thrive in these environments. This review presents a general overview of these unusual biotopes and compares them with other similar environments in the Mediterranean Sea and the Gulf of Mexico, with a focus on their microbial ecology.