Showing papers by "King Abdullah University of Science and Technology published in 2013"
TL;DR: A crystal engineering or reticular chemistry strategy that controls pore functionality and size in a series of MOMs with coordinately saturated metal centres and periodically arrayed hexafluorosilicate anions enables a ‘sweet spot’ of kinetics and thermodynamics that offers high volumetric uptake at low CO2 partial pressure (less than 0.15 bar).
Abstract: A series of porous crystalline materials known as metal–organic materials are prepared, and a full sorption study shows that controlled pore size (rather than large surface area) coupled with appropriate chemistry lead to materials exhibiting fast and highly selective CO2 sorption. Metal organic frameworks are porous crystalline materials widely studied as potential gas separation and storage materials for clean energy applications. A general trend in this field has been the development of materials with the largest possible surface area with the aim of maximizing uptake of gases. In this paper the authors generate a series of metal organic frameworks and carry out sorption experiments that suggest that surface area may not be as important as was thought. Rather, pore size, coupled with appropriate chemistry, are the keys to fast CO2 uptake and strong CO2 sorption. Materials designed on these principles attain high selectivity for CO2 over nitrogen, oxygen, methane and hydrogen even in the presence of moisture. The energy costs associated with the separation and purification of industrial commodities, such as gases, fine chemicals and fresh water, currently represent around 15 per cent of global energy production, and the demand for such commodities is projected to triple by 2050 (ref. 1). The challenge of developing effective separation and purification technologies that have much smaller energy footprints is greater for carbon dioxide (CO2) than for other gases; in addition to its involvement in climate change, CO2 is an impurity in natural gas, biogas (natural gas produced from biomass), syngas (CO/H2, the main source of hydrogen in refineries) and many other gas streams. In the context of porous crystalline materials that can exploit both equilibrium and kinetic selectivity, size selectivity and targeted molecular recognition are attractive characteristics for CO2 separation and capture, as exemplified by zeolites 5A and 13X (ref. 2), as well as metal–organic materials (MOMs)3,4,5,6,7,8,9. Here we report that a crystal engineering7 or reticular chemistry5,9 strategy that controls pore functionality and size in a series of MOMs with coordinately saturated metal centres and periodically arrayed hexafluorosilicate (SiF62−) anions enables a ‘sweet spot’ of kinetics and thermodynamics that offers high volumetric uptake at low CO2 partial pressure (less than 0.15 bar). Most importantly, such MOMs offer an unprecedented CO2 sorption selectivity over N2, H2 and CH4, even in the presence of moisture. These MOMs are therefore relevant to CO2 separation in the context of post-combustion (flue gas, CO2/N2), pre-combustion (shifted synthesis gas stream, CO2/H2) and natural gas upgrading (natural gas clean-up, CO2/CH4).
1,877 citations
TL;DR: In this paper, the authors present a cost analysis of the reverse osmosis process and the main parameters influencing the total water cost produced by different desalination technologies, including capital and operating costs, as well as local incentives or subsidies.
1,132 citations
TL;DR: Classification methods of lncRNAs are summarized according to their four major features, namely, genomic location and context, effect exerted on DNA sequences, mechanism of functioning and their targeting mechanism, and the view on potential further studies.
Abstract: Long non-coding RNAs (lncRNAs) have been found to perform various functions in a wide variety of important biological processes. To make easier interpretation of lncRNA functionality and conduct deep mining on these transcribed sequences, it is convenient to classify lncRNAs into different groups. Here, we summarize classification methods of lncRNAs according to their four major features, namely, genomic location and context, effect exerted on DNA sequences, mechanism of functioning and their targeting mechanism. In combination with the presently available function annotations, we explore potential relationships between different classification categories, and generalize and compare biological features of different lncRNAs within each category. Finally, we present our view on potential further studies. We believe that the classifications of lncRNAs as indicated above are of fundamental importance for lncRNA studies, helpful for further investigation of specific lncRNAs, for formulation of new hypothesis based on different features of lncRNA and for exploration of the underlying lncRNA functional mechanisms.
946 citations
TL;DR: In situ characterization of the oxide surface with ATR-FTIR and Raman during the PMS decomposition suggested that surface Cu(II)- Cu(III)-Cu(II) redox cycle was responsible for the efficient sulfate radical generation from PMS.
Abstract: A simple, nonhazardous, efficient and low energy-consuming process is desirable to generate powerful radicals from peroxymonosulfate (PMS) for recalcitrant pollutant removal. In this work, the production of radical species from PMS induced by a magnetic CuFe2O4 spinel was studied. Iopromide, a recalcitrant model pollutant, was used to investigate the efficiency of this process. CuFe2O4 showed higher activity and 30 times lower Cu2+ leaching (1.5 μg L–1 per 100 mg L–1) than a well-crystallized CuO at the same dosage. CuFe2O4 maintained its activity and crystallinity during repeated batch experiments. In comparison, the activity of CuO declined significantly, which was ascribed to the deterioration in its degree of crystallinity. The efficiency of the PMS/CuFe2O4 was highest at neutral pH and decreased at acidic and alkaline pHs. Sulfate radical was the primary radical species responsible for the iopromide degradation. On the basis of the stoichiometry of oxalate degradation in the PMS/CuFe2O4, the radical ...
892 citations
TL;DR: The design of the composite material is expected to significantly increase the Au SPR intensity and consequently boost the hot electron injection from the Au nanocrystals into the conduction band of TiO(2), leading to a considerably enhanced water splitting performance of the material under visible light.
Abstract: A visible light responsive plasmonic photocatalytic composite material is designed by rationally selecting Au nanocrystals and assembling them with the TiO2-based photonic crystal substrate. The selection of the Au nanocrystals is so that their surface plasmonic resonance (SPR) wavelength matches the photonic band gap of the photonic crystal and thus that the SPR of the Au receives remarkable assistance from the photonic crystal substrate. The design of the composite material is expected to significantly increase the Au SPR intensity and consequently boost the hot electron injection from the Au nanocrystals into the conduction band of TiO2, leading to a considerably enhanced water splitting performance of the material under visible light. A proof-of-concept example is provided by assembling 20 nm Au nanocrystals, with a SPR peak at 556 nm, onto the photonic crystal which is seamlessly connected on TiO2 nanotube array. Under visible light illumination (>420 nm), the designed material produced a photocurren...
680 citations
TL;DR: It is shown that replacing branched side chains by linear ones in the BDT motifs induces a critical change in polymer self-assembly and backbone orientation in thin films that correlates with a dramatic drop in solar cell efficiency, making PBDTTPD one of the best polymer donors for use in the high-band-gap cell of tandem solar cells.
Abstract: While varying the size and branching of solubilizing side chains in π-conjugated polymers impacts their self-assembling properties in thin-film devices, these structural changes remain difficult to anticipate. This report emphasizes the determining role that linear side-chain substituents play in poly(benzo[1,2-b:4,5-b′]dithiophene–thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers for bulk heterojunction (BHJ) solar cell applications. We show that replacing branched side chains by linear ones in the BDT motifs induces a critical change in polymer self-assembly and backbone orientation in thin films that correlates with a dramatic drop in solar cell efficiency. In contrast, we show that for polymers with branched alkyl-substituted BDT motifs, controlling the number of aliphatic carbons in the linear N-alkyl-substituted TPD motifs is a major contributor to improved material performance. With this approach, PBDTTPD polymers were found to reach power conversion efficiencies of 8.5% and open-circuit voltages ...
654 citations
TL;DR: The main idea of the proposed approach is to construct a small dimensional local solution space that can be used to generate an efficient and accurate approximation to the multiscale solution with a potentially high dimensional input parameter space.
603 citations
TL;DR: The rational design and synthesis of ultrasmall (<10 nm) Fe3O4@Cu2-xS core-shell nanoparticles, which offer both high photothermal stability and superparamagnetic properties are reported, which should provide improved understanding of synergistic effect resulting from the integration of magnetism with photothermal phenomenon.
Abstract: Photothermal nanomaterials have recently attracted significant research interest due to their potential applications in biological imaging and therapeutics. However, the development of small-sized photothermal nanomaterials with high thermal stability remains a formidable challenge. Here, we report the rational design and synthesis of ultrasmall (<10 nm) Fe3O4@Cu2–xS core–shell nanoparticles, which offer both high photothermal stability and superparamagnetic properties. Specifically, these core–shell nanoparticles have proven effective as probes for T2-weighted magnetic resonance imaging and infrared thermal imaging because of their strong absorption at the near-infrared region centered around 960 nm. Importantly, the photothermal effect of the nanoparticles can be precisely controlled by varying the Cu content in the core–shell structure. Furthermore, we demonstrate in vitro and in vivo photothermal ablation of cancer cells using these multifunctional nanoparticles. The results should provide improved un...
533 citations
TL;DR: In this article, a two-dimensional diluted magnetic semiconductor (MoS2) is proposed, which is doped by transition metal atoms from the IIIB to VIB groups.
Abstract: Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS2 doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number of valence electrons is smaller or equal to that of Mo. Doping of atoms from the VIIB to IIB groups becomes energetically less and less favorable. Magnetism is observed for Mn, Fe, Co, Zn, Cd, and Hg doping, while for the other dopants from these groups it is suppressed by Jahn-Teller distortions. Analysis of the binding energies and magnetic properties indicates that (Mo,X)S2 (X = Mn, Fe, Co, and Zn) are promising systems to explore two-dimensional diluted magnetic semiconductors.
487 citations
TL;DR: The study supports the importance of the synergistic effect of exposed open metal sites and proximal highly localized charge density toward materials with enhanced CO2 sorption energetics.
Abstract: A series of fcu-MOFs based on rare-earth (RE) metals and linear fluorinated/nonfluorinated, homo/heterofunctional ligands were targeted and synthesized. This particular fcu-MOF platform was selected because of its unique structural characteristics combined with the ability/potential to dictate and regulate its chemical properties (e.g., tuning of the electron-rich RE metal ions and high localized charge density, a property arising from the proximal positioning of polarizing tetrazolate moieties and fluoro-groups that decorate the exposed inner surfaces of the confined conical cavities). These features permitted a systematic gas sorption study to evaluate/elucidate the effects of distinctive parameters on CO2–MOF sorption energetics. Our study supports the importance of the synergistic effect of exposed open metal sites and proximal highly localized charge density toward materials with enhanced CO2 sorption energetics.
452 citations
TL;DR: The goal is to provide a survey that will help researchers to better position their own work in the context of existing solutions, and to help newcomers and practitioners in computer graphics to quickly gain an overview of this vast field.
Abstract: This paper provides a comprehensive overview of urban reconstruction. While there exists a considerable body of literature, this topic is still under active research. The work reviewed in this survey stems from the following three research communities: computer graphics, computer vision and photogrammetry and remote sensing. Our goal is to provide a survey that will help researchers to better position their own work in the context of existing solutions, and to help newcomers and practitioners in computer graphics to quickly gain an overview of this vast field. Further, we would like to bring the mentioned research communities to even more interdisciplinary work, since the reconstruction problem itself is by far not solved.
TL;DR: The results demonstrate that mining the interdependencies between particles improves tracking performance and overall computational complexity, and both methods consistently outperform state-of-the-art trackers.
Abstract: In this paper, we formulate object tracking in a particle filter framework as a structured multi-task sparse learning problem, which we denote as Structured Multi-Task Tracking (S-MTT). Since we model particles as linear combinations of dictionary templates that are updated dynamically, learning the representation of each particle is considered a single task in Multi-Task Tracking (MTT). By employing popular sparsity-inducing $$\ell _{p,q}$$ mixed norms $$(\text{ specifically} p\in \{2,\infty \}$$ and $$q=1),$$ we regularize the representation problem to enforce joint sparsity and learn the particle representations together. As compared to previous methods that handle particles independently, our results demonstrate that mining the interdependencies between particles improves tracking performance and overall computational complexity. Interestingly, we show that the popular $$L_1$$ tracker (Mei and Ling, IEEE Trans Pattern Anal Mach Intel 33(11):2259---2272, 2011) is a special case of our MTT formulation (denoted as the $$L_{11}$$ tracker) when $$p=q=1.$$ Under the MTT framework, some of the tasks (particle representations) are often more closely related and more likely to share common relevant covariates than other tasks. Therefore, we extend the MTT framework to take into account pairwise structural correlations between particles (e.g. spatial smoothness of representation) and denote the novel framework as S-MTT. The problem of learning the regularized sparse representation in MTT and S-MTT can be solved efficiently using an Accelerated Proximal Gradient (APG) method that yields a sequence of closed form updates. As such, S-MTT and MTT are computationally attractive. We test our proposed approach on challenging sequences involving heavy occlusion, drastic illumination changes, and large pose variations. Experimental results show that S-MTT is much better than MTT, and both methods consistently outperform state-of-the-art trackers.
TL;DR: In this paper, a model based on the Boltzmann equation that unifies these approaches is presented. But the model fails to describe the experimentally observed thickness dependencies, which is a limitation of the drift-diffusion model.
Abstract: In bilayer nanowires consisting of a ferromagnetic layer and a nonmagnetic layer with strong spin-orbit coupling, currents create torques on the magnetization beyond those found in simple ferromagnetic nanowires. The resulting magnetic dynamics appear to require torques that can be separated into two terms, dampinglike and fieldlike. The dampinglike torque is typically derived from models describing the bulk spin Hall effect and the spin transfer torque, and the fieldlike torque is typically derived from a Rashba model describing interfacial spin-orbit coupling. We derive a model based on the Boltzmann equation that unifies these approaches. We also consider an approximation to the Boltzmann equation, the drift-diffusion model, that qualitatively reproduces the behavior, but quantitatively differs in some regimes. We show that the Boltzmann equation with physically reasonable parameters can match the torques for any particular sample, but in some cases, it fails to describe the experimentally observed thickness dependencies.
TL;DR: In this article, the authors examined the device characteristics of BHJ solar cells based on poly(di(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene-co-octylthieno[3,4-c]pyrrole-4,6-dione) and found that thermal annealing drastically reduced the concentration of PCBM in the mixed regions.
Abstract: Most optimized donor-acceptor (D-A) polymer bulk heterojunction (BHJ) solar cells have active layers too thin to absorb greater than ∼80% of incident photons with energies above the polymer's band gap. If the thickness of these devices could be increased without sacrificing internal quantum efficiency, the device power conversion efficiency (PCE) could be significantly enhanced. We examine the device characteristics of BHJ solar cells based on poly(di(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene-co-octylthieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) with 7.3% PCE and find that bimolecular recombination limits the active layer thickness of these devices. Thermal annealing does not mitigate these bimolecular recombination losses and drastically decreases the PCE of PBDTTPD BHJ solar cells. We characterize the morphology of these BHJs before and after thermal annealing and determine that thermal annealing drastically reduces the concentration of PCBM in the mixed regions, which consist of PCBM dispersed in the amorphous portions of PBDTTPD. Decreasing the concentration of PCBM may reduce the number of percolating electron transport pathways within these mixed regions and create morphological electron traps that enhance charge-carrier recombination and limit device quantum efficiency. These findings suggest that (i) the concentration of PCBM in the mixed regions of polymer BHJs must be above the PCBM percolation threshold in order to attain high solar cell internal quantum efficiency, and (ii) novel processing techniques, which improve polymer hole mobility while maintaining PCBM percolation within the mixed regions, should be developed in order to limit bimolecular recombination losses in optically thick devices and maximize the PCE of polymer BHJ solar cells.
TL;DR: In this paper, the first mixed matrix composite membrane made of commercially available poly (amide-b-ethylene oxide) (Pebax®1657, Arkema) mixed with the nano-sized zeolitic imidazole framework ZIF-7 was successfully deposited as a thin layer on a porous polyacrylonitrile (PAN) support.
TL;DR: In this article, a perfluorinated covalent triazine-based framework (FCTF-1) was designed and synthesized for selective CO2 capture from flue gas, and the incorporation of fluorine groups played multiple roles in improving the framework's CO2 adsorption and separation capabilities.
Abstract: We designed and synthesized a perfluorinated covalent triazine-based framework (FCTF-1) for selective CO2 capture. The incorporation of fluorine (F) groups played multiple roles in improving the framework's CO2 adsorption and separation capabilities. Thermodynamically, the strongly polar C–F bonds promoted CO2 adsorption via electrostatic interactions, especially at low pressures. FCTF-1's CO2 uptake was 1.76 mmol g−1 at 273 K and 0.1 bar through equilibrium adsorption, exceeding the CO2 adsorption capacity of any reported porous organic polymers to date. In addition, incorporating F groups produced a significant amount of ultra-micropores (<0.5 nm), which offered not only high gas adsorption potential but also kinetic selectivity for CO2–N2 separation. In mixed-gas breakthrough experiments, FCTF-1 exhibited an exceptional CO2–N2 selectivity of 77 under kinetic flow conditions, much higher than the selectivity (31) predicted from single-gas equilibrium adsorption data. Moreover, FCTF-1 proved to be tolerant to water and its CO2 capture performance remained excellent when there was moisture in the gas mixture, due to the hydrophobic nature of the C–F bonds. In addition, the moderate adsorbate–adsorbent interaction allowed it to be fully regenerated by pressure swing adsorption processes. These attributes make FCTF-1 a promising sorbent for CO2 capture from flue gas.
TL;DR: The read operation of memristor-based memories is investigated and a new technique for solving the sneak paths problem by gating the memory cell using a three-terminal memistor device is introduced.
TL;DR: A broadband terahertz wave deflector based on metasurface induced phase discontinuities and a Fresnel zone plate consequently developed from the beam deflector is capable of focusing a broadband terAhertz radiation.
Abstract: This work was supported by the U.S. National Science Foundation (Grand No. ECCS-1232081), the National Science Foundation of China (Grant Nos. 61138001, 61028011, 61007034, 61107085, and 61107053) and the National Instrumentation Program of China (Grant No. 2011YQ150021).
TL;DR: The facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion.
Abstract: In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu2O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu2O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu2O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of −3.95 mA cm–2 and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm–2). This is the highest value ever reported for a Cu2O-based electrode coated with a metal/co-catalyst-free protective layer. The photostabi...
TL;DR: A vertically aligned Ta(3)N(5) nanorod photoelectrode is fabricated by through-mask anodization and nitridation for water splitting to yield a high photocurrent density and one of the highest activities reported for photoanodes so far.
Abstract: A vertically aligned Ta(3)N(5) nanorod photoelectrode is fabricated by through-mask anodization and nitridation for water splitting. The Ta(3)N(5) nanorods, working as photoanodes of a photoelectrochemical cell, yield a high photocurrent density of 3.8 mA cm(-2) at 1.23 V versus a reversible hydrogen electrode under AM 1.5G simulated sunlight and an incident photon-to-current conversion efficiency of 41.3% at 440 nm, one of the highest activities reported for photoanodes so far.
TL;DR: It is shown how a link/community-based strategy triggers substantial prediction improvements because it accounts for the singular topology of several real networks organised in multiple local communities - a tendency here named local-community-paradigm (LCP).
Abstract: Growth and remodelling impact the network topology of complex systems, yet a general theory explaining how new links arise between existing nodes has been lacking, and little is known about the topological properties that facilitate link-prediction. Here we investigate the extent to which the connectivity evolution of a network might be predicted by mere topological features. We show how a link/community-based strategy triggers substantial prediction improvements because it accounts for the singular topology of several real networks organised in multiple local communities - a tendency here named local-community-paradigm (LCP). We observe that LCP networks are mainly formed by weak interactions and characterise heterogeneous and dynamic systems that use self-organisation as a major adaptation strategy. These systems seem designed for global delivery of information and processing via multiple local modules. Conversely, non-LCP networks have steady architectures formed by strong interactions, and seem designed for systems in which information/energy storage is crucial.
ETH Zurich1, Centre national de la recherche scientifique2, George Mason University3, VU University Amsterdam4, California Institute of Technology5, Max Planck Society6, Wageningen University and Research Centre7, University of Bristol8, King Abdullah University of Science and Technology9, Princeton University10, Beijing Normal University11, Commonwealth Scientific and Industrial Research Organisation12
TL;DR: In this paper, the authors presented monthly global land evapotranspiration (ET) synthesis products, merged from these individual data sets over the time periods 1989-1995 (7 yr) and 1989-2005 (17 yr).
Abstract: . Land evapotranspiration (ET) estimates are available from several global data sets. Here, monthly global land ET synthesis products, merged from these individual data sets over the time periods 1989–1995 (7 yr) and 1989–2005 (17 yr), are presented. The merged synthesis products over the shorter period are based on a total of 40 distinct data sets while those over the longer period are based on a total of 14 data sets. In the individual data sets, ET is derived from satellite and/or in situ observations (diagnostic data sets) or calculated via land-surface models (LSMs) driven with observations-based forcing or output from atmospheric reanalyses. Statistics for four merged synthesis products are provided, one including all data sets and three including only data sets from one category each (diagnostic, LSMs, and reanalyses). The multi-annual variations of ET in the merged synthesis products display realistic responses. They are also consistent with previous findings of a global increase in ET between 1989 and 1997 (0.13 mm yr−2 in our merged product) followed by a significant decrease in this trend (−0.18 mm yr−2), although these trends are relatively small compared to the uncertainty of absolute ET values. The global mean ET from the merged synthesis products (based on all data sets) is 493 mm yr−1 (1.35 mm d−1) for both the 1989–1995 and 1989–2005 products, which is relatively low compared to previously published estimates. We estimate global runoff (precipitation minus ET) to 263 mm yr−1 (34 406 km3 yr−1) for a total land area of 130 922 000 km2. Precipitation, being an important driving factor and input to most simulated ET data sets, presents uncertainties between single data sets as large as those in the ET estimates. In order to reduce uncertainties in current ET products, improving the accuracy of the input variables, especially precipitation, as well as the parameterizations of ET, are crucial.
15 Apr 2013
TL;DR: Mizan is introduced, a Pregel system that achieves efficient load balancing to better adapt to changes in computing needs and does not assume any a priori knowledge of the structure of the graph or behavior of the algorithm.
Abstract: Pregel [23] was recently introduced as a scalable graph mining system that can provide significant performance improvements over traditional MapReduce implementations. Existing implementations focus primarily on graph partitioning as a preprocessing step to balance computation across compute nodes. In this paper, we examine the runtime characteristics of a Pregel system. We show that graph partitioning alone is insufficient for minimizing end-to-end computation. Especially where data is very large or the runtime behavior of the algorithm is unknown, an adaptive approach is needed. To this end, we introduce Mizan, a Pregel system that achieves efficient load balancing to better adapt to changes in computing needs. Unlike known implementations of Pregel, Mizan does not assume any a priori knowledge of the structure of the graph or behavior of the algorithm. Instead, it monitors the runtime characteristics of the system. Mizan then performs efficient fine-grained vertex migration to balance computation and communication. We have fully implemented Mizan; using extensive evaluation we show that---especially for highly-dynamic workloads---Mizan provides up to 84% improvement over techniques leveraging static graph pre-partitioning.
TL;DR: In this paper, the structural stability and spin-orbit?induced spin splitting in the transition metal dichalcogenide monolayers MXY (M?=?Mo, W and X, Y? =?S, Se, Te) were investigated.
Abstract: The Rashba effect in quasi two-dimensional materials, such as noble metal surfaces and semiconductor heterostructures, has been investigated extensively, while interest in real two-dimensional systems has just emerged with the discovery of graphene. We present ab initio electronic structure, phonon, and molecular-dynamics calculations to study the structural stability and spin-orbit?induced spin splitting in the transition metal dichalcogenide monolayers MXY (M?=?Mo, W and X, Y?=?S, Se, Te). In contrast to the non-polar systems with X?=?Y, in the polar systems with X ? Y the Rashba splitting at the ?-point for the uppermost valence band is caused by the broken mirror symmetry. An enhancement of the splitting can be achieved by increasing the spin-orbit coupling and/or the potential gradient.
TL;DR: In this paper, a comprehensive meta-analysis of organic zooplankton values at the base of the food web, dissolved inorganic carbon δ13C values, and seawater δ18O values to create, for the first time, robust isoscapes for the Atlantic Ocean is presented.
Abstract: Ecogeochemistry—the application of geochemical techniques to fundamental questions in population and community ecology—has been used in animal migration studies in terrestrial environments for several decades; however, the approach has received far less attention in marine systems. This review includes comprehensive meta-analyses of organic zooplankton δ13C and δ15N values at the base of the food web, dissolved inorganic carbon δ13C values, and seawater δ18O values to create, for the first time, robust isoscapes for the Atlantic Ocean. These isoscapes present far greater geographic variability in multiple geochemical tracers than was previously thought, thus forming the foundation for reconstructions of habitat use and migration patterns of marine organisms. We review several additional tracers, including trace-element-to-calcium ratios and heavy element stable isotopes, to examine anadromous migrations. We highlight the value of the ecogeochemistry approach by examining case studies on three components of connectivity: dispersal and natal homing, functional connectivity, and migratory connectivity. We also discuss recent advances in compound-specific stable carbon and nitrogen isotope analyses for tracking animal movement. A better understanding of isotopic routing and fractionation factors, particularly of individual compound classes, is necessary to realize the full potential of ecogeochemistry.
TL;DR: An efficient and stable photoanode is reported that couples an active barium-doped tantalum nitride nanostructure with a stable cobalt phosphate co-catalyst and yields a maximum solar energy conversion efficiency more than three times higher than that of state-of-the-art single-photon photoanodes.
Abstract: Spurred by the decreased availability of fossil fuels and global warming, the idea of converting solar energy into clean fuels has been widely recognized. Hydrogen produced by photoelectrochemical ...
TL;DR: It is shown that phase-pure SnO is not necessarily the highest mobility phase; instead, well-controlled amounts of residual metallic tin are shown to substantially increase the hole mobility and this high mobility is realized by careful phase engineering.
Abstract: Here, we report the fabrication of nanoscale (15 nm) fully transparent p-type SnO thin film transistors (TFT) at temperatures as low as 180 °C with record device performance. Specifically, by carefully controlling the process conditions, we have developed SnO thin films with a Hall mobility of 18.71 cm(2) V(-1) s(-1) and fabricated TFT devices with a linear field-effect mobility of 6.75 cm(2) V(-1) s(-1) and 5.87 cm(2) V(-1) s(-1) on transparent rigid and translucent flexible substrates, respectively. These values of mobility are the highest reported to date for any p-type oxide processed at this low temperature. We further demonstrate that this high mobility is realized by careful phase engineering. Specifically, we show that phase-pure SnO is not necessarily the highest mobility phase; instead, well-controlled amounts of residual metallic tin are shown to substantially increase the hole mobility. A detailed phase stability map for physical vapor deposition of nanoscale SnO is constructed for the first time for this p-type oxide.
TL;DR: A recent major breakthrough in the understanding of strigolactone biosynthesis is reviewed, which has revealed the unexpected simplicity of the originally postulated complex pathway.
Columbia University1, Argonne National Laboratory2, Lawrence Livermore National Laboratory3, University of Illinois at Urbana–Champaign4, University of Michigan5, Idaho National Laboratory6, Lawrence Berkeley National Laboratory7, King Abdullah University of Science and Technology8, Colorado State University9, Oak Ridge National Laboratory10, Stanford University11, Princeton Plasma Physics Laboratory12, Pacific Northwest National Laboratory13, Sandia National Laboratories14, University of Texas at Austin15, Stony Brook University16, IBM17, Harvard University18, SLAC National Accelerator Laboratory19, Fermilab20, Colorado School of Mines21, Cornell University22, Technische Universität München23, Southern Methodist University24, Rice University25, University of Erlangen-Nuremberg26, Rensselaer Polytechnic Institute27, Los Alamos National Laboratory28
TL;DR: This study considers multiphysics applications from algorithmic and architectural perspectives, where “algorithmic” includes both mathematical analysis and computational complexity, and “architectural’ includes both software and hardware environments.
Abstract: We consider multiphysics applications from algorithmic and architectural perspectives, where âalgorithmicâ includes both mathematical analysis and computational complexity, and âarchitecturalâ includes both software and hardware environments. Many diverse multiphysics applications can be reduced, en route to their computational simulation, to a common algebraic coupling paradigm. Mathematical analysis of multiphysics coupling in this form is not always practical for realistic applications, but model problems representative of applications discussed herein can provide insight. A variety of software frameworks for multiphysics applications have been constructed and refined within disciplinary communities and executed on leading-edge computer systems. We examine several of these, expose some commonalities among them, and attempt to extrapolate best practices to future systems. From our study, we summarize challenges and forecast opportunities.
TL;DR: The integration of the self-cleaning property into the all-inorganic separation mesh by using TiO2 enables the convenient removal of the contaminants by ultraviolet (UV) illumination, and allows for the facile recovery of the separation ability of the contaminated mesh, making it promising for practial oil-water separation applications.
Abstract: Oil–water separation has recently become a global challenging task because of the frequent occurrence of oil spill accidents due to the offshore oil production and transportation, and there is an increasing demand for the development of effective and inexpensive approaches for the cleaning-up of the oily pollution in water system. In this study, a self-cleaning underwater superoleophobic mesh that can be used for oil-water separation is prepared by the layer-by-layer (LbL) assembly of sodium silicate and TiO2 nanoparticles on the stainless steel mesh. The integration of the self-cleaning property into the all-inorganic separation mesh by using TiO2 enables the convenient removal of the contaminants by ultraviolet (UV) illumination, and allows for the facile recovery of the separation ability of the contaminated mesh, making it promising for practial oil-water separation applications.